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  Potential for Absorption Cooling   Generated from Municipal Solid Waste in Bangkok  A Comparison between Waste Incineration &  

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  Potential for Absorption Cooling   Generated from Municipal Solid Waste in Bangkok  A Comparison between Waste Incineration &  
 Potential for Absorption Cooling Generated from Municipal Solid Waste in Bangkok A Comparison between Waste Incineration & Biogas Production with Combustion Erika Hedberg Helén Danielsson Environmental Technology and Management Degree Project Department of Management and Engineering LIU‐IEI‐TEK‐A‐‐10/00807‐‐SE ii Abstract This master’s thesis has been performed in Bangkok, Thailand at the company Eco Design Consultant Co., Ltd. The aim is to investigate the possibilities to generate absorption cooling from municipal solid waste in the Bangkok area. The investigation includes a comparison between waste incineration and biogas production with combustion to see which alternative is preferable. During the investigation, a Swedish perspective has been used. The research for the report mainly consisted of published scientific articles from acknowledged sources as well as information from different Thai authorities. Also, experts within different areas were contacted and interviewed. In order to determine which of the two techniques (waste incineration or biogas production with combustion) that is best suited to generate absorption cooling, a model was designed. This model involved several parameters regarding e.g. plant efficiency, amount of treated waste and internal heat usage. As for the results of the model, three parameters were calculated: the generated cooling, the net electricity generation and the reduced greenhouse emissions. The overall Thai municipal solid waste generation in Thailand is estimated to approximately 15 million tons per year and the majority of the waste ends up at open dumps or landfills. There are only two to three waste incinerators in the country and a few projects with biogas generation from municipal solid waste. The main electricity is today generated from natural gas which makes the majority of the Thai electricity production fossil fuel based. As for absorption cooling, two applications of this technique has been found in Thailand during the research; one at the Naresuan University and one at the Suvarnabhumi airport in Bangkok. The model resulted in that the best alternative to power absorption cooling technique is waste incineration. This alternative has potential to generate 3200 GWh cooling per year and 1100 GWh electricity per year. Also, this alternative resulted in the largest decrease of greenhouse gas emissions, ‐500 000 tons per year. The model also showed that the same amounts of generated cooling and electricity can never be achieved from biogas production with combustion compared to waste incineration. Regardless, waste incineration has an important drawback: the citizens of Thailand seem to oppose further development of waste incineration in the country. The biogas technique seems more approved in Thailand, which benefits this alternative. Due to the high moisture and organic content in the municipal solid waste, a combination between the two waste handling alternatives is suggested. This way, the most energy can be withdrawn from the waste and the volume of disposed waste is minimized. Our overall conclusion is that the absorption cooling technique has great potential in Thailand. There is an increasing power‐ and cooling demand, absorption cooling generated from either or both of the alternatives can satisfy these demands while reducing greenhouse gas emissions. We also believes that the cost for using absorption cooling has to be lower than for the current compression cooling if the new technique is to be implemented further. iii iv Acknowledgements We would like to express our gratitude to the persons that have assisted and helped us in different ways during the process of writing this thesis. In no particular order, the persons we want thank are: Mattias Lindahl, our supervisor who has guided us during this entire process and has offered his knowledge and support. Dr Akajate Apikajornsin and Dr. Prin Boonkanit who welcomed us to Thailand and to Eco Group Co. Ltd., and have assisted us during our research in Bangkok. The respondents of our interviews, for taking their time to answer our questions and presenting the practical perspectives of the researched areas. We have found all of the interviews very interesting. Our opponents Andres Adelmann and Sissela Lidebjer for useful feedback and comments. Louise Trygg, who has offered interesting input and guided us when there has been confusing moments. Our colleagues at Eco Group Co. Ltd. who all have assisted in welcoming us and assisting in different ways during our research, but also for making our time in Bangkok interesting and entertaining. Thank you! Erika Hedberg & Helén Danielsson Linköping 26th May 2010 v vi Table of Contents 1 2 3 Introduction ..................................................................................................................................... 1 1.1 Background .............................................................................................................................. 1 1.2 Purpose .................................................................................................................................... 1 1.3 Limitations ............................................................................................................................... 2 Method ............................................................................................................................................ 3 2.1 Model ...................................................................................................................................... 3 2.2 Interviews ................................................................................................................................ 3 Theoretical Frame of Reference ...................................................................................................... 5 3.1 Thailand ................................................................................................................................... 5 3.2 The Global Warming and the Greenhouse Effect ................................................................... 5 3.3 Combined Heat and Power ..................................................................................................... 5 3.3.1 3.4 CHP in Sweden ................................................................................................................. 6 Waste Management ................................................................................................................ 7 3.4.1 Waste Handling in Sweden .............................................................................................. 7 3.5 Landfills and Open Dumps ....................................................................................................... 8 3.6 Waste Incineration .................................................................................................................. 8 3.6.1 Flue Gas Purification and Residuals ................................................................................. 9 3.6.2 Waste Incineration in Sweden ......................................................................................... 9 3.7 Biogas .................................................................................................................................... 10 3.7.1 Production ..................................................................................................................... 10 3.7.2 Combustion of Biogas .................................................................................................... 11 3.7.3 Biogas in Sweden ........................................................................................................... 11 3.8 Environmental Aspects of Waste Management Techniques ................................................ 11 3.8.1 Landfilling and Open Dumping ...................................................................................... 11 3.8.2 Waste Incineration ........................................................................................................ 12 3.8.3 Biogas ............................................................................................................................ 12 3.9 District Heating and Cooling .................................................................................................. 13 3.10 Compression Cooling ............................................................................................................. 14 3.11 Absorption Cooling ................................................................................................................ 15 3.11.1 Distribution .................................................................................................................... 16 3.11.2 The Absorption Cooling Machine .................................................................................. 16 3.12 Efficiency of ACM Compared to CCM .................................................................................... 18 3.13 The Swedish Electricity Market ............................................................................................. 19 vii 4 3.13.1 Price Development ........................................................................................................ 20 3.13.2 CHP and Absorption Cooling in the Swedish Energy System ........................................ 21 Results ........................................................................................................................................... 23 4.1 Interviews .............................................................................................................................. 23 4.1.1 4.2 Waste Management in Thailand ........................................................................................... 24 4.2.1 Waste Situation ............................................................................................................. 24 4.2.2 Waste Development ...................................................................................................... 24 4.2.3 The Waste Composition ................................................................................................ 26 4.2.4 Waste Incineration in Thailand ..................................................................................... 26 4.2.5 Biogas in Thailand .......................................................................................................... 27 4.3 The Thai Power Generation and Electricity Market .............................................................. 28 4.3.1 The Authorities .............................................................................................................. 29 4.3.2 Private Participation ...................................................................................................... 29 4.3.3 Independent, Small and Very Small Power Producers .................................................. 30 4.3.4 Electricity Prices and Price Development ...................................................................... 31 4.3.5 Renewable Energy in Thailand ...................................................................................... 32 4.3.6 Thailand Power Development Plan ............................................................................... 33 4.4 5 Situation in Bangkok ...................................................................................................... 23 Absorption Cooling in Thailand ............................................................................................. 34 Model ............................................................................................................................................ 37 5.1 In‐Parameters ........................................................................................................................ 38 5.2 Waste Incineration ................................................................................................................ 39 5.2.1 Energy Content and Torch Fuel Usage .......................................................................... 39 5.2.2 Electricity and Heat Generation .................................................................................... 40 5.2.3 Internal Energy Usage and Net Energy Output ............................................................. 41 5.3 Biogas Production and Combustion ...................................................................................... 41 5.3.1 Organic Fraction of MSW and Sorting Percentage ........................................................ 42 5.3.2 Electricity and Heat Generation .................................................................................... 42 5.3.3 Internal Energy Usage and Net Energy Output ............................................................. 43 5.4 Absorption Cooling ................................................................................................................ 44 5.4.1 Generated from Waste Incineration ............................................................................. 44 5.4.2 Generated from Biogas Combustion ............................................................................. 44 5.5 Greenhouse Gas Emissions ................................................................................................... 44 5.5.1 Waste Incineration ........................................................................................................ 45 viii 5.5.2 Biogas Production and Combustion .............................................................................. 48 5.6 Results from the Model ......................................................................................................... 50 5.7 Sensitivity Analysis ................................................................................................................ 50 6 5.7.1 Percentage of Collected Waste ..................................................................................... 50 5.7.2 Efficiencies Waste Incineration ..................................................................................... 51 5.7.3 Energy Input Waste Incineration ................................................................................... 51 5.7.4 Sorting Percentage Biogas Process & Biogas Yield ........................................................ 51 5.7.5 Efficiencies Biogas Production and Combustion ........................................................... 51 5.7.6 Energy Input Biogas Production and Combustion ......................................................... 52 5.7.7 Chiller Parameters ......................................................................................................... 52 5.7.8 Organic Fraction and Calorific Value of MSW ............................................................... 52 Analysis .......................................................................................................................................... 55 6.1 Data Collection ...................................................................................................................... 55 6.2 Energy Situation and Energy Development in Thailand ........................................................ 56 6.3 The Thai Waste Situation ...................................................................................................... 56 6.3.1 Waste Development ...................................................................................................... 57 6.4 Waste Incineration ................................................................................................................ 57 6.5 Biogas Production and Combustion ...................................................................................... 58 6.6 Absorption Cooling and Distribution ..................................................................................... 58 6.6.1 6.7 The Thai Electricity Market, Prices and Costs ........................................................................ 60 6.7.1 6.8 Cooling Recipients ......................................................................................................... 59 Investors ........................................................................................................................ 61 Model .................................................................................................................................... 62 6.8.1 Results from the Model ................................................................................................. 63 6.8.2 Sensitity Analysis ........................................................................................................... 64 6.9 Feasibility in Bangkok ............................................................................................................ 67 7 Conclusions .................................................................................................................................... 69 8 Further Research ........................................................................................................................... 71 9 List of References .......................................................................................................................... 73 9.1 Printed sources ...................................................................................................................... 73 9.2 Web Based Sources ............................................................................................................... 75 9.3 Personal Sources ................................................................................................................... 81 10 Appendix .................................................................................................................................... 83 ix x List of Figures Figure 3‐1 ‐ Schematic picture displaying difference between Combined Heat and Power Production and Power Production ............................................................................................................................. 6 Figure 3‐2‐ The EU Waste Hierarchy ....................................................................................................... 7 Figure 3‐3 – Waste treatment in Sweden distributed on different treatment methods ........................ 8 Figure 3‐4 – Waste incineration process ................................................................................................ 9 Figure 3‐5 – The biogas production steps ............................................................................................. 10 Figure 3‐6 ‐ Schedule displaying compression cooling and absorption cooling .................................... 16 Figure 3‐7 – Comparison of Carnot‐factor for compressor cooling and absorption cooling ................ 19 Figure 3‐8 – Price development of the Swedish electricity price, no taxes included. .......................... 21 Figure 4‐1 – Tones of waste generated in Thailand 1998‐2006 ............................................................ 25 Figure 4‐2 – The amount of generated waste in Bangkok 1998‐2006 .................................................. 25 Figure 4‐3 ‐ Thailand’s Fuel Mix for Power Generation (Jan 2010). ...................................................... 28 Figure 4‐4 ‐ Thailand’s Electricity Industry Structure ............................................................................ 31 Figure 4‐5 ‐ New power project investments for 2008‐2021 presented in MW ................................... 34 Figure 5‐1 – A schematic figure of the different flows in the model .................................................... 37 Figure 10‐1 – Treatment of waste generated from manufacturing production in Sweden ................. 83 Figure 10‐2 – Waste composition of MSW in weight percent for Sweden ........................................... 83 Figure 10‐3 – Waste composition of MSW in percent of total for Thailand ......................................... 84 Figure 10‐4 – Percent of used energy in Thailand 1986‐2009 .............................................................. 84 Figure 10‐5 – Electricity bill for a one room apartment in Bangkok ..................................................... 85 xi List of Tables Table 3‐1 – Estimated characteristics for different ACMs ..................................................................... 17 Table 4‐1 “Adder” to the Normal Tariff for SPPs and VSPPs ................................................................. 30 Table 5‐1 –Results from Model ............................................................................................................. 50 Table 10‐1 – Alteration of Percentage Organic Fraction ....................................................................... 86 Table 10‐2 – Alteration of Calorific Value MSW .................................................................................... 87 Table 10‐3 – Alteration of Electric Efficiency Waste Incineration ......................................................... 88 Table 10‐4 – Alteration of Heat Efficiency Waste Incineration ............................................................. 89 Table 10‐5 – Alteration of Internal Electricity Usage Waste Incineration ............................................. 90 Table 10‐6 – Alteration of Sorting Percentage Biogas Production ........................................................ 91 Table 10‐7 – Alteration of Biogas Yield ................................................................................................. 92 Table 10‐8 – Alteration of Electric Efficiency Biogas Combustion ........................................................ 93 Table 10‐9 – Alteration of Thermal Efficiency Biogas Combustion ....................................................... 94 Table 10‐10 – Alteration of Internal Electricity Usage Biogas Production & Combustion .................... 95 Table 10‐11 – Alteration of Internal Heat Usage Biogas Production & Combustion ............................ 96 Table 10‐12 – Alteration of Percentage of Collected Waste ................................................................. 97 Table 10‐13 – Alteration of COP Absorption Chiller .............................................................................. 98 Table 10‐14 – Alteration of COP Compression Chiller ........................................................................... 99 Table 10‐15 – Alteration of Torch Fuel Waste Incineration ................................................................ 100 xii Abbreviations ACM AOB BAT BMA CCM CFC CHP CO₂ CO2 eq. COP CTF DCAP EGAT EPPO ERC EU GHG GWP HCFC IPP MEA MSW NEPC NG OFMSW PCD PDP PEA PTT RQ SEK SO₂ THB TNSO/NSO TOU VAT VSPP WTE Absorption Cooling Machine Airport Operation Building Best Available Technology Bangkok Metropolitan Administration Compressor Cooling Machine Chlorofluorocarbon Combined Heat and Power Carbon Dioxide Carbon Dioxide Equivalents Coefficient of Performance Clean Technology Fund District Cooling System and Power Plant Co., Ltd. Electricity Generating Authority of Thailand Energy Policy and Planning Office (Thailand) Energy Regulatory Commission (Thailand) European Union Greenhouse Gas Global Warming Potential Hydrochlorofluorocarbon Independent Power Producers (Thailand) Metropolitan Electricity Authority (Thailand) Municipal Solid Waste National Energy Policy Council (Thailand) Natural Gas Organic Fraction of Municipal Solid Waste Pollution Control Department (Thailand) Power Development Plan (Thailand) Provincial Electricity Authority (Thailand) Petroleum Authority of Thailand Research Question Swedish krona (currency of Sweden) Sulfur Dioxide Thai bath (currency of Thailand) The National Statistic Office (Thailand) Time of Use Value Added Tax Very Small Power Producers (Thailand) Waste to Energy xiii xiv Introduction 1 Introduction The introduction part will give a short background as to why the subject of this thesis is interesting, as well as the purpose of the thesis and an explanation of the limitations that has been made. 1.1 Background It is getting more and more important to save energy and to use a wiser energy approach due to the current environmental situation. It is important to use energy, materials and fuels in a sustainable way; generating energy from waste is one way to recover the energy in the waste. Today, large volumes of waste are however put on landfills and open dumps. This way the potential of using the energy is lost and huge areas are occupied by waste. Since 2002 it is forbidden to landfill combustible materials in Sweden. Instead, the majority of the waste is incinerated and at some incineration plants the energy is recovered through electricity and/or heat generation. The heat is mostly used as district heating, and sometimes cooling. The organic fraction of the waste can be transformed into energy in the form of biogas as well. When organic materials are digested without oxygen, biogas is produced. In Thailand, the waste management is rather different than in Sweden. The majority of the waste is put on open dumps and only a fraction is incinerated. This generates large volumes of waste and unused resources. Thailand is also, unlike Sweden, a tropical country with warm temperature. The capital city, Bangkok, has an average temperature over 25 °C during the entire year. Due to the high temperature, the Thai people have a large cooling demand. This demand is today mostly generated by electricity‐driven cooling machines. Absorption cooling machines are in contrast to compression cooling machines, driven by heat instead of electricity. Combined heat and power generation, together with absorption cooling machines, therefore offers an interesting alternative to produce cooling when it comes to achieving a decrease of carbon dioxide emissions. 