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A greenhouse gas analysis of solid waste management in the Greater Vancouver regional district 2000

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A GREENHOUSE GAS ANALYSIS OF SOLID WASTE MANAGEMENT IN THE GREATER VANCOUVER REGIONAL DISTRICT b y P H I L I P K . B A R T O N B . A . S c , T h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , 1 9 9 6 A T H E S I S I N P A R T I A L F U L F I L L M E N T O F T H E R E Q U I R E M E N T S F O R T H E D E G R E E O F M A S T E R O F A P P L I E D S C I E N C E i n T H E F A C U L T Y O F G R A D U A T E S T U D I E S ( D e p a r t m e n t o f C i v i l E n g i n e e r i n g ) W e a c c e p t t h i s t h e s i s a s c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A A u g u s t , 2 0 0 0 © P h i l i p K . B a r t o n , 2 0 0 0 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of The University of British Columbia Vancouver, Canada DE-6 (2/88) ABSTRACT A G R E E N H O U S E G A S A N A L Y S I S O F S O L I D W A S T E M A N A G E M E N T I N T H E G R E A T E R V A N C O U V E R R E G I O N A L D I S T R I C T by Philip K. Barton A greenhouse gas analysis of the Greater Vancouver Regional District's (GVRD's) solid waste management system is presented in this thesis. This investigation quantifies the greenhouse gas (GHG) emissions resulting from the GVRD's current system of landfilling, incinerating, composting and recycling of the municipal solid waste generated within its boundaries and provides recommendations for future management. The definition of municipal solid waste (MSW) in this thesis is the sum total of all waste generated from residential, industrial, commercial and institutional sources, and excludes the typically categorized demolition and land-clearing (DLC) waste. The waste components newsprint, office paper, ferrous metal, glass, high-density polyethylene, low- density polyethylene, food scraps and yard trimmings are investigated individually while the remaining waste is analyzed as a whole. This research finds that the GVRD solid waste system in 1998, instead of causing greenhouse gas emissions, actually prevented the release of 180,000 tonnes of carbon dioxide equivalent (tC02e). The existing waste management system created GHG benefits largely from landfill carbon sequestration and by allowing recyclables to offset virgin manufacturing by industry. Energy generation during incineration and at landfills also provided some GHG benefits. These benefits are accounted for as negative emissions and more than compensate for the important GHG emissions identified by this research such as landfill CH4, CO2 released during the combustion of diesel fuel and plastics and N 2 0 emissions. Modelling of this waste system into a spreadsheet program allowed the demonstration of the GHG response to future management changes. Several scenarios were programmed into the Model which illustrate the critical importance future management changes can have on the overall GVRD emissions; of particular relevance when analyzed from the perspective of emissions trading. Major conclusions derived from the scenarios are: the difference between pursuing improvements in landfill gas (LFG) collection and doing nothing could be almost 300,000 tC02e/yr, the initiation of electricity generation could reduce emissions by 55,000 tC02e/yr, considering incineration as a replacement for landfill disposal could bring in credits of 140,000 tC02e/yr when electricity generation is provided, the future methane liability of landfilling requires extensive consideration since modelling ultimate decomposition calculates an emissions increase of over 300,000 tC02e/yr. Each of these projects have emissions trading opportunities and at an assumed $5/tC02e, significant revenue could be generated in this manner. A number of recommendations complete this thesis. The most important are: to strongly encourage the GVRD to begin actively participating in emissions trading or to bank credits for future regulatory requirements, to investigate improving the L F G collection system at the Cache Creek Landfill, to investigate electricity generation at the Burnaby Incinerator and to encourage greater recycling of metal, glass and plastic. ii TABLE OF CONTENTS: CONDENSED INTRODUCTION 1 1.1 B A C K G R O U N D 2 1.2 G R E E N H O U S E G A S E S & C L I M A T E C H A N G E 5 1.3 S O L I D W A S T E M A N A G E M E N T 7 1.4 R E C E N T P O L I C Y D E V E L O P M E N T S 13 1.5 R E S E A R C H OBJECTIVES 15 1.6 THESIS O V E R V I E W 16 METHODOLOGY 18 2.1 I N T R O D U C T I O N 18 2.2 G L O B A L W A R M I N G P O T E N T I A L 19 2.3 B I O M A S S D E C O M P O S I T I O N / C O M B U S T I O N 20 2.4 L A N D F I L L C A R B O N S E Q U E S T R A T I O N 22 2.5 N I T R O U S O X I D E E M I S S I O N S 29 2.6 R E C Y C L I N G A N A L Y S I S 44 2.7 U N C E R T A I N T Y W I T H T H E E S T I M A T E S 70 2.8 S P R E A D S H E E T P R O G R A M 70 2.9 W A S T E M A S S E S T I M A T E S 78 2.10 R E M A I N I N G W A S T E S 85 2.11 G H G E M I S S I O N S N O T I N V E S T I G A T E D 89 2.12 S T A N D A R D S 90 RESULTS & DISCUSSION 91 3.1 E X I S T I N G S Y S T E M 91 3.2 S C E N A R I O S 100 CONCLUSIONS & RECOMMENDATIONS 105 BIBLIOGRAPHY 108 5.1 R E F E R E N C E S 108 5.2 P E R S O N A L C O M M U N I C A T I O N S 114 APPENDICES 115 in TABLE OF CONTENTS: DETAILED A B S T R A C T i i L I S T O F T A B L E S v i i L I S T O F F I G U R E S v i i i L I S T O F A C R O N Y M S i x A C K N O W L E D G M E N T S x INTRODUCTION 1 1.1 B A C K G R O U N D 2 1.2 GREENHOUSE GASES & CLIMATE CHANGE 5 1.3 SOLID WASTE M A N A G E M E N T 7 1.3.1 Landfill Disposal 9 1.3.2 Incineration 10 1.3.3 Backyard & Centralized Composting 11 1.3.4 Recycling 12 1.4 RECENT POLICY DEVELOPMENTS 13 1.5 RESEARCH OBJECTIVES 15 1.6 THESIS OVERVIEW 16 METHODOLOGY 18 2.1 INTRODUCTION 18 2.2 G L O B A L WARMING POTENTIAL 19 2.3 BIOMASS DECOMPOSITION/COMBUSTION 20 2.4 LANDFILL CARBON SEQUESTRATION 22 2.4.1 Introduction 23 2.4.2 Literature Review 24 2.4.3 Application to GVRD Landfills 26 2.5 NITROUS OXIDE EMISSIONS 29 2.5.1 Global Nitrogen Cycle 29 2.5.2 Global Nitrous Oxide Cycle 30 2.5.3 Anthropogenic Interference with the Global Nitrogen Cycle 32 2.5.4 Anthropogenic Interference with the Global Nitrous Oxide Cycle 33 2.5.5 Implications for Waste Management 34 Landfill Disposal 35 iv Composting 41 Incineration 42 2.5.6 Summary 44 2.6 RECYCLING ANALYSIS 44 . 2.6.1 Newsprint . 45 Literature Review 46 Local Situation 50 2.6.2 Office Paper 56 2.6.3 Ferrous Metal 59 2.6.4 Glass 61 2.6.5 High-Density Polyethylene , 63 2.6.6 Low-Density Polyethylene 65 2.6.7 Forest Carbon Sequestration 66 2.7 UNCERTAINTY WITH THE ESTIMATES 70 2.8 SPREADSHEET PROGRAM 70 2.8.1 Explanation 71 2.8.2 Examples 73 2.8.3 Modelling Scenarios 77 2.9 WASTE MASS ESTIMATES 78 2.10 REMAINING WASTES 85 2.11 G H G EMISSIONS NOT INVESTIGATED 89 2.12 STANDARDS 90 RESULTS & DISCUSSION 91 3.1 EXISTING SYSTEM 91 3.2 SCENARIOS 100 CONCLUSIONS & RECOMMENDATIONS 105 BIBLIOGRAPHY 108 5.1 REFERENCES 108 5.2 PERSONAL COMMUNICATIONS 114 Appendix A: General Calculations 115 Appendix B: Municipality Calculations 129 B. l CITY OF ABBOTSFORD 131 B.2 CITY OF BURNABY 131 B.3 CITY OF COQUITLAM 132 B.4 CORPORATION OF D E L T A 132 B.5 CITY OF L A N G L E Y 134 B.6 TOWNSHIP OF L A N G L E Y - 134 v B.7 DISTRICT OF M A P L E RIDGE 135 B.8 CITY OF NEW WESTMINSTER 135 B.9 CITY OF NORTH V A N C O U V E R 136 B. 10 DISTRICT OF NORTH V A N C O U V E R 137 B. l 1 DISTRICT OF PITT MEADOWS 138 B. 12 CITY OF PORT COQUITLAM 13 9 B. 13 CITY OF PORT M O O D Y 13 9 B. 14 CITY OF RICHMOND 140 B.15 CITY OF SURREY 140 B. 16 CITY OF V A N C O U V E R 141 B.l7 DISTRICT OF WEST V A N C O U V E R 142 B. 18 CITY OF WHITE ROCK 143 B.19 E L E C T O R A L A R E A A (U.B.C. & U.E.L.) 143 B.20 E L E C T O R A L A R E A C (BOWEN ISLAND & HOWE SOUND) 143 Appendix C: Newsprint Waste Management 145 Appendix D: Office Paper Waste Management 160 Appendix E: Ferrous Metal Waste Management 165 Appendix F: Glass Waste Management 166 Appendix G: High-Density Polyethylene Waste Management 167 Appendix H: Low-Density Polyethylene Waste Management 172 Appendix I: Food Waste Management 173 Appendix J: Yard Trimmings Waste Management 188 Appendix K: Remainder Waste Management 203 Appendix L: Spreadsheet Program 210 Appendix: References 260 Appendix: Personal Communications 263 vi LIST OF TABLES Table 2-1: First-Order Decay Rate Constants 29 Table 2-2: Global Reactive Nitrogen Sources 32 Table 2-3: Global N 2 0 Budget 33 Table 2-4: Review of Nitrous Oxide Emissions from Composting 41 Table 2-5: Review of Nitrous Oxide Emissions from Incineration 42 Table 2-6: List of Worksheets 72 Table 2-7: Incineration of Food Waste from District of North Vancouver 74 Table 2-8: Centralized Composting of Yard Waste from City of Vancouver 75 Table 2-9: Correction for Mixed Recyclables 82 Table 2-10: City of Burnaby Waste Generation, Recycling & Disposal 83 Table 2-11: Waste Percentages 85 Table 2-12: Waste Estimates by CH2M Hill Engineering 86 Table 2-13: Components of the Remainder 87 Table 3-1: Waste Mass Estimates for the City of Vancouver 92 Table 3-2: GHG Emission Factors for the City of Vancouver 93 Table 3-3: GHG Emissions for the City of Vancouver 98 Table 3-4: GHG Emissions for the GVRD 99 vn LIST OF FIGURES Figure 1-1: Important GHGs from Waste Management Operations 3 Figure 2-1: Nitrification & Denitrification Pathways 31 Figure 2-2: Potential N2O Emissions from Waste Management 35 Figure 3-1: Relative Importance of Emissions to Newsprint Disposal 96 Figure 3-2: Relative Importance of Emissions to Food Waste Disposal 96 vm LIST OF A CRONYMS A A C allowable annual cut Bl Burnaby Incinerator BNF biological nitrogen fixation C A A D carbon available for anaerobic decomposition C C L F Cache Creek Landfill CPL Crown Packaging Limited - Paper Mill Division CSF carbon storage factor D L C demolition and land-clearing (waste) GERT Greenhouse Gas Emission Reduction Trading Pilot Program G H G greenhouse gas GVRD Greater Vancouver Regional District GWP Global Warming Potential HDPE high-density polyethylene ICI insitutional, commercial, industrial (waste) IPCC Intergovernmental Panel on Climate Change LDPE low-density polyethylene L F G landfill gas MSW municipal solid waste M T C E metric tonnes of carbon equivalent MWP mixed waste paper OCC old corrugated cardboard RDO residential dropoff TMP thermo-mechanical pulp TS transfer station USEPA United States Environmental Protection Agency V C R Voluntary Challenge & Registry (Federal Government) V L F Vancouver Landfill WS worksheet (in spreadsheet Model) ix A CKNO WLED GEMENTS Without the support (and prodding) of my advisor, Professor Jim Atwater, the quality and depth of this investigation would not have been possible. The funding by the GVRD and Stantec Environmental (Calgary) was greatly appreciated and provided the resources necessary to make this research a reality. The assistance of John Paul of Transform Compost Systems and Neil Bird of Woodrising Consulting is also appreciated. The substantial proofreading effort of Margaret Wojtarowicz, Kevin Frankowski and Daniel Walker helped the timely completion of this thesis. Lastly, the extraordinary patience of the significant other of this author, Dara Hendren, must be acknowledged. If she ever has to listen to further ponderings about global climate change, emissions trading or nitrous oxide emissions she will probably be sick. Readers wishing to contact this author in the future with questions or comments should send e-mail to pkbarton@hotmail.com or to jatwater@civil.ubc.ca. x Chapter 1 INTRODUCTION A greenhouse gas analysis of the Greater Vancouver Regional District's (GVRD's) solid waste management system is presented in this thesis. This investigation quantifies the greenhouse gas (GHG) emissions resulting from the GVRD's current system of landfilling, incinerating, composting and recycling of the municipal solid waste generated within its boundaries and provides recommendations for future management. The definition of municipal solid waste (MSW) in this thesis is the sum total of all waste generated from residential, industrial, commercial and institutional sources, and excludes the typically categorized demolition and land-clearing (DLC) waste. The waste components newsprint, office paper, ferrous metal, glass, high-density polyethylene, low- density polyethylene, food scraps and yard trimmings are investigated individually while the remaining waste is analyzed as a whole. Waste management is important from a greenhouse gas (GHG) perspective since it contributes to the observed increases in the atmospheric concentrations of all three of the most significant greenhouse gases, carbon dioxide (CO2), methane (CH4) and nitrous oxide (N20). Large quantities of carbon and nitrogen are contained in the municipal solid waste stream and thus there is the potential for significant atmospheric releases of C 0 2 , C H 4 and N 2 0 . It is these three greenhouse gases which this research investigates. As a result of the 1997 Kyoto Protocol to the United Nations Framework Convention on Climate Change, Canada is committed to reduce GHG emissions. Though it is still unclear in which manner our Federal government will elect to successfully reach its emissions target (an approximate per capita reduction of 30% over the next 10 years), it is quite likely that in the next decade either GHG emissions trading, GHG emissions taxing or direct legislation (or a combination of all three) will be implemented to force reductions in all sectors, waste management included. This research assists the GVRD's assessment of any opportunities which may exist in a future GHG emissions trading environment and/or its assessment of any liabilities which may exist in a future G H G emissions taxing environment. The intent of this research is to provide an important planning tool to assist in determining the future direction of waste management in the GVRD. This thesis estimates the greenhouse gas emissions resulting from the existing system of landfilling, incinerating, composting (backyard and centralized) and recycling of newsprint, office paper, ferrous metal, glass, plastic (high-density and low-density polyethylene), food scraps and yard trimmings. The remaining waste is grouped together, defined as the Remainder, and is also analyzed. These eight main components of the municipal waste stream were investigated individually so that the current participation in source-separation can be more effectively directed at "greenhouse gas reducing" activities. In addition, the member municipalities were investigated separately to more accurately model the existing system. In order for this analysis to serve as a 1 planning tool, the GVRD requires an assessment of the existing system - a baseline against which any proposed changes, can be compared. For this reason, in addition to this report, an adaptable spreadsheet program has been developed to model the response of G H G emissions to changes in waste tonnages and other improvements made by the program user. This Introduction chapter consists of 6 parts. The first section, Background (1.1), provides a framework of the scope and intent of the research. Greenhouse Gases & Climate Change (1.2), the second section, explains the international scientific consensus which is concerned with the increasing atmospheric concentrations of greenhouse gases. The third section, Solid Waste Management (1.3), introduces the GVRD's existing system of Landfilling (1.3.1), Incineration (1.3.2), Backyard & Centralized Composting (1.3.3) and Recycling (1.3.4). These respective sections briefly discuss the important greenhouse gas implications of these activities. In the fifth section, Recent Policy Developments (1.4), new policies with potential to affect waste management in the future are discussed. Research Objectives (1.5), the fifth section, present the goals of this investigation. The last section, Thesis Overview (1.6), presents an overview of the thesis to assist readers in understanding the analysis performed. 1.1 BACKGROUND The planning of municipal solid waste management is largely influenced by economic and environmental considerations. Current waste management systems, which include various activities such as landfill disposal, incineration, composting and recycling, have occurred as a result of these two main considerations. For example, the relatively recent interest in recycling (starting in the late 1980's) was initiated largely because of increasing awareness in environmental issues and possibly because of economic factors. Landfilling continues to be one of the most popular methods for disposal because the economics are attractive and it satisfies the present environmental (i.e. regulatory) considerations. These systems, which evolved out of the driving factors thus far, could potentially be faced with many changes in the future as a new consideration gains importance. A new consideration could be the strong international effort to reduce the emissions of greenhouse gases to the atmosphere. There is now an international scientific consensus that human-induced increases in the atmospheric concentrations of greenhouse gases have great potential to raise the surface temperature of the planet. The climatic change which is believed to result could raise global sea levels, increase the intensity of severe weather conditions and increase the frequency of heat waves and droughts. Reducing the emissions of these greenhouse gases will likely be one of the most challenging endeavors of the entire international community in the 21st Century. 