1.2 Purpose The purpose of this master’s thesis is to investigate the possibilities for absorption cooling generated from municipal solid waste in Bangkok. Waste incineration will be compared with biogas production and combustion as driving force for the absorption cooling. The questions at aim together with short explanations of their relevance are presented below: RQ1. Is absorption cooling generated from MSW an alternative to replace a part of the compression cooling in Bangkok? Would this achieve a decrease in GHG emissions? Absorption cooling is a technique that under certain circumstances offers cooling with less GHG emission than compression cooling. This fact combined with the large amount of generated waste in the region and the big use of compression cooling makes this question relevant. RQ2. Which alternative would generate the largest GHG emission reduction if used to drive the absorption cooling; waste incineration or biogas production with combustion? What other factors affect the comparison of the alternatives, and how? 1 Introduction Both these alternatives offer ways of driving the absorption cooling with waste as input. Since the processes are so different they need to be evaluated toughly to know which would decrease the GHG emissions more than the other, compared using compression cooling. RQ3. What other factors, environmental, technical as well as societal, needs to be taken into consideration if absorption cooling generated from MSW would constitute a relevant option? The answers to question number one as well as question number two might only be true under certain circumstances. These circumstances need to be identified. 1.3 Limitations To perform this investigation a number of limitations need to be made so that the analyzed system does not become too large. Since the analysis includes many different systems the approach will first and foremost be a system view. Due to this system view the investigation of technical details will not be very specific. A model will be used to perform a comparison between waste incineration and biogas production with combustion. This model is a simple model used to compare the two alternatives from a system view. Specific limitations made in the model are explained further in Chapter 5. To compensate for some of these limitations, a sensitivity analysis will be performed. The sensitivity analysis will show what impact some of the simplifications and assumptions have had on the results. Regarding the generated waste in Bangkok, this will only be considered as potential energy, the possibilities regarding recycling will not be evaluated. This could affect both the answers to RQ1 and RQ2. If recycling was an alternative, this might be more desirable than to use the waste for producing cooling. If recycling was performed, the amount of waste available after recycling could decrease significantly and the content of the waste available after recycling could also change considerably. These changes would alter the conditions for both biogas production and waste incineration, which in turn would affect the conditions for the absorption cooling in RQ1. The comparison in RQ2 will probably not be affected to the same extent, since RQ2 is a comparison between processes based on the same input. Although a change in waste content would change the conditions for the processes in different ways. The reasonability and details of distributing absorption cooling in Bangkok will be limited. Bangkok is a big area and an analysis of the distribution possibilities and details is too large to all be included since Bangkok does not have any district heating or cooling networks at the moment. Since the distribution needs to be managed in one way or another, this could affect the answer to RQ1. It is however assumed that the distribution can be handled somehow, there are many examples of densely populated cities that have district heating or cooling and Bangkok is not considered to be different from these. It is rather a question of how much this would cost, and how complicated the process would be. If using CHP production from either waste incineration or biogas combustion, the generated heat will only be considered as a potential heat source for absorption cooling. 2 Method 2 Method To answer the questions at issue and to reach the purpose of this master’s thesis, a series of steps will be taken. The first step will be to perform a literature study where relevant literature, articles and reports on the subject are read and summarized in a theoretical frame of reference. This step will be preformed to achieve a greater knowledge in the different energy and environmental areas. The next step will be to research the relevant systems in Bangkok and Thailand, including literature studies, observations and interviews. This work will be performed at the consulting‐firm Thai company called Eco Group Co. Ltd. in Bangkok. The results from the research regarding the systems in Bangkok will be presented as results. The interview methods are further explained in chapter 2.2. Another step of the process will be to make a model of a system in Bangkok. Based on this model calculations and/or simulations will be made, in order to determine the effects of using absorption cooling, and to decide whether waste incineration or biogas production and combustion is the best option. The method for the model is explained further in chapter 2.1. When sufficient amounts of material, as well as results from the model, are gathered, this will lead to results. The results will be analyzed and discussed, and will finally result in conclusions and give answers to the questions at issue. The project will have a Swedish perspective and in the analysis part comparisons will be made between the Swedish and Thai waste and energy systems. This is because the idea for this thesis originates from a Swedish perspective and it is important to identify the differences between the energy systems in the countries. Therefore this perspective will be maintained throughout the work, especially when investigating the plausibility for the techniques in Thailand. The Swedish perspective will not be as present in the comparison in the model. The target audience for this report is mainly Thai citizens. Therefore the Swedish energy systems and waste management will be presented rather thoroughly, in order to give the reader an understanding for the Swedish perspective. 2.1 Model A model will be constructed in order to compare the GHG emissions and the generated energy from the two different waste management alternatives suggested. The model will be performed in MS Excel and the calculations, as well as results, will be presented in the thesis. The different waste management alternatives will share the same in‐parameters and a sensitivity analysis will be made in order to investigate the parameters dependence. 2.2 Interviews A part of the investigation will involve personal interviews. The interviews will be considered as a more precise source of information regarding the areas where information has been lacking. Since the report investigates different energy and environmental areas, the interviewed persons will be local experts in these different areas. Therefore, the questions will be different for each interview and designed to achieve as precise information as possible. Before the interview, the investigated area will be studied and evaluated. During the interviews, one person will be asking the questions and another person will be taking notes. After the interview the obtained answers will be discussed and evaluated as soon as possible so that there are no misunderstandings or lost information. Further, the interviews will be 3 Method considered as open and there will be no restrictions against attendant questions. Instead, discussions will be welcomed to evolve new and interesting questions on the current subject. There are no restrictions for the length of the interviews; the main intention is to achieve answers as extensive as possible. 4 Theoretical Frame of Reference 3 Theoretical Frame of Reference To be able to present the results of the thesis in a comprehensive way, some background information is necessary. Different technical solutions such as combined heat and power, biogas production, waste incineration, district cooling and different cooling techniques are addressed. Information regarding different energy systems that are relevant are also included, as well as facts about waste management systems and the environmental aspects of these different waste management systems. Regarding the different cooling techniques the absorption cooling is the most extensive. The theoretical frame of reference contains mostly information about the Swedish energy systems, techniques and waste management, while facts about the systems in Thailand are presented in Chapter 4, except for a short introduction of Thailand. 3.1 Thailand Thailand, previously Siam, is a country in the southeast of Asia. The country is 513 115 km² and is separated into 76 provinces. The nation has 66.1 million inhabitants and the population is expected to be close to 70 million in 2050. The main capital, Bangkok, has 5.7 million inhabitants. (Nationalencyklopedin 2010a) Thailand mainly has a tropical monsoonal climate although in the south part, the climate consists of tropic rainforest with two rain seasons. The warmest period is between March and April and the yearly average temperature is 24‐30 °C for the entire country. (Nationalencyklopedin 2010a) The currency in Thailand is Thai baht (THB). The value of the baht is 0.223 Swedish kronor (SEK). (Riksbanken 2010) One baht equals 100 satang. The value of the baht in relation to the US dollar is one dollar equals 31.36 THB. (Thaivisa 2010) These values are valid for 22nd of April 2010 and will be used throughout the thesis. 3.2 The Global Warming and the Greenhouse Effect The global warming refers to the increased average temperature on Earth during the last hundred years. One of the most accepted explanations to this phenomenon is the emissions of greenhouse gases made by the humans. The greenhouse effect is when greenhouse gases, such as carbon dioxide, methane, dinitrogen oxide and fluorine compounds lay around the Earth and effect the out flowing heat balance. This effect exists naturally and without it the Earth would be about 35 °C colder. However, the effect has been amplified by the greenhouse gas emissions from the humans, mainly originating from combustion of fossil fuels. This has led to an increased average temperature on the Earth. (Miljöportalen 2010) 3.3 Combined Heat and Power Combined heat and power (CHP), also known as co‐generation, refers to the process of simultaneous production of heat and power. A CHP plant uses the heat that goes to waste when only producing electricity. The heat produced is used for district heating, industry application or in other ways. When using CHP production, 80‐90% of the energy content in the fuel can be used instead of only approximately 50% which is the maximum when only producing electricity in thermal power plants. (Nationalencyklopedin 2010b) 5 Theoretical Frame of Reference Figure 3‐1 shows a schematic picture of a comparison between a CHP plant and a power plant. It displays the possibilities to use the heat from a CHP plant for district heating and/or absorption cooling through district heating or other applications instead of simply using a cooling tower to remove the heat. Figure 3‐1 ‐ Schematic picture displaying difference between Combined Heat and Power Production and Power Production (adapted from Karlsson 2008) The traditional type of CHP plant is a steam power station. Gas turbines and a combination of a gas turbine and a steam power station, a combination cycle, are also common. A common way of producing only power, i.e. when the heat is not used, is through condensing power plants. (Nationalencyklopedin 2010b) The fuel type used in CHP plants differs according to fuel access, boiler type, etcetera. Commonly used fuels are natural gas, oil, coal, biofuel and municipal solid waste. (Svensk Fjärrvärme 2010a) In Sweden, the municipalities are responsible for collecting, transporting and treating the MSW generated in their region. The municipalities do however charge for this service. (Nationalencyklopedin 2010c) 3.3.1 CHP in Sweden Since Sweden has a varying climate, the heat demand varies a lot over the year. About 95% of the heat produced in CHP plants is used in district heating grids. (Avfall Sverige 2009a) Many Swedish CHP plants are run by natural gas or biofuels. (Svensk Fjärrvärme 2009) The energy generation in a CHP plant involves energy losses like all energy transformations, although they are not as great as when only producing electricity. For every two TWh of fuel, a standard 6 Theoretical Frame of Reference Swedish CHP plant generates approximately 1.1 TWh of heat and 0.6 TWh of electricity. That means that the total energy losses are approximately 15%. (ÅF Energi och Miljöfakta 2010a) 3.4 Waste Management All countries in the world generate waste. Waste is classified as material that the owner wants to, or is responsible to, disposes of. The previous definition is from the Environmental Code in Sweden and it is the same all over the European Union. (Nationalencyklopedin 2010c) There are a several ways of handling waste. Elements such as economy, environmental awareness and political management control measures determine the country’s waste management. (Sundberg 2008) Sweden, for example, follows the EU’s framework directive for waste handling, the waste hierarchy. According to this, the waste should be taken care of in the following order; reduce, reuse, recycle, recover and dispose, as displayed in Figure 3‐2. Figure 3‐2‐ The EU Waste Hierarchy (Covanta Energy 2010)
One way of treating waste is to reuse the energy in the refuse material. This is called waste‐to‐energy (WTE) and waste incineration plant with heat‐ or/and electricity generation is one example of this approach as well as biogas production with combustion. (Sundberg 2008) 3.4.1 Waste Handling in Sweden Since 2002, there is a ban against landfilling combustible materials in Sweden. The ban was expanded in 2005 to also include landfilling of organic waste, with some exceptions. (Naturvårdsverket 2009a) Between the years of 1994‐2006 the number of landfills in Sweden decreased from 300 to 160. This number will continue to decrease in the future due to stricter laws. (Avfall Sverige 2009b) Today there are about 260 larger waste treatment plants in Sweden where about one hundred of them are landfills, thirty uses waste combustion with energy and heat recovery and about forty are biological treatment plants. Figure 10‐1 in Appendix shows the current situation regarding the waste treatment methods for the Swedish manufacturing production. Figure 3‐3 shows the history for the different treatment methods for the years 2000‐2008. (ÅF Energi och Miljöfakta 2010b) During 2006, the amount of generated non‐hazardous waste in Sweden was about 121 million tones. (Naturvårdsverket 2009b) The ban against landfilling combustible and organic waste has led to an increased amount of incinerated waste and an increased amount of energy generated from the combustion process. In 7 Theoretical Frame of Reference 2007, about 4% of the waste in Sweden was landfilled. (ÅF Energi och Miljöfakta 2010d) Since the ban of landfilling organic waste, the biological treatment has increased over the past years. The year of 2007, approximately 561 000 tons of MSW was treated biologically. This number represented 11.9% of the total amount of treated MSW. (Avfall Sverige 2009c) Figure 3‐3 – Waste treatment in Sweden distributed on different treatment methods (adapted from ÅF Energi och Miljöfakta 2010b) 3.5 Landfills and Open Dumps One of the most common ways of handling disposed material is to put it on landfills or open dumps. There is a difference between sanitary landfilling and open dumping; on an open dump, the waste is disposed without further treatment. (Encyclopædia Britannica 2010b) Open dumping and landfilling cause methane leakage into the atmosphere and can also cause leakage to ground water, human diseases, odor and large dioxin emissions due to landfill fires. On sanitary landfills the waste is put in several thin layers with soil covering the waste layers. All the layers are packed with heavy machinery to prevent settling, odor and leakage. The possibilities for landfill fires are also minimized when using sanitary landfilling. (Avfall Sverige 2009d) 3.6 Waste Incineration There are mainly two different ways of incinerating waste material, grate firing and fluidized bed combustion. (ÅF Energi och Miljöfakta 2010c) When using grate firing, the waste is loaded into the fire and the material is sparked. (Tekniska Verken 2009a) When using fluidized‐bed combustion, the bed contains reactive or inert particles (a sand bed) which, together with strong up flowing air, makes the bed behave like a turbulent fluid. The material is said to be floating. (ÅF Energi och Miljöfakta 2010e) This type of combustion is commonly used when having a fuel that is of low quality, i.e. fuel that is difficult to burn. It is also well adapted for combustion with different waste materials and it is sometimes used for combustion of coal and peat. (Access Science 2010a) Regarding the electric efficiency of waste incineration plants, larger plants are more effective than smaller. (Grosso, Motta & Rigamonti 2010) Figure 3‐4 shows a simplified example of a waste incineration plant with energy recovery in form of electricity generation. At (1) the waste is tipped into a bunker where a crane picks it up and transports the waste into a hopper (2). The waste is then continuously loaded into the incinerator (3). Inside the incinerator, the heat is used for the boiler where the steamed water later in the process is, in this case, transformed into electricity via a generator. When the material is burnt, the 8 Theoretical Frame of Reference bottom ash is collected (5) and an electromagnet is used to separate the metal from the ash. To clean the flue gases from fine ash, SO₂ and dioxins, the smoke has to pass to a cleaning system with a scrubber reactor (6). In (7), the gas has to pass through a fine particulate removal system. The gas is then released through the chimney (8). (BBC NEWS 2010) Figure 3‐4 – Waste incineration process (BBC NEWS 2006) 3.6.1 Flue Gas Purification and Residuals When incinerating the waste, there are several toxic pollutions that have to be taken care of before releasing the gas out in the air. There is a condensation process, in which both gaseous (e.g. sulfur dioxide, phenol) and stable forms (e.g.. metal dust) of pollutions are separated from the gas. There are normally two purification processes; one dry and one wet step. (Naturvårdsverket 1993) In the first step, dry flue gas purification, the process is to separate the dust from the gases. This is done by letting the gas pass a textile filter. Before the gas enters the filters, active coal and calk are added so that heavy metals, dioxins etcetera are captured. The dust is then collected in a special silo. For the wet flue gas purification process, the chimney gases are washed with water. This is made in two cleaning steps and one heat recycling step. In these steps sulfur, ammonia, heavy metals and chlorides are removed and in the last step the heat from the chimney gases is taken care of. After the cleaning processes, the chimney gas is sent out to the air. (Tekniska Verken 2009b) When waste is incinerated, there are some residuals left. The slag products, mainly fly ash, soil ash and non‐burnt material, are transported from the boiler for further recycling or reusing. Metals such as iron are separated with magnets and are recycled. In Sweden, the slag gravel is used for replacing natural material in the building sector. There are also toxic residuals that have to be safely landfilled in special cells. (Naturvårdsverket 1993) 3.6.2 Waste Incineration in Sweden The incineration plants in Sweden normally use different waste materials according to supply, combustion capacity, etcetera. Since Sweden has cold temperatures and a large heat demand during the winter, incineration plants with co‐generation sometimes use different fuels during peak seasons. The most common fuel at Swedish waste incineration plants is household waste, approximately 60%. (Avfall Sverige 2009e) Other rather common materials used for combustion are industrial waste, construction material, demolished tires and wood residuals. The amount of energy in one ton of Swedish household waste is about three MWh. (Naturvårdsverket 2010a) For further information regarding the Swedish composition of MSW, see Figure 10‐2 in Appendix. 9 Theoretical Frame of Reference The waste incineration in Sweden contributes with 20% of the energy to the district heating grid. (Avfall Sverige 2009f) 6% of the electricity consumed in Sweden originates from CHP plants (Svensk Fjärrvärme 2010b) and 0.3% of the total electrical energy produced in Sweden originates from waste incineration (Avfall Sverige 2009f). During 2007 13.6 TWh of district heating and electricity were produced from waste incineration in Sweden. (ÅF Energi och Miljöfakta 2010b) 3.7 Biogas Another way of waste management is biogas production. Biogas consists, like natural gas, mainly of methane gas but there is a difference in the weight and in the production. Biogas is generated from organic materials while natural gas is located natural in the earth crust. Since biogas is classified as a renewable fuel, it can replace the use of fossil fuels. (Svensk Biogas 2010a) Biogas is a methane rich gas that consists of 55‐75% of methane, 30‐45% of carbon dioxide and 1‐2% of hydrogen sulphide. (Hilkiah et al. 2008) The biogas generation can be divided into two different processes according to their temperature; mesophilic (14‐40° C) and thermophilic (40‐60° C). The mesophilic processes is slower than the thermophilic, but instead it is more stable and not as sensitive to changes in the surrounding environment. (Nationalencyklopedin 2010d) 3.7.1 Production The process of producing biogas can include the following steps: Firstly, the incoming organic material is dispersed in a large tank. After this, the material is heated up to a temperature of 70 °C during at least one hour. This process takes place in order to eliminate the bacteria in the waste. Next, the waste is cooled down and after this the material enters the digestion chamber. In the digestion chamber the temperature is approximately 38 °C, the process is anaerobic (no oxygen is present) and material will be located here during a period of approximately 30 days. When the digestion process is over, the biogas that has been produced has a methane gas content of approximately 65%, the carbon dioxide content is roughly 35%. If the gas is to be used as vehicle fuel it is upgraded and the carbon dioxide is removed so that the methane content is around 97%. Depending on the material input for the digestion process, there is a possibility to produce bio sludge. The bio sludge can favorably be used as fertilizer. The process of producing biogas is displayed in Figure 3‐5. (Svensk Biogas 2010b) Dispersing of organic material
Heating step to remove bacteria
Washing to remove CO2
Cooling
97% methane
gas for e.g. vehicle fuel
Digestion
Combustion of biogas