2 Briefly, the main greenhouse gas implications of waste management are: • Emissions of C O 2 from the combustion of diesel fuel during curbside collection, processing at transfer stations and subsequent transportation to landfills, incinerators, recycling or composting facilities. • Emissions of C H 4 from the anaerobic decomposition in landfills or from anaerobic zones of inadequately aerated compost piles. • Emissions of N 2 O from the nitrification and denitrification of nitrogen present in organic wastes. This can occur at landfills (predominantly from landfill leachate) or during composting and there can also be thermal formation during incineration. • Emissions of C O 2 from fossil fuel energy required in the processing of recyclable materials such as paper, metal, glass and plastics into new products. • The prevention of C O 2 emissions from fossil fuels when energy is produced in the form of steam at incinerators or in the form of recovered and utilized methane at landfills. This energy can prevent the consumption of fossil fuels which would otherwise be necessary. • The prevention of C O 2 emissions when carbon storage or carbon sequestration occurs. This is the capture and secure storage of carbon that would otherwise be emitted to the atmosphere. This occurs with wastes that resist decomposition in the anaerobic conditions of landfills. • The prevention of C O 2 emissions by substituting recycled materials for virgin materials. This prevention would be the result of reduced fossil fuel energy consumption when using recycled rather than virgin materials for the manufacture of similar items. The following matrix illustrates many of these emissions in a waste management context: F i g u r e 1 - 1 : I m p o r t a n t G H G s from W a s t e M a n a g e m e n t O p e r a t i o n s Fossil Fuel-C02 CH 4 N 2 0 Energy Generation* Carbon Storage* Recycled vs Primary - C O 2 * Collection ++ Transportation ++ Landfill Disposal ++ ++ + ++ Incineration + ++ ++ Centralized Composting + + ++ + Backyard Composting + ++ + Recycling ++ ++ ++ major importance + minor importance * GHG prevention activity (negative emission) For greenhouse gas emissions to be a new consideration in solid waste planning, it is necessary to have an extensive understanding of the implications presented above. Furthermore, there is tremendous variation among the greenhouse gas emission response of the five main components of the GVRD waste management system: landfill disposal, 3 incineration, recycling, backyard composting and centralized composting. The need to possess this understanding has fostered the interest in this research. Three reports and five research papers (of which this author is aware) have also compared the greenhouse gas emissions from waste management processes. However, the rapidly evolving science of greenhouse gas emissions and the importance of localized conditions makes this thesis necessary. As an example of the evolving science, the United States Environmental Protection Agency (USEPA 1998) report did not consider that nitrous oxide is emitted during the composting or landfilling of waste and did not consider that N 2 O emissions from incinerators are a function of the waste nitrogen content. These issues are discussed in Section 2.5 and are quantitatively important for nitrogen- containing wastes such as food scraps and yard trimmings. In fact, none of the reviewed research adequately assesses nitrous oxide emissions. While these limitations do exist in the work by the USEPA, it is important to mention that that report is the most extensive and valuable research available so far; indeed, the provocative questions raised in that work conceived this very thesis. The second report, Environment Canada (1995), was completed before the Intergovernmental Panel on Climate Change (IPCC) developed methodology in which the carbon emissions from the decomposition of sustainable biomass can be considered as "GHG neutral" and need not be counted as an emission". As a result, the Environment Canada report considers composting and waste incineration as sources of C O 2 emissions. In addition, that report does not consider landfill carbon sequestration or the potential for nitrous oxide emissions from waste management. All of these shortcomings also occur in new life-cycle analysis work by the industry groups, Corporations Supporting Recycling and the Environment and Plastics Industry Council (CSR 1999). These industry groups, together with Environment Canada, have developed a spreadsheet program which neglects nitrous oxide emissions, neglects landfill carbon sequestration and ignores the GHG neutrality of biomass carbon emissions. Five journal papers were located and are reviewed. The paper by Hunt (1995) only analyzed the difference between the landfilling or incinerating of paper and plastic - and is thus incomplete for use here. The papers by Eschenroeder (1999), Aumonier (1996) and Pipatti & Savolainen (1996), while valuable, all compared the impact of landfilling or incinerating municipal solid waste as a whole - they did not investigate any waste components individually. Thus these three studies suffer from inaccuracies resulting from the very local question - What is municipal solid waste? A comprehensive methodology for modeling the GHG benefits of landfilling the biodegradable fraction of municipal solid waste versus composting this fraction has been developed at the University of Calgary (Hettiaratchi et al. 1998). This useful model compares landfilling in Edmonton against the new Edmonton Co-Composting facility and determines significant GHG benefits by the management alternative. However, this study assumes zero landfill gas collection for flaring or energy utilization over the next 30 years. As a result, this research gives composting GHG benefits which may be largely undeserved, at least in jurisdictions other than Edmonton. For readers unfamiliar with the science of greenhouse gases and their inter-relationship with climate change the next section provides an introduction to this important issue. 4 1.2 GREENHOUSE GASES & CLIMATE CHANGE Greenhouse gases, the most important of which are water vapor, carbon dioxide (CO2), methane ( C H 4 ) , and nitrous oxide (N2O), allow the atmosphere to act like a greenhouse window - letting in much of the sun's energy while simultaneously only allowing a portion of it to escape immediately back to space. This occurs by permitting the entry of solar energy, which the Earth absorbs and then re-emits in the form of infrared radiation. While some of this infrared radiation escapes immediately back into space, most is temporarily trapped by greenhouse gases. This warms the lower atmosphere and the Earth's surface to a much greater extent than would otherwise have occurred. If it were not for this natural greenhouse effect, the Earth would be 33°C colder than the average temperature of 15°C (Environment Canada 1997b). This would result in a chilly mean temperature o f - 1 8 ° C on Earth and life would be profoundly different. Unfortunately, as a result of human activity, in particular the burning of fossil fuels and deforestation, the atmospheric concentrations of the greenhouse gases C O 2 , C H 4 and N 2 O and others have been rising. For several thousand years before the Industrial Revolution began in the mid-1700's, a steady balance was maintained in which the atmospheric concentration of C O 2 , as measured from ice cores, remained within 10 parts per million (ppm) of an average level of 280 ppm (Houghton 1997). However, since the Industrial Revolution this concentration has increased almost 30%, from 280 ppm to over 360 ppm, and continues to increase at an average rate of 1.5 ppm every year (ibid). In addition, the atmospheric concentration of C H 4 (a greenhouse gas estimated to be 21 times more effective in the trapping of infrared radiation then CO2) has increased by 145% since pre- industrial times, from a level of 700 parts per billion (ppb) to that of 1721 ppb in 1994 IPCC 1995a). The third most important greenhouse gas, N 2 O - estimated to be 310 times more effective at absorbing infrared radiation then C O 2 - has increased from a pre- industrial level of 275 ppb to a level of 311 ppb in 1992, an increase of 13% (ibid). It was in 1827, when a French scientist, Jean Baptiste Fourier, first recognized the warming effect of greenhouse gases in the atmosphere. He also noted the similarity between greenhouse gases in the atmosphere trapping infrared radiation and in the glass of a greenhouse, which led to the phrase "greenhouse effect" (Houghton 1997). In 1896, the Swedish chemist, Svante Arrhenius, calculated what would be the effect of increasing the concentrations of greenhouse gases. He estimated that doubling the concentration of C O 2 would increase the global average temperature by 5 to 6 C - an estimate not far from the present understanding (ibid). Nearly 50 years transpired before an amateur British scientist, Guy Stewart Callendar, calculated the warming due to the increasing atmospheric concentration of carbon dioxide from the burning of fossil fuels, and discovered supporting evidence correlating the effect of carbon dioxide on global temperatures (ibid). It was in 1957 that Roger Revelle and Hans Suess of the Scripps Institution of Oceanography in California first raised concern about the implications of fossil fuel-related C O 2 emissions on global climate change. These scientists published a paper pointing out that with the build-up of carbon dioxide in the atmosphere, human beings were carrying out a large-scale geophysical experiment. "Within a few centuries we are returning to the atmosphere and oceans the concentrated organic carbon stored in 5 sedimentary rocks over hundreds of millions of years." (Revelle and Suess 1957; Houghton 1997) Since then, a great deal of scientific investigation has occurred looking into the mechanisms and interactions of greenhouse gases with climate and climate change. The understanding of atmospheric science has advanced to such a level today that several position statements of international scientific consensus have recently been distributed. The Intergovernmental Panel on Climate Change (1PCC), a scientific body of leading atmospheric scientists established in 1988 by the United Nations Environment Programme and the World Meteorological Organization, stated in 1995 that: "Global mean surface temperatures has increased by between 0.3 and 0.6 °C since the late 19th century, a change that is unlikely to be entirely natural in origin. The balance of evidence, from changes in global mean surface air temperature and from changes in geographical, seasonal and vertical patterns of atmospheric temperature, suggests a discernible human influence on global climate... .Global sea level has risen by between 10 and 25 centimeters over the past 100 years and much of the rise may be related to the increase in global mean temperatures." (IPCC 1995b) This has been followed by the American Geophysical Union, a prominent scientific body of 35,000 earth and planetary scientists, stating in a January 1999 position statement that: "There is no known geologic precedent for the transfer of carbon from the Earth's crust to atmospheric carbon dioxide, in quantities comparable to the burning of fossil fuels, without simultaneous changes in other parts of the carbon cycle and climate system. This close coupling between atmospheric carbon dioxide and climate suggests that a change in one would in all likelihood be accompanied by a change in the other." (American Geophysical Union 1999; Dunn 1999) From this international scientific consensus, 160 nations agreed to the Kyoto Protocol to the United Nations Framework Convention on Climate Change in 1997. In this Protocol, the 38 developed countries of the world committed themselves to stabilize and ultimately reduce, their atmospheric emissions of greenhouse gases. Developing countries agreed to monitor their emissions and are encouraged to voluntarily reduce emissions but are not subject to binding commitments. Canada signed this convention and is committed to reducing greenhouse gas emissions. Between the commitment period of 2008 to 2012, Canada is required to reduce to a level 6% below what the national emissions were in 1990. Unfortunately, our national emissions were 601 million tonnes of C O 2 equivalent in 1990 (this includes C O 2 , but also C H 4 and N 2 0 converted into units of C0 2 ) , but have increased to 682 millions tonnes in 1997, and are predicted to reach annual emissions of 750 million tonnes by 2010 (Environment Canada 1999). Not only is energy consumption expected to increase in the coming decade, but the population is expected to increase as well. The per capita reductions necessary to reach Canada's Kyoto commitment, national emissions of only 565 million tonnes per year, will be an enormous undertaking. It will likely represent a decrease of the per capita emissions by 20 to 30%. 6 The national emissions in 1997, the 682 million tonnes of carbon dioxide equivalents, break down into 76% as carbon dioxide, 13% as methane, 9% as nitrous oxide with various trace gases completing the total (ibid). Reversing the increase and continuing downwards to satisfy Canada's international commitment will require a strong and determined effort by government and industry. It is also important to recognize that Kyoto is only the beginning. The Kyoto Protocol is inadequate and it is commonly recognized that this agreement will not by itself, significantly reduce the rate of climate change. While it represents a necessary first step towards emission reductions it is only the beginning in a long series of conventions to reduce global emissions (Rolfe 1998). Dutch researchers have estimated that in order to avoid extreme changes in climate (defined as sea level increases of no more then 20 centimetres and global temperature increases of no more than 1°C over the next century), greenhouse gas emissions will need to be reduced to 37% below 1990 levels by 2050 and to 64% below by 2100 (Alcamo and Kreileman 1996). As the reductions to prevent extreme climate change are much greater than the average 5.2% reductions committed by the vast majority of developed countries, the Kyoto Protocol is not expected (by itself) to successfully stop Global Climate Change. Therefore much greater and deeper emission reductions will undoubtedly be required in the future. Though there is a tremendous amount of uncertainty regarding how our country will actually decrease the national emissions in the coming years, it is likely that reductions will be required by all sectors. Waste management will probably be called upon to decrease its contribution to climate change along with all other sectors, be it industry, government or the general population. Not only will emission reductions to satisfy the Kyoto Protocol be expected from waste management in the next decade but even deeper cuts will be likely in the long-term future. The next section presents an overview of the GVRD's existing system of solid waste management and discusses the important greenhouse gas implications of these activities. The concepts in the next section represent the opportunities for the participation of waste management in reducing emissions in a carbon-constrained environment. 1.3 SOLID WASTE MANAGEMENT The solid waste management system of the Greater Vancouver Regional District serves the population of the 1.98 million residents in the 20 municipalities and two electoral areas that make up the metropolitan area of Greater Vancouver. One Fraser Valley municipality, Abbotsford, outside the GVRD boundaries, also participates in this waste management system. For simplicity, Anmore and Belcarra have been included with the City of Port Moody and the Village of Lions Bay has been included with Electoral Area C in this report. As a result, this report will refer to the GVRD as consisting of 23 member municipalities but only 20 municipal entities are investigated. 7 There are five main components to this waste management system: landfill disposal, incineration, recycling, backyard composting and centralized composting. In 1998, this system managed 1,120,000 tonnes of general waste and 681,910 tonnes of recyclables and composted organics from all the various residential, industrial, commercial and institutional sources represented in these municipalities (GVRD 1999). Two landfills are currently in use by the GVRD, the Cache Creek Landfill and the Vancouver Landfill (at Burns Bog), while one incinerator, the Burnaby Incinerator, is also owned by the GVRD. In 1998, the Cache Creek Landfill provided disposal for 474,873 tonnes of waste, the Vancouver Landfill disposed of 379,554 tonnes and the Burnaby Incinerator combusted 247,078 tonnes (ibid). Recyclables in the GVRD collected curbside and by other means are delivered to a number of depots in the Lower Mainland for processing and subsequent marketing to various industries for reuse. The recycling depots operated by E T L Recycling Services, International Paper Industries and Browning Ferris Industries are just three examples of these. In addition to recycling, many of the member municipalities have been actively encouraging backyard composting for residents to manage their own food scraps and yard trimmings. In some jurisdictions, backyard composters have been distributed to more than 30% of the population of ground-level (single-family) residences (Pers. comm. A l Lynch 1999). It is estimated that each composter annually diverts 250 kg of food scraps and yard trimmings from collection (Pers. comm. Bev Weber). In order to keep yard trimmings out of the waste stream, a separate curbside collection of yard trimmings has been initiated in many municipalities. Other jurisdictions have elected to provide residential drop-off (RDO) locations. Many of the municipalities have contracted with Fraser Richmond Bio-Cycle (FRBC) to manage the collected yard trimmings. FRBC provides centralized composting of yard wastes by turned windrows and then subsequently markets the finished compost. The City of Vancouver operates its own composting facility at the Vancouver Landfill, and while the RDO of yard trimmings has been in existence for quite some time, they recently initiated curbside collection of yard trimmings. To serve the flows of this large quantity of waste from the member municipalities, several transfer stations (TSs) exist in the GVRD. In total, six transfer stations, the Coquitlam TS, the Vancouver TS, the North Shore TS, the Matsqui TS, the Langley TS and the Maple Ridge TS, facilitate the flow of waste from collection vehicles to disposal sites. In terms of 1998 masses, the Coquitlam TS with 316,360 tonnes, the Vancouver TS with 273,377 tonnes and the North Shore TS with 194,683 tonnes were by far the three most important transfer stations (GVRD 1999). It is important to recognize that all these operations require fossil energy, predominantly in the form of diesel fuel, a fossil fuel. The curbside collection of wastes, the processing of wastes at transfer stations and the transportation of wastes to disposal facilities all require the combustion of diesel fuel. This combustion directly results in a greenhouse gas emission of approximately 2.8 kg of C 0 2 equivalent (includes C O 2 , but also C H 4 and N 2 O converted into units of C O 2 ) per L of diesel fuel (Environment Canada 1997a). 8 The remainder of this section will discuss the greenhouse gas issues associated with the five waste management methods employed in the GVRD: landfill disposal, incineration, recycling and backyard and centralized composting. While discussed in a general manner, the following discussion is particularly suited to the local situation in the GVRD. 1.3.1 Landfill Disposal Landfills are well known to be emitters of methane to the atmosphere. In 1997, landfills in Canada were estimated to have emitted 1 million tonnes of C H 4 or 21.0 million tonnes of C O 2 equivalent. This represents 3.1% of Canada's estimated national GHG emissions of 682 million tonnes in 1997 (Environment Canada 1999). If organic wastes are landfilled the resulting anaerobic decomposition will emit nearly equal parts of C H 4 and C O 2 . The anaerobic decomposition of a simple six carbon sugar is: C 6 H i 2 0 6 3C0 2 + 3CH 4 The methane represents a strong greenhouse gas emission because it is 21 times more effective as a greenhouse gas than carbon dioxide. However, the C O 2 emission, while being a greenhouse gas, does not have to be considered a greenhouse gas emission. These organic materials were originally formed when photosynthesis fixed the inorganic carbon of C O 2 to organic carbon. The decomposition of these organic materials liberates the same carbon that was originally removed and is therefore completing the cycle. As a result, the C O 2 emission during anaerobic decomposition at landfills is "GHG neutral" and can be ignored as an emission. The logical extension of this is that if the landfill methane produced can be collected and combusted to C O 2 , then no GHG emission would result. This is indeed what occurs at many active and inactive landfills - methane is collected and flared. However, not all of the methane is collected; while at some sites a large portion is managed in this manner, at other sites much of the methane escapes collection systems - or there is no collection system - and it is emitted to the atmosphere. There is also the potential for microorganisms in the cover material of the landfill to cause the oxidation of C H 4 to C O 2 . Research conducted in the U.S. suggests that about 10% of the methane which had escaped collection was oxidized (Czepiel et al. 1996). Of even greater benefit than collecting all the methane and flaring it, is to collect all the methane and utilize it for energy purposes - to essentially use the landfill methane to replace natural gas, a fossil fuel. By using a GHG neutral bioenergy source like landfill methane to avoid the consumption of a fossil fuel, greenhouse gas benefits are realized. These benefits are the prevented C O 2 emissions from the combustion of natural gas. It is important to recognize that when the carbon in fossil fuels is released to the atmosphere as C O 2 , it is considered to be a greenhouse gas emission. But this carbon was also originally photosynthesized from carbon in the atmosphere. However, the time scale of millions of years necessary to create geological formations of fossil fuels is appropriate for climate change concerns while the months, years or decades time scale for the closed carbon cycle of food or paper is not the carbon of concern. Assessing the C O 2 emissions from composting food waste, carbon which was only fixed 6 months previous, as a greenhouse gas emission would be putting a "red-herring" in front of efforts attempting to reduce emissions from fossil fuels - the main contributor to Global Climate Change. 9 There are two important remaining issues with landfill disposal: landfill carbon sequestration and nitrous oxide emissions. Landfill carbon sequestration is the capture and secure storage of carbon that would otherwise be emitted to the atmosphere. This can occur when organic waste is disposed in landfills but resists decomposition in the anaerobic conditions. Because this photosynthesized carbon from atmospheric-carbon becomes stored in landfills it reduces the atmospheric concentration of C O 2 . This concept is thoroughly discussed in Chapter 2 - Methodology. For the introduction here it will suffice to state that different waste materials greatly vary in providing landfill carbon sequestration. While newsprint and branches, with their high lignin content, largely resist anaerobic decomposition, office paper and food scraps readily decompose in landfills and provide more methane than carbon sequestration. It needs to be recognized that the disposal of plastics in landfills cannot be considered a sequestration activity. The removal of petroleum products from geological reservoirs, their manufacture into plastics and their disposal in landfills at the end of their useful life is just substituting one sequestration for another (remember that the time scale is again relevant). There is no net difference to the atmosphere and as such must be ignored from the perspective of sequestration. Much of the nitrogen contained in the food and yard waste components of M S W can be traced back to chemical fertilizers applied onto agricultural lands or onto backyard residences. When these organic wastes are disposed in landfills, the resulting anaerobic decomposition will release the nitrogen as ammonia (NH3) or ammonium (NH 4 + ) . Due to the low pH from the presence of volatile fatty acids in the fill, the vast amount of nitrogen will be in the ammonium form. The nitrification of the ammonium to nitrate (NO3") is greatly restricted because of the lack of suitable electron acceptors in the anaerobic conditions. Furthermore, with nitrification restricted, denitrification is also restricted. Thus there is little potential for N 2 O to be emitted with the vented landfill gas. However, water percolating through the fill can entrain the ammonium and remove it as landfill leachate. Leachate is typically transferred to wastewater facilities for treatment. From this point forward, the nitrogen is free to nitrify and denitrify (in fact, depending on the treatment plant, the nitrogen may be encouraged to nitrify and denitrify) and N 2 O emissions are a strong possibility. As much of this nitrogen was originally created by human activity, any subsequent emission as N 2 O is an important GHG emission. This is discussed in greater detail in Section 2.5. 1.3.2 Incineration The G V R D utilizes one incinerator for waste disposal purposes, the Burnaby Incinerator. During 1998, this Incinerator combusted 247,075 tonnes of M S W which resulted in 820,000 tonnes of steam being generated. Over half of this steam was transferred to the adjacent Crown Packaging Limited (CPL) facility for the pulping of cardboard. Were it not for the steam from the Incinerator, CPL would be using natural gas-fired boilers, fossil energy, to produce the necessary steam. Consequently, a definite greenhouse gas benefit from the avoided natural gas consumption is realized by the transfer of steam to CPL. 10 The combustion of municipal solid waste at the Bumaby Incinerator is supported by the chemical energy inherent in the wastes. With the exception of metals, glass and ceramics, all the other components are organic and will burn. As the oxidation of organic wastes must release C O 2 , it is necessary to once again discuss the origins of the emitted carbon. When biomass wastes such as paper products, food scraps and yard trimmings are combusted, they will be releasing the same carbon previously photosynthesized; they can be considered GHG neutral and thus ignored. In contrast, plastics contain fossil- carbon (as these materials are manufactured from petroleum products). This is carbon that was also photosynthesized but it occurred millions of years ago. Combusting plastics in an incinerator is identical to burning fossil fuels for energy; both contain the carbon of concern in human-induced climate change. While paper, food and yard waste can be considered bioenergy upon combustion, plastics must be considered a source of greenhouse gas emissions. Fortunately, the combustion of plastics generates steam which is used by another industry and thus eliminates the need for the combustion of natural gas (another source of fossil-carbon). Also of importance with respect to waste incineration is the potential for nitrous oxide emissions. The formation of nitrous oxide can result from five separate pathways: • thermal conversion of N2 gas in air to N 2 O during combustion (immediate emis.), • thermal conversion of N in fuel (wastes) to N 2 O (immediate emission), • thermal conversion of ammonia (NH3) injected in the flue gases (immediate emis.), • microbial N 2 O conversion of NOx emitted and later denitrified (future emission) and • microbial N 2 O conversion of N H 3 injected but unreacted (future emission). All of these pathways will be thoroughly discussed in Section For this introduction it should be noted that the thermal conversion of the nitrogen in food waste is likely the greatest source of nitrous oxide emissions during incineration. 1.3.3 B a c k y a r d a n d C e n t r a l i z e d C o m p o s t i n g The greenhouse gas implications of the backyard or centralized composting of food scraps and yard trimmings are virtually identical. The greatest exception would be the diesel fuel necessary for the curbside collection vehicles and windrow equipment to perform centralized composting. Both waste materials are biological in origin and thus any C O 2 from decomposition is GHG neutral and can be ignored. By diverting these organic wastes from landfill disposal and composting them, the prevention of any future methane emissions at the landfill is achieved. However, by composting there is also no opportunity for energy generation in the form of steam at the incinerator or collected methane at the landfill. Also of concern in the composting process, is the potential for nitrous oxide and methane emissions. As with the N 2 O emitted from landfill leachate, N 2 0 can result during the microbial leakage associated with the nitrification and denitrification of the nitrogen in the organic wastes. Several research papers have been obtained which report the existence of these emissions. A greater discussion of this issue is provided in Section There is also an opportunity for methane gas to be emitted from composts which 11 are inadequately aerated. This has been observed to occur with passively aerated static piles (composts which are turned infrequently) and is assessed in Appendices I and J. 1.3.4 Recycling Recycling is a critical component of integrated solid waste management. In fact, the mass of waste currently recycled in the GVRD nearly equals the mass which is landfilled and is almost three times that which is incinerated. For this reason, any waste analysis neglecting recycling would be largely inaccurate. As to be discussed, recycling has important greenhouse gas repercussions. However, complicating the emissions-from- recycling issue is that many of these repercussions are outside the jurisdictional authority of the GVRD. Nevertheless, they require discussion here. Recycling requires the expenditure of energy. As most of this energy is derived from fossil fuels, it therefore contributes greenhouse gas emissions to the atmosphere. Recyclables require curbside collection, processing at recycling depots and subsequent transportation to the factories or mills where they will be manufactured into new products. In addition, the manufacturing of new products from recycled materials also requires fossil energy consumption. However, this consumption of energy and the associated greenhouse gas emissions are not the only considerations. There is great potential for large savings in the energy requirements of making Widget A from recycled materials (wholly or in part) as opposed to making Widget A entirely from virgin materials. When recycled materials are substituted for virgin materials and the energy consumption is decreased there is a consequent reduction of greenhouse gas emissions. Extensive research by various organizations have observed decreased energy requirements and decreased GHG emissions by substituting recycled materials for primary materials. However, the converse can also be true; several researchers have questioned the recycling of paper - while it is more energy efficient to make recycled paper than virgin paper, it may actually increase the consumption of fossil energy. In contrast, virgin paper production typically utilizes wood waste as its energy source (wood waste being a form of GHG neutral bioenergy). This research is reviewed in Section 2.6 - Recycling Analysis. The utilization of energy by industry (and the associated GHG emissions) for the manufacture of products used by society is outside the interest of planners in waste management. However, the greenhouse gas implications of landfill disposed or incinerated waste products which could have been recycled require assessment. By disposing or combusting paper products which would otherwise have been recycled, a municipality is preventing the substitution of recycled fibre for virgin fibre at a pulp and paper mill. If there is a GHG benefit to substituting recycled feedstocks for virgin feedstocks, this issue has to be addressed when, disposing or incinerating of recyclables. For example, increasing waste incineration of paper products to generate bioenergy may result in greater GHG emissions at the pulp mill. As a result, the GHG emissions of recycling newsprint, office paper, ferrous metal, glass and plastic (high-density and low- density polyethylene) is investigated in this thesis. It is important to note, however, that the recycling investigation was restricted to comparing the emissions from taking recycled and virgin materials to an identical intermediate product. This is not the same as 12 manufacturing the final product for it is only following the respective materials until they converge, defined by one consultant as the "Energy Convergence Point" (Tellus 1994). For example, the recycling of ferrous metal is only analyzed until steel ingots have been produced but not a final product. From this analysis it is possible to assess the GHG implications of substituting recycled materials for virgin materials. Lastly, this thesis presents research into the potential for carbon storage in forests in Canada to be affected by increased paper recycling reducing the demand for the harvesting of primary timber. It is important to recognize that many of the energy (and thus greenhouse gas) ramifications of virgin vs. recycled manufacturing are outside the authority of waste planners at the GVRD and could cause complications in future emissions trading; not the least of which being "Who owns the emissions credit?". If the GVRD endeavors to reduce the GHG emissions under its responsibility but resulted in increasing the emissions of a manufacturing organization there would be no net benefit to the atmosphere. Full life-cycle impacts need to be taken into account when attempting to reduce emissions. This discussion has further relevance when explained in conjunction with emissions trading where the action has to result in a "net reduction" - the credit cannot be invalidated by indirect emissions leaking from other sources. Developments in the national and international policy to reduce emissions will be important to the greenhouse gas implications of waste management discussed in this section. The emissions of C O 2 , C H 4 or N 2 O from GVRD's waste management could be reduced in the future and traded for revenue or taxed in the future to force reductions to be implemented. This is the focus of the next section. 