Figure 3‐5 – The biogas production steps (Svensk Biogas 2010b) 10 Theoretical Frame of Reference For the digestion process to be optimal the temperature should be kept constant and the pH‐value is supposed to be little over 7. During an anaerobic biogas digestion process, heat has to be added. This can be compared with aerobic digestion (i.e. composting) where a lot of heat is produced. (Bioenergiportalen 2008) 3.7.2 Combustion of Biogas To be able to incinerate the biogas that has been produced, the gas firstly has to be dried. It also has to be cleaned from corrosive materials and particles. After this, the gas is combusted in a gasturbine (for larger production scale) or in an engine (for smaller production scale). The efficiency of the electricity generation from combustion of biogas is normally around 30‐40% (depending on the efficiency in the turbine/engine). The heat produced through the combustion can also be utilized if heat recovery is used. (Biogasportalen 2009a) 3.7.3 Biogas in Sweden The total biogas production was approximately 1400 GWh during 2008 in Sweden, which was a 12% increase since 2006. The biggest part of the production is in wastewater treatment plants, but there are also production from landfills and industrial facilities. (Biogasportalen 2008) In the south of Sweden, there is a natural gas grid supplying several big cities and at some places, biogas is fed into this gas grid, replacing natural gas. (Energigas Sverige 2010) The biogas can also be used as vehicle fuel and it is considered a cleaner fuel compared to both diesel and gasoline. (Svensk Biogas 2010c) 3.8 Environmental Aspects of Waste Management Techniques Regardless of the type of waste management, there are benefits and draw backs to all of them. Whether the benefits and drawbacks are economical, political or environmental the different treatment methods have to be evaluated. 3.8.1 Landfilling and Open Dumping As mentioned earlier in 3.5, one of the most common ways to treat waste is by landfills or open dumps. On an organized landfill, the waste is covered with soil and other material such as mining waste, which also decrease the volume of the waste. When covering the waste, this prevents settings. Today, there are a large number of open dumps in the world, especially in developing countries. This is mainly due to the small costs in disposing the waste instead of treating it. When not covering the waste or decreasing the volume of it, landsliding is a common risk. (Avfall Sverige 2009d) In both landfills and open dumps, the different materials take long time to digest. At most landfills and dumps, methane gas generation, as well as carbon dioxide generation, occurs naturally from the organic waste. When organic waste is digested with oxygen, carbon dioxide is generated, while digestion of organic material without oxygen present generates methane gas. Both these are greenhouse gases. (ÅF Energi och Miljöfakta 2010d) The GHG generation can continue a long time even after the waste has been landfilled. (Avfall Sverige 2009d) When using landfills or especially open dumps, there are risks of landfills fires. These fires can occur when the organic waste is decomposing and therefore producing heat that can ignite. There are great risks with these fires. The waste contains several different materials and the emissions from the fires can be hazardous. (Naturvårdsverket 2009c) 11 Theoretical Frame of Reference Even today, not everything is known about the effects regarding the emissions from landfills and open dumps. The waste materials at open dumps and landfills can affect the ground water due to stormwater. The main emissions from the stormwater are nitrogen, oxygen consuming subjects, metals and organic environmental toxins such as dioxins. (Naturvårdsverket 2008) The effects from the stormwater can however somewhat be controlled by using physical barriers and regularly controls. (ÅF Energi och Miljöfakta 2010d) There are several heavy metals involved at open dumps and landfills. An investigation including tests on samples from the Thai Nonthaburi dumpsite showed that the three most common heavy metals in the waste were zinc, copper and manganese. (Prechthai, Parkpian & Visvanathan 2008) Prechthai, Parkpian & Visvanathan (2008) also conclude that it is necessary to focus on removing heavy metals from the leachate. 3.8.2 Waste Incineration When incinerating waste in facilities with flue gas purification systems, the emissions are controlled and the dioxin emissions are much smaller than from landfills. (ÅF Energi och Miljöfakta 2010a) Since 1980’s, the dioxin emissions from waste incineration has decreased with 99% and today the emissions to air from waste incineration is about 0.8 g/year. (Naturvårdsverket 2009d) When using waste incineration, the volume of the waste is also decreased, normally by 90‐95%. (ÅF Energi och Miljöfakta 2010a) In the chimney gases from the waste incineration, several heavy metals are involved, e.g. mercury, zinc and cadmium. There are other non‐organic materials such as hydrogen chloride and hydrochloric acid in the gases as well. Today, all Swedish waste incineration stations are supplied with effective cleaning system to decrease the emissions. Due to this, the total amount of emissions from the waste incineration has decreased although the incineration has increased. (ÅF Energi och Miljöfakta 2010f) Most ashes from biofuels contain important minerals and nutrients and it is therefore important to restore the ashes to the forest. All biofuels contain metals since plants absorb metals from the ground. Most of these metals stay in the ashes after incineration and are therefore a risk for ecosystems when the ash is restored to the forest. (ÅF Energi och Miljöfakta 2010g) Waste incineration is not a step against reducing the production of waste. Instead, it is by some, considered as a shortcut for minimizing the waste and that it acts like a barrier, neglecting recycling. (Greenpeace 2005) There are also some concerns regarding the possibility of developing cancer from the chimney gases. (BBC NEWS 2010) 3.8.3 Biogas Biogas can be considered as waste‐to‐energy since the organic part of the municipal solid waste is used as feedstock for the production. This leads to reduced waste volumes on landfills. Biogas does not contain as many particles as fossil fuels. (Svensk Biogas 2010c) Methane is about 23 times stronger as a GHG, compared to carbon dioxide. The methane transforms into carbon dioxide during combustion. (EPA 2010) The carbon dioxide that is generated when the biogas is incinerated does not affect the climate changes, it is said to be carbon dioxide neutral. (Biogasportalen 2009b) This means that there is no net contribution of carbon dioxide to the atmosphere. When carbon dioxide is released by combustion, this is later added to the plants in the photosynthesis, resulting in growth of new biomass. (Nationalencyklopedin 2010e) 12 Theoretical Frame of Reference The fertilizer from the biogas production is of high quality. The nutrients are not lost in the process since the digestion process takes place in closed facilities. When using the fertilizer from the biogas production, this reduces the need for commercial fertilizers. (Svensk Biogas 2010c) As mentioned with waste incineration, biogas production from MSW also has a drawback regarding the fact that it does not prevent the waste generation. 3.9 District Heating and Cooling District cooling as well as district heating, are ways to supply heating or cooling. As the name indicates the production of heating or cooling does not take place at the same location as it is used. Instead of using smaller heat or cold producing machines, the production is centralized. Environmental benefits are achieved since it is more efficient to produce heating and/or cooling at one bigger and better adapted facility, instead of at several smaller ones. There are advantages of a more practical nature for the end users as well: there is no noise, no dripping and no maintenance is required. The use of district cooling frees spaces as well. (Svensk Fjärrvärme 2005b) The first district heating system in the world started running in USA in 1877. This system was based on distribution of steam. In Europe it took until 1900 before the first district heating system was built in Germany. At present, district heating exists in most countries where there is a need for heat. (Werner & Fredriksen 1993) The district cooling systems appeared later than the district heating systems. One of the first district cooling systems was taken into operation in 1962 in USA, while the first to use it in Europe were the French, in 1967. The first Swedish system was in place in 1992 in Västerås. (Svensk Fjärrvärme 2002) In Sweden, district heating is more common than district cooling. District heating provides approximatley half of the heated buildings and premises in Sweden. However, the need for district cooling is also growing. This increased demand is believed to be a result of higher demands of indoor comfort, as well as the prohibition of some of the most common refrigerants. Nevertheless, the world’s energy usage for producing cold is greater than the usage for producing heat. (Svensk Fjärrvärme 2005a) & (Svensk Fjärrvärme 2005b) For both district heating and district cooling, water is often used to transport the heating or cooling. The transportation is via pipelines. (Svensk Fjärrvärme 2005a) District heating can however also be hot steam, delivered to for instance industries that use steam in their processes. (Svensk Fjärrvärme 2003) District cooling recipients can be residential buildings, hospitals, industries, offices etcetera. The cooled water that is distributed is used to chill the air that is circulating in the room. The water is returned to the production facilities afterwards to be cooled once again. (Svensk Fjärrvärme 2005a) Cooling of the water for district cooling can be achieved in three different ways: •
•
•
Free cooling Absorption cooling Compression cooling If free cooling is used, this means that naturally cold sources are used, such as water from lakes or rivers. Absorption cooling is a technique that is powered by heat. The heat can be hot water or 13 Theoretical Frame of Reference steam, a common alternative in Sweden is to use hot water from a district heating system. Compression cooling uses electricity as source of energy. (Svensk Fjärrvärme 2005a) Regarding heating, district heating gives the user more freedom compared to having a boiler and being dependent on one single source of energy. (Svensk Fjärrvärme 2009) 3.10 Compression Cooling The second law of thermodynamics state that heat cannot by itself move from a body or location with low temperature, to a body or location with high temperature. So to achieve cooling, power of some kind is needed, which can be high temperature heat or electrical energy. (Nationalencyklopedin 2010f) To refrigerate is by definition “the process of removing heat from an enclosed space or from a substance for the purpose of lowering the temperature”. In other words, the goal is to achieve a lower temperature than that of the surrounding environment. (Encyclopædia Britannica 2010a) A compressor‐driven cooling machine (CCM) normally refers to the use of the vapor‐compression refrigeration cycle. This is the most commonly used working cycle for cooling facilities. The same cycle is used for heat pumps, but when heat is desired the warm side (the condenser) is used instead of the cold side (the evaporator). The vapor‐compression refrigeration cycle is a closed system in which a refrigerant (the working medium) circulates. The refrigerant is alternating between liquid and gas form in the four steps of the cycle: •
•
•
•
The compressor in which the refrigerant is compressed isentropically (constant entropy) from saturated vapor to superheated vapor. The refrigerant has a temperature high above the surrounding temperature. The condenser, where the refrigerant releases heat to the surroundings and transforms into saturated liquid. The temperature of the refrigerant is still higher than the surrounding temperature. The expansion valve, where the pressure drops and therefore also the temperature of the refrigerant, which is now lower than the temperature of the surrounding environment. The evaporator, in which the refrigerant evaporates by absorbing heat from the cooled space. The refrigerant enters as a saturated mixture and leaves as saturated vapor. After the evaporator the refrigerant enters the compressor again, and the cycle is complete. (Cengel & Turner 2004) Common refrigerants that have been used for long times are called CFCs (chlorofluorocarbons) and HCFCs (hydrochlorofluorocarbons). These are being phased out however, since the chlorine depletes Earth's stratospheric ozone layer. (Access Science 2010b) For industrial applications, ammonia and Freon‐22 are the most commonly used refrigerants. Freon‐11 and Freon‐12 are mostly used in air conditioning units. Freon was more common earlier in e.g. refrigerators, but today it is forbidden to apply in new systems. (Nationalencyklopedin 2010g) In refrigerant systems, ammonia is commonly used due to its high vaporization heat. Ammonia is hazardous and poison in larger volumes. (Nationalencyklopedin 2010h) 14 Theoretical Frame of Reference 3.11
Absorption Cooling Absorption cooling has become more popular lately but the technique is actually quite old. Already during the 19th century patents were granted and around 150 years ago the development started. (Rydstrand, Martin & Westermark 2004) The absorption chilling machine (ACM) works according to the same principle as the compression cooling machine, but with some alternations. The essential difference is that instead of an electrical compressor, absorption cooling utilizes a generator and an absorber, i.e. a thermal compressor. (Energy Solutions Center 2010) The other big difference is that the absorption cooling process uses two working mediums for the process, a refrigerant combined with an absorbent. Normal working medium combinations are lithium bromide/water or water/ammonia. In the lithium bromide combination the lithium bromide works as absorbent and the water as refrigerant while in water/ammonia solution, the water is the absorbent and the ammonia is the refrigerant. The absorption cooling process consists of the following steps (here with the example of lithium bromide/water as working couple): (Zinko et al. 2004) •
•
•
•
The absorber, in which water steam from the evaporator and concentrated absorbent, lithium bromide, are mixed. The lithium bromide absorbs the steam and a low pressure is achieved. This also releases heat that needs to be cooled off to maintain the low pressure. When the lithium bromide cannot absorb any more water, it is pumped to: The generator, where heat in some form is added, which vaporizes the water, and therefore the lithium bromide and the water are separated again. On its way to the generator, the solution also passes a heat‐exchanger, in order to decrease the amount of heat that needs to be added in the generator. The separated absorbent is fed via the heat exchanger as well as an expansion valve, back to the absorber. The water steam, on the other hand, is fed to: The condenser, where heat is removed from the vaporized refrigerant and condenses. The condensed refrigerant is afterwards passed on via an expansion valve, to: The evaporator, where the pressure and temperature is low enough for the refrigerant to vaporize through absorbing heat from the cooled space. This is where the actual desired cooling occurs. The water, in the form of steam, is passed on to the absorber and the cycle is complete. (Zinko et al. 2004) The basic schedule of both compression cooling and absorption cooling is displayed in Figure 3‐6. 15 Theoretical Frame of Reference Figure 3‐6 ‐ Schedule displaying compression cooling and absorption cooling (adapted from Martin, Setterwall & Andersson 2005) 3.11.1 Distribution When using absorption cooling to satisfy a cooling demand this can be done in different ways. One option is to have the ACM placed at the premises of the heat producing company, and the cold water is distributed to the customer from there. This is district cooling. The other alternative is that the absorption cooling machine is placed closer to the customer, and the hot water is delivered there through district heating pipes. The cold water is afterwards transported from there to the customer. This alternative is referred to as district heat driven cooling machine. District heat driven cooling machines are suitable when there is an existing district heating system, which is the case in e.g. Sweden. District cooling is more common the USA and Japan while district heat driven cooling machines occurs more in Europe. (Rydstrand, Martin & Westermark 2004) 3.11.2 The Absorption Cooling Machine There are a number of different absorption cooling machines that require driving temperatures within certain intervals and they also provide different efficiencies. Here, the conventional single‐ and double‐effect will be presented, as well as the low temperature driven semi‐effect ACM. The conventional absorption cooling machines require a heat source with temperatures from 120°C for a single‐effect (SE) ACM up to 170°C for a double effect (DE) ACM. The efficiency of the energy use for the absorption chiller can be calculated as the relation between the cooling effect of the cold water and the added driving effect. This relation is called the Coefficient of Performance (COP). The COP of a single‐step water/lithium bromide absorption cooling machine is approximately 0.7 or 0.8, while for a double‐effect the COP can be 1.2. The main application of the conventional ACMs is to place them next to e.g. production facilities where waste heat of high temperature is available. If 16 Theoretical Frame of Reference these conventional ACM are used with district heating as heat source, this gives a lower COP due to lower temperature of the district heating. (Zinko et al. 2004) The SE ACM works in two different pressure levels, while the DE ACM works in three different pressure levels. The SE‐machine has a high pressure level in the generator and condenser, and a low pressure level in the evaporator and absorber. For the DE‐machine an additional pressure level is added, named a high‐pressure generator and a high‐pressure condenser. The heat that is emitted in the high‐pressure condenser can be reused in the low‐pressure generator. The result is that more heat can be absorbed in the evaporator with the same amount of added heat. Due to the three pressure levels in a double‐effect machine this is more advanced than a single‐effect one since more pumps and heat‐exchangers are needed. On the other hand, if a cooling tower is needed as a heat sink, the installed cooling tower capacity per cooling effect is less for a double‐effect ACM than for single‐effect. This brings the price level of the DE‐ACM closer to the SE‐ACM, although the DE is normally more expensive. (Rydstrand, Martin & Westermark 2004) There are ACMs that can be powered by low temperature heat (70‐90°C), for example district heat water. This ACM is called a semi‐step (SS) ACM. The principle for this is the same as the DE‐ACM but without the internal heat exchange. The SS‐ACM has two generators, two absorbers, one condenser and one evaporator. The two generators is the reason to why driving heat within a larger interval can be used. As a result of this, larger heat exchange areas are needed, and possibly more pumps, which increases the price of the machine. The expected COP for a machine like this is 0,7. The interest for the low temperature heat driven ACM has increased in many parts of the world where there is access to low temperature heat like solar heat, earth heat, heat from CHP production or from waste incineration. (Rydstrand, Martin & Westermark 2004) The estimated characteristics for the three mentioned ACMs can be viewed in Table 3‐1 below. Table 3‐1 – Estimated characteristics for different ACMs (Rydstrand, Martin, Westermark 2004) Type of ACM COPelectricity Required temperature [°C]
Single Effect (SE) 0.7 120 Double Effect (DE) 1.2 150‐170 Semi Step (SS) 0.7 > 65 The investment cost for an ACM is higher than for a CCM. However, the overall cost for the ACM can be decreased by at least 50% by placing the absorption cooling nearby a natural heat sink, e.g. a lake. This is compared to the alternative where cooling towers are needed. (Martin, Setterwall & Andersson 2005) According to Zinko et al. (2004) the cooling effect and thereby the investment cost is a function of the temperature of the heat used in the ACM. Zinko et al. (2004) also states that it is a matter of a system optimization with the parameters heat, cooling and electrical power, and the price differences among these. For the ACM to be economically profitable, there has to be a thermodynamic difference, a factor between the electricity price and the heat price of about 2.5‐3. The biggest usage possibility can be found when the driving heat originates from facilities with waste heat or from CHP plants where the heat is considered as a byproduct from the electricity production. (Zinko et al. 2004) 17 Theoretical Frame of Reference 3.12 Efficiency of ACM Compared to CCM As mentioned before the single‐effect ACM has a COP of approximately 0.8. The COP for a CCM is higher, as high as 4.5 for a large scale water cooled chillers, while 2‐4 is common in Europe for smaller CCMs. The COP value for the ACM is however based on heat as power source, while for the CCM the value is based on electricity as source of power. Due do this, absorption cooling is often considered to be an inefficient way to produce cooling. Rydstrand, Martin & Westermark (2004) explains why this is approach is inaccurate. The efficiency of a thermodynamic process can be valued with an ideal Carnot‐process as a reference. What Rydstrand, Martin & Westermark (2004) refers to as the Carnot‐factor is the efficiency of a process, divided by the efficiency of a Carnot‐process working with the same internal temperatures. (Rydstrand, Martin & Westermark 2004) The Carnot‐factor does, per definition, equal one for an ideal process. For expansion in a steam turbine the Carnot‐factor is normally between 0.5 and 0.7, where 0.7 is for a very large steam turbine (e.g. condense power plant) and 0.5 for an average sized CHP plant. For a compressor driven cooling machine the Carnot‐factor is also around 0.5‐0.7 depending on size and efficiency. Consequently, the Carnot‐factor for producing cooling with a compression cooling machine that is run of electricity from a steam turbine, the total Carnot‐factor is 0.25‐0.5. Regarding an absorption cooling machine, the Carnot‐factor is 0.7 when no consideration is taken to external heat transfer. The conclusion is that cooling produced with an ACM is a thermodynamic shortcut compared to first generating electricity in a steam turbine and afterwards using the electricity to produce cooling with a CCM. The Carnot‐factor for absorption cooling is in comparison approximately twice as big as for compression cooling. Figure 3‐7 shows this comparison. (Rydstrand, Martin & Westermark 2004) 18 Theoretical Frame of Reference Figure 3‐7 – Comparison of Carnot‐factor for compressor cooling and absorption cooling (adapted from Rydstrand, Martin & Westermark 2004) The conclusions of Rydstrand, Martin & Westermark (2004) are that combined production of electricity, heat and cooling can be performed with a better fuel‐usage compared to separate productions. The most energy efficient alternative is a low‐temperature driven ACM together with CHP production. (Rydstrand, Martin & Westermark 2004) 3.13 The Swedish Electricity Market Sweden is part of the Nordic electricity market called Nordpool, where all the Nordic countries are included, except Iceland. The Swedish market was deregulated in 1996. The purpose of the deregulation was to increase competition, as well as freedom of choice for the consumers, and to create better possibilities for a good price development of electricity. The other countries in Europe are working on deregulating their electricity markets as well; however the pace of deregulation is different for the countries. (ÅF Energi och Miljöfakta 2010h) 19 Theoretical Frame of Reference Trygg (2006) explains that “the most common argument for deregulation is the inefficiency of regulation”. A truly competitive market offer incentives to minimize the prize, although a deregulation is not the same as perfect competition. (Stoft 2002 see Trygg 2006, p. 14) When it comes to environmental impact assessments and other environmental analyses, impacts due to electricity usage needs be evaluated in order to perform the assessment or analysis. The reasons for performing an environmental impact assessment can be many, for instance politicians, scientists and others need it to estimate the impact from different decisions, which is important in order to make sure that the development is moving in a sustainable direction. At present there is no established way to estimate the environmental consequences from electricity usage and production. The Swedish energy agency have performed research and discussed the matter to decide on a way to evaluate environmental impact from electricity production. Their conclusion recommends that environmental evaluation of electricity always should be made with marginal electricity. One of the alternatives, the most reasonable alternative, would be to use average electricity. (Statens Energimyndighet 2006) Marginal electricity is defined as the electricity production that will disappear as a result of reduced electricity usage or additional electricity production. Likewise, the term is also valid for the opposite, i.e. marginal electricity is the added production due to an increase of electricity usage or decreased production. (Statens Energimyndighet 2006) Average electricity on the other hand, is defined as the sum of all emissions that electricity production within a certain system boundary causes, divided by the total amount of produced electricity within the same system boundaries, on a yearly basis. For this definition, the suitable system boundary in is all the Nordic countries. Therefore it is called Nordic average electricity in Sweden. (Statens Energimyndighet 2006) 3.13.1 Price Development The development of the electricity price in Sweden is presented in Figure 3‐8. During the last ten years the price has continued to increase, the different accommodations following each other. The prices are from 1st of January every year and do not include taxes. Since 2007, the price of electricity certificates is included in the electricity market price. (Statistic Sweden 2010) 20 Theoretical Frame of Reference 1
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Swedish Electricity Prices