1.4 RECENT POLICY DEVELOPMENTS How can the international effort to reduce emissions of greenhouse gases affect waste management? As previously discussed, in the 1997 Kyoto Protocol Canada committed to reduce emissions to 6% below the 1990 level between the years 2008 and 2012. Considering that with the population growth during this time, the cuts will represent per capita reductions between 20 and 30%, a monumental undertaking. For the successful attainment of this target, it is very likely that the emissions trading of G H G credits, the taxation of GHG emissions or direct legislation to reduce emissions (or a combination of these three) will be implemented in the next decade. These mechanisms could greatly impact the current economics of waste management. For example, if one activity is demonstrated to result in lower emissions than another, such as using composting to divert organic waste away from landfill disposal (thereby preventing future methane emissions), there is a real GHG benefit translated into an economic motivator in the following ways. In an emissions trading program, composting projects could claim credits for the resulting GHG benefit. These credits could be sold to another party, such as an energy company, which is being forced by regulations to reduce its emissions. The revenue generated by trading credits could then be used to finance the composting 13 project. Under a taxation system, the methane emissions from a landfill could be taxed as a GHG emission, potentially making composting a more economically attractive activity to pursue instead of landfilling. Both of these systems could profoundly change the current economics of waste management. Trading is fueled by the government legislating an emissions cap which can only be exceeded by possessing an equivalent amount of emissions credits. A typical GHG emission reduction trade occurs when a buyer with high cost options for emission reductions purchases a lower cost option from a seller and enters into a contract to transfer ownership of the emission reduction credit (ERC) (GERT 1998). To qualify as a greenhouse gas reduction, the activity must result in the atmosphere experiencing a net reduction in greenhouse gas emissions. These reductions are measured against a baseline which is determined by the emissions path that would have occurred in the absence of the specific activity. Greenhouse gas emission reductions become credits when "i) the action has been implemented, ii) the action generates a reduction, and iii) the reduction has been verified." (USD 1998) These emission reduction credits may be traded within a future legally binding emission trading system or may be accumulated and used against possible future compliance requirements. Emissions trading is already occurring. A landfill gas utilization project initiated by Norseman Engineering for the Port Mann Landfill will prevent an estimated emission of 210,000 tonnes of carbon dioxide equivalent (tCC^e) over the next 14 years (through the upgrade of the L F G collection system). The GHG credits were purchased by a consortium of Canadian energy companies, the Greenhouse Emissions Management Consortium (GEMCo), for $1 per tCC^e and thus the project will be implemented. The resulting $210,000 payable over the next 14 years as the GHG emission reductions are realized will finance the project. Another example is a proposed composting project in Southern Ontario which is estimated to prevent 31,422 tC02e of future methane emissions over the next 12 years. This will be achieved by diverting 111,000 tonnes of yard waste away from landfill disposal. While up for sale, the GHG credits from this project have not been purchased at this time. Both of these credit trading projects are part of the Greenhouse Gas Emission Reduction Trading Pilot Program (GERT) which is a combined effort between the Federal Government, several provincial environment ministries and a number of industry and non-profit groups (GERT 1998). This pilot program was initiated in June 1998 and will continue as a learning exercise until Dec 2001. The lessons learned in this pilot program will likely prove invaluable to the full- scale implementation of emission trading. Internationally, carbon taxation is also occurring. Finland is the first country in the world to introduce a CO2 tax. In September, 1998, this carbon tax on heat and transportation fuels was raised to US$19.2 per tC02. Also in Scandinavia, the Norwegian government is proposing a carbon tax of US$13.3 per tC02, and in the United Kingdom, the potential is also strong for instituting a carbon tax (Hanisch 1998). Though it is not clear in which manner our Federal government will elect to successfully reach its target in the Kyoto Protocol, it appears that every organization at all levels of the 14 government and each industrial sector will have to reduce emissions. Personal lifestyle changes by Canadians will also be necessary to reduce emissions. These governmental agencies and private companies will likely have to undertake meaningful reductions or purchase the credits, from another party's meaningful reductions. This is part and parcel with the emissions trading option. In contrast, under carbon taxation, meaningful reductions will also occur, but out of brute necessity - it will become too costly to continue emitting. Discussing trading or taxing is all speculative since the required reductions or the price of carbon, either traded or taxed, is yet to be determined. A carbon-constrained environment has yet to be developed and at the GERT pilot program, the carbon credits in the nine projects available for trading as of May 17, 1999, ranged in value from $1.00 to $14.00 per tonne of C 0 2 equivalent (tC02e) (GERT 1999). BC Hydro has committed over $2 million for the purchase of GHG offsets over the 2000- 2001 time frame (BC Hydro 2000). The impact that these new policies could have on future waste management are sufficient to warrant this analysis. The next section explains in detail the objectives of this research. 1.5 RESEARCH OBJECTIVES There are two main objectives to this study: (1) to perform a greenhouse gas emissions analysis of the GVRD's existing solid waste management system and (2), to develop a planning tool which can evaluate the positive and negative GHG impacts of changes to this waste management system. Before attempting to include greenhouse gases in future waste management it is necessary to have a critical understanding of the existing system. This research analyzes the current system and then enables, with a spreadsheet program, changes in waste management to be assessed from the perspective of greenhouse gas emissions. In this spreadsheet program the mass flows of waste into various management processes are variables that can be changed. In addition, parameters important in calculating greenhouse gas emissions, such as the effectiveness of landfill gas collection systems or the energy efficiency of waste incineration, are also variables subject to change by the user. This thesis, together with the spreadsheet program, enables planners to evaluate opportunities which may exist in a future GHG emissions trading program or liabilities which may present themselves in a future GHG emissions taxing system. This thesis estimates the greenhouse gas emissions resulting from the existing system of landfilling, incinerating, composting (backyard and centralized) and recycling of newsprint, office paper, ferrous metal, glass, plastic (high-density and low-density polyethylene), food scraps and yard trimmings. The remaining waste is grouped together, defined as the Remainder, and is also analyzed. These eight main components of the municipal waste stream were investigated individually so that the current participation in source-separation can be more effectively directed at "greenhouse gas reducing" activities. In addition, the 23 member municipalities were investigated separately to more accurately model the GVRD. 15 By using the results of this research with the currently debated price of carbon (either traded or taxed), it is possible to assess changes in waste management from the perspective of financial incentives. Any future changes which are performed voluntarily in order to reduce GHG emissions can be claimed for credits. When traded, these credits assist in financing the proposed project. However, if the changes to future operation are required by legislation, their implementation is no longer voluntary and would be ineligible for crediting. The importance of emissions trading in future waste management cannot be understated. However, in order to assess changes it is necessary to have a baseline upon which to improve. This baseline is the existing waste management system. 1.6 THESIS OVERVIEW The end of the first chapter is an opportune moment to present an overview of this thesis. This chapter has introduced the concern with greenhouse gases emissions and the recent developments in policy-making to mitigate global climate change. Together with an explanation of solid waste management in the GVRD, the inter-relationships between emissions and policy are discussed. It is the importance of these inter-relationships which necessitates this research and provides the impetus for Section 1.5 - Research Objectives. The next chapter, Chapter 2 - Methodology, explains the calculations which are used to estimate the GHG emissions. This chapter consists of 12 major sections : • Methodology Introduction • Global Warming Potential • Biomass Decomposition/Combustion • Landfill Carbon Sequestration • Nitrous Oxide Emissions • Recycling Analysis • Uncertainty with the Estimates • Spreadsheet Program • Waste Mass Estimates • Remaining Wastes • GHG Emissions not Investigated • Standards These methods represent the current state of the knowledge on these issues and were developed from an extensive review of available literature. These sections lay out the methods utilized in the 12 appendices. However, the fine details which are necessary to actually calculate greenhouse gas emissions are included in the appropriate appendices for that issue. It is the intent of this thesis that readers learn a specific concept in the next chapter and then refer to the appropriate appendix to learn how it is actually implemented "for number crunching." As a result, readers should feel comfortable in jumping back and forth to learn the principles used to assess GHG emissions. 16 The results and discussion of this thesis are presented in Chapter 3 . This is followed by Chapter 4 - Conclusions & Recommendations. The 12 appendices after the Bibliography constitute a major portion of this thesis. These appendices present all of the calculations which are used in the spreadsheet program to model emissions. These calculations serve as sample calculations to provide readers with an understanding of the numbers and equations contained in the accompanying spreadsheet. Many of these appendices are presented as independent modules which are developed separately. Because of this lack of interdependency, a degree of repetition results for readers. However, in instances of excessive repetition, such as transportation issues after the North Shore Transfer Station for the three North Shore municipalities, only one complete version is provided. The first appendix, Appendix A - General Calculations, contains general parameters and calculations which are not specific to either a single municipality or a waste component. This is followed by Appendix B - Municipality Calculations, which presents all the diesel fuel consumption data necessary for curbside collection, processing at transfer stations and subsequent transportation to disposal, recycling or composting facilities. This also includes the estimates of the masses of different waste components which are disposed or recycled. It was necessary to estimate waste masses specific to individual municipalities because of the highly variable contribution of wastes from ICI sources which is independent of the residential population of that jurisdiction. This appendix (and the entire report) assumes that waste from Anmore and Belcarra are essentially from the City of Port Moody and that waste from the Village of Lions Bay can be included with Electoral Area C. The next 9 appendices are specific to the 9 waste components analyzed in this thesis. They provide the calculations used to estimate the GHG emissions to be expected from landfilling, incinerating, composting or recycling of newsprint, office paper, metal, glass, plastic, food and yard waste, and remainder. The important results derived in Appendix A through K are the emission factors required to calculate emissions from various management methods. When these emission factors are multiplied by the tonnage of waste managed in this manner, the estimated GHG emission will result. Appendix L - Spreadsheet Program, is the last appendix and contains the greenhouse gas Model of the GVRD's existing waste management system. 17 Chapter 2 METHODOLOGY The calculations in the appendices are based on the methodology developed in this chapter. An extensive review of previous research and the available guidelines for estimating greenhouse gas emissions is performed for this thesis. In addition, a number of individuals involved in waste management in the Lower Mainland were contacted to acquire data for this investigation. These personal communications with representatives of organizations such as the GVRD, City of Vancouver, Wastech Services, North Shore Recycling Program and Montenay proved invaluable to this work. Much of this collected data is directly used in the calculations in the appendices. 2.1 INTRODUCTION This chapter explains the important concepts used to develop the methodology for this investigation. Twelve sections are required in this methodology to describe these principles. However, the fine details which are necessary to actually calculate greenhouse gas emissions are included in the associated appendices. For example, the GHG neutrality of combusting newsprint for energy is discussed in Section 2.3 - Biomass Decomposition/Combustion but the actual calculations for this energy are developed in Appendix C - Newsprint Waste Management. In fact, all the calculations conducted for this study are included in the appendices. It is these calculations that are used to program the spreadsheet. With the great utility of this spreadsheet program accredited in no small part to the fact that mass inputs and parameters can be changed to calculate new emissions, the calculations provided in the appendices become essentially sample calculations. The methodology section, together with the sample calculations in the appendices, serve to provide the reader with valuable information so that changes can be made to the spreadsheet in the future. Of critical importance to the methodology used throughout this report are the guidelines developed by the Intergovernmental Panel on Climate Change (IPCC) to calculate GHG emissions. Canada and the other 160 signatory parties to the United Nations Framework Convention on Climate Change have agreed to develop inventories of GHGs for the purposes of developing mitigation strategies and monitoring the progress of those strategies (USEPA 1998). These national inventories are estimated using guidelines developed by the IPCC. These guidelines are the three volumes of the Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories (IPCC 1997). While throughout this investigation an attempt has been made to remain consistent with the IPCC guidelines, in several instances it has been necessary to make changes. This resulted from a careful evaluation of the subject. Most notable is the concept of landfill carbon sequestration (already included in a recent USEPA (1998) report) and the 18 potential for nitrous oxide emissions. All changes are documented throughout this report. It is my opinion that these changes were necessary to refine the GHG estimates and it is hoped that future IPCC methodology will reflect these changes. This chapter consists of 12 major sections. The first, Section 2.1 - Introduction, provides an overview of this chapter and introduces the methodology used in this report. Global Warming Potential (2.2) is the second section and explains the internationally accepted convention by which different greenhouse gases are converted into a common unit based on each gases relative ability to trap infrared radiation. The next section, Biomass Decomposition/Combustion (2.3), describes guidelines by the Intergovernmental Panel on Climate Change which draws clear distinctions between C 0 2 released from fossil fuel combustion and C O 2 released during the decomposition of biomass. This has important ramifications in this thesis as waste management contributes substantial emissions of both. Section 2.4 - Landfill Carbon Sequestration, reviews the available literature on this emerging issue. To properly assess landfill disposal from a greenhouse gas perspective, it is necessary to quantify not only the C H 4 emissions but also the ability of landfills to store the carbon from biomass which resists anaerobic decomposition. The next section, Nitrous Oxide Emissions (2.5), presents an extensive review of the current understanding of this important issue. N 2 0 can leak from the cells of microorganisms during nitrification and denitrification. Because of the high nitrogen content of food and yard components of MSW, the potential emissions during the management of these wastes is of particular importance. Section 2.6 - Recycling Analysis, discusses the methods employed in this study to estimate the emissions associated with recyclables. Uncertainty with the Estimates (2.7), presents the uncertainty that is always associated with estimating data. While much of the data in this thesis contains minimal uncertainty, many parameters are highly uncertain and require separate discussion in this section. The next section, Spreadsheet Program (2.8), illustrates the workings of the spreadsheet to educate users in its operation. Waste Mass Estimates (2.9) provides the methodology utilized to estimate the masses of the 8 waste components analyzed in the 23 member municipalities in the GVRD. Each municipality is analyzed individually because of the large differences between the fractions of waste from residential or ICI sources. After the 8 investigated waste components are removed from MSW there will be still be a remainder. This remainder is discussed in Section 2.10 - Remaining Wastes from the perspective of GHG implications. GHG Emissions not Investigated (2.11) draws a boundary around the focus of this research, thereby excluding the thousands of direct & indirect sources of emissions which could be included in this study as a result of our energy intensive society. The last section, Standards (2.12), provides readers with the units and other conventions used throughout this thesis. 2.2 GLOBAL WARMING POTENTIAL The three greenhouse gases evaluated in this report, C O 2 , C H 4 and N 2 O , greatly vary in their relative contribution to global warming. Each of these gases has different radiative forcings (the capacity to absorb infrared radiation) and different atmospheric lifetimes. To complicate matters further, there are direct radiative forcing effects or indirect 19 radiative forcing effects. Direct radiative forcing is when the gas itself is a greenhouse gas. Indirect radiative forcing effects occur when the chemical transformation of the original gas produces a gas or gases that are greenhouse gases, or when a gas influences the atmospheric lifetimes of other greenhouse gases (Environment Canada 1997a). The radiative forcing of C O 2 is estimated to be 0.018 W/m 2«ppm while that of C H 4 is 0.37 W/m2*ppm or 20.6 times greater and N 2 0 is 3.7 W/m 2 ,ppm or 206 times greater. The atmospheric lifetime of C H 4 , N 2 0 and C 0 2 , is estimated to be 12.2 years, 120 years, and variable based upon the carbon cycle (IPCC 1995). With all this variation, the concept of Global Warming Potential (GWP) was developed to allow for the comparison of the relative ability of each greenhouse gas to trap heat in the atmosphere. The GWP is defined as: "the time-integrated change in radiative forcing due to the instantaneous release of 1 kg of a trace gas expressed relative to the radiative forcing from the release of 1 kg of C 0 2 . . .The GWP of a greenhouse gas takes into account both the instantaneous radiative forcing due to an incremental concentration increase and the lifetime of the gas." (Environment Canada 1997a) A 100 year reference period is recommended by the IPCC when dealing with global warming potentials (IPCC 1995). The latest information from the IPCC has estimated the 100 year time-frame GWP of C H 4 to be 21 and the GWP of N 2 0 to be 310 (relative to C 0 2 on a mass basis) (ibid). The GWP for C H 4 also takes into account the indirect contributions due to tropospheric ozone and stratospheric water vapour production. These are the Global Warming Potential values that are used in this report. 2.3 BIOMASS DECOMPOSITION/COMBUSTION This section presents the internationally accepted guidelines which draw a clear distinction between the C 0 2 emitted during the combustion of fossil fuels and the C 0 2 emitted during the decomposition or combustion of biomass. The C 0 2 from the consumption of fossil fuel results from human activities and is believed to be causing Global Climate Change while the quantitatively greater carbon cycling for biomass is a natural closed process. Separating these two is necessary, for otherwise, this research would have to consider the decomposition of biomass during the composting process as a GHG emission; of little merit when remembering that the alternative is natural rotting on the ground. The IPCC methodology for addressing C 0 2 emissions from biomass has already been mentioned in the introduction but requires further discussion as it is extremely important for this study. Specifically, these are the C 0 2 emissions resulting from the decomposition or combustion of paper products, food scraps or yard trimmings, defined as biomass for the remainder of this section. The carbon in biomass material was originally removed from the atmosphere by photosynthesis, and under natural conditions, will eventually cycle back to the atmosphere as C 0 2 . This carbon is part of a natural 20 process which cycles through the atmosphere, water, soils and biota, and is far greater in magnitude than carbon resulting from human intervention, the carbon from fossil fuels or deforestation. But the focus of the United Nations Framework Convention on Climate Change is not on these natural processes but on the anthropogenic emissions, emissions resulting from human activities and subject to human control, as it is these emissions that have the potential to disrupt the carbon's biogeochemical cycle and alter the atmosphere's heat trapping ability (USEPA 1998). The difference in C O 2 emissions from the decomposition of biogenic materials and the combustion of fossil fuels was explained succinctly in a U.S. Environmental Protection Agency report (ibid): "Thus, for processes with C O 2 emissions, if (a) the emissions are from biogenic materials and (b) the materials are grown on a sustainable basis, then those emissions are considered to simply close the loop in the natural carbon cycle - that is, they return to the atmosphere C O 2 which was originally removed by photosynthesis. In this case, the C O 2 emissions are not counted. ... On the other hand, C O 2 emissions from burning fossil fuels are counted because these emissions would not enter the cycle were it not for human activity. Likewise, C H 4 emissions from landfills are counted - even though the source of carbon is primarily biogenic, C H 4 emissions would not be emitted were it not for the human activity of landfilling the waste, which creates anaerobic conditions conducive to C H 4 formation." As a result, the C O 2 emissions resulting from composting, incineration or landfilling of biomass are considered to be "neutral" and thus are not considered to be greenhouse gas emissions. Therefore, the release of C O 2 during anaerobic decomposition at landfills, the biomass-C02 emission from combustion at incinerators and the C O 2 resulting from aerobic decomposition during composting are not considered as greenhouse gas emissions. In fact, incineration can just be thought of as an accelerated version of composting with an energy generating component included. It is important to recognize the important assumption that biomass is sustainably grown and harvested. The combustion of paper that was manufactured from unsustainable harvested trees would not be GHG neutral; there is no future tree growth to fix this carbon once again. This assumption is necessary to neglect any C O 2 emissions from biomass decomposition/oxidation. This report assumes that paper products, food scraps and yard trimmings are sustainably harvested. Separating the C O 2 resulting from fossil fuels and the C O 2 resulting from biomass decomposition or combustion is necessary to prevent effort being wasted on natural processes which are not a concern for Global Climate Change. For example, this distinction causes the calculations in the appendices to account for the diesel fuel consumption (for conversion into units of C O 2 emitted) associated with the curbside collection, transfer station processing and subsequent transportation of yard trimmings to a centralized composting facility. It also includes the diesel fuel consumption necessary to operate the equipment required to perform composting of this material. However, it does not consider any of the emissions which result when this organic material is 21 oxidized by microorganisms to inorganic C O 2 . This is simply the conclusion of the cycle which started when inorganic C O 2 in the atmosphere was fixed by photosynthesis to organic carbon. Readers may have already noticed that a reference time-frame is inherent in treating biomass decomposition as GHG neutral. Fossil fuels contain carbon which was also originally C O 2 in the atmosphere and was fixed by photosynthesis into the organic carbon of biomass. This occurred millions of years ago and the fossil fuel carbon has been stored deep underground in geological reservoirs in the interim. Liberating this carbon into the atmosphere is fundamentally different than liberating the carbon in an apple core which was photosynthesized 6 months or 6 years ago. Even liberating the carbon in paper products which were photosynthesized by tree growth 50 years ago is fundamentally different than liberating carbon from fossil fuels created millions of years ago. Especially when remembering that a new tree will be growing in the location where the previous one was harvested - the sustainable harvesting assumption. It is these boundaries which are used in the calculations in the appendices. Landfill methane emissions also require discussion in the context of biomass carbon cycling. If the C O 2 emission from a landfill is neutral but C H 4 emissions are G H G contributions, would it not be more accurate to subtract C H 4 by the C O 2 which would have occurred otherwise. This improvement is based on the fact that the methane results from a biomass waste and if the material can decompose anaerobically (without oxygen), it would likely decompose aerobically (breakdown with oxygen is inherently easier). Though methane is 21 times more effective than C O 2 , it would be more accurate to subtract the C O 2 that would otherwise have occurred if the methane emission did not. This reduces landfill methane emissions by approximately 5% and is defined by this author as CO2 Subtraction. However, this improvement has not been included in this report so that it would be consistent with the IPCC methodology, but it is logical that it may be included in future work. What if photosynthesis removes C 0 2 from the atmosphere to create biomass but the carbon is never returned to the atmosphere? If the biomass resists the decomposition necessary to return the carbon to the atmosphere, this process can be interpreted as a GHG benefit and is analogous to permanently converting grassland to forests to sequester carbon. Both examples are reducing the atmospheric concentration of C O 2 to assist in mitigating Global Climate Change. This removal of carbon from the atmosphere and permanent storage can occur when biomass is disposed in landfills and resists decomposition in the anaerobic conditions. The next section reviews this emerging issue. 2.4 LANDFILL CARBON SEQUESTRATION The anaerobic decomposition of municipal solid waste has been well documented in the past and will not be reviewed in this thesis. However, this report will address the emerging issue of partial decomposition of organic materials in landfills in this section. The three organic components of municipal solid waste which are critical to the degradation reported in the literature are cellulose (40-50% dry mass), lignin (10-15%) and hemicellulose (9-12%) (Barlaz 1989a). Both the decomposed and undecomposed 22 organics are of concern in GHG emission considerations. The decomposed portion of the organics leads to methane emissions, whereas the portion resistant to decomposition presents the carbon sequestration potential of landfills. It is important to note that carbon sequestration is not included in the latest IPCC guidelines but was considered in a 1998 analysis by the U.S. Environmental Protection Agency (USEPA 1998). Even under optimal conditions for biodegradation, complete anaerobic decomposition of organic materials cannot be expected. The presence of recalcitrant lignin and large particle sizes can limit the access of hydrolytic bacteria to some of the biodegradable material (Baldwin et al. 1998; Stinson and Ham 1995; Cummings and Stewart 1994; Wang et al. 1994; Tong et al. 1990). Complicating the matter further still is the fact that lignin concentrations of specific MSW components are highly variable. These issues are important for assessing the GHG emissions associated with landfill disposal and will be the focus of the discussion in this section. After the introduction of cellulose, hemicellulose and lignin biodegradability (2.4.1), a literature review of landfill carbon sequestration is presented (2.4.2). This is followed by a discussion of how this issue is applied to the two GVRD landfills analyzed in this thesis (2.4.3). 2.4.1 I n t r o d u c t i o n It has been reported that over 90% of the methane potential of MSW results from the cellulose plus hemicellulose fraction (Barlaz et al. 1989a) and the remaining biodegradable constituents are soluble sugars and proteins. Cellulose is the principal structural molecule in plants; in fact, half of all the organic carbon in the biosphere has been estimated to be contained in cellulose (Curtis and Barnes 1989). In its frequently occurring fibrous form, its tensile strength is very great and it is insoluble in water. Cellulose is a carbohydrate; a polymer made up largely of glucose, and corresponds to the empirical formula of (CeHioOsV However, the degree of polymerization (DP) is very large, often ranging between 1000 and 5000, giving molecular weights between 163,000 and 810,000. Hemicelluloses are nonfibrous wood components. While cellulose is comprised mainly of glucose units, the hemicelluloses contain primarily sugar units other than glucose - such as xylose or mannose. The DP of hemicelluloses is much lower than cellulose; it is typically 150±30 (McGraw-Hill 1962). Lignin accounts for between 20 to 30% of wood material and functions as a filler or cementing substance to impart rigidity to the tissues. It is thought that lignin probably exists in wood as branched-chain polymer molecules comprising a vast network. This network may be further intermeshed and/or chemically combined with hemicellulose or other nonlignin components of wood (ibid). Lignin is highly recalcitrant. Not only does it strongly resist anaerobic decomposition, but it also prevents the decomposition of the embedded cellulose and hemicellulose components of the lignin matrix (Micales and Skog 1997). By themselves, the majority of cellulose and hemicellulose can be readily degraded. Under idealized laboratory decomposition conditions, Barlaz (1989b) observed the decomposition of 72% of the cellulose and hemicellulose of MSW but negligible decomposition of lignin. 