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Figure 3‐8 – Price development of the Swedish electricity price, no taxes included (Statistic Sweden 2010) 3.13.2 CHP and Absorption Cooling in the Swedish Energy System Since district heating is big in Sweden, district heat driven absorption cooling machines are relatively common as well. The current production, 700 GWh, is generated from about thirty plants. However, the potential for absorption cooling is believed to be 2000‐5000 GWh. (Svensk Fjärrvärme 2010c) Figure 3‐8 – Price development of the Swedish electricity price, no taxes included (Statistic Sweden 2010)shows that the Swedish electricity price has increased during the last ten years. The Swedish energy usage is higher than the overall European usage which together with increasing electricity prices will make it difficult for Swedish industries to manage. This situation contributes in a need for electrical energy savings and therefore many industries will probably convert to district heating instead of electricity. (Trygg 2006) With an increasing district heating demand, CHP plant together with the electricity generation will be benefited. (Trygg 2006) With marginal electricity perspective and considering coal condense power produced on the margin in Sweden presently, electricity generation from CHP using biomass or waste can replace fossil coal condense power, which helps to reduce global CO₂ emissions. (Zinko et al. 2004) According to Zinko et al. (2004) the problem with CHP plants in Sweden and their electricity generation, is the fact that the heat demand is decreasing during the summer. This could be prevented and electricity could be produced in large amount all year if there were an existing heat demand during the summer month. (Zinko et al. 2004) By using ACMs for cooling demand this would increase the heat demand which would results in more electricity generated in the CHP plants. (Trygg 2006) 21 Theoretical Frame of Reference 22 Results 4 Results In this part of the report, the results from the research and interviews will be presented. The results include waste management, waste incineration and biogas in Bangkok and Thailand. Also, the current absorption cooling situation and the electricity market and generation in Thailand will be presented. Bangkok is the main target during this work, but since some figures and information only exists for the entire country, these will be presented. The overall situation in Thailand is also relevant in some regards. The information and material that has been used during this thesis mostly originates from written as well as electronic references. The written sources are mainly technical reports, while the electronic ones are also mostly documents and reports. In addition to these, interviews have also been performed, and a number of personal references are used in the thesis. As for the technical reports and articles studied, the majority originates from Science Direct. As recent articles written as possible has been used. The articles used have mostly been found through searching this data‐base for keywords associated to our research. Science Direct has been accessed through the University of Linköping. Other data‐bases and the internet have also been used in order to find relevant documents. The majority of the web pages and articles used have been found through independent investigations, although some web‐pages have been found through recommendations from our colleges at Eco Group Co. Ltd. Other times the personal sources have supplied material that would have been unavailable or hard to find in other ways. Most of the investigated material for this thesis, regaring Thailand, has considered and presented hydropower as a non‐renewable fuel. Therefore, in the Results, hydropower will be presented in the same way, as a non‐renewable resource. 4.1 Interviews There were four interviews made during the time for the thesis. The personal interviews were initiated through Eco Group Co. Ltd. and they were all located in the Bangkok‐area. One of the interviews was however preformed through Skype and this interview was not initiated by the personnel at Eco Group Co. Ltd. The persons that have been interviewed are: •
•
•
•
•
Dr. Sombat Teekasap, assistant proffesor at the Federation of Thai Industries and the Industrial Environment Institute Ph.D Chris Greacen at Palang Thai Mr. Sakarin Tangkavachiranon, Planning and Efficiency Division Manager at DCAP Mr. Kiatiwongs Singha, Specialist Engineer at Suvarnabhumi Airport Ph.D Poonsak Chanchampee at Suvarnabhumi Environmental Cares Co. Ltd. All of the interviews were preformed without any interpreter and no audio‐ or video recording took place. After the interviews, the respondents were given the change to control the information in the thesis by email contact. 4.1.1 Situation in Bangkok During the writing of this thesis (February to May 2010) there has been some political disturbance in Bangkok. There have been demonstrations during a long period of time and these have resulted in 23 Results parts of Bangkok being occupied by demonstrators and means of transportation have been limited. The disturbances resulted in 85 deaths and with several people injured as well. (UD 2010) 4.2 Waste Management in Thailand The waste situation in Thailand is rather different than in Sweden. Most of the waste is put on open dumps and the amount of generated waste is much higher. 4.2.1 Waste Situation Today, there is about 15 million tons of waste produced in the country every year. (Teekasap 2010) This number represents 0.8‐1.0 kg waste/capita/day. 85% of this waste is collected and 93% of the total waste generated has recycling possibilities. (PCD 2006b) When the waste is collected, 72% is put on opened dumps, 20% is put on landfills, 7% is put on sanitary landfills and 1% is incinerated. Figure 4‐1 shows the variation of generated amount of waste in Thailand during the years 1998‐2006. (SWLF 2000) The number of open dumps is decreasing and the waste is instead treated at landfills. There have been regulations during the past 10 years where new landfills have to be authorized and people who live nearby have to approve them. There is still some illegal dumping of waste but this has decreased since it is difficult to transport large amount of waste illegally. (Teekasap 2010) In 2005, there were 966 landfills in Thailand; 107 engineered and 859 open dump landfills. (Chanchampee 2009) In the Bangkok area, there are no landfills. There are however 3‐4 transit stations were the waste is packed and sent to landfills in other provinces. (Teekasap 2010) According to Chanchampee (2009), the total recycled amount of waste generated in 2005 represented 22%. After the collection, the amount of waste treated through composting/anaerobic digestion was 200 000 ton. (Chanchampee 2009) There are different alternatives for disposing of household waste in Bangkok; either one common larger bin for apartment complexes, or a smaller private bin for private houses. Either way, it is collected by a waste truck and it is the Bangkok Metropolitan Administration (BMA) who handles the collection, which the owner of the building has to pay for. (Teekasap 2010) BMA is connected to the Governor of Bangkok. (BMA 2010) 4.2.2 Waste Development Whether the amount of generated waste is increasing or decreasing depends on the economical situation in the country. If the economical situation is good, the consumption is increasing and so is the waste generation. (Teekasap 2010) Thailand is currently trying to improve their waste management. The 23 March 2005, the Thai government decided that the country should introduce an environmentally friendly waste management. The government announced that they will not tolerate the country to become an end receiver of waste that has to bear the all the costs for waste handling and emissions. They also decided that Thailand will use the application cradle to cradle and that industrial waste management should achieve a cleaner and a less emission creating production lines. (PCD 2006a) Cradle to cradle is defined as “a production where all material inputs and outputs are seen either as technical or biological nutrients. Technical nutrients can be recycled or reused with no loss of quality and biological nutrients composted or consumed” (Sustainable Dictionary 2006). 24 Results A system for separating household waste in one bin for wet material and one bin for dry material has started in Bangkok. In a near future, the wet waste is supposed to generate biogas in a biogas plant while the dry waste should be treated in a sorting plant. According to Teekasap’s (2010) estimations, the system might be fully developed during the next ten years. (Teekasap 2010) Ton
Amount of Generated Waste in Thailand
14 800 000
14 600 000
14 400 000
14 200 000
14 000 000
13 800 000
13 600 000
13 400 000
13 200 000
13 000 000
1998
1999
2000
2001
2002
2003
2004
2005
2006
Year
Figure 4‐1 – Tones of waste generated in Thailand 1998‐2006 (TNSO 2006) The waste situation in Thailand looks somewhat different than the waste situation in Bangkok, see Figure 4‐1 and Figure 4‐2 (observe the scale difference). In Thailand, the waste amount has increased, while it has decreased over the last years in Bangkok. The waste generation in Bangkok is predicted to reach 18 000 tons per day in 2015, which represents 6 500 000 ton per year. (Chaya & Gheewala 2007). Ton
Amount of Generated Waste in Bangkok
3 600 000
3 500 000
3 400 000
3 300 000
3 200 000
3 100 000
3 000 000
2 900 000
2 800 000
2 700 000
1998
1999
2000
2001
2002
2003
2004
2005
2006
Year
Figure 4‐2 – The amount of generated waste in Bangkok 1998‐2006 (TNSO 2006) 25 Results For the period 2007‐2010, the Thai government has set up the Environmental Quality Management Plan (EQM). The EQM has three aims: •
•
•
“Increase recycling target to 30% Increase safe residual waste management to 40% Alternative energy recovery: 102,5 MW alternative energy recovered from MSW” (Chanchampee 2009) 4.2.3 The Waste Composition Regarding the waste composition in Thailand, the biggest parts are organic and plastic materials and over 60% of the waste is biodegradable. (Chaya & Gheewla 2007) For further information regarding the details of the composition, see Figure 10‐3 in Appendix. (PCD 2006b) The moisture content in the Thai waste is about 40‐60%. (Kaosol 2009) It can, however be as high as 80% during the rain season. The organic part in the MSW varies according to some fruit season. Normally, the organic part represents 55‐65%. (Teekasap 2010) As for the calorific value in the waste, the moisture content plays a significant role. The net heat value is decreasing with higher moisture content and the mass loss is also decreased. (Liang et al. 2008) 4.2.4 Waste Incineration in Thailand Aaccording to Udomsri, Martin & Fransson (2010), there are currently two waste incinerators in Thailand. However, according to Chanchampee (2009) there are three waste incinerators in the country. One of these is located at Phuket while another one is situated at Koh Samui. The capacities for these plants are 250 kg/h for the Phuket plant and 140 kg/h for the plant in Koh Samui. (Udomsri, Martin & Fransson 2010) The incinerator at Koh Samui does not have energy recovery. (Teekasap 2010) The one at Phuket on the other hand has an electric effect of 2.5 MW. (Udomsri, Martin & Fransson 2010) According to Teekasap (2010) the output is however only 0.5 MW due to the old technique used. The mass burn incineration represents less than 1% of the total MSW amount treated in Thailand (Chanchampee 2009). According to Teekasap (2010), the reason why the waste incineration technique is not further expanded is because it does not seem to be an appropriate waste disposal technique in Thailand. The incineration is also very expensive. Since the moisture content of the overall waste is so high, torch fuel has to be used. Normally, natural gas is used, but diesel is also commonly used as well as liquefied petroleum gas. (Teekasap 2010) According to Liang (2008), the efficiency of the incineration process is decreased with increased moisture content. About five years ago, Thailand adopted a new law for flue gas purification systems. The demanded standard of the cleaning systems is at European level; by using catalytic filters, the particulates are being taken care of. The residuals from the incineration is stabilized and put on landfills. (Teekasap 2010) During the last years there have been plans for expanding the waste incineration in Thailand. However, due to anti‐incineration campaigns, the expanding plans were dismissed. (Udomsri, Martin & Fransson 2010) According to Teekasap (2010), there are no further plans of expanding the waste 26 Results incineration in Thailand. It is too expensive for investors, a new plant costs about 2 000 million THB (466 million SEK) and it is also too bureaucratic. Teekasap (2010) explained how it is difficult to fabricate a normal power plant due to high costs and how it is even harder to build a waste incineration power plant. He also mentioned that since the waste composition is changing from day to day, it is difficult to use incineration technique properly. However, Teekasap (2010) believes that the waste incineration technique in Thailand has a future, if using plasma‐incineration. This technique uses a sustained electrical arc between two points. This arc, together with a gas, will result in an ionized gas stream called plasma which that can break down waste molecules into non‐
hazardous particles. (Gomez et al. 2009) In the case of investing in waste incineration, Teekasap (2010) believes that several smaller incineration plants placed outside the city are preferable to fewer, larger ones. Udomsri, Martin & Fransson (2010) present a waste incineration technique alternative for future power production; “Electrical power production via conventional incineration and hybrid power plants employing integrated natural gas‐fired topping cycles…” According to this, their solution has short payback time, the highest cycle efficiency and MSW could be used as fuel. The solution is supposed to be able to cover 2.5‐8% of Bangkok’s electricity consumption. (Udomsri, Martin & Fransson 2010) 4.2.5 Biogas in Thailand The main biogas production is today generated from the agriculture sector via small pig and cow farms. Normally, the produced biogas is incinerated to generate electricity. The biogas can also be used as cooking gas. This is however not optimal since the Thai kitchen demands constant high temperatures, which is not achieved from the biogas. (Teekasap 2010) Financially, the biogas investors are private (VSPP). All investors are accepted, lately there has been quite a few foreign investors. However, there are usually Thai people involved in the project since it otherwise is difficult for foreigners to understand the Thai energy and electricity systems as well as the Thai language. (Teekasap 2010) According to Teekasap (2010), there is an existing project with producing biogas from MSW in the north of Thailand. Regarding the sorting of the waste for biogas production, he thinks there are different ways of doing this. One way is to cover all the waste, non‐sorted, with air‐tight plastic or tarpaulin. Then, the digestion takes place for about 30‐40 days and after that the biogas is sucked out of the “tent”. After this, the waste can be sorted; metals and plastic are recycled and the rest goes to landfilling. Teekasap (2010) believes that the biogas production will be developed and expanded in Thailand. The potential feedstock for biogas production from MSW is about 1/3 of the fifteen million tons of waste generated in Thailand every year. Today there are one or two biogas plants that generate biogas from MSW in Thailand and in the future Teekasap (2010) believes there will probably be ten more. The existing plants have a capacity of producing 1 MW biogas from about 100 tons per day. But for further development, the technique has to be proven functional and this can take five to ten years. There is also the issue of financial support. (Teekasap 2010) Regarding the size and location of biogas plants, Teekasap (2010) thinks it is best to have many small plants located locally in the country. This is due to the logistical problems in collecting the waste 27 Results which generated large amounts of emissions. The plants also need space; for a plant of 100 tons, approximately one hectare is needed. (Teekasap 2010) When using the waste heat from the biogas combustion, the total efficiency can be increased. This is not made today in the Thai biogas plants but there are some experiments in the field. Teekasap (2010) believes the optimal temperature in the digestion chamber during biogas production in Thailand to be around 50 °C. This temperature is rather easy to achieve since the surrounding temperature normally is around 30 °C. (Teekasap 2010) Teekasap (2010) believes there is a market for the residuals from the biogas production. The fertilizer from biogas production is better than the normal, dry fertilizer. (Teekasap 2010) 4.3 The Thai Power Generation and Electricity Market Thailand started generating electricity in 1897, at this time it was however only for consumption in Bangkok. During the 20th century, the main source of energy was wood, which later changed to imported oil and after that into lignite. Lignite continued to be the main source for energy until natural gas was discovered in the country in the early 1980s. (Foran 2006) The total power generation for Thailand, was approximately 150 TWh during 2009. The main fuel for this power production was natural gas (NG). The second largest energy generating fuel is coal and lignite and the third largest is hydropower. (EPPO 2009a) The fuel mix for Thailand’s power generation can be viewed in Figure 4‐3. Fuel Mix for Power Generation in Thailand
Import and Others
4%
Lignite/Coal
21%
Oil
0,2%
Hydro
5%
Natural Gas
70%
Figure 4‐3 ‐ Thailand’s Fuel Mix for Power Generation (Jan 2010) (adapted from EPPO 2010) Over the years, the fuel mix has changed. From 1986 the amount of hydropower has decreased while the amount of natural gas has increased significantly. Figure 10‐4 in Appendix shows the percentage of power production from the different fuels since 1986. (EPPO 2009b) Electricity produced from natural gas constitutes marginal electricity in Thailand. (Pipattanasomporn et al. 2000) 28 Results The main electricity consumer in Thailand is air conditioning units. (Jaruwongwittaya & Chen 2009)
Pongtornkulpanich et al. (2008) writes that the electricity usage due to air conditioning is 50 TWh per year. This usage accounts for approximately 40% of the total energy usage in Thailand, during the year of 2008 (EPPO 2009c). There has been a rapid growth of new buildings which also has lead to an increase in air conditioning units, approximately 400 000 units per year. (Jaruwongwittaya & Chen 2009) 4.3.1 The Authorities The electricity market in Thailand is regulated by the government. It is mainly managed by three different bodies; the state enterprises EGAT (Electricity Generating Authority of Thailand), MEA (Metropolitan Electricity Authority) and PEA (Provincial Electricity Authority). EGAT is responsible for the generation as well as the transmission of electricity while MEA and PEA handle the distribution. (Pipattanasomporn et al. 2000) Since 2007, the Energy Regulatory Commission (ERC) also has certain functions within the Thai power generation, one function being tariff regulation. (ERC 2009) MEA distributes to the area of Bangkok Metropolis and the two surrounding provinces named Samut Prakran and Nonthaburi and PEA covers the rest of the country. (PEA 2010) Thailand has however been in the process of privatizing the power market for quite some time now, and EGAT does no longer have the monopoly on producing power, but the electricity market is still government controlled. (Foran 2006) 4.3.2 Private Participation EGAT was formed in 1968 and at that time they had monopoly on power production. In the 1990s, electricity demand increased, and EGAT started sharing power production with private companies. (Foran 2006) Two programs were launched, named IPP (Independent Power Producers) program and SPP (Small Power Producer) program. (Pipattanasomporn et al. 2000) In 2004 new regulations regarding very small power producers (VSPPs) were passed at the cabinet. (Palang Thai 2010) According to these programs the different private power producers are allowed to connect to the grid and sell electricity as well. (EPPO 2007a) The regulations regarding how the VSPPs are allowed to connect to the grid is called net metering and is less complicated and with fewer requirements. (Amranand 2008) These programs will be explained further in 4.3.3. In 2000, studies and plans were initiated on how to make the power sector competitive by the year of 2003. Due to different (mostly political) reasons the plan was not realized and the power sector was not privatized in 2003, although the road towards privatization continued. In 2003 another deadline was set for the deregulation, this time EGAT was supposed to be privatized in March 2004. In February 2004 there were however massive demonstrations against the privatization, and it was put on hold. The protesters were mainly union members from EGAT, PEA and MEA. This delayed the process further, but in 2005 the process started over and in 2006 EGAT was about to privatized yet again. (Foran 2006) Also this time the privatization failed when a petition was handed in to the Supreme Court, concerning the way the privatization process had been handled. The result was that all preparations for the privatization were nullified since the Supreme Court reached the conclusion “that the process of transforming this state enterprise [EGAT] into a corporation was unlawful”. (Tangwisutijit 2006) 29 Results 4.3.3 Independent, Small and Very Small Power Producers The IPPs, SPPs and VSPPs do however offer some private participation in the electricity market, although EGAT still maintains in control. The IPPs are all large scale private power producers, their power production could originate from natural gas, coal or heavy oil. The SPPs are private power producers that generate electricity in capacities between 10 MW and 90 MW, while VSPPs are the private power producers with capacities below 10 MW. Both the SPPs and the VSPPs are either using co‐generation, generating both heat and electricity from fossil fuels, or they are generating electricity from renewable sources like biomass, biogas, waste, solar and wind. (EGAT 2009a) “Given the renewable energy potential remaining to be tapped, rising oil prices and problem of global warming“ the government issues a few changes regarding the VSPP and SPP programs in 2007. One change was to make the VSPP and SPP programs “more investor friendly and practical”. Another change was to grant a higher tariff for SPPs and VSPPs producing from renewable sources. This higher tariff is accomplished by an “adder” to the normal tariff, i.e. the producer receives extra payment for the generated electricity. This adder can be viewed in Table 4‐1. (Amranand 2008) Table 4‐1 “Adder” to the Normal Tariff for SPPs and VSPPs (adapted from Amranand 2008) Fuel/Technology Adder (Baht/kWh) Number of Years Biomass 0.30 (US$ 0.97) for VSPP 7 Competetive bidding for SPP Biogas 0.30 (US$ 0.97) 7 Mini‐hydro (50‐200 kW)
0.40 (US$ 1.29) 7 Micro‐hydro (< 50 kW) 0.80 (US$ 2.58) 7 Municipal Wastes 2.50 (US$ 8.06) 7 Wind 3.50 (US$ 11.29 10 Solar 8.0 (US$ 25.81) 10 Remarks: 1) Exchange Rate: 32 Baht/USD 2) The level of normal tariff is 2.0‐2.5 baht/kWh (US$ 6.25‐7.81) The VSPPs that are under the co‐generation category must have (and prove) primary energy savings of at least 10%, otherwise they will receive penalties. (Palang Thai 2010) The structure and relations between the utilities can be viewed in Figure 4‐4. The figure also shows the generation percentage of the different utilities. 30 Results Figure 4‐4 ‐ Thailand’s Electricity Industry Structure (EPPO 2010) EGAT purchases all the electricity produced by the IPPS, and most of the electricity generated by the SPPs, through power purchase agreements (PPAs). (Pipattanasomporn et al. 2000) The SPPs are also allowed to sell and distribute directly to industry customers at close proximity. (Probe International 2005) The VSPPs sell their electricity directly to the distributing authorities (MEA or PEA), according to the same rate that the authorities pay EGAT. (Palang Thai 2010) When SPPs supply customers directly with electricity, these are mainly industries and the price for this electricity is lower than the rates that MEA and PEA provide. (Greacen 2010) 4.3.4 Electricity Prices and Price Development The ERC determine the electricity prices in Bangkok. There are seven different price schedules depending on what service the customer needs: 1.
2.
3.
4.
5.
6.
7.