23 There is a great deal of variability in the lignin content of many individual MSW components. This variability is demonstrated in office paper, which is largely delignified (one study measured the lignin content to be 2.3% (Barlaz 1998)), or in branches and newspapers, which are highly lignified (the same study measured lignin contents of 33% and 24%, respectively). The lignin content is "important because it is both a physical and chemical barrier to microbial attack." (Wang et al. 1994) In one study, about 40% of the cellulose in newsprint was degraded, while 90 and 97%, respectively, in delignified office and filter paper decomposed anaerobically (Khan 1997). In another study, the partial delignification of newsprint by acid chlorite treatment significantly increased the amount of cellulose available for decomposition and resulted in about 75% of the cellulose being degraded. By comparison, the cellulose decomposition in untreated newsprint was limited to 50% (Stinson and Ham 1995). Lastly researchers at the USDA Forest Service have performed calculations which "suggest that maximally only 30% of the carbon from paper and 0-3% of the carbon from wood are ever emitted as landfill gas." (Micales and Skog 1997) 2.4.2 L i t e r a t u r e R e v i e w Resulting from the ability of organic components of MSW to resist decomposition, the potential therefore exists for the long-term sequestration of carbon in sanitary landfills. It is worth noting that these are anaerobic conditions largely because there is no identified anaerobic microbial lignin attack (as opposed to white rot fungus which attacks aerobically). In fact, from the perspective of greenhouse gas emissions, the organic carbon deposited in landfills has to be partitioned into one of only three pathways: "(1) eventual atmospheric emission as methane, (2) eventual atmospheric emission as carbon dioxide following microbial oxidation or combustion, and (3) long-term sedimentary storage in landfill reservoirs." (Bogner and Spokas 1995) Two research investigations have attempted to estimate the amount of carbon being sequestered in landfills worldwide. The first one by Bogner and Spokas (1995), also partially described in Bogner (1992), developed a highly conservative estimate based on idealized laboratory decomposition studies with well-mixed waste and elevated moisture contents by Barlaz (1989b). It is likely that actual landfills, with high rates of compaction and restricted moisture infiltration, will have an even greater proportion of recalcitrant organic carbon and thus a greater amount of sedimentary storage would be expected. Bogner and Spokas (1995) estimated that about 30 million metric tonnes of carbon annually enters sedimentary storage by deposition in landfills - a considerable amount when compared to the estimated 20-30 million tonnes of carbon annually entering sedimentary storage worldwide from other sources (mainly marine). The second investigation into the long-term storage of carbon in landfills was performed by Barlaz (1998) and is also discussed in Eleazer et al. (1997) and USEPA (1998). This also simulated enhanced anaerobic decomposition in laboratory-scale reactors. This research placed various types of organic waste in separate reactor vessels "in which was maintained anaerobic conditions similar to those in a landfill, but controlled to favor maximum methane generation." The experiments included shredding, seeding, leachate recycling and the maintenance of sufficient concentrations of nitrogen and phosphorus to ensure nutrient availability. These reactors were allowed to run for periods varying from 24 three months to two years. The experiment for each reactor was finished when either no measurable methane was being emitted (below instrument detection limit), or when it was determined that the reactor had produced at least 95% of the methane that it would produce if run indefinitely. The amount of methane and the amount of undecomposed carbon remaining in each reactor at the end of the experiment was measured. The goal of this second study was to determine the "ultimate biodegradability" that is to be expected. The most significant contribution of this research is the study of the major individual components of MSW separately, and the subsequent determination of component-specific "Carbon Storage Factors". Once again, this storage determination is conservative; actual decomposition in a traditional landfill would be expected to be lower. The measured Carbon Storage Factor (CSF) represents the mass of carbon that was stored (not anaerobically degraded) per initial dry mass of component. Not surprising, the highest storage capability was observed with the high lignin MSW components, and the lowest storage was demonstrated by the lower lignin content materials. The measured CSF for grass, leaves, branches and newsprint was 0.32, 0.54, 0.38 and 0.42 kg C/dry kg, corresponding to lignin concentrations of 23, 43, 33 and 24%, respectively. Food waste and office paper exhibited low storage, with CSFs of 0.08 and 0.05 kg C/dry kg at low lignin concentrations of 11 and 2.3%, respectively. The carbon measured by the CSF includes not only the portion of cellulose and hemicellulose (and in the case of food waste - protein) which resisted anaerobic decomposition, but also most of the lignin content - very little lignin was actually degraded. In an extrapolation of this data, Barlaz used these results to generate a global landfill carbon storage value. He estimated the global carbon sequestration due to MSW burial to be 118.7 million metric tonnes of carbon annually. This global carbon sequestration value is much greater than the previous value estimated by Bogner and Spokas. Inspection of these Carbon Storage Factors for development in this thesis has discovered inconsistencies in the data reported by Barlaz (1998). For example, the CSF for leaves was reported as 0.54 kg C per dry kg while the initial carbon content of the leaves was only reported as 0.49 kg C per dry kg. This impossible result raises important questions about the results. The method used to calculate the CSF is a back-calculation based upon the carbon remaining in the reactor at the end of the experiment, but corrections were necessary to attribute the necessary fraction to the seed introduced to insure successful decomposition. It appears the initial carbon content was not used at any time for the calculation of CSF's and that the uncertainty with the correction for the seed has caused problems with some of the CSF's reported. Upon personal communication with Morton Barlaz and Jim Atwater, a new method for estimating Carbon Storage Factors is developed and employed in this thesis. Using the methane emission reported in USEPA (1998) to calculate the moles of C H 4 emitted and by assuming equal moles of C O 2 , it is possible to estimate the Carbon Available for Anaerobic Decomposition (CAAD). When this C A A D is subtracted from the initial carbon content reported in Barlaz (1998), a revised CSF results. The actual calculations for the revised CSF's are presented in the respective appendix for each biodegradable material investigated. Only one material changes appreciably with this revision: the CSF for leaves is decreased (from the 25 previous 0.54 kg C/dry kg to a new 0.43 kg C/dry kg). All the remaining biodegradable waste components (newsprint, office paper, grass and branches) change only slightly. The above revision has not been used on the CSF for food waste due to the fact that the laboratory-scale reactors for food contained a greater proportion of seed than the other reactors. If the above revisions are used on food waste, the CSF increases by 150%, an unreasonable amount. It is this author's belief that the current CSF is likely the more appropriate and it is thus left unrevised. 2.4.3 A p p l i c a t i o n to G V R D L a n d f i l l s The application of this issue to the analysis in this thesis must be addressed. What proportion of office paper, newsprint, food and yard waste will remain undecomposed in the Cache Creek or Vancouver Landfill? It requires noting that only the sequestration of these four biomass materials is of consequence, because they do not contain the carbon of concern from a climate change perspective. Any carbon which is stored in this manner is a G H G benefit to the atmosphere. However, the disposal of plastics is not to be considered a net GHG benefit - plastics contain carbon from petroleum products that, as fossil fuels, was already in storage. As a result, the plastics have simply been moved from one 'storage' state to another, and are not considered in this analysis. To estimate landfill carbon sequestration and the inverse of this issue, landfill methane emissions, a Time-Dependant model is developed in this thesis. In this model, all of the carbon disposed in a landfill has to eventually follow one of four distinct pathways: atmospheric emission as C H 4 , atmospheric emission as C O 2 , long-term storage or awaiting decomposition (though not yet degraded, this carbon is not to be considered sequestered). In this manner, emissions for the next 20 years are estimated. In this model, the organic-carbon in the newsprint, office paper and food and yard waste components of MSW disposed in landfills will be partitioned according to the pathways described above. The landfill carbon sequestration estimates as reported by Barlaz (1998), and revised for this thesis as described in the previous section, are likely the most appropriate. However, since the Cache Creek Landfill (CCLF) is a dry landfill (there is little appreciable leachate (Pers. comm. Louie DeVent), the actual sequestration may be greater. The Vancouver Landfill (VLF) is a wet landfill (a substantial quantity of leachate is annually transferred to the nearest wastewater treatment plant (Pers. comm.. Paul Henderson) and is likely better represented by the experiments by Barlaz. If data for dry landfill sequestration becomes available in the future, the estimates can be revised. The flip side of the sequestered fraction is the Carbon Available for Anaerobic Decomposition (as described in the previous section) which is the total C H 4 and C O 2 which was emitted from the anaerobic reactors during the enhanced decomposition simulated by Barlaz. This C A A D is used in this thesis to estimate the methane generation potential at the landfills. At the end of 20 years, organic carbon in this model can decompose (to C O 2 or CH 4 ) , it can be sequestered or it can simply be awaiting decomposition. However, this is not to say that carbon has to decompose anaerobically - organic carbon can be removed in the leachate and be aerobically degraded at wastewater treatment plants. While identifying 26 this possibility is valuable, the following estimates demonstrate the relative lack of importance of this issue. At the Vancouver Landfill, 2,115,772 m 3 of leachate was collected and transferred to the Annacis Island Wastewater Treatment Plant in 1999 (Pers. comm.. Paul Henderson). Using a typical B O D 5 concentration of 100 mg/L (Metcalf & Eddy 1991), it is possible to calculate the mass of organic carbon contained in this leachate. This can be compared with the annual loss of carbon as landfill gas as a result of anaerobic decomposition. The most recent estimate is that the landfill gas production rate was 5082 cubic feet per minute in 1999 (Pers. comm. Paul Henderson). These calculations are below. Mass of Carbon in Leachate = (2,115,772 m3]̂ 100 m g °/j *  2 /mol C 32 g / /mol 0 2 j ' IDE I O O O V )=• 0 - 5 tonnes/ h 000 V ,  79 tonnes of C Volume of LFG = (5,082 f t"/. j f - ^ - l feO 1 1 1 ' 1 1 /*24h/*365 r f / ]{\000 V 3)= 75.7* 109 L V' / r nm\3.28ftJ V / h / d />"'JX /in' Mass of Carbon in Landfill Gas = (75.7 * 109 L ) Q ^ ~ ^ ] ( ' 2 ^ m o l ) ( 1 ° " t 0 n n / ^ ] = 4 0 > 6 0 0 t o n n e s o f Carbon The estimated 79 tonnes of carbon leaving the landfill as leachate is virtually irrelevant when compared to the 40,600 tonnes of carbon leaving the landfill as carbon dioxide or methane gas. Furthermore, since the Cache Creek Landfill is a dry landfill with little appreciable leachate (any leachate which is collected is spread on the active face to return the leachate back to the fill (Pers. comm. Louie DeVent)), this issue has even less importance. As a result of the demonstrated lack of importance, the potential for landfill leachate to provide aerobic decomposition of the organic carbon deposited in landfills is ignored. It is also helpful to compare the mass of carbon in landfill gas with the mass of carbon in place at the landfill site. Since beginning operation in 1966, an estimated 11.3 million tonnes of waste has been deposited in the Vancouver Landfill by 1999 (CRA 1999), or an average 330,000 tonnes per year. By assuming a moisture content for MSW of 25% and a carbon content for MSW of 50%, it can be estimated that each year 124,000 tonnes of carbon is deposited in the landfill. However, only about 40,000 tonnes of carbon, or one part in three, actually escapes in the landfill gas each year. These simple estimates suggest that sequestration is indeed occurring at the local Vancouver Landfill. Now part of the landfill gas (LFG) resulting from anaerobic decomposition may be collected. The methane gas component can be flared or utilized for energy. The remaining portion will escape collection and will be emitted to the atmosphere. However, some of the C H 4 which escapes collection can still be oxidized to C O 2 by microorganisms in the landfill cover materials prior to emission. New research by Czepiel et al. (1996) estimated the landfill oxidation rate of 10% for landfill methane. This study investigated a landfill that had a 1-2 m cover consisting of sandy-clay loam with intermittent low shrubs and grasses in older sections. This estimate will be used as an oxidation rate representative of the CCLF and the V L F for methane by-passing collection. 27 The last "fraction" or "partition" for organic carbon in this model is that which has yet to decompose. In this model, part of the organic carbon that will eventually decompose will not do so within the first 20 years; this carbon is part of the C A A D which hasn't yet decomposed after 20 years. Due to its future degradability potential, it cannot be considered as having entered long-term storage. Critical to this time-dependant modelling is the first-order decay rate constant used. Various decay rates are published in available literature. Several of these were experimented with for this research but it is difficult to know which is of the greatest accuracy. The first order decay rate constant used by the GVRD in modelling methane emissions at the CCLF, 0.02 yr"1, can be used to simulate the future degradation in the C C L F (GVRD 1999b). This is the decay rate developed by the U.S. Environmental Protection Agency for dry landfills (USEPA 1997). Unfortunately, this is an estimate of the degradation rate of general MSW and is not specific to any particular waste component. Conestoga-Rovers & Associates used a decay rate constant of 0.028 yr"1 when modelling the landfill gas at the V L F in a recent assessment for the City of Vancouver (Conestoga-Rovers 1999). This decay constant was developed by Levelton & Associates (for Environment Canada) in a province by province evaluation of landfill emissions (B.H. Levelton 1991). This higher decay rate represents the greater degradation to be expected at a wet landfill over the dry Cache Creek Landfill. When using the 0.02 yf'decay rate it can be estimated that only 33% of the C A A D will degrade within the 20 year time period and when using the higher 0.028 yr"', 43% of the C A A D is expected within the time period. This author believes it more useful to assume that over half of the C A A D of newsprint, office paper and Remainder and that over three-quarters of the C A A D of food scraps and yard trimmings is realized in the first 20 years after disposal (food waste is known to be readily decomposable and since yard waste is comprised of about 50% grass, this component is also easily degraded). By using a decay rate of 0.04 yr"1 for paper and Remainder disposed in the Cache Creek Landfill, 56% of the C A A D will materialize in the 20 years. For the Vancouver Landfill, the decay rate of 0.05 yr"1 will result in 64% of the C A A D being depleted. Using 0.07 yr"1 for the food and yard waste disposed at Cache Creek, 77% of C A A D will be decomposed. At Vancouver, 0.08 yr"1 calculates that 82% of the C A A D degrades. Lastly, if users wish to model the ultimate methane generation, 100% decomposition of the C A A D , then inputting the decay rate as 0.14 yr"1 will cause this. 28 These decay rates are displayed in the table below. Due to the nature of the spreadsheet Model, users can change the decay rates in the future to suit their needs. T a b l e 2-1 : F i r s t - O r d e r D e c a y R a t e C o n s t a n t s Landfill Waste Component Decay Rate (year"') % ofCAADin first 20 years Source Cache Creek MSW 0.02 33 GVRD 1999b Vancouver MSW 0.028 43 Conestoga-Rovers 1999 Cache Creek Paper & Remainder 0.04 56 assumption Vancouver Paper & Remainder 0.05 64 assumption Cache Creek Food & Yard 0.07 77 assumption Vancouver Food & Yard 0.08 82 assumption either 0.14 100 change to ultimate any decomposition Also important in modelling GHG emissions is the expected collection efficiency of the generated landfill gas. This Model slowly increases, year after year, not only the collection effectiveness but also the proportion utilized for energy (to replace fossil energy). 2.5 N I T R O U S O X I D E E M I S S I O N S The potential is great for significant releases of nitrous oxide during waste management, especially food and yard waste management, and consequently requires consideration. Given that N 2 0 is a strong greenhouse gas, it is estimated to be 310 times more effective in trapping infrared radiation than C 0 2 , it has to be considered in this research. In order to facilitate this, the Global Nitrogen Cycle (2.5.1) and the Global Nitrous Oxide Cycle (2.5.2) must be introduced. This is followed by the Anthropogenic Interference with the Global Nitrogen Cycle (2.5.3) and the consequent Anthropogenic Interference with the Global Nitrous Oxide Cycle (2.5.4). Finally this human-induced interference will be assessed for its Implications for Waste Management (2.5.5). This section will discuss the ramifications for Landfill Disposal (, Composting ( and Incineration ( in turn. A detailed discussion of this can be found in Barton & Atwater (2000). This entire section is a summary of that paper. While it may appear that much of the following information is unrelated to the primary focus of the thesis, this review is provided to impress upon readers the uncertainty of the reported data and the crude understanding of this issue. As a result, the actual emissions measured in the future can and may be much greater than are currently estimated. 