Residential service Small general service Medium general service Large general service Specific business service Government institutions and non‐profit organizations Water pumping and for agricultural purposes These price schedules have different monthly tariffs depending on consumption. For example, tariff 1 (residential service) has three different monthly tariffs: 1.1 Normal tariff with consumption not exceeding 150 kWh per month 1.2 Normal tariff with consumption exceeding 150 kWh per month 1.3 Time Of Use (TOU) tariff All different tariffs have varying price levels depending on how much the customer uses and voltage level. The prices increase with a higher electricity use. (MEA 2010) 31 Results A normal household with consumption below 150 kWh per month automatically falls under the 1.1 tariff (residential service with normal tariff under 150 kWh). If the customer exceeds an electricity usage of 150 kWh during three consecutive months, he or she will be charged according to tariff 1.2. If the usage is below 150 kWh during three consecutive months, the customer will again be charged according to tariff 1.1. A customer under the 1.2 tariff has the option of paying the 1.3 TOU tariff as well. (MEA 2010) The average electricity price for tariff 1.1 (except for the first five units which are free of charge) is 2.13 THB or 0.47 SEK, the average for tariff 1.2 is 2.5 THB or 0.56 SEK. (MEA, 2010) Considering all tariffs the average price is 2.2 baht or 0.49 SEK per unit. (ERC 2009) These tariffs are however only the base tariff. The base tariff covers investment costs, transmission and distribution costs, energy costs, inflation rates and exchange rates. On top of this there is a service charge, value added tax (VAT) as well as a fuel adjustment mechanism (Ft) that is added. The service charge varies depending on which tariff is used and the VAT is 7% of the total electricity price. The Ft is adjusted every four months, the period January to April 2010 is set to 92.55 Satang per unit. (EGAT 2009b) An electricity bill for a one room apartment in Bangkok using 170 kWh/month works out to be 561 THB according to tariff 1.2, which represents an average of 3.30 THB or 0.74 SEK per kWh, with all the charges included, see Figure 10‐5 in Appendix. An occurring event is that landlords and apartment owners add an extra charge for the electricity usage in apartments and condos. This way they make an extra profit and/or cover the electricity usage in common areas of the apartment buildings. The average electricity price for these overcharged units is approximately 10 THB or 2.23 SEK. Teekasap (2010) Greacen (2010) believes that the Thai citizens are becoming more aware of the environmental consequences of their electricity usage, but that it is still the price that is the most important factor. Regarding power generation however, there are smaller groups that are directly affected by e.g. new coal fired power plants, and these citizens are very concerned about their situation. (Greacen 2010) 4.3.5 Renewable Energy in Thailand The year of 2008 (December), the total power capacity in Thailand was approximately 29 GW. This number represents both generated and domestic purchased power (EGAT, IPP and SPP). The renewable resources, mostly biomass, represented 288 MW which is about 1% of the grand total capacity. (EGAT 2009a) In November 2009 the Thai Government submitted a proposal to the Clean Technology Fund, CTF. CTF is a trust found started by ten industrial countries which “provides a very low‐interest long‐term financing (20‐40 years) for activities that will (i) reduce carbon emissions by the power sector; (ii) encourage energy savings in the transport sector by shifting to more efficient forms of transport; and (iii) promote efficient use of energy in buildings, industries and agriculture.” The proposal, also known as the Clean Technology Fund Investment Plan for Thailand, is supposed to support Thailand’s move toward low‐carbon growth. The investment plan presents five programs in order to reduce greenhouse gas emissions in, among other, the energy sector. The five programs will cost around 4.3 billion dollars (30 billon SEK or 135 billion baht) in total and the majority of this money will come from domestic sources, including the government itself. The amount of money requested from the Thai Government is $300 million and The World Bank (together with the International Finance Corp.) 32 Results is prepared to lend $500 million to these programs. However this has to be approved by the World Bank Group’s Board of Executive Directors. (The World Bank 2010) The electricity generation together with the transport sector generates the most GHG emissions in Thailand and in Bangkok those two sectors represent 84% of the emissions. (The Thai Government 2009) Recently, the Ministry of Energy presented the Alternative Energy Development Plan (AEDP) which has five visions: 1. To increase the amount of alternative energy to represent at least 20.3% of the total final energy consumption the year 2022 2. For Thailand to rely more on domestic energy sources and increase the energy security 3. To promote and encourage communities to utilize locally available resources and thereby integrate green energy utilization. 4. To improve the development of domestic alternative energy technology industry 5. To promote high efficiency alternative energy production (The Thai Government 2009) 4.3.6 Thailand Power Development Plan The Electricity Generating Authority of Thailand (EGAT) has formulated a power developing plan (PDP) that covers areas such as reliability of power supply, fuel diversification and power demand forecast. The PDP is executed according to the framework of the Ministry of Energy and the PDP covering the years 2007‐2021 was approved by the National Energy Policy Council (NEPC) and the cabinet in June 2007. This PDP was however reviewed twice and resulted in “Thailand Power Development Plan 2007‐2021: PDP 2007 Revision 2” which was endorsed by the cabinet and NEPC in March 2009. According to the latest version of the PDP, the total installed capacity in Thailand the year of 2021 is estimated to 52 GW. This number represents the total installed capacity with the old, retired power plants excluded. The plan also describes the new power projects for the years 2008‐
2021. These are presented in Figure 4‐5. 33 Results New Power Project Investments in Thailand 2008‐2021 [MW]
Nuclear; 2 000
Import; 3 300
Wind and solar; 6
IPP; 1 600
Natural Gas; 14 890
VSPP; 564
SPP; 1 986
Coal; 4 000
Hydro; 1 815
Figure 4‐5 ‐ New power project investments for 2008‐2021 presented in MW (EGAT 2009a) The biggest part of the new power projects includes natural gas as fuel and the second largest part represent coal based power plants. According to Teekasap (2010), the natural gas resources in Thailand will be depleted within twenty years or faster and that nuclear power is not avoidable due to the lack of natural resources in the country. The PDP explains that nuclear power is necessary to the power development in Thailand due to facts like that it will increase the efficiency and reliability in power generation as well as nuclear power plants do not generate GHG emissions. The SPP section represents energy from co‐generation based on fossil fuels (83%) and renewable fuels (17%) and the VSPP section is unspecified, however it represents either co‐generation or renewable fuels. (EGAT 2009a) 4.4 Absorption Cooling in Thailand At the Suwarnabhumi airport outside Bangkok, a co‐generation system is operational, producing electricity and chilled water through absorption cooling. The system, run by DCAP (District Cooling System and Power plant Co., Ltd), provides the Suwarnabhumi airport with electricity and cooling. DCAP is owned by EGAT (35%), PTT (35%) and MEA (30%). (Tangkavachiranon 2010) The plant uses natural gas as fuel, about 17 million ft³ (about 0.5 million m³) per day, and the main function is the electricity generation. The power plant is a combined cycle power plant that generates about 54 MW and the efficiency of the co‐generation plant is about 54%. Currently, the gas turbine used at the plant has too low efficiency which results in a very low, or no profit. However, the gas turbine is to be replaced in a near future. The electricity is mainly used at the airport but the non‐used electricity, about 5%, is distributed through EGAT. If there is a shortage of electricity, this is bought from EGAT as well. The rate of the electricity is set according to the steam process and is less than the rates MEA and PEA have, i.e. falling under the SPP category. (Tangkavachiranon 2010) After the electricity generation, the waste steam is transported about 2‐3 km and then used for producing chilled water through ten double‐effect absorption cooling machines working with LiBr/H2O as working couple. There are however only eight chillers in operation normally. (Singha 34 Results 2010) The double‐effect ACM were chosen due to their high COP‐value compared to single‐effect ACM. The system has a high reliability according to Tangkavachiranon(2010), about 95% with few breakdowns. (Tangkavachiranon 2010) The cooling that the system produces is sufficient for cooling the airport and other surrounding facilities as well. Chilled buildings at the airport are the main terminal, the concourse buildings (including all the gates), the AOB (airport operation building) and one hotel. The cooling system in the buildings consists of air‐handling units with varying sizes between 30‐40 RT (Refrigerant Tons; 1 RT = 12 000 Btu/hour of heat = 3.517 kW). The chilled water is sent through pipes in the ground. There are two pipes (d=500‐600 mm) with incoming cooling (T=5‐6 °C) and one pipe (d=900 mm) for returning water (T=11‐14 °C). In September 2009, Suwarnabhumi airport bought 7 million RTh from DCAP. This usage represents one month cooling usage and the cost was 39 million THB or 8.7 million SEK. However, the usage differs depending on the outdoor temperature. (Singha 2010) According to Singha (2010) there have been some problems with the cooling efficiency during the warmest month, April. This is due to the high surrounding temperature causing the cold water temperature in the pipes to rise. This results in less cooling at the airhandling units in the buildings and warmer indoor climate. (Singha 2010) Another example of a functional absorption cooling system is from the School of Renewable Energy Technology (SERT), Naresuan University, Phitsanulok in Thailand. Their absorption cooling machine is a solar driven LiBr/H2O machine. The system also includes heat buffering in the form of a storage tank, as well as an LPG‐fired backup heating unit. The evacuated tube solar collectors cover 81% of the heat demand for the absorption cooling machine, while the backup system covers the remaining 19%. (Jaruwongwittaya & Chen 2009) Greacen (2010) believes that absorption chillers are a promising technology and that they can have a future in Bangkok. He explained how it might be difficult to install large absorption chillers in apartments and condos, since most of the apartments in Bangkok do not have central systems for cooling but separate air conditioning units. Installing absorption chillers in buildings that are under construction would be easier, for example malls and industries. The absorption chiller at the airport was installed at the same time as the airport was built. (Greacen 2010) Tangkavachiranon (2010) believes that the market for absorption cooling in Thailand is “not good”. This is due to the fact that the fuel price and electricity price do not relate. 35 Results 36 Model 5 Model In this part of the report the model is presented. The model consists of calculations. These model calculations, performed in MS Excel, are based on the results in Chapter 4. The model is constructed so that a comparison between the effects due to waste incineration and biogas production with combustion can be made, both together with absorption cooling and both generated from MSW. The model is not made for a specific plant, the values and data used are averages or template values believed to represent what a plant constructed in Bangkok would be like. The model only includes energy and material flows, no financial aspects are included. Construction of plants and distribution of the absorption cooling is not included in the model either. The input for the model consists of data regarding the waste. The model itself consists of data and calculations for the different processes. Finally, the outputs of the model are the following: •
•
•
Generated absorption cooling Net electricity output Greenhouse gas emissions The model handles the waste generated and collected in Bangkok during one year and all the calculations originate from this amount. The output of the model is presented in 5.6, while the input‐
parameters, calculations and assumptions will be presented first in this chapter. Figure 5‐1 presents the different flows included in the model. Figure 5‐1 – A schematic figure of the different flows in the model 37 Model When data regarding production, incineration and combustion facilities have been made, these have been made with the assumption that BAT (Best Available Technology) will be used, or parameters that are believed to represent BAT. If the Waste‐to‐Energy systems suggested in this thesis were to be implemented in Bangkok, it is assumed that these need to be of high quality in order to offer an interesting alternative to the present systems. Due to difficulties in finding parameters for BAT technologies in countries with similar surroundings as Thailand, the majority of the values used originated from Swedish plants. When choosing parameters for the plants, these will be chosen for larger plants. Since the amount of available MSW is quite large it is considered a better option to have large production and/or incineration and combustion plants. The transportations of waste for both the waste incineration and the biogas production are not taken into account in the model. This will be analyzed further in 6.8. The internal electricity usage for both scenarios is assumed to originate from natural gas, since gas in the marginally produced in Thailand, see 4.3, produced in a turbine with an efficiency of 50% (Börjesson & Berglund 2003). The generated electricity within the incineration/combustion plants is also assumed to replace electricity produced from natural gas and the cooling produced replaces compression cooling driven by natural gas produced electricity. The biogas process uses heat (for digestion) which will be taken from the biogas combustion process. Both WTE scenarios will lead to a decrease amount of landfilled/dumped wasted, which would lead to reduced emissions of methane gas and carbon dioxide. These reduced emissions are not taken into consideration, i.e. they are not included in the calculations even though they give reduced emissions. Generally, the abbreviation WI is used to display different value regarding the waste incineration alternative while BG represents the biogas production and combustion. Also, the calculations are displayed with rounded numbers, but have been performed with specific numbers. 5.1 In­Parameters The Thai waste contains 63.6% organic waste, 16.2% plastic and 8.2% paper. The complete waste composition can be viewed in Figure 10‐3 in Appendix. (PCD 2006) The amount of collected waste in Thailand is 14.8 million tones per year, out of this 21.1% is generated in Bangkok (TNSO 2007). 85% of the generated waste is collected. (PCD 2006b) Calculations for amount of generated and collected MSW in Bangkok: MSW : Municipal Solid Waste m (GMSW )Thailand : Mass of Generated MSW in Thailand [kg] mMSW : Mass of Available (Generated and Collected) MSW in Bangkok [kg] P (G MWS ) Bangkok : Percentage Generated in Bangkok [%] P (C MSW ) : Percentage Collected [%] 38 Model m (G MWS ) Thailand = 1.5 ⋅ 10 10 kg (1) P (G MSW ) Bangkok = 21 .1% (2) P (C MSW ) = 85 % (3) m MSW = m (G MSW ) Thailand ⋅ P (G MSW ) Bangkok ⋅ P (C MSW ) (4) (1), (2), (3) & (4): m MSW = 1.5 ⋅ 10 10 ⋅ 0.211 ⋅ 0.85 = 2.7 ⋅ 10 9 kg (5) 5.2 Waste Incineration In this part of the model, calculations regarding the energy content of the waste and of the torch fuel used will be presented along with the electricity and heat generation. The internal energy usage will be calculated as well as the net energy output. 5.2.1 Energy Content and Torch Fuel Usage The calorific value of the waste varies between 8 and 12 MJ/kg according to the Pollution Control Department (PCD) (2006). Udomsri, Martin & Fransson (2010) say that the value varies between 6 and 12 MJ/kg in the country and that in Bangkok the lower heating value is 9 MJ/kg, which is the value used in the model. Natural gas is assumed to be used as torch‐fuel for the waste incineration. The incineration process needs 3 m3 per ton of MSW (Scipioni et al. 2009) Calorific value for natural gas is 39.5 MJ/m3. (Naturvårdsverket 2010c) All the waste collected is assumed to be incinerated. Calculations for volume of NG used and energy content of the available MSW and NG: NG : Natural Gas E : Energy Content [MJ] or [GWh] (both units are used, it is however always specified which one is used in each calculation) CV : Calorific Value [MJ/kg] V : Volume [m3] (5): m MSW = 2.7 ⋅ 10 9 kg CV MSW = 9.0 MJ / kg (6) E MSW = CV MSW ⋅ m MSW (7) 39 Model (5), (6) & (7): E MSW = 9 ⋅ 2.7 ⋅ 10 9 = 2.4 ⋅ 10 10 MJ (8) V NG = 3 ⋅ 10 −3 ⋅m MSW (9) (5) & (9): V NG = 3 ⋅ 10 −3 ⋅ 2 .7 ⋅ 10 9 = 8.0 ⋅ 10 6 m 3 (10) CVNG = 4.0 ⋅ 101 MJ / m 3 (11) ENG = VNG ⋅ CVNG (12) (10), (11) & (12): E NG = 8.0 ⋅ 10 ⋅ 4.0 ⋅ 10 = 3.1 ⋅ 10 MJ (13) 6
1
8
E MSW & NG = E MSW + E NG (14) (8), (13) & (14): E MSW & NG = 2.4 ⋅ 10 10 + 3.1 ⋅ 10 8 = 2.4 ⋅ 10 10 MJ (15) This equation clearly shows the relation between the energy content of the MSW in comparison to the energy content of the NG. 5.2.2 Electricity and Heat Generation Qiu and Hayden (2009) write that the electrical efficiency of a MSW incineration plant is normally below 25% due to low steam parameters. Poma, Vittorio & Consonni (2010) use 19.4% as the electrical efficiency and 41.8% as thermal efficiency for a waste incineration plant when investigating the impact of waste incineration plant integrated with a combined cycle in Italy. For this model, the total efficiency of the waste incineration is assumed to be 91%, with an electrical efficiency of 22% and thermal efficiency of 69%. These values are presented for a waste incineration plant with an effect of 30 MW representing today’s technique in Sweden according to Hansson et al (2007). Calculations for electricity and heat generation: η : Efficiency [‐] el : Electric/Electricity th : Thermal η el ,WI = 0.22 (16) η th,WI = 0.69 (17) 40 Model E out = Ein ⋅η (18) 10
9
3
(15), (16) & (18): Eel ,out ,WI = 2.4 ⋅ 10 ⋅ 0.22 = 5.3 ⋅ 10 MJ = 1.5 ⋅ 10 GWh (19) ´10
10
3
(15), (17) & (18) Eth ,out ,WI = 2.4 ⋅ 10 ⋅ 0.69 = 1.7 ⋅ 10 MJ = 4.6 ⋅ 10 GWh (20) 5.2.3 Internal Energy Usage and Net Energy Output The internal energy usage for the incineration process is assumed to be 142 kWh/ton of MSW. This value is collected from the IPPC (2006). Scipioni et al (2009) present two different electrical usages for waste incineration plants: 151 or 145 kWh/ton for a system with dry/wet flue gas purification. These numbers are however for plants without heat recovery. An energy balance for the Swedish waste incineration plant at Sävenäs confirms these numbers with an energy usage of 140 kWh per ton of MSW (Renova 2008). Calculations for internal electricity usage: int : Internal (5): mMSW = 2.7 ⋅ 10 kg 9
−7
The internal energy usage 142 kWh/ton of MSW: Eint,el ,WI = 1.4 ⋅ 10 ⋅ mMSW (21) 9
2
−7
(5) & (21): Eint,el ,WI = 1.4 ⋅ 10 ⋅ 2.7 ⋅ 10 = 3.8 ⋅ 10 GWh (22) 3
(19): Eel ,out ,WI = 1.5 ⋅ 10 GWh E net ,out = E out − Eint (23) 3
2
3
(22), (19) & (23): E net ,el ,out ,WI = 1.5 ⋅ 10 − 3.8 ⋅ 10 = 1.1 ⋅ 10 GWh (24) 5.3 Biogas Production and Combustion In this chapter the calculations regarding the amount organic fraction of the MSW that is used for biogas production will be presented. Also, as in chapter 5.2, the calculations of electricity and heat generation together with the internal energy usage and net energy output for biogas production and combustion will be shown. 41 Model 5.3.1 Organic Fraction of MSW and Sorting Percentage When modelling the biogas production the waste is assumed to be sorted before the production. The material left after the sorting goes to landfill. After the sorting process, 90% of the organic waste is assumed to be present for the biogas production. This means that 10% of the organic material, as well as all the non organic material, is sent to landfill. The energy usage for the sorting process is not included in the model. The organic part of the waste is 63.6% (PCD 2006b). Calculations for the amount of OFMSW that is used for biogas production and the amount that goes to landfill: P (OFMSW ) : Percentage Organic Fraction of MSW [%] P ( BG OFMSW ) : Percentage of OFMSW used in Biogas Process (after sorting) [%] P ( LFOFMSW ) : Percentage of OFMSW that goes to Landfill [%] m ( BG OFMSW ) : Mass of the OFMSW used in Biogas Production [kg] m ( LFOFMSW ) : Mass of the OFMSW that goes to Landfill [kg] P (OFMSW ) = 63.6% (25) P ( BG OFMSW ) = 90 % (26) (5): m MSW = 2.7 ⋅ 10 9 kg m ( BG OFMSW ) = m MSW ⋅ P (OFMSW ) ⋅ P ( BG OFMSW ) (27) (5), (25), (26) & (27): m ( BG OFMSW ) = 2.7 ⋅ 10 9 ⋅ 0.633 ⋅ 0.9 = 1 .5 ⋅ 10 9 kg (28) P ( LFOFMSW ) = 1 − P ( BG OFMSW ) (29) m ( LFOFMSW ) = m MSW ⋅ P (OFMSW ) ⋅ P ( LFOFMSW ) (30) (5), (25), (26), (29) & (30): m ( LFOFMSW ) = 2.7 ⋅ 10 9 ⋅ 0.633 ⋅ (1 − 0.9) = 1.7 ⋅ 10 8 kg (31) 5.3.2 Electricity and Heat Generation The biogas production is assumed to occur with a biogas yield of 3.7 GJ/ton of raw material. This value is taken from Börjesson & Berglund (2003, p. 4) for organic municipal waste with a dry matter content of 30% (i.e. a moisture content of 70%). The efficiency of the turbine is set to 40% electrical 42 Model efficiency and 45% thermal efficiency corresponding to the efficiency of a large turbine engine (over 1 MW) (Börjesson & Berglund 2003). Calculations for electricity and heat generation: BGY : Biogas Yield [MJ/kgOFMSW] BGY = 3.7MJ / kgOFMSW (32) (28): m( BGOFMSW ) = 1.5 ⋅ 10 kg 9
E BG = BGY ⋅ m( BGOFMSW ) (33) (32), (28) & (33): E BG = 3.7 ⋅ 1.5 ⋅ 10 = 5.6 ⋅ 10 MJ (34) 9
9
(18): E out = Ein ⋅ η η el , BG = 0.40 (35) η th, BG = 0.45 (36) 9
9
2
(18), (34) & (35): E el ,out , BG = 5.6 ⋅ 10 ⋅ 0.40 = 2.2 ⋅ 10 MJ = 6.2 ⋅ 10 GWh (37) 9
9
2
(18), (34) & (36): Eth ,out , BG = 5.6 ⋅ 10 ⋅ 0.45 = 2.5 ⋅ 10 MJ = 7.0 ⋅ 10 GWh (38) 5.3.3 Internal Energy Usage and Net Energy Output The energy usage for the production and combustion is set to 64 kWh electricity and 89 kWh heat per ton of treated OFMSW. These are values for a “large‐scale biogas plants using traditional, one‐
stage digestion technology operating at mesophilic temperatures” with organic MSW as feedstock. (Börjesson & Berglund 2006) Calculations for internal electricity usage: Eint,el , BG = 6.4 ⋅ 10 −8 ⋅ m( BGOFMSW ) (39) Eint,th, BG = 8.9 ⋅ 10 −8 ⋅ m( BGOFMSW ) (40) (28): m( BGOFMSW ) = 1.5 ⋅ 10 kg 9
43 Model 9
1
−8
(28) & (39): Eint,el , BG = 6.4 ⋅ 10 ⋅ 1.5 ⋅ 10 = 9.7 ⋅ 10 GWh (41) 9
2
−8
(28) & (340): Eint th , BG = 8.9 ⋅ 10 ⋅ 1.5 ⋅ 10 = 1.4 ⋅ 10 GWh (42) (23): E net ,out = Eout − Eint 2
1
2
(37), (41) & (23): E net ,el ,out , BG = 6.2 ⋅ 10 − 9.7 ⋅ 10 = 5.3 ⋅ 10 GWh (43) 2
2
2
(38), (42) & (23): E net ,th ,out , BG = 7.0 ⋅ 10 − 1.4 ⋅ 10 = 5.7 ⋅ 10 GWh (44) 5.4 Absorption Cooling The absorption cooling machine is assumed to be either a low‐temperature driven lithium bromide semi‐effect absorption chiller or a traditional single step lithium bromide absorption chiller, see 3.11. Both these machines have COPthermal around 0.7. (Rydstrand, Martin, Westermark 2004) The electricity use for the absorption cooling machine is so small that it is neglected. COP AC : Coefficient of Performance for Absorption Chiller COP AC = 0.7 (45) E cooling = COP AC ⋅ E heat (46) 5.4.1 Generated from Waste Incineration Calculations for absorption cooling generated from waste incineration: (20): E th ,out = 4.6 ⋅ 10 3 GWh (22), (45) & (46) : E cooling = 0.7 ⋅ 4.6 ⋅ 10 3 = 3.2 ⋅ 10 3 GWh (47) 5.4.2 Generated from Biogas Combustion Calculations for cooling generated from biogas combustion: (44): E net ,th ,out = 5.7 ⋅ 10 2 GWh (44), (45) & (46): E cooling = 0.7 ⋅ 5.7 ⋅ 10 2 = 4.0 ⋅ 10 2 GWh (48) 5.5 Greenhouse Gas Emissions The greenhouse gas emissions are included in the model while a general discussion regarding other emissions can be viewed in the Analysis. The greenhouse gas emissions will be calculated using Global Warming Potential (GWP). GWP describes the effect a gas has on climate change, in relation to carbon dioxide. Based on the GWP, emissions are calculated in carbon dioxide equivalents (CO2 44 Model eq). This way, carbon dioxide equivalents present a standard of measuring the impacts of emitted greenhouse gases. Carbon dioxide has a GWP of one, while methane has a GWP of 21. (IETA 2009) Emissions from the two different processes are presented separately. All electricity used for processes are assumed to originate from natural gas produced electricity, since this is the marginally produced electricity in Thailand. Likewise, all electricity produced is assumed to replace natural gas produced electricity. The absorption cooling produced replaces compression cooling, also produced from electricity originating from natural gas. The replaced compression cooling is assumed to have been produced with compression cooling machine with COP=2. This value is representative for smaller cooling machines, like the ones the absorption cooling would replace. (Rydstrand, Martin & Westermark 2004) Emission factor for natural gas is 57 kg per GJ (Naturvårdsverket 2010b). Equations used when calculating emissions (generated or avoided) from natural gas produced electricity: EF : Emission Factor [kg/MJ] or [kg/kg] m CO 2 eq : Mass of greenhouse gas emissions (generated or avoided) in CO2 equivalents [ton] EFNG = 5.7 ⋅ 10 −2 kg CO2 / MJ NG (49) η turbine ,el = 0.5 (50) E NG =
E el
η turbine
(51) m CO 2 ,eq = E NG ⋅ EF NG (52) (49), (50), (51) & (52): m CO 2 ,eq =
E el
⋅ 5.7 ⋅ 10 − 2 (53) 0 .5
5.5.1 Waste Incineration GHG emissions originating from the waste incineration process are due to the incineration of the fossil parts of the waste as well as the use of internal electricity and torch‐fuel. The reduction of GHGs occurs due to replaced electricity and replaced compression cooling. The emission factor for waste is 25 kg CO₂ per GJ waste. (Naturvårdsverket 2010b) This value varies according to waste composition and it is hard to find a value appropriate for the Thai waste composition. This represents the fossil part of the waste. 45 Model 5.5.1.1 Generated Emissions Emissions from incineration of MSW (“inc”): (5): m MSW = 2.7 ⋅ 10 9 kg (6): CV MSW = 9.0 MJ / kg EFMSW = 2.5 ⋅ 10 −2 kg CO2 / MJ MSW (54) m CO 2 eq ,inc = m MSW ⋅ CV MSW ⋅ EF MSW (55) (5), (6), (54) & (55): mCO2eq ,inc = 2.7 ⋅ 10 9 ⋅ 9 ⋅ 2.5 ⋅ 10 −2 = 6.0 ⋅ 10 5 ton (56) Emissions from torch fuel usage (“TF”): (10): V NG = 8.0 ⋅ 10 6 m 3 (11): CV NG = 4.0 ⋅ 10 1 MJ / m 3 (49): EFNG = 5.7 ⋅ 10 −2 kg CO2 / MJ NG m CO 2 eq ,TF = V NG ⋅ CV NG ⋅ EF NG (57) (10), (11), (49) & (57): mCO2eq ,TF = 8.0 ⋅ 10 6 ⋅ 4.0 ⋅ 101 ⋅ 5.7 ⋅ 10 −2 = 1.8 ⋅ 10 4 ton (58) Emissions from internal electricity usage (“int,el”): 2
9
(22): Eint,el ,WI = 3.8 ⋅ 10 GWh = 1.3 ⋅ 10 MJ (53): m CO 2 eq =
E el
⋅ 5.7 ⋅ 10 − 2 0 .5
(22) & (53): mCO2 int, el =
1.3 ⋅ 10 9
⋅ 5.7 ⋅ 10 − 2 = 1.5 ⋅ 10 5 ton (59) 0 .5
46 Model 5.5.1.2 Avoided Emissions Avoided emissions from replaced electricity usage (“repl,el”): 3
9
(19): Eel ,out ,WI = 1.5 ⋅ 10 GWh = 5.3 ⋅ 10 MJ (53): m CO 2 eq =
E el
⋅ 5.7 ⋅ 10 − 2 0 .5
(19) & (56): m CO2eq , repl .el =
5.3 ⋅ 10 9
⋅ 5.7 ⋅ 10 − 2 = 6.0 ⋅ 10 5 ton (60) 0 .5
Avoided emissions from replaced compression cooling (“repl,CC”): 3
(47): Ecooling ,WI = 3.2 ⋅ 10 GWh COPCC = 2 (61) Erepl ,CC =
Ecooling
COPCC
(62) 3.2 ⋅ 10 3
= 1.6 ⋅ 10 3 GWh = 5.8 ⋅ 10 9 MJ (63) 2
(47), (61) & (62): E repl ,CC =
(53): m CO 2 eq =
E el
⋅ 5.7 ⋅ 10 − 2 0 .5
(53) & (63): mCO2eq , repl ,CC =
5.8 ⋅ 10 9
⋅ 5.7 ⋅ 10 − 2 = 6.7 ⋅ 10 5 ton (64) 0 .5
5.5.1.3 Total Emissions The generated emissions and avoided emissions add up to: (56), (58), (59), (60) & (63): m CO 2 eq ,TOT = m CO 2 eq ,inc + m CO 2 eq ,TF + m CO 2 eq 2 ,int, el − m CO 2 eq , repl ,el − m CO 2 eq , repl ,CC = = 6.0 ⋅ 10 5 + 1.8 ⋅ 10 4 + 1.5 ⋅ 10 5 − 6 .0 ⋅ 10 5 − 6.7 ⋅ 10 5 = = − 5 .0 ⋅ 10 5 ton (65) 47 Model 5.5.2 Biogas Production and Combustion The GHG emissions that occur due to the production and combustion of biogas are from the production of electricity used in biogas process and the methane leakage from landfilling the organic parts left after sorting of the waste. Reduction of greenhouse gas emissions takes place due to replaced electricity production from generated electricity as well as replaced compression cooling. 5.5.2.1 Generated Emissions The material left after that the waste has been sorted is considered to be put on open dumps. These dumps generate a number of emissions, both to the ground and to the air. The treated and calculated emissions are carbon dioxide (CO2) and methane (CH4). 1 kg of CH₂ represents 21 kg of CO₂ in GWP (EPA 2010). The emissions are 10.6 m3 CO2 and 15.8 m3 CH4 per ton of organic landfilled waste. The emissions represent open dumping during a 1‐5 year time period. (Obersteiner et al. 2007) Emissions from landfilling (”LF”): Densities of 1.80 kg/ m3 for CO2 and 0.68 kg/ m3 for CH4 give emission factors according to: EFLF ,CO2 = 1.1 ⋅ 10 −2 ⋅ 1.8 = 1.9 ⋅ 10 −2 kg CO2 / kg OFMSW (66) EFLF ,CH 4 = 1.6 ⋅ 10 −2 ⋅ 0.7 = 1.1 ⋅ 10 −2 kg CH 4 / kg OFMSW (67) (31): m ( LFOFMSW ) = 1.7 ⋅ 10 8 kg (