2.5.1 G l o b a l N i t r o g e n C y c l e Nitrogen is a critical element for life. It is an essential component of amino acids, which are the building blocks of proteins, which in turn are the building blocks of all life. It is estimated that 16% of protein, or 0.16 kg of N per kg of protein, is nitrogen (IPCC 1997). The cycling of global nitrogen throughout terrestrial and aquatic ecosystems and the atmosphere is critical for this building block. 29 The Earth's atmosphere is 78% by volume molecular nitrogen, N 2 gas, and thus it is an immense reservoir. It is estimated that 5 billion million metric tonnes of nitrogen are contained in the atmosphere, ocean, terrestrial and marine biota, soil organic matter and sedimentary rocks. Although N is abundant, the vast majority of it is in a form which can be used by only a few living organisms (Mackenzie 1998). It is estimated that <0.02% (or ~1 million million tonnes) of global N is actually accessible to living organisms, most is either diatomic nitrogen (N 2 gas) in the atmosphere (-78%) or tied up in sedimentary rocks (-20%) (ibid). To be available for utilization by living organisms, it must be in the form of reactive or fixed nitrogen (defined as "N bonded to C, O or H (e.g. NO y , NH X , organic N)" (Galloway 1998)). Only a few species of aquatic and terrestrial bacteria and blue-green algae can fix the nearly inert N 2 molecule into ammonium (NH4 +) for utilization. This conversion is called biological N-fixation (BNF) and it has been estimated that in preindustrial times, 90-130 xlO 6 metric tonnes of N was annually fixed by this natural process (Galloway 1995). Lightning contributes an estimated additional 3-5 xlO 6 metric tonnes of N fixation annually. This reactive or fixed nitrogen moves through the terrestrial N cycle by the death of plants and microorganisms, mineralization - the breakdown of amino acids, assimilation - uptake by plants and by immobilization - uptake by microorganisms (Kinzig and Socolow 1994). Assuming an annual fixation rate of 130 million tonnes, this is miniscule in relation to the pool of total nitrogen (1 part in 38 million) or to the pool of reactive nitrogen (1 part in 7800). However it is upon this fixation rate which organisms depend. Since plant and animal life can only utilize reactive nitrogen as nutrients, and not diatomic nitrogen, "all life ultimately depends on nitrogen fixation" (Ayres et al 1994). For nitrogen to remain in steady state conditions there must also be the return of reactive N to the N 2 reservoir (though this reactive N may transfer through several from due to oxidations and reductions before returning to N 2). The majority of this is accomplished by the microbial processes, nitrification and denitrification. There is also pyrodenitrification which occurs during forest fires. In nitrification, ammonium (NH4 +) is oxidized to nitrate (NO3") by mainly autotrophic bacteria under aerobic conditions in order to derive energy. In denitrification, nitrate is reduced to N 2 by mainly facultative heterotrophic bacteria under anoxic (oxygen restricted) conditions. These bacteria use the nitrate as a terminal electron acceptor so that they can concurrently derive energy from the breakdown of organic carbon (Beauchamp 1997). During pyrodenitrification, "two nitrogen atoms that were in separate molecules in plants or soil bind to one another to make N 2 , as the result of a sequence of high-temperature reactions." (Ayres et al. 1994) By these three processes, equal amounts of N (the approximately 93 to 135 xlO 6 tonnes N fixed annually) are returned to the atmosphere as N 2 gas. 2.5.2 G l o b a l N i t r o u s O x i d e C y c l e Nitrous oxide (N 20) is a stable gas which leaks from microbial cells during nitrification and denitrification (Firestone and Davidson 1989). Though the predominant product of nitrification is nitrate (NO3"), and of denitrification is N 2 , a portion of the N can be emitted as nitrous oxide. 30 Though some parts of the nitrification and denitrification pathways are not well understood, particularly the pathways encompassing nitric oxide (NO), the generally accepted metabolic pathways are shown below. The dashed lines signify unconfirmed pathways. F i g u r e 2 - 1 : N i t r i f i c a t i o n & D e n i t r i f i c a t i o n P a t h w a y s NITRIFICATION (Hooper 1984; Firestone and Davidson 1989): NO nitric oxide A N,0 nitrous oxide t , N O , i A \ T N H / — > N H 2 O H — > [HNO]% ^N0 2 —>N0 3 ammonium hydroxyl-amine \ j nitrite nitrate N 0 2 N H O H nitrohydroxyl-amine DENITRIFICATION (Firestone and Davidson 1989): NO nitric oxide i i I i : ^ N O , — » N 0 2 - - - - M X ] - ™ > N 2 0 —> N 2 nitrate nitrite nitrous oxide nitrogen gas The "hole-in-the-pipe" or "process-pipe" conceptualization by Firestone & Davidson has been used to visualize the N 2 0 production in soils. These researchers consider that N 2 0 production is a factor of, (1), the amount of nitrogen cycling between the soil-plant- microbial system, and (2), the ratios of the N 20/N03 _ and N 2 0 / N 2 products of nitrification and denitrification. These two factors, the overall movement of nitrogen through the pipe, and the amount of leakage (the size of the holes in the pipe), control the emission of N 2 0 . Agricultural research has found that anywhere from 0.001% to 6.8% of the nitrogen applied to fields is emitted as N 2 0 (Mosier et al. 1996), and the ratio of N20/N03~ produced as a result of nitrification has been reported as high as 20% (Martikainen 1985), but is generally below 1% (Firestone and Davidson 1989). Though both processes have been demonstrated to result in N 2 0 leakage, denitrification is considered to be the major source of N 2 0 from soils (Sahrawat and Keeney 1986). The production of N 2 0 during nitrification in soils has been demonstrated to result from: "a reductive process in which the organisms use N0 2" as an electron acceptor, especially when 0 2 is limiting. This mechanism not only allows the organisms to conserve limited 0 2 for the oxidation of N H 4 + (from which they gain energy'for growth and regeneration), but also avoids the potential for accumulation of toxic levels of N 0 2 \ " (Hutchinson and Davidson 1993; Poth and Focht 1985) The nitrous oxide leakage during denitrification is considered to result when: "the availability of oxidant (N-oxide) greatly exceeds the availability of reductant (most commonly organic carbon), then the oxidant may be 31 incompletely utilized, i.e. N 2 0 will be produced." (Firestone and Davidson 1989) "Conversely, when the overall rate of denitrification is limited by the supply of oxidant, most of the N-oxide is converted to N 2 . " (Hutchinson and Davidson 1993) The latest estimate of the IPCC (1995) is that 9 xlO 6 tonnes of N 2 0 - N is naturally emitted to the atmosphere by soil processes, forest and brush fires and the oceans. As there is no chemical loss in the troposphere (the lower -12 km of the atmosphere (Mackenzie 1998)), this 9 xlO 6 tonnes of N 2 0 - N slowly rises to the stratosphere where it is destroyed. The destruction of N 2 0 occurs at an altitude above 30 km (in the stratosphere) and returns this nitrogen to the N 2 reservoir. It takes, on average, 120 years for N 2 0 to reach this altitude and to be destroyed (IPCC 1995). The N 2 0 is destroyed predominantly by photodisassociation into N 2 molecules and O atoms. However, approximately 10% of the N 2 0 reacts with electronically excited oxygen atoms (formed by the photolysis of ozone) to form NO. The production of NO is important in stratospheric ozone chemistry, since NO catalytically destroys ozone (Abbatt and Molina 1993). 2.5.3 A n t h r o p o g e n i c In te r fe rence o f the G l o b a l N i t r o g e n C y c l e The crux of the problem is that humans have approximately doubled the global rate of N fixation, from an estimated pre-industrial rate of 93-135 xlO 6 tonnes N/yr to an estimated 243-295 xlO 6 tonnes N/yr fixed currently (Galloway 1998). The increased fixation of elemental N 2 gas has been a direct result of nitrogenous fertilizer production, human- induced increases in the cultivation of leguminous crops (which host a symbiotic relationship with biological N-fixing bacteria) and by the combustion of fossil fuels. Estimates adapted from Galloway (1998) of this anthropogenic interference are provided in Table 2-2. Table 2-2: G loba l Reactive Ni t rogen Sources Global Nitrogen Fixation (million tonnes N/year) Natural Biological N Fixation 90-130 Lightning 3-5 Natural Source Subtotal 93-135 Synthetic Fertilizers 80-90 Human-Induced Biological N Fixation 40 Fossil Fuel Combustion 30 Anthropogenic Source Subtotal 150-160 T O T A L SOURCES 243-295 (Percent Anthropogenic) (51-66%) Fertilizer production by the Haber-Bosch process fixes N 2 to ammonia (NH3) thereby reproducing at high temperature and pressure what bacteria can accomplish with enzymes at ambient temperature and pressure (Kinzig and Socolow 1994). Human-induced biological N-fixation occurs by the increased cultivation of leguminous crops such as soybean and alfalfa which symbiotically host nitrogen fixing bacteria in their root nodules. The last source of reactive N is the by-product of the combustion of fossil fuels. 32 Whereas nitrogen fixation from fertilizer production and the cultivation of leguminous crops is intentional, the reactive N produced as a result of combustion is not intentional. The combustion of fossil fuels causes nitrogen that was originally in air as N 2 gas or nitrogen that was originally sequestered in the fuel as organic-N to be oxidized to nitric oxide (NO) or nitrogen dioxide (N02). 2.5.4 A n t h r o p o g e n i c In te r fe rence of the G l o b a l N i t r o u s O x i d e C y c l e As a direct result of enhancing of the global nitrogen cycle, there has been a consequent enhancing of the global nitrous oxide cycle. The atmospheric N 2 0 concentration has increased from a pre-industrial level of 275 ppb to a level of 311 ppb in 1992, an increase of 13% (IPCC 1995). This is estimated to contribute 6% of the human-induced increase in the infrared radiation absorbing ability of the atmosphere (Erisman et al 1998). In addition, this concentration continues to increase by about 0.8 ppb annually (IPCC 1995). The most recent budget, as of 1998, of global nitrous oxide is provided in Table 2-3 (adapted from Mosier et al. (1998)) T a b l e 2 - 3 : G l o b a l N 2 0 B u d g e t G l o b a l Sources a n d S i n k s o f N 2 0 ( m i l l i o n tonnes N 2 0 - N / y e a r ) Identified Natural Sources 9.0 Identified Anthropogenic Sources 7.2 Total Identified Sources 16.2 Unaccounted Sources 0 Total Sinks (Photolysis) 12.3 Atmospheric Increase 3.9 Agricultural activities dominate the emissions of anthropogenic nitrous oxide with industrial sources (primarily fossil fuel combustion) providing the remainder of emissions. It is only since 1998 that the budget of N 2 0 sources and sinks has been successfully balanced. Previous budgets were not balanced because sinks exceeded sources with the missing emissions labeled as "unaccounted sources." In the newest IPCC methodology, there are new sources of N 2 0 which were previously not included (IPCC 1997). In this new methodology, "three sources of N 2 0 are distinguished: (i) direct emissions from agricultural soils, (ii) emissions from animal production systems, and (iii) N 2 0 emissions indirectly induced by agricultural activities." (IPCC 1997; Mosier et al. 1998) It is the N 2 0 emissions indirectly resulting from agriculture with which this research is concerned, because it is the source of the emissions that result from the MSW stream. Reactive N exported from farms as food products can cause indirect emissions of N 2 0 . This reactive N is eventually nitrified and denitrified and N 2 0 leakage can result. These 33 sources of N 2 0 are considered indirect because they do not actually occur on farms but are nevertheless, agricultural in origin. For instance, the nitrification and denitrification of reactive N used in food production (and the associated N 2 0 leakage) may occur at wastewater treatment plants. As a result, N 2 0 emissions from wastewater treatment can be considered indirectly agricultural in origin, in fact, any N 2 0 emissions from reactive N downstream of food production are indirectly agricultural N 2 0 emissions. This will be further discussed in the following section, Implications for Waste Management (2.5.5). 2.5.5 I m p l i c a t i o n s f o r W a s t e M a n a g e m e n t The existence of anthropogenic nitrogen in MSW has important implications for waste management. Municipalities are typically given the responsibility to perform waste management. Given that fertilizer nitrogen, either in food or yard waste, has the potential to emit N 2 0 during this management, municipalities are responsible for the emissions. To assess this potential source of GHG emissions, a survey of available research has been performed. This survey only found nine papers on the N 2 0 emissions from composting, ten papers on the N 2 0 emissions from waste incineration and only two papers on the N 2 0 emissions from waste disposed in landfills. However, 26 papers and one patent were found on the N 2 0 emissions resulting during wastewater treatment - a frequent destination of landfill leachate. Each of the management alternatives, landfill disposal, composting and incineration will be reviewed from the perspective of N 2 0 emissions in this section. These papers actually generate many more questions than they answer. For all of the papers, only the immediate emissions of N 2 0 were measured during the investigated process. There was no attempt to quantify any future emissions resulting from ammonia, nitric oxide or nitrate losses during the process, or from the future decomposition of the organic matter. For example, gaseous emissions of NH3 are common during wastewater treatment or composting, but atmospheric discharges of this reactive nitrogen are not considered with respect to subsequent N 2 0 emissions. Ammonia has an atmospheric lifetime of only a few hours to a few days and is mainly removed by wet and dry deposition. However, a portion, perhaps 10%, is oxidized to NO, and a third fraction is removed by reacting with nitrates or sulphates to form ammonium-containing aerosols, (NH4)2S04 and NH4NO3. These aerosols are later removed by rainfall or dry fallout (Matthews 1994). Nitrogen oxides (N0 X = NO + N0 2 ) are short-lived gases and they have an atmospheric lifetime between 1-10 days. Nitrogen oxides are removed from the atmosphere by conversion to nitric acid (HNO3), which is followed by wet or dry deposition (Olivier et al 1998; Logan 1983). In addition, nitrogen oxides are suspected to indirectly contribute to global warming - they deplete the atmospheric concentration of the OH radical; a radical which limits the atmospheric lifetime of CH4. With OH depleted, the potential exists for methane to have a longer atmospheric lifetime than it would otherwise be able to (Mackenzie 1995). Once these nitrogen compounds (NH 3, N H 4 + , NO, (NH 4) 2S0 4 , NH4NO3, H N 0 3 , etc) are returned to land or water surfaces by wet or dry deposition, this reactive nitrogen is again available for nitrification/denitrification, and the associated N 2 0 emissions can result. As 34 a result, discharges of reduced or oxidized nitrogen compounds only temporally and spatially alter the nitrous oxide emissions but do nothing to prevent these emissions. Another example of a. future N2O emission originates from the organic nitrogen contained in wastewater sludge or finished compost. As this organic-nitrogen will eventually undergo decomposition, the released ammonium (NH/) is now available to undergo nitrification and denitrification. A simplified conceptualization of N 2 0 emissions during waste management operations and of potential future emissions is demonstrated in Figure 2-2. F i g u r e 2 - 2 : P o t e n t i a l N 2 0 E m i s s i o n s f r o m W a s t e M a n a g e m e n t N-,0 Fert i l izer Human Consumption A . Agriculture ^ Food Products ^^""""""^ l e a c h f t i — ^ (-25%) Landfill ing N 2 0 N20 N2 V N20 NH3 t 1 Food process ing wastewater S sludge n "*"" r Treatment ~ N 2 ° solid waste i n c i n e r a t i o n ^ 1 . „ l l r - Agriculture L o S s e s H u m a n c ° n r s u m p t l 0 n Management r f , m n n i . H n n ^ * M n Human-induced BNF A r~7W^ C „ „ H c o m p o s t i n g NO (~75%) Food Processing N;0 NH3 N20 /\ N20 N2 To reiterate, N 2 0 emissions in waste management from the reactive nitrogen in food waste are considered indirectly agricultural in origin by the IPCC. This is because the nitrogen was originally fixed for food production. In addition, the nitrogen component of yard trimmings may also be synthetic fertilizer in origin. During waste management, there can be immediate or future emissions of N 2 0 . Immediate emissions occur during the operation in question, be it wastewater treatment, composting, landfilling or incineration. Future emissions occur as a result of the future nitrification and denitrification of reactive N which