)
m CO 2 eq , LF = m ( LFOFMSW ) ⋅ EF LF ,CO 2 + 21 ⋅ EF LF ,CO 4 (68) (66), (67), (31) & (68): mCO2 , LF = 1.7 ⋅ 10 8 ⋅ (1.9 + 21 ⋅ 1.1) ⋅ 10 −2 = 4.1 ⋅ 10 4 ton (69) Emissions from internal electricity usage (“int,el”): 1
8
(41): Eint,el , BG = 9,7 ⋅ 10 GWh = 3.5 ⋅ 10 MJ (53): m CO 2 eq =
E el
⋅ 5.7 ⋅ 10 − 2 0 .5
(41) & (53): m CO2 int, el =
3.5 ⋅ 10 8
⋅ 5.7 ⋅ 10 − 2 = 4.0 ⋅ 10 4 ton (70) 0 .5
5.5.2.2 Avoided Emissions Avoided emissions from replaced electricity usage (“repl,el”): 2
9
(37): Eel ,out , BG = 6.2 ⋅ 10 GWh = 2.2 ⋅ 10 MJ 48 Model (53): m CO 2 eq =
E el
⋅ 5.7 ⋅ 10 − 2
0 .5
(37) & (53): mCO2eq ,repl .el =
2.2 ⋅ 10 9
⋅ 5.7 ⋅ 10 − 2 = 2.6 ⋅ 10 5 ton (71) 0.5
Avoided emissions from replaced compression cooling (“repl,CC”): 2
(48): E cooling , BG = 4.0 ⋅ 10 GWh (61): COPCC = 2 (62): E repl ,CC =
Ecooling
COPCC
(48), (61) & (62): E repl ,CC =
(53): m CO 2 eq =
4.0 ⋅ 10 2
= 2.0 ⋅ 10 2 GWh = 5.5 ⋅ 10 7 MJ (72) 2
E el
⋅ 5.7 ⋅ 10 − 2 0 .5
(53) & (72): mCO2eq , repl ,CC =
5.5 ⋅ 10 7
⋅ 5.7 ⋅ 10 − 2 = 6.3 ⋅ 10 3 ton (73) 0 .5
5.5.2.3 Total Emissions The generated emissions and avoided emissions add up to: (69), (70), (71) & (73): m CO 2 eq ,TOT = m CO 2 eq , FL + m CO 2 eq ,int, el − m CO 2 eq , repl ,el − m CO 2 eq , repl ,CC = = 4 .1 ⋅ 10 4 + 4 .0 ⋅ 10 4 − 2 .6 ⋅ 10 5 − 6 .3 ⋅ 10 3 = = − 1 .8 ⋅ 10 5 ton (74) 49 Model 5.6 Results from the Model In Table 5‐1, the output of the model is presented. This output is considered the results of the model. Table 5‐1 –Results from Model Generated Cooling
Net Electricity Output
Emissions
Waste
Incineration
3250
1100
-500
Biogas Production
& Combustion
400
530
-180
[GWh per year]
[GWh per year]
[1000 ton CO2 eq per year]
Both alternatives generate cooling and electricity. The electricity output is the net output, i.e. the internal electricity usage is also taken into account. Both alternatives do also have negative amounts of emissions, i.e. they both replace greenhouse gas emissions, when compared to the current situation. The waste incineration alternative generates a lot more cooling and electricity than the biogas alternative. If waste incineration was implemented under these circumstances it would generate approximately eight times more cooling and two times more electricity compare to the biogas alternative. The waste incineration alternative does also replace the largest amount of greenhouse gas emissions, almost three times the amount that the biogas production and incineration replaces. 5.7 Sensitivity Analysis The model includes quite a few parameters, the determination of these involved difficulties at times. Sometimes it was hard to find values representing the situation in Thailand. Other times, the knowledge and/or time were not sufficient to make perfect parameter choices. Due to this, a sensitivity analysis is of big importance, in order to see which parameters influence the results. Especially the parameters that were chosen without complete information are important to study. Consequently, most parameters were varied and the sensitivity analysis is quite extensive. The results will be presented here shortly, one parameter at a time, while all of the results from the sensitivity analysis are presented in Appendix: Table 10‐1 to Table 10‐14. Some of the alterations of efficiencies only include decreases of the efficiencies, since all, or some, of the possible increases results in a total efficiency of over 100%. When only one or two increases have been possible without reaching efficiencies over 100%, these have been performed. The emissions output parameter is negative for all of the alterations, i.e. it will in all of the cases represent a decrease in GHG emissions relative to the situation today. Therefore these emissions will be referred to as replaced emission, and an increase in the replaced emissions therefore implies a larger negative amount of emissions. 5.7.1 Percentage of Collected Waste Alterations of the percentage of collected waste affect all parameters for both alternatives, see Table 10‐12 in Appendix. The increase of 30% was not performed since this would mean a higher collection percentage than 100%. Both of the alternatives are affected in similar ways; a decreased collecting percentage results in less generated cooling and less net electricity output while the emissions reduction also decreases. 50 Model 5.7.2 Efficiencies Waste Incineration When decreasing the electrical efficiency for the waste incineration, the net electricity output decreases while the amount of generated cooling stays the same, see Table 10‐3 in Appendix. When the net electricity output is decreasing, the reduced emissions decrease since the amount of replaced NG‐produced electricity is decreasing. The biogas alternative is not affected by this parameter. Table 10‐4 in Appendix shows the results when altering the heat efficiency of the waste incinerator. Only one of the positive alterations has been made. When decreasing the thermal efficiency, the generated cooling is decreasing while the net electricity output stays the same. Decreased efficiency also contributes to lower amounts of reduced emissions, due to less replaced compression cooling. The biogas alternative is not affected by these alterations. 5.7.3 Energy Input Waste Incineration Table 10‐5 in Appendix presents the alterations regarding internal electricity usage in waste incinerators. If either increasing or decreasing the internal usage, the amount of generated cooling stays the same. However, a higher internal usage results in decreased net electricity output. The emissions are also affected; decreased internal usage results in more replaced emissions and increased internal usage gives less replaced electricity: a decrease of 30% replaces 550 000 ton of carbon dioxide compared to 504 000 ton which was the case without the alteration. The alteration of the torch fuel usage in the waste incineration process did not affect the results significantly, see Table 10‐15 in Appendix. A 30% increase changed the generated cooling from 3252 GWh to 3260 GWh, the net electricity output reached 1108 GWh instead of 1102 GWh and the reduced emissions decreased from 504 000 ton to 503 000 ton. 5.7.4 Sorting Percentage Biogas Process & Biogas Yield In Table 10‐6 (see Appendix), alterations in the sorting percentage regarding the biogas production are investigated. The increasing of the sorting percentage only involves a 10% increase. The increased sorting percentage contributes to both a higher amount of generated cooling and a higher net electricity output. The reduced emissions decrease with decreasing sorting percent, due to an increasing amount of landfilled organic waste, as well as less replaced electricity and compression cooling, and the same is true for the opposite. For the 30% decrease the reduced emissions are 3 000 ton instead of 181 000 which is the value without the alteration. The change in sorting percent does not affect the waste incineration outputs since 100% of the waste is considered to be combusted. Table 10‐7 in Appendix presents the outgoing results affected by a change in biogas yield. The waste incineration alternative is not affected by this alteration. However, when increasing the biogas yield, the generated cooling rises, as well as the net electricity output. The emissions are also affected; increased biogas yield contributes to an increased reduction. 5.7.5 Efficiencies Biogas Production and Combustion According to Table 10‐8 in Appendix, the generated cooling is not affected by an altered electric efficiency for the biogas combustion. The net electricity output is however affected; a higher electrical efficiency contributes to an increased net electricity output. Since the amount of replaced NG produced electricity is increases with an increased net electricity output, a positive alteration in electrical efficiency results more replaced emissions. 51 Model Alterations in the thermal efficiency of the biogas combustion, see Table 10‐9 in Appendix, affects the amount of generated cooling; when increasing the efficiency, the generated cooling increases. The net electricity output stays the same. The replaced emissions are also somewhat affected, a 30% decrease in thermal efficiency changes the replaced emissions from 182 000 ton to 179 000 ton. 5.7.6 Energy Input Biogas Production and Combustion Increasing alterations of the internal electricity usage for the biogas production and combustion contributes to lower amount of net electricity output, see Table 10‐10 in Appendix. The generated cooling is not affected by any alterations regarding this parameter. As for the emissions, increased internal electricity usage results in less replaced emissions due to less replaced NG produced electricity. The situation is the opposite for a decrease in internal electricity usage. When changing the internal heat usage in the biogas process, see Table 10‐11 in Appendix, it is only the generated cooling and the emissions that are affected. The emissions are however only marginally influenced; if increasing the internal heat usage, the emissions are somewhat lower. A 30% decrease in thermal efficiency changes the replaced emissions from 181 000 ton to 182 000 ton. This is due to less produced cooling and less replaced compression cooling. 5.7.7 Chiller Parameters When altering the COP for the absorption chiller, this affected both alternatives, see Table 10‐13 in Appendix. The emission reduction for the waste incineration was affected a lot more than the emission reduction for the biogas alternative. For a 30% decrease, the reduced emissions for the biogas alternative changed from 181 000 ton to 180 000 ton. For the waste incineration alternative, the decrease is from 504 000 ton to 304 000 ton. The generated cooling and the net electricity output were more similar in their changes, when comparing the two alternatives. The alterations of the COP value for the compression cooling chillers that are assumed to be replaced with absorption chillers were performed with different alterations than previous ones, see Table 10‐14 in Appendix. The COP of two, which is used is the model, represents a smaller compression cooling unit, like those used in apartments. However, this COP can vary and be as high as four. Therefore the positive alterations were changed for this parameter; the increases are 100%, 50% and 25%, while the decreases are the same as before. A 100% increase results in a COP value of four, which could be the case, even though this is more common for larger compression cooling machines. The alterations only affect the reduced emissions, for both alternatives, since it is only the replaced compression cooling that is altered in the model. An increase in COP decreases the amount of reduced emissions, since a higher COP value implies that the cooling that is replaced occurred with a higher efficiency. The 100% increase resulted in the waste incineration reduced emissions changing from 504 000 ton to 170 000 ton, while for the biogas alternative the change was from 181 000 ton to 178 000 ton. 5.7.8 Organic Fraction and Calorific Value of MSW None of the alternations of the organic fraction of MSW affects the outgoing parameters of the waste incineration, since there is no relationship between these parameters in the model calculations, as shown in Table 10‐1 in Appendix. The biogas production is however affected; the amount of generated cooling as well as the net electricity output is increasing with higher organic fraction in the waste. An increase in electricity, 528 to 686 GWH, and cooling output, 397 to 517 GWh, results in more replaced electricity and cooling, the emissions from landfill/open dump are also 52 Model reduced due to the lower part of OFMSW that is sent to landfills. This increases the total replaced emissions from 181 000 to 236 000 ton. Table 10‐2 in Appendix shows the changes in the outgoing parameters due to alternations in the calorific value of the MSW. The biogas alternative is not affected by this alteration since it is not connected with this parameter in the model calculations. The waste incineration alternative is however affected; a higher calorific value contributes to a higher amount of generated cooling as well as electricity output. The total emissions from the waste incineration are decreasing with increasing calorific value. This is due to more replaced natural gas produced electricity. Even the largest negative change of calorific value has higher outgoing parameters than the biogas alternative. 53 Model 54 Analysis 6 Analysis In this chapter, the results from Chapter 4 and Chapter 5 will be discussed and analyzed. As mentioned, the thesis is performed through a Swedish perspective, so when analyzing the Thai systems, this perspective is present. The perspective has turned out to be relevant in order to define the differences between the energy systems that are evaluated. The Swedish perspective will not be analyzed separately, instead it is included throughout the analysis. 6.1 Data Collection The process of collecting information and facts for the results has involved certain challenges, this is however often the case during this kind of process. Often, the information wanted has not been available; sometimes it has only been available in Thai and other times ambiguous information has been found. There have also been some difficulties with information being out of date. This has made the process of finding information hard and more time consuming than expected. When possible, different sources and references were studied and compared in order to find accurate information. The situation with difficulties of finding desired information results in not having complete information. References that have not been considered as trustful have not been used, but this has instead left gaps in the research. Sometimes when ambiguous information has been encountered, this has been used anyway. Other times, assumptions and simplifications have been made in order to interpret the material. This makes it plausible that incorrect information is present in the thesis to some extent. Incorrect information is however not considered to be present in any large extent, and it is assumed to not affect the results or conclusions largely. Regarding the studied materials about the energy system and such in Thailand, several of the writers are Thai authorities. These documents have involved some unclear information regarding the Thai energy market and its development. The authors are generally precautious regarding the formulations of the objectives in the documents. When there has been a possibility for an interview with an expert within a certain area, this information has been used as fact. This has involved risk of personal opinions and bias information. Another possible source for bias information has been the interview questions. These have been designed in order to collect as much information as possible. That is, the question may sometimes have been designed with the hope of receiving a certain answer. This way of interviewing has however made it possible to receive more precise information at a higher level of knowledge. Since the interviews were all performed in English, the language barriers might have influenced. During the investigation, there have been some issues with the different definitions of the word landfill. Written in chapter 4.2.1, there are open dumps, landfills and sanitary landfills operating in Thailand. We have tried to figure out the difference between landfills and sanitary landfills, but our sources do not come up with a complete answer. Therefore we are aware of that there could be some errors in the statistics treated in the thesis. However, we believe that the results and overall conclusions will not be largely affected by this definition issue since there is only a small fraction of the waste influenced. 55 Analysis Due to political situation in Bangkok during the time this thesis was written, see 4.1.1, the results may have been influenced. More interviews than those performed were desired, it is possible that the number of interviews has been affected negatively by the disturbances. 6.2 Energy Situation and Energy Development in Thailand It has been clear that Thailand currently is encouraging green energy solutions, but it is only in a small scale and they seem to be in the early phases compared to, e.g. Sweden. As Figure 4‐3 shows, the power generation in Thailand today is mostly generated from fossil fuels, mainly natural gas, and the renewable resources only represent a fraction. The PDP presented in 4.3.6, includes some obscurities regarding the different power projects and which fuel type they are based on. However, since it seems like the natural gas will be depleted within twenty years, see 4.3.6, investing in such a large amount of natural gas based power projects seems quite unconsidered. The investments in renewable resources during these years are small compared with the fossil fuel based projects. The interest of reducing the Thai GHG emissions is expressed in the Clean Technology Fund Investment Plan for Thailand, see 4.3.5. Since Thailand might receive financial support for renewable projects from the World Bank through the Clean Technology Fund, we think the projects based on renewable fuels in the PDP seem quite small. We do however think that some of the money from the CTF favorably could be used to develop the waste incineration and the biogas production and combustion, or at least improve the current waste handling. This would be a step toward reduced usage of fossil fuels and thereby GHG emissions. In 4.3 it is explained that natural gas is considered as marginal electricity in Thailand. We are aware that the source for this statement is quite outdated, but it was the only one available. The majority of the fuel for power generation in Thailand originates from natural gas, the second largest is lignite/coal, implying that if using average electricity the GHG emissions would be similar. 6.3 The Thai Waste Situation According to the European waste hierarchy, see chapter 3.4.1, recycling is a better alternative than waste incineration. We do not know which alternative is the most resource‐efficient for Thailand. We do however think that the waste should be reduced and reused to the extent possible, and it is very likely that recycling is a better option than waste incineration. Neither of the waste treatment methods used in the thesis prevents waste generation, which needs to be taken into consideration when evaluating different waste handling methods. However, since waste prevention does not seem to be a prioritized issue in Thailand, other waste treatment methods have to be considered in order to reduce the waste volumes. The current waste treatment which mainly consists of landfilling and open dumping indicates that both waste incineration and biogas production would be improvements. With both of the suggested alternatives: waste incineration or using producing biogas with combustion as waste treatment, the waste volume is decreased and the energy in the material is used. As for the research regarding the emissions from the landfills and open dumps, we have not found much information involving Thailand. This could be due to lack of data, classified material or information only available in Thai. Even if we have not found any sources stating clearly that landfilling and open dumping is the worst waste treatment methods, we draw this conclusion out of the investigated information found, see further in 3.8.1. According to the EU’s waste hierarchy 56 Analysis landfilling is the last alternative for waste treatment and we therefore considered this as a non‐
preferable method. 6.3.1 Waste Development As explained in chapter 1.3 we have not considered the recycling possibilities for the generated waste. That is, we have not compared the alternative of recycling the waste instead of generating energy from it. The results in chapter 4 have showed that a lot of the waste has recycling possibilities which verifies the fact that if recycling was possible this could alter the conditions and affect the research questions. The overall Thai waste has recycling possibilities of about 93%, see 4.2.1. If all of this was recycled, the possibilities for energy recovery from the waste would be a lot smaller. We reckon that the waste incineration would probably be more affected than the biogas production since recycling would be an option for non‐organic materials such as paper and plastic, while the organic part has fewer recycling options. If the paper and plastic content was changed, this would affect the possible waste incineration, while production of biogas would not be affected if the organic part was the same. If either of the two investigated waste treatment methods would be introduced in Bangkok, it is not likely that all of the generated municipal solid waste will be used for this, at least not within a near future. Developments like these take time and we do not expect Bangkok to go from hardly any waste incineration and/or biogas production with combustion to generate absorption cooling and electricity from all the waste in Bangkok. Still, this is the available amount of waste and we want to present the potential that exists. We still want to make it clear that we consider all steps towards more sustainable waste treatment methods as good ones, even if it is only one new facility. Our result, see Figure 4‐2 and Figure 4‐1, show that the waste generation curves for the previous years in Thailand and Bangkok differ. We have not found any indication why this is and the lack of knowledge about the future makes it hard to predict the development. Since the waste generation in Bangkok is predicted to expand to as high as 18 000 tons/day in 2015, see 4.2.1, we do not consider a decrease likely at the moment. We are aware of the fact that the statistics end at 2006 and that the waste generation trend could have changed since then. 6.4 Waste Incineration Our research shows that the waste incineration in Thailand is not nearly as developed as in Sweden. In Sweden there is only a fraction of the MSW that ends up at landfills and a major part is incinerated, see chapter 3.4.1. The fact that waste incineration is developed to such an extent in Sweden is however not a valid reason to guarantee the feasibility in Thailand, since the conditions in Thailand are very different compared to Sweden. In Thailand, both the citizens and the government seem to be against further development and building of new incineration plants, see 4.2.4. We consider waste incineration an important aspect in order to reduce the waste volume and thereby the landfills and open dumps in Thailand. What can be said though, is that if there is a big opposition against waste incineration among the citizens, this is an important factor to consider when evaluating the option of waste incineration, especially since there already are cases when waste incineration projects has been postponed due to opposition and demonstrations by the citizens. We believe that the doubts among the citizens regarding the waste incineration process originate from bad experience concerning emissions and efficiencies. Better communication between the government and the Thai citizens, as well as education about the technique might be an idea for 57 Analysis improved success with implementing new waste incinerators. However, the moisture content in the waste could be a significant drawback regarding the waste incineration technique in Thailand. Since the moisture content affects the calorific value, see 4.2.3, more torch fuel is probably needed. The relations between these parameters have been treated in the sensitivity analysis, see 6.8.2. There have been some doubts regarding the number of waste incinerators in Thailand. Some of the studied reports mention that there are three waste incinerators while others say it is only two, see chapter 4.2.4. We see the low number of waste incinerators in the country as an indication of how undeveloped the technique is. Since there are investigated cases where MSW and natural gas combustion are combined, see 4.3.5, we consider this to be an alternative waste incineration technique for Thailand. This alternative technique uses natural gas which is classified as a fossil fuel, but the amount used is probably less than if only using natural gas to condense power plants. The fact that the payback period was calculated relatively low together with a higher overall efficiency than normal stand‐alone plant speaks in favor of this technique. If Thailand would decide to invest in some kind of waste incineration technique, we think that this alternative should be contemplated and evaluated further. 6.5 Biogas Production and Combustion We find that biogas production would be well suited for Thailand since the country has a high temperature all year around, see chapter 3.1. Due to this the energy needed to run the biogas production process would probably be less than in a Swedish biogas plant, which has a lower surrounding temperature. The fact that the organic part in the waste is relatively high in Thailand too, see chapter 4.2.3, implies that the amount of generated biogas would probably be higher compared to a biogas processes based on OFMSW in Sweden. The alternative way of generating biogas with a tarp instead of a digestion chamber, see 4.2.5, might be an option. Using a tarp instead of a large digesting facility is probably cheaper, but we are uncertain of the usage of the fertilizer due to the lack of waste sorting before the process. As mentioned in 4.2.2, some households in Bangkok are currently separating their MSW into wet and dry. If this system was to be developed and expanded the conditions for biogas production would be very good. This is however only preformed in a small scale today and the area is still unexplored. We have seen some examples of this system during our time in Bangkok, but what we have seen is that the system does not work well: there are two separate bins, one for wet waste and one for dry waste, placed at the garbage disposal room, but no one seems to take consideration to this and generally people throw their mixed garbage in either bin. The biogas production today is mostly generated from smaller plants within the agricultural sector. Even though there is biogas production from MSW, we consider this production very small and the area rather undeveloped. 6.6 Absorption Cooling and Distribution As mentioned in chapter 3.11.1, there are different ways of handling the distribution of absorption cooling: district cooling generated by an ACM or district heat driven ACM. There is no extended district cooling grid in Bangkok, neither is there a district heating grid. We are not sure how extended a network needs to be in order to be defined as a district cooling or heating network. We will 58 Analysis however refer to also a smaller extension of district heating and/or cooling pipes as a network in this text. Today, the absorption cooling usage in Thailand is small and the area is not extended. However, we think that the few applications implemented is very good examples for others to follow. Both the ACM at the airport in Bangkok as well as the ACM at one of the universities in the north of Thailand shows that the technique works and that it is possible to use it in Thailand, even though none of the studied examples use heat or electricity generated from MSW. We believe that the best way to deliver absorption cooling in the Bangkok‐area is to deliver heating to a locally placed ACM. In comparison to Sweden, Thailand has the advantage of high temperatures, meaning that insulation of the district heating pipes is not as crucial as it is in Sweden. Regarding the distance that the cooling needs to be transported, it is instead more important that heat losses are avoided, due to the warmer climate. Another difference is the already extended district heating grids in Sweden. This makes the application of district heat driven ACM easier to implement than when there is neither a district heating grid, nor a district cooling grid. When considering working pairs in the absorption cooling system, the aspect of hazardous substances should be reflected. Ammonia for example is hazardous and poisonous in larger volumes. However, we believe that compared with the refrigerants in compressor cooling systems, the working pairs in absorption cooling systems are better. Also, the working pairs are held in a closed system and do not reach the costumer. When considering the possibility of investing in a grid to supply ACM with heat, we believe there needs to be a high reliability level of delivery, regarding energy supply, a well functioning grid etcetera. When using waste as fuel, either for waste incineration or biogas production, this fuel does not offer the same reliability as e.g. a fossil fuel like coal. The waste volumes and content can vary during seasons and increase or decrease during time, see chapter 4.2.1 and 4.2.3. In Sweden, for example, there is not always enough waste available for the desired waste incineration, in order to generate all the district heating needed. In those cases, it is rather common that the district heating utility uses other fuels as a supplement. It is probably not likely that there will be a lack of available waste in Bangkok, at least not to start with, since the waste generation is so big. The waste content does however vary, and if this is not taken into consideration, it could affect the reliability of both alternatives. If the organic part of the waste increases, this gives a higher moisture level, which affects the waste incineration process. The biogas production could similarly suffer if the organic part was lower than expected. 6.6.1 Cooling Recipients The possible recipients of the absorption cooling are many: apartment buildings, industries, malls, hotels, hospitals, universities and schools, office buildings etcetera. The most important aspect here is probably if compression cooling is going to be replaced or if it is a new construction where absorption cooling can be implemented from the start. We believe installations taking place from the point of construction to be a lot more successful, but we do not want to exclude conversions. We also consider it to be of big importance if there is a central cooling system installed in the buildings already. We agree with Greacen (2010), see chapter 4.4, and consider it most likely that absorption cooling will be implemented in new constructions, regardless of what kind of building this is. 59 Analysis Today, most of the apartments have separate air conditioning units and every resident is in control of his/her cooling usage and this is paid for through the electricity bill, see 4.4. We have not found much information regarding how the separate units could be constructed if using absorption cooling in apartments, but there is a chance that the absorption cooling would lead to less individual control and this could be a drawback. Regarding other potential customers, these offer a different situation. When the cooling recipients are malls, industries, hospitals, schools, etcetera, these probably need to install or already have central cooling in one way or another anyway, so the option of absorption cooling feels more available compared to apartment buildings where central cooling normally is not installed. Since the absorption cooling needs to be distributed in the buildings through some sort of central system, and since we consider it easier to have central heating in buildings with large and open spaces, in comparison to apartment buildings with several smaller spaces, apartment buildings are possibly not the most convenient customer. 6.7 The Thai Electricity Market, Prices and Costs Since no financial calculations have been made, it is impossible to say whether or not absorption cooling with either of the generation alternatives would be profitable. To perform calculations that are specific enough to have validity, a more precise scenario would probably be needed. Regardless, a conversion from compression cooling to absorption cooling affects prices and costs for cooling producers as well as for cooling recipients. Even though no calculations have been made, some factors affecting prices for both cooling recipients and suppliers will be analyzed here to the extent that is possible without thorough investigations of these areas. We consider the electricity prices in Thailand today to be rather high, see chapter 4.3.4. In relation to the general price level in the country and compared to electricity prices in Sweden we think the 0.72 SEK per kWh is relatively high, see 4.3.4. A high electricity price is very likely to make the suggested systems more profitable. This would increase the income from the generated electricity and a larger cost would be avoided through the replaced compression cooling. Regarding the apartment tenants paying the even higher average of 2.23 SEK per kWh, we consider this to be a very high price for electricity. It is hard to say how widespread this phenomenon with higher price level is. However, it is the landlord/owner who adds this extra cost and if absorption cooling was an alternative instead of air conditioning, he/she would most likely find a way to make extra profit from this as well. It is believed by some that a deregulation of the electricity market would make the power generation more efficient than in a regulated market, see 3.13. This implies that a deregulation of the Thai electricity market would make power generation more efficient. A deregulation would most probably affect the electricity price in some way, how it would be affected depends on a lot of different factors. It is difficult for us to make assumptions regarding how the electricity market will change and develop, it is also hard to guess how a deregulation would affect the prices. As mentioned, if the electricity prices increased, we think this would increase the probability that absorption cooling would be profitable. If the prices decreased, we think this would most likely only be small decrease, but even a small decrease might affect whether or not the absorption cooling is profitable. There have been some difficulties understanding all the rules regarding the net‐metering and the SPP and VSPP rates, see 4.3.3‐4.3.4. It seems like it is only generation from renewables that is eligible for the adder, we have not found information stating that CHP‐generation receives the adder as well. Still, both CHP and electricity generation from renewable fuels are promoted through the existence 60 Analysis of the SPP and VSPP programs. We believe the current situation with the programs and the adders probably has a large role in order to make power generation from renewables and CHP feasible. If the market was deregulated, these programs might change, and we think that some way of ensuring and/or promoting energy production from renewable energy sources like this still need to exist. Regarding the requirement levels for the CHP generation, we considerer these to be quite low, the demand for a primary energy saving of 10 % is a good start, but we think this should be increased in order to gain more energy savings from CHP. If absorption cooling was installed in apartment buildings, this would probably alter the way the residents pay for their cooling. It might change from a varying cost paid for a varying amount of cooling (electricity) to a fixed priced for a fixed amount of cooling. Depending on how much each customer uses their air conditioning unit, it might be a decrease or an increase in price if a conversion to absorption cooling was realized. For the absorption cooling to be accepted by the residents, they have to be appealed by the advantages with central absorption cooling compared to separate air conditioning units. Generally, we think that unless the price for absorption cooling is lower than for the currently used compression cooling, the Thai citizens will not be willing to pay extra for the environmental benefits. We do not consider the environmental awareness big enough in Thailand for that. On the other hand, we are not sure this is the case in Sweden or any other country either. The fact that electricity prices increase with increasing consumption, see chapter 4.3.4, might affect the willingness for cooling recipients to convert to absorption cooling. From our observations we think that the electricity usage for the air conditioning units are probably the biggest part, or one of the bigger parts, of the electricity usage in Bangkok homes. If this large part could be replaced with a cheaper alternative, this should appeal to them. 6.7.1 Investors The SPPs and the VSPPs either generate electricity from renewable fuels or they run CHP production from fossil fuels, while EGAT mostly has only electricity generation from fossil fuel, and a small fraction of production from renewable, see chapter 4.3.3 for further information. As we see it, there are two different scenarios as to how Bangkok can implement absorption cooling generated from waste. One option is that EGAT invests and initiates the waste incineration or biogas production and combustion combined with the absorption cooling. Our model has been made with the assumption that all the waste is treated in large plants and we consider this most likely if EGAT were the investors. We have wondered whether the IPPs could be possible investors too, but according to our sources they do not generate electricity from renewables or CHP at all. We have had some problems understanding the separation of IPPs from SPPs and VSPPs. At first it seemed that the only difference was size, that SPPs are SPPs because they have smaller generation capacities than IPPs, but there is also the separation with IPPs generating from fossil fuels and the SPPs and VSPPs generating with CHP or from renewables. Probably all the CHP and renewable projects are not large enough to fall under the category IPP anyway, but if one of the IPPs wanted to invest in CHP generation for instance, we are not sure how this would be categorized. Other possible investors would be if SPPs and/or VSPPs realized the potential and started several separate projects where they combine waste incineration or biogas production and combustion with absorption cooling. This seems likely since it is them who so far have produced the biggest portion 61 Analysis from renewables and/or with CHP. The separation of the two, CHP and renewables, does however indicate that this might be new territory. As it is now, if they are using CHP, this is from fossil fuels. It seems they have not quite realized the possibility for CHP from renewables, or waste incineration. Possibly they do not consider it to be reasonable for different reasons. The investment cost for absorption cooling machines is rather high compared to compressor cooling machines. According to our sources, see chapter 3.11.2, the investment cost can be decreased by 50% if the absorption cooling is placed nearby a natural heat sink. Even if the investment cost for ACM is high, the source of energy, i.e. waste, can be considered as free, at least to some. At the moment it is BMA who handles the collection of waste, which they are paid for. It has been hard determining the relations between BMA and the Thai government, but most likely they are connected to each other. However, if EGAT was to invest in any of the WTE schemes suggested, we do not think it would be a problem for them to coordinate the waste collection with BMA. The aspect of using “free fuel” is important when evaluating costs for implementing absorption cooling. It is hard to tell whether the SPPs and VSPPs are genuinely interested in alternative ways of producing energy due to environmental reasons, or if the price adder is the only reason for them to invest in such energy production. Probably it is the later alternative, as much else in Thailand and the world; it is most often financial aspects that have the biggest impact. If it is the later alternative, they will receive the adder, as the situation is today at least. The adder levels are not always easy to understand, the adder for biogas is 0.30 THB (0.07 SEK) per kWh, while for MSW it is 2.5 THB (0.56 SEK) per kWh. It does not explain how this biogas should be produced, if produced from MSW it might even fall under the MSW category. An additional income from the waste heat should be interesting for them, we think. As mentioned earlier though, presently it is either CHP or electricity generating from renewables. This might indicate that our implementation would not have much success. EGAT on the other hand is government owned and the organization is a lot bigger than any of the smaller producers. In combination with the clean tech fund we consider it reasonable that they invested in this. Another reason to why we believe EGAT would be appropriate for this implementation is the current absorption chiller at the airport, which is a joint venture between EGAT and other state owned, or previously state owned, companies. 6.8 Model The transportations of waste have not been included in the model. However, we believe that the transportations would be more or less the same for both waste incineration and biogas production with combustion and the comparing results would not be affected. If including the transportations, the overall emissions from each alternative would be increased. Regarding the model calculations, see Chapter 5, we have assumed all of the collected waste to be used for energy recovery in the case with waste incineration, while the waste used in the biogas process is subjected to a sorting process in which 10% of the organic waste if lost. This percentage is used since this alternative involves a sorting process where waste could be lost. In other words, the alternative of producing and incinerating biogas means that a part of the organic waste as well as all of the non‐organic waste ends up on landfill or open dump, while all of the collected waste is used in the waste incineration alternative. We are however aware that 100% of the collected waste does not reach the production facilities to start with. We are unsure how much losses the collection percentage of 85% includes, whether this takes into account losses during transportation etcetera. 62 Analysis Regardless, these losses during transportation would be the same for both waste incineration and the biogas production, while the sorting percentage for the biogas production only is relevant due to the sorting needed. Consequently, due to the lack of information within this area, we consider the best option in the model is to incinerate all of the collected waste. The emissions from the waste incineration have been calculated with a value representing the waste composition in Sweden. The emissions generated from incinerating waste depend on the actual waste composition, but we did not find an accurate value for the waste in Thailand. An alternative could have been to calculate the emissions from the plastic part of the waste since it is this part that mainly contributes to the fossil emissions. Since the fossil parts of the Thai and Swedish waste does not differ too much, the used value is still considered to be fairly accurate. In the sections 4.2.4 and 4.2.5, one opinion is described on the best way to locate biogas and waste incineration plants. This way includes minimized transportations and emissions as well as lower costs. In this thesis, we have however chosen to base the model on larger plants. Since the input for our model is 100% generated waste, larger plants with higher capacity seem more reasonable and the larger plants have a higher efficiency and possibly a lower cost per produced kWh. However, we think that using smaller plants is the most likely way in which the situation will develop which contributes to some differences in our model, e.g. overall efficiencies on the plants. 6.8.1 Results from the Model The results for the model, see chapter 5.6, show that the waste incineration alternative generates the most electricity and cooling as well as the largest reduction of GHG emissions. This is probably due to the high overall efficiency in the plant as well as the fact that 100% of the MSW is treated. For the biogas alternative, there is waste material lost to landfills/open dumps resulting in less energy recovery. Even if the results show that waste incineration is the best alternative according to our model, this is only based on three outgoing parameters. These parameters are needed in order to compare the results. At the same time there are several other aspects and emissions to take into consideration when deciding which alternative that is the most optimal for the Thai waste management system. The amount of generated cooling in the model, from either waste incineration or biogas production with combustion, represent 6.5% and 0.8% of the amount of electricity used for compression cooling the year of 2008 in Thailand, see 5.6 and 4.3. However, we are aware that we are comparing energy used for compression cooling (electricity) with energy achieved by absorption cooling, which is not optimal. This is due to a lack of information and knowledge regarding the different cooling systems. Both alternatives of waste incineration and biogas production and combustion are expected to replace the current waste management of mainly landfilling/open dumping. Open dumping and landfilling involves generation of methane gas and carbon dioxide, see 3.8.1. These emissions have not been involved in the calculations. For the biogas scenario, the emissions due to landfilling of a smaller part of the organic waste are included. If either of the alternatives was implemented and all of the waste was used, this would decrease the landfilling/open dumping emissions significantly. This decrease would however be the same for both scenarios, and this does not affect the comparison. Still, the reduced emissions would be a lot bigger, and we think this is an import aspect that has not been included in the model. 63 Analysis 6.8.2 Sensitity Analysis The sensitivity analysis that was performed revealed many areas that can be analyzed thoroughly. Due to the sensitivity analysis we can identify the parameters that affect the results of the model more than others. Here we will present this analysis. All of the results from the alternations in the analysis can be viewed in 10.2 Appendix. Regarding the alterations of most of the efficiencies, these have only included decreases since the increases resulted in efficiencies over 100%. However, we think we have chosen rather high efficiencies to start with. As mentioned earlier we reckon that the suggested techniques need to be of high quality if they will ever be considered as relative options. Therefore increases in efficiency are not very likely, even if the intervals of the alterations would have been smaller. The alterations in electrical efficiency are done without relation to the thermal efficiency. The same is true for the opposite; the alterations of thermal efficiency are done without relation to the electrical efficiency. Both alternatives are modeled like this, although we do not think this is the case in reality. At a plant with a generally low efficiency, low electrical efficiency, as well as low thermal efficiency could be the case. However, an increase of the thermal efficiency could also result in a decrease of electric efficiency, or vice versa. We think this depends very much on the type of plant and the desired output of the plant, so it is impossible to say how this relation would be. Regardless, it is interesting to see how the separate alterations of the efficiencies affect. 6.8.2.1 Percentage of Collected Waste The alteration of the collecting percentage of MSW affected both scenarios similarly, see Table 10‐12. It is not specified what the collection percentage of 85% involves. We have considered the possibility that this percentage does not take collection losses into consideration. If this is the case, a decrease in this percentage can show the impact of such losses. An increase in collection percentage can also represent a future scenario when the amount of generated waste has increased. All of the alterations affected all parameters, implying that this parameter is significant for all scenarios. 6.8.2.2 Efficiencies Waste Incineration Regardless of even the highest decrease of the electrical efficiency of the waste incinerator (‐30%), see Table 10‐3, the waste incinerator alternative is a better choice than biogas production and combustion, according to the outgoing parameters. The decrease in thermal efficiency, see Table 10‐4, only affects the amount of generated cooling and the amount of emissions. The reduction in emissions is affected quite a lot due to this change, meaning that the amount of produced cooling is relatively important. 6.8.2.3 Energy Input Waste Incineration Regarding Table 10‐5, we expected the internal electricity usage for the waste incineration to have larger influence on the outputs. It turned out this parameter does not affect the output in any significant way, the outgoing parameters for the waste incineration alternative is still much better than those for the biogas alternative. When altering the torch fuel usage in the waste incineration process, see Table 10‐15, this gave some unexpected results. Beforehand we thought this parameter would increase the GHG emissions significantly, this was not the case. This is probably explained by the fact that the model does not contain any relation between the energy content of the MSW and the amount of NG used. As the 64 Analysis model is constructed, when the amount of NG is increase, this increases the energy input into the incineration plant, which increases the amount of generated cooling and electricity. And when more cooling and electricity is generated, this replaces larger amounts of NG produced electricity. This implies that the end result is more or less the same; more NG electricity is produced only to replace NG produced electricity, except for the different efficiencies. In reality, we think there will probably be some relation between the energy content of the MSW and how much torch fuel is used. We think it is more likely that an increase of torch fuel usage is initiated by a decrease in quality of the waste, and when more natural gas is used, this does not increase the output of the incineration plant much. If this relation was taken into consideration in the model, the increased usage of natural gas would reduce the amount of replaced emissions, since less cooling and electricity would be generated. The amount of natural gas fuel needed was only found in one article, i.e. this value has been used. This fact together with the unexpected results when varying the parameter suggests that this area involve important uncertainties. 6.8.2.4 Sorting Percentage Biogas Process & Biogas Yield When altering the sorting percentage for the biogas production, this affects the emissions reduction quite a lot, as can be viewed in Table 10‐6 . This shows that this parameter is important to take into consideration. A lower sorting percentage implies that a larger amount of organic waste ends up on landfill, and the amount of produced biogas decreases since less OFMSW reaches the digester. Since the net electricity output and generated cooling was no affected in the same extent as the replaced emissions, this displays the negative affects regarding landfilling of organic waste. The sorting percentage of 90% has been chosen rather randomly, which is a large reason to question its influence and we find the alteration of this parameter important. If the system with the separate bins, see 4.2.5, was implemented, we think this percentage is more likely to be high. Even though this parameter can be questioned, we think 90% is reasonable. The decrease of the biogas yield affected the biogas alternative negatively, see Table 10‐7. This parameter is valid for Swedish conditions, for waste with a dry matter content of 30%, meaning that the moisture content is 70%. We have several sources regarding the moisture content of the waste, varying from 40% to 80%, see 4.2.3, and no source regarding the moisture content of the organic part of the waste. Therefore, we consider 70% to be quite reasonable since we think the moisture content would increase when separating the organic part. Regardless, even if increasing the biogas yield parameter with 30%, the waste incineration alternative is still considered a more efficient treatment method. This biogas yield is based on a mesophilic process although the termophilic process might be better to use in Thailand. Also, the differences in biogas yield between the different processes have not been investigated completely. However, we do not think that the biogas yield for a termofilic process is lower when compared to a mesophilic one since the temperature is higher. So this value is assumed to increase if a termofilic process was used. 6.8.2.5 Efficiencies and Energy Input Biogas Production and Combustion Regarding the alterations of thermal efficiency for the biogas combustion, this affected the emissions only marginally, see Table 10‐9. We believe this is due the relatively small amount of replaced cooling to start with. Similarly, the alteration of internal heat usage for the biogas process, see Table 10‐11, only affected the amount of generated cooling and reduced emissions from the biogas alternative marginally. Considering that the biogas process actually use a significant amount of the heat 65 Analysis generated (20% without the alterations) implies that the biogas alternative does in fact not generated a very large amount of cooling. The conclusions drawn from the alteration of the internal electricity usage for the biogas process is that it does not affect the outgoing parameters much, see Table 10‐10. Before the calculations were preformed, this parameter was thought to be an important aspect for the outgoing results. This was however not the case. The alterations of electric efficiency for the biogas combustion had effects similar to the ones from the alteration of internal heat usage, see Table 10‐8. 6.8.2.6 Chiller Parameters The alteration of the COP for the absorption chiller, see Table 10‐13, resulted in larger affects regarding the reduced emissions for the waste incineration alternative than the biogas alternative. This result was quite unexpected, and shows the large difference in amount of generated cooling between the two alternatives. The result of these alterations is interesting when contemplating to use a different absorption chiller. The COP‐value of 0.7 is quite low, and with a different absorption chiller this can be increased. The alterations of COP value for the compression cooling, see Table 10‐14, were found to be very interesting. The high increase of 100% resulted in larger emission reductions for the biogas alternative than for the waste incineration alternative, and this is the only time this has occurred during the sensitivity analysis. Still, the amount of generated cooling and net electricity output is a lot larger for the waste incineration than for the biogas production and combustion. This shows how important the COP factor is when determining how absorption cooling performs regarding GHG emissions in relation to the more common compression cooling. 6.8.2.7 Organic Fraction and Calorific Value of MSW When altering the OFMSW parameter it is only the biogas production that is affected, and consequently the biogas combustion. The generated cooling and the net electricity output increase, and the replaced emissions increase. Still, all the outgoing parameters regarding the biogas alternative are lower in comparison to the unaffected waste incineration out parameters. If the waste incineration calculations in the model were connected with the organic fraction of the waste, see Table 10‐1, this alternative would also be affected by an alteration. A higher calorific value in the MSW benefits the waste incineration alternative, see Table 10‐2, while the biogas alternative remains the same. However, there are some uncertainties regarding how the biogas alternative would be affected by a change in calorific value in reality. We believe that a higher calorific value in the MSW could originate from an increased non‐organic fraction. In other words, an increase in calorific value of the MSW could have the same effect as a decrease of the OFMSW, i.e. affect the biogas alternative negatively, see Table 10‐1. Since these parameters are not depending on each other in the model, we cannot determine how both processes would stand in relation to each other due to this alteration. In Table 10‐1 the organic fraction of the MSW is altered, which affects the biogas production. In Table 10‐2 the calorific value of the MSW is altered which affects the waste incineration. However, we believe that the organic fraction is well connected with the calorific value. In 4.2.3 it is said that the calorific value is highly depending on the moisture content. A higher organic fraction in the waste 66 Analysis would probably mean higher moisture content, which would suggest a connection between the organic fraction and the calorific value. 6.9 Feasibility in Bangkok There are a lot of different aspects that needs to be combined in order for the ideas presented to become reality: waste incineration or biogas production, the CHP generation, the absorption chiller, the economic feasibility, finding investors, finding customers, managing the distribution etcetera. The fact that we have investigated the rather specific case of absorption cooling generated from waste might seem limited. From a Swedish perspective however, this did not seem too specific in the beginning of the thesis work. Along the process, we have considered the fact that only investigating absorption cooling might have been enough. Implementing absorption cooling in Bangkok would be a challenge on its own, implementing it combined with waste incineration and/or biogas production with combustion would be even tougher. As mentioned, it is relatively common in Sweden with district heating generated from waste incineration, and absorption chillers powered by district heating are becoming more common as well. A major difference between Sweden and Bangkok is that Bangkok does not have district heating networks. To use existing district heating networks is rather convenient, even though this might cause problems in the district heating network as well. If absorption cooling became extended in Bangkok the distribution could be adapted to suit the absorption cooling very well. Production of biogas from waste occurs in Sweden too, but the use of biogas for CHP production is not common. However, it seems that the biogas production is a lot more accepted in Thailand than waste incineration. As we have expressed before, we believe that waste incineration would be difficult to implement if there still exists a large opposition against the technique among the Thai citizens. This conclusions apply even if the results from the model, see Chapter 5.6, clearly shows that the biggest amount of energy (both cooling and electricity), together with the largest amount of reduced GHG emissions, can be achieved from the waste incineration alternative. During our research we have come across the opinion that absorption cooling generated from natural gas might be a reasonable alternative instead of generating the cooling from waste. Since this case has not been evaluated in this thesis we cannot say whether this is a reasonable alternative or not, what we can say is that this solution would probably be a lot easier to implement than absorption cooling generated from MSW. NG is the most common fuel for electricity generation in Thailand, which could make the implementation with absorption cooling more accessible than absorption cooling generated from waste. On the other hand, natural gas is still a fossil fuel and it is not expected to last for very much longer in Thailand. Regardless if waste incineration or biogas production with combustion were chosen to power the absorption chiller, these are both fairly new techniques in Thailand. Since the absorption cooling technique is not exactly expanded in Bangkok either, the combination might be overwhelming for developers and investors. The different techniques might need time to mature separately before they are combined. At the same time, when a new technique is being implemented, the investors might as well go the whole hog. The combined heat and power generation also adds to the complexity of the implementation. This is however a crucial part in order for the suggestions to be interesting. Smaller natural gas fired absorption chiller might be an alternative, but if electricity generation takes place too, this requires more of the facilities. We have based the model on larger plants, which we believed to be the most 67 Analysis reasonable. This way the efficiencies for electricity production are high, while the absorption chillers can be locally placed. To implement absorption cooling in Thailand generated from MSW is an extended task. During the development of the thesis and after some insight in the Thai system, we have come to the conclusion that using either only waste incineration or biogas production with combustion not is an optimal alternative. Instead, we believe that a combination of these two techniques would be preferable due to the complexity in the Thai waste handling system. An increased organic fraction and thereby moisture content largely affects the waste incineration negatively but instead benefits the biogas production. This indicates that both alternatives are needed in order to achieve the highest efficiencies for the different techniques as well as the lowest emissions and highest reduced waste volumes. 68 Conclusions 7 Conclusions The conclusions made in this thesis work will be presented here, as answers to and discussions regarding, the research questions. RQ1) Is absorption cooling generated from MSW an alternative to replace a part of the compression cooling in Bangkok? Would this achieve a decrease in GHG emissions? Based on the assumption that the distribution of absorption cooling can be handled, absorption cooling generated from MSW is a reasonable alternative to replace at least a smaller amount, and preferably a larger amount, of the currently extended use of compression cooling. There is a large potential to decrease the GHG emissions if the cooling is generated from waste. The combinations of two currently undeveloped techniques in Thailand (absorption cooling and energy generation from waste) might be difficult to implement simultaneously, regardless of the benefits that would be achieved by this. RQ2) Which alternative would generate the largest GHG emission reduction if used to drive the absorption cooling; waste incineration or biogas production with combustion? What other factors affect the comparison of the alternatives, and how? Waste incineration would generate the largest GHG emissions reduction, by a factor of three, when compared to biogas production with combustion, according to the calculations in this thesis. Waste incineration would also generate the largest amounts of cooling and electricity in this comparison, by factors of eight and two, respectively. The waste incineration technique might struggle in Bangkok due to the high moisture content of the waste, while the possibility for large waste volume reduction speaks in favor for this alternative. Biogas production and combustion in Thailand are supported by the benefits of a high organic fraction of the waste, as well as the warm climate. When considering the biogas alternative, this still leads to large amount of waste on landfill/open dump. Variations of the COP values regarding the chillers, both absorption chillers and the compression chillers that the absorption chillers will replace, affect the comparison of the two WTE alternatives significantly. A combination of the two alternatives might be the best solution. This way the organic fraction of the waste is utilized in a suitable way through biogas production, while waste incineration efficiency is better without the organic fraction of the waste. RQ3) What other factors, environmental, technical as well as societal, needs to be taken into consideration if absorption cooling generated from MSW would constitute a relevant option? The societal factor regarding opposition for waste incineration in Thailand needs be considered; if the citizens oppose waste incineration this is a barrier that would be hard to overcome. The distribution of cooling is a significant issue that has to be evaluated, however, district heat driven locally placed absorption chillers are considered the best alternative. Potential cooling recipients needs to be evaluated, it is considered the best option to focus on corporate customers instead of private ones, and that new constructions are the best alternative when implementing absorption cooling. Except for the GHG emissions there are additional emissions, e.g. from open dumps and particulate emissions from waste incineration that needs to be considered. If absorption cooling generated from waste will be an alternative, it is believed that it needs to be financially beneficial for both recipients as well as producers. In order to achieve this, the power generation in Thailand, today and in the future, has to be evaluated. 69 Conclusions 70 Further Research 8 Further Research Some questions and ideas regarding unexplored areas have aroused during the thesis work, which will be presented here. As mentioned, this thesis focuses on the rather specific case of absorption cooling generated from MSW. This scenario has meant that the separate techniques of absorption cooling, waste incineration and biogas production combined with combustion have not received as much focus as they would have needed. Since all these techniques are considered as undeveloped in Bangkok, the combinations have felt overwhelming to handle at times. Based on this, we think it would be interesting to investigate the areas separately, especially the feasibility for absorption chillers in Thailand and Bangkok, regardless of which fuel chosen as energy source. Further investigations regarding which chillers would be best suited and a determination of how the distribution could be handled in an optimal way would be interesting. The financial feasibility has been out of scope in this thesis, although it has been identified as an important parameter. Both the waste incineration and biogas production from MSW are interesting areas to investigate independently. We have concluded that maybe the combination of using both waste incineration and biogas production from MSW is the best option when the largest energy recovery possible is desired. This area needs to be examined further. 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26) UD (Svenska Utrikesdepartementet) (2010). Reseinformation Thailand. Available: <http://www.swedenabroad.com/Page____4908.aspx> (2010‐05‐26) ÅF Energi och Miljöfakta (2010a). Förbränning. Available: <http://www.energiochmiljo.se.lt.ltag.bibl.liu.se/abonnemang.asp?cat=b2&type=M&chapter=
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&page=5> (2010‐02‐10) ÅF Energi och Miljöfakta (2010e). Fluidiserande bäddar. Available: <http://www.energiochmiljo.se/abonnemang.asp?cat=abo_mall&sid=223> (2010‐02‐18) ÅF Energi och Miljöfakta (2010f). Aktiviteter som ger miljöpåverkan. Available: <http://www.energiochmiljo.se/abonnemang.asp?cat=b2&type=M&chapter=3&subchapter=8
&page=6> (2010‐02‐19) ÅF Energi och Miljöfakta (2010g). Restprodukter från förbränning. <http://www.energiochmiljo.se.lt.ltag.bibl.liu.se/abonnemang.asp?cat=a&type=M&chapter=3
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&subchapter=8&page=2> (2010‐04‐20) 9.3 Personal Sources Teekasap, Sombat (2010). Ass. Prof. Dr. The Federation of Thai Industries, The Industrial Environment Institute. Interview date: 16 March, 2010 at Bansomdejchaopraya Rajabhat University, Bangkok Greacen, Chris (2010). Ph.D. Palang Thai. Interview Date: 22nd April, 2010 through Skype Tangkavachiranon, Sakarin (2010). Planning and Efficiency Division Manager DCAP. Interview Date: 6th May, 2010 at DCAP office, Bangkok Singha, Kiatiwongs (2010). Specialist Engineer. Suvarnabhumi Airport. Interview Date: 6th May, 2010 at Suvarnabhumi Airport, Bangkok Chanchampee, Poonsak (2010). Ph.D and General Manager Suvarnabhumi Environment Cares Co. Ltd. Interview Date: 6th May, 2010 at Suvarnabhumi Airport, Bangkok 81 List of References 82 10 Appendix 10.1 Figures Treatment of Waste Generated from Manufacturing Production in Sweden
Landfill
11%
Composting & Digestion
3%
Others
4%
Recycling of Material
43%
Energy Utilization
39%
Figure 10‐1 – Treatment of waste generated from manufacturing production in Sweden (ÅF Energi och Miljöfakta 2010i) Waste Composition MSW Sweden [weight percent] Remaining non‐
combustibly waste
4%
Paper
17%
Remaining combustibly waste
4%
Food and garden material
51%
Hazardous waste
1%
Plastic
11%
Dipers
Textile Glass Metals
5%
2%
2%
3%
Figure 10‐2 – Waste composition of MSW in weight percent for Sweden (ÅF Energi och Miljöfakta 2010j) 83 Waste Composition MSW Thailand
[% of total] Metal
2%
Wood Rubber/Lether
1%
1%
Glass
Clothes
4%
1%
Misc
3%
Paper
8%
Organic 64%
Plastic
17%
Figure 10‐3 – Waste composition of MSW in percent of total for Thailand (PCD 2006b) [%]
Percent of Used Energy in Thailand
1986‐2009
80,0
70,0
60,0
Hydro
Fuel Oil
Coal &
Natural Gas
Diesel
Imported
Others
50,0
40,0
30,0
20,0
10,0
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
0,0
Year
Figure 10‐4 – Percent of used energy in Thailand 1986‐2009 (EPPO 2009a) 84 10.2 Electricity Bill Figure 10‐5 – Electricity bill for a one room apartment in Bangkok during the period of 8/2 – 8/3 2010 85 10.3 Tables from the Sensitivity Analysis Between the alterations, the original scenario is presented as 0%. Table 10‐1 – Alteration of Percentage Organic Fraction Parameter: Percentage Organic Fraction P (OFMSW )
Waste
Incineration
Biogas Production &
Combustion
Unit
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
517
686
-236
457
607
-209
437
580
-200
397
528
-181
[GWh]
[GWh]
[1000 ton CO2 eq.]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
3247
1102
-504
3247
1102
-504
3247
1102
-504
358
475
-163
338
448
-154
278
369
-127
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
Alteration
30%
15%
10%
0%
-10%
-15%
-30%
86 Table 10‐2 – Alteration of Calorific Value MSW Parameter: Calorific Value MSW CV MSW
Alteration
30%
15%
10%
0%
-10%
-15%
-30%
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Waste
Incineration
Biogas Production &
Combustion
Unit
4209
1540
-701
3728
1321
-602
3568
1248
-570
3247
1102
-504
2927
956
-438
2767
883
-405
2286
664
-306
397
528
-181
397
528
-181
397
528
-181
397
528
-181
397
528
-181
397
528
-181
397
528
-181
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
87 Table 10‐3 – Alteration of Electric Efficiency Waste Incineration Parameter: Electric Efficiency Waste Incinerator η el ,WI Alteration
30%
-15%
10%
0%
-10%
-15%
-30%
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Waste
Incineration
Biogas Production &
Combustion
Unit
3247
1546
-686
3247
1324
-595
3247
1250
-564
3247
1102
-504
3351
954
-464
3403
880
-444
3558
658
-385
397
528
-181
397
528
-181
397
528
-181
397
528
-181
397
528
-181
397
528
-181
397
528
-181
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
88 Table 10‐4 – Alteration of Heat Efficiency Waste Incineration Parameter: Heat Efficiency Waste Incineratorη th ,WI
Waste
Incineration
Alteration
Biogas Production &
Combustion
Generated Cooling
30%
15%
10%
0%
-10%
-15%
-30%
[GWh]
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
3572
1102
-570
3247
1102
-504
2923
1102
-437
2760
1102
-404
2273
1102
-304
397
528
-181
397
528
-181
397
528
-181
397
528
-181
397
528
-181
89 Unit
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
Table 10‐5 – Alteration of Internal Electricity Usage Waste Incineration Parameter: Internal Electricity Usage Waste Incineration E int, el ,WI
Alteration
30%
15%
10%
0%
-10%
-15%
-30%
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Waste
Incineration
Biogas Production &
Combustion
Unit
3247
989
-457
3247
1046
-480
3247
1065
-488
3247
1102
-504
3247
1140
-519
3247
1159
-527
3247
1215
-550
397
528
-181
397
528
-181
397
528
-181
397
528
-181
397
528
-181
397
528
-181
397
528
-181
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
90 Table 10‐6 – Alteration of Sorting Percentage Biogas Production Parameter: Sorting Percentage Biogas Production P ( BG OFMSW )
Waste
Incineration
Alteration
30%
15%
10%
0%
-10%
-15%
-30%
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
437
580
-241
397
528
-181
358
475
-122
338
448
-92
278
369
-3
91 Biogas Production &
Combustion
Unit
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
Table 10‐7 – Alteration of Biogas Yield Parameter: Biogas Yield BGY
Alteration
30%
15%
10%
0%
-10%
-15%
-30%
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Waste
Incineration
Biogas Production &
Combustion
Unit
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
545
715
-261
471
621
-221
447
590
-208
397
528
-181
348
465
-155
324
434
-142
250
340
-102
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq
[GWh]
[GWh]
[1000 ton CO2 eq]
92 Table 10‐8 – Alteration of Electric Efficiency Biogas Combustion Parameter: Electric Efficiency Biogas Combustionη el , BG
Alteration
30%
-15%
10%
0%
-10%
-15%
-30%
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Waste
Incineration
Biogas Production &
Combustion
Unit
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
397
715
-258
397
621
-220
397
590
-207
397
528
-181
397
465
-156
397
434
-143
397
340
-105
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
93 Table 10‐9 – Alteration of Thermal Efficiency Biogas Combustion Parameter: Thermal Efficiency Biogas Combustion η th, BG
Alteration
30%
15%
10%
0%
-10%
-15%
-30%
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Waste
Incineration
Biogas Production &
Combustion
Unit
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
545
528
-184
471
528
-183
447
528
-182
397
528
-181
348
528
-181
324
528
-180
250
528
-179
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
94 Table 10‐10 – Alteration of Internal Electricity Usage Biogas Production & Combustion Parameter: Internal Electricity Usage Biogas Production & Combustion E int, el , BG
Alteration
30%
15%
10%
0%
-10%
-15%
-30%
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Waste
Incineration
Biogas Production &
Combustion
Unit
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
397
498
-170
397
513
-176
397
518
-178
397
528
-181
397
537
-185
397
542
-187
397
557
-193
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
95 Table 10‐11 – Alteration of Internal Heat Usage Biogas Production & Combustion Parameter: Internal Heat Usage Biogas Production & Combustion E int, th , BG
Alteration
30%
15%
10%
0%
-10%
-15%
-30%
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Waste
Incineration
Biogas Production &
Combustion
Unit
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
3247
1102
-504
369
528
-181
383
528
-181
388
528
-181
397
528
-181
407
528
-182
412
528
-182
426
528
-182
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
96 Table 10‐12 – Alteration of Percentage of Collected Waste Parameter: Percentage of Collected Waste P (C MSW )
Waste
Incineration
Alteration
30%
15%
10%
0%
-10%
-15%
-30%
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
3734
1268
-579
3572
1212
-554
3247
1102
-504
2923
992
-453
2760
937
-428
2273
772
-352
457
607
-209
437
580
-200
397
528
-181
358
475
-163
338
448
-154
278
369
-127
97 Biogas Production &
Combustion
Unit
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
Table 10‐13 – Alteration of COP Absorption Chiller Parameter: COP Absorption Chiller COP AC = 0,7
Alteration
30%
15%
10%
0%
-10%
-15%
-30%
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Waste
Incineration
Biogas Production &
Combustion
Unit
4222
1102
-703
3734
1102
-603
3572
1102
-570
3247
1102
-504
2923
1102
-437
2760
1102
-404
2273
1102
-304
517
528
-183
457
528
-182
437
528
-182
397
528
-181
358
528
-181
338
528
-181
278
528
-180
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
98 Table 10‐14 – Alteration of COP Compression Chiller Parameter: COP Compression Chiller COPCC
Alteration
100%
50%
25%
0%
-10%
-15%
-30%
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Waste
Incineration
Biogas Production &
Combustion
Unit
3247
1102
-170
3247
1102
-281
3247
1102
-370
3247
1102
-504
3247
1102
-578
3247
1102
-621
3247
1102
-789
397
528
-178
397
528
-179
397
528
-180
397
528
-181
397
528
-182
397
528
-183
397
528
-184
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
99 Table 10‐15 – Alteration of Torch Fuel Waste Incineration Parameter: Torch Fuel Waste Incineration
Alteration
30%
15%
10%
0%
-10%
-15%
-30%
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Generated Cooling
Net Electricity Output
Emissions
Waste
Incineration
Biogas Production &
Combustion
Unit
3260
1108
-503
3254
1105
-503
3252
1104
-503
3247
1102
-504
3243
1100
-504
3241
1099
-504
3235
1096
-504
397
528
-181
397
528
-181
397
528
-181
397
528
-181
397
528
-181
397
528
-181
397
528
-181
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
[GWh]
[GWh]
[1000 ton CO2 eq]
100 
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