exits the operation, usually in the fomi of ammonia or nitrogen oxides (NOx = NO + N0 2 ) emissions or organic-nitrogen in compost or sludge. While waste managers are responsible for the release of reactive nitrogen, once the nitrogen is released they have no way of controlling its conversion to N 2 0 . The following sub-sections review the potential for N 2 0 emissions to result from wastes that are landfilled, composted or incinerated. It is the intent of these reviews to complement the N 2 0 calculations in Appendix C through Appendix K. - Landfill Disposal Does the reactive nitrogen in landfilled MSW (predominantly in the food and yard waste components) contribute N 2 0 emissions to the atmosphere? A literature review has only located two research papers addressing this question. Unfortunately, only the Japanese study actually investigated the N 2 0 emissions resulting from waste disposed in landfills - 35 the other research paper, a Swedish study, examined the emissions from different materials as cover soils. In the Japanese study, two landfills, one active and the other closed, both with over 10 million tonnes of refuse in place, were examined (Tsujimoto 1994). Average N 2 0 emissions of 40.2 g/day and 7.8 g/day for the active and closed landfills, respectively, were observed in the landfill gas vented. This emission, while important (40 g/d of N 2 0 will equal the annual greenhouse gas emission of 4.5 tonnes of C 0 2 equivalent [using the N 2 0 global wanning potential of 310] or the combustion of approximately 1600 L of diesel fuel1), represents only 9.3 kg of N 2 0 - N annually or 0.02% of an assumed 50,000 kg of nitrogen in the waste (using a nitrogen content of 0.5% for typical waste (White et al 1995)). Either this small emission indicates limited nitrification/denitrification taking place or limited N 2 0 leakage of the nitrification/denitrification taking place. (For further discussion of N 2 0 leakage refer to Section 2.5.2 - Global Nitrous Oxide Cycle) Given the anaerobic nature of landfills, it is likely the former. The Swedish study, determined that about 1.6% of sludge nitrogen used as a landfill cover soil will be emitted as N 2 0 - N during the first two years (Borjesson and Svensson 1997). This is similar to the 1.25% N 2 0 - N estimate for fertilizer and manure nitrogen found in agriculture research (IPCC 1997) and is not surprising considering that the land application of sludge is analagous to fertilization. Can appreciable amounts of nitrous oxide eventually become emitted from nitrogenous waste disposed in landfills? The Japanese study has demonstrated the existence of an emission, albeit a small one. Appreciable N 2 0 emissions likely occur indirectly via landfill leachate or landfill gas. Reactive nitrogen contained in landfilled organic waste is released when anaerobic decomposition occurs. At this point, ammonia-nitrogen is free to undergo nitrification and denitrification, to be leached by water percolating through the fill or to be volatilized in the vented landfill gas. Ammonia nitrogen can dissolve in the percolating water and exit the landfill in the leachate. Landfill leachate is known to be high in nitrogen, with a typical total nitrogen concentration (Organic-N + NH3 -N + NO3- N) between 25 and 1600 mg/L for active landfills and between 105 and 170 mg/L for mature landfills (Tchobanoglous et al. 1993). In recent years, leachate ammonia concentrations in excess of 2000 mg/L are even being reported (Henderson and Atwater 1995; Robinson et al. 1998; Rettenberger 1998). On a dry volume basis, the typical ammonia content of landfill gas has been reported between 0.1 and 1.0% (Tchobanoglous et al. 1993). Assuming that a minimum of nitrification (and thus little denitrification) occurs inside the landfill because of the anaerobic environment, the likely pathway of N 2 0 emissions is from the treatment of landfill leachate or the release of ammonia gas to the atmosphere. As a result, a review of the literature on the N 2 0 emissions reported during wastewater treatment is necessary along with a discussion of the wet and dry deposition of ammonia emitted to the atmosphere. A survey of available research conducted on the N 2 0 emissions from wastewater treatment found 26 papers. Interestingly, the studies of actual wastewater treatment plants observed very low N 2 0 emissions, but laboratory experiments generally reported much higher N 2 0 emissions. ' Using the emission estimate of 2.8 kg of C0 2 /L of diesel from Environment Canada (1997a) 36 Studies using laboratory-scale reactors have demonstrated high N 2 O losses but have also observed a profound ability to affect these emissions; therefore the possibility exists for mitigation of a large portion of these emissions. The conversion of ammonium-nitrogen (NH4-N) to N 2 O during nitrification has been demonstrated by Zheng et al. ( 1 9 9 4 ) to be between 2 .3 and 7 . 0 % at dissolved oxygen (DO) concentrations between 0.1 and 6.8 mg/L. They also found N 2 0 conversions as high as 1 6 % and as low as 2 . 3 % at solids retention times (SRT) of 3 days and 10 days, respectively. It was concluded that high N 2 O production resulted when incomplete nitrification occurred. Thus preventing incomplete nitrification by maintaining DO levels greater than 0.5 mg/L and having SRTs of greater than 5 days would greatly reduce N 2 0 emissions. By also using reactors, Hanaki et al. ( 1 9 9 2 ) observed that as much as 8 % of influent nitrate-nitrogen (NO3-N) was transformed to N 2 O during denitrification, though several experiments demonstrated very little N 2 O . The high conversion to N 2 0 was observed at a COD/NO3 -N ratio of 3 . 5 , an SRT of 0 .5 days and a pH of 6 .5 . These researchers concluded that " N 2 O production can be avoided by achieving complete denitrification [by maintaining] high COD/NO3 -N in wastewater, long SRTs and neutral to alkaline pH conditions." Work by Hong et al. ( 1 9 9 3 ) also agrees with this; they concluded that "the lower the ratio of COD/NO3 -N, the higher the percentage of N 2 O in the produced gas was" and that short hydraulic retention times resulted in higher N 2 O production. Several papers have reported extremely high N 2 O conversion rates in the laboratory. Osada'et al. ( 1 9 9 5 ) reported a 3 5 % N 2 O - N conversion in a fill and draw activated sludge process while treating swine wastewater under continuous aeration but only a 0 . 7 % N 2 O - N conversion during intermittent aeration. Experiments on a sequencing-batch reactor (SBR) found that as much as 4 0 % of the removed nitrogen was emitted as N 2 0 ; most of which occurred during the low DO period in aeration (Okayasu et al 1 9 9 7 ) . During the aerobic treatment of swine slurry, nitrous oxide emissions could represent up to 3 0 % of the total nitrogen content of the slurry (Beline et al 1 9 9 9 ) . Research by Spector ( 1 9 9 8 ) , observed that N 2 0 accumulated to a maximum and was subsequently reduced to N2 gas, when reducing nitrate with methanol in a closed reactor. At maximum accumulation, 5 0 to 80%o of the reduced nitrate was in the form of N 2 O . This scientist noted that if the same experiment had been performed in an open reactor, "most or all the N 2 O retained at ^max would have been discharged to the atmosphere:" In contrast to this laboratory research are the findings from several investigations at full- scale facilities. Three studies at WWTP's performing biological nitrogen removal (BNR) reported very low N 2 0 emissions. Kimochi et al ( 1 9 9 8 ) reported N 2 O - N conversions between 0 .01 and 0 . 0 8 % of influent nitrogen. This WWTP was modified to attempt to reduce these emissions and they found that by maintaining a dissolved oxygen concentration of over 0.5 mg/L during the aerobic/nitrification stage and allowing 6 0 minutes for the anoxic/denitrification stage, that complete nitrification and denitrification with a minimum of nitrous oxide production could be achieved. In fact, their findings state: "an optimum combination of aerobic and anoxic conditions and their suitable control are very important for improving nitrogen removal efficiency and controlling N 2 0 emissions." At a pilot plant, Thorn and Sorensson ( 1 9 9 6 ) , observed an average nitrous oxide production rate of 0 . 0 0 9 1 mg N L"1 h"1 in the denitrification basin. 3 7 However there is insufficient information to convert this value into a percentage of influent nitrogen. Research at a Swiss WWTP with a predenitrification anoxic tank followed by three aerobic tanks also observed a very low nitrous oxide emission (<0.1% of influent nitrogen) (von Schulthess and Gujer 1996). However, two studies at secondary treatment facilities (aeration tanks only treating biochemical oxygen demand) have also determined negligible emissions. At the municipal WWTP in Durham, New Hampshire, Czepiel et al. (1995) found N 2 0 emissions of only 1.6 xlO"6 g of N 2 0 / L of wastewater or 3.2 g N20/person*year. Though it is not provided, if one assumes a typical nitrogen content of raw wastewater of 40 mg of N/L (Metcalf & Eddy 1991), this is a N 2 O - N conversion of influent nitrogen of only 0.0025%. Sumer et al. (1995) reported an N 2 0 - N conversion of 0.001% of influent-N at an activated sludge plant in Germany; however, this plant included a pre-trickling filter to increase nitrification in the aeration tank. If the conversions of reactive nitrogen to N 2 O have been demonstrated by these five scientific studies to be extremely low and therefore of almost no importance, then why discuss it? Unfortunately, the complete picture is much more complicated and uncertain to allow for this simple dismissal. At the three BNR plants low emissions were observed; it appears that the processes to successfully promote nitrogen removal are consistent with the same processes which ensure complete nitrification & denitrification and thus minimize N 2 O emissions. However, is this representative of all BNR facilities? Kimochi reported that the aerobic/anoxic conditions and their control are very important for controlling emissions. As demonstrated by laboratory research, the possibility exists for poorly operated BNR plants to be important sources of N 2 O emissions. Furthermore, for the two investigations at secondary treatment facilities, there is a distinct possibility that the emissions are not low because the nitrification and denitrification which occurs in the WWTP produces little N 2 0 . Rather, the emissions are low because it appears that little nitrification or denitrification actually occurred at the secondary treatment plant studied by Czepiel et al. (1995). While nitrification was encouraged at the activated sludge plant studied by Sumer et al. (1995), there was little or no opportunity for denitrification. Remember, agricultural research has identified denitrification as the more important N 2 O source of the two processes. An example of past inadequate identification of nitrous oxide emission sources has been demonstrated by a very recent investigation of the South Platte River in Colorado (McMahon and Dennehy 1999). It was found that the N 2 O emissions from this single river, which receives Denver's wastewater effluent, approached the emission estimated by Czepiel et al. (1995) for all the primary plants in the U.S. In a much older study, researchers investigating the surface water bodies receiving wastewater effluent from Washington, D . C , U.S.A., found data to imply that "the loss of nitrogen as N 2 O could account for between 2 and 4% of the total nitrogen released by the wastewater treatment plants." (McElroy et al. 1978) As a result of the uncertainty around estimating N 2 0 emissions from wastewater, the latest guidelines of the IPCC (1997) (and Mosier et al (1998)) advise using an emission coefficient of 0.01 kg N 20-N/kg sewage-N produced (it ranges between 0.002 and 0.02 38 kg N20-N/kg sewage-N produced). This estimate assumes that 1% of wastewater nitrogen will be emitted as N2O-N either immediately or in the future. This estimate will likely be improved upon with new research. The United States has used this emission coefficient as an estimate in the Environmental Protection Agency's latest national greenhouse gas inventory (USEPA 1999). This results in an estimated emission of 27,000 tonnes of N 2 0 from 1997 alone and can be converted to 8.4 million tonnes of carbon dioxide equivalent, MtCC^e. While it is only a small part of the 6651 MtCC^e estimated to be emitted by the U.S. in 1997, it is a more important part of the 931 MtCChe non-energy related greenhouse gas emissions (energy accounts for 86% of total U.S. greenhouse gas emissions). Furthermore, this may be an underestimate. The estimated nitrous oxide contribution from U.S. agriculture which produced the food in the first place is 283 MtCChe for 1997. Several researchers have estimated the nitrogen efficiency of their respective countries agricultural industry (efficiency of N in food products vs. total N input required) to be 10% for Norway (Bleken and Bakken 1997) and 25% for Germany (Isermann and Isermann 1998). Overall, Isermann and Isermann (1998) estimated the N efficiency of European Union agriculture as only being between 20-30%o. Assuming the same to be true for the United States, a similar conversion of about 25%> taken from the farm as food products could result in an actual waste derived N 2 0 emission as high as 94 MtC02e (from both liquid and solid forms of waste). To bring this discussion closer to home, the typical ammonia concentration and annual quantity of leachate at the Vancouver Landfill has been obtained from the Landfill Operations Branch of the City of Vancouver (Pers. comm. Paul Henderson). In the 1999 calendar year, 2,115,772 m 3 of leachate was transferred to the Annacis Island Wastewater Treatment Plant with an average ammonia concentration of 157 mg/L as nitrogen. Using the IPCC estimate of 1.0% eventual N 2 0 emission from the influent nitrogen to a wastewater facility in the calculations below and a nitrous oxide global wanning potential of 310, it is possible to estimate that Vancouver Landfill's contribution of N 2 0 from leachate nitrogen is: Mass of Nitrogen = (2,115,772 m 3 T157 m g N / Y10"9 tonnes/ U 0Q0 W 3) = 332 tonnes of N N 2 0 Emission = (332tonnesN) 0.01 2 N , 0 - N , 'L\ /mgyv / m - 'N 4 4 g l N 2 'mol (310)CWP =1617tC02e As a result of these calculations, it is possible to assess a currently neglected source of greenhouse gas emissions, an estimated 1600 tonnes of CO2 equivalent annually. To put this in perspective, it would be helpful to compare this with the currently estimated methane emission at this same landfill. The most recent estimate for this landfill is that in 1999, the landfill gas production rate was 5082 cubic feet per minute of which 50% was methane. Staff estimate that approximately 22% of the generated landfill gas is 39 being collected and flared (Pers. comm. Chris Underwood)2. From this data is possible to calculate the current methane greenhouse gas emission: Volume of LFG=(5,082 f t 3 / . T - ^ - l (60min/ *24 h /*365^/ YlOOoV 3)= 75.7*109 L Massof C H 4 = (75.7*109 L ) f ^ ] ( 0 . 5 ) M E T H A N E * ( 1 6 ^ J f I O " 6 t o m e % ) ( 2 l ) G W P *(l-0.22) = 443,000tC02e ^22.4Ly The calculations above have estimated the atmospheric emission of methane to be 443,000 tC0 2e in 1999. When compared to this value, the nitrous oxide emission is less than half a percent. This estimate is likely because the majority of the landfill methane emissions result from the cellulose of disposed paper products. These same paper products also have low or negligible nitrogen contents, and therefore contribute little N 2 0 emissions. However, when analyzing the GHG implications of landfilling food or yard wastes (with their high nitrogen contents), N 2 0 emissions are of greater importance.. Also remember that the actual N 2 0 emissions can be much greater than the currently stipulated guideline of a 1.0% conversion rate. This will be illustrated in the next chapter, Results of the Analysis (Chapter 3). A further complicating factor is that of nitrogen sequestration. Whereas the potential for carbon sequestration was previously discussed, reactive nitrogen can also be stored in landfills and will prevent nitrous oxide emissions. While the calculations above estimate that 332 tonnes of nitrogen exited the V L F as leachate in 1999, 336,633 tonnes of waste was disposed in this landfill in the same year (Pers. comm. Mike Stringer). From an old Environment Canada (1978) report, a MSW moisture content of 24% and a dry MSW nitrogen content of 0.8% results in an estimated 2050 tonnes of nitrogen in the disposed waste. While the annual mass of waste disposed in the V L F has increased in its 30 odd years of existence, the possibility exists that much more nitrogen is being deposited than will have the opportunity to exit. Not to be overlooked is the possibility that reactive nitrogen, as ammonia, will exit the landfill in vented gas. Future wet or dry deposition will return this ammonia gas to soils or surface water bodies where nitrification and denitrification can occur. Thus the potential for future N 2 0 emission also exists from this pathway. If the landfill gas containing ammonia is collected and combusted, the ammonia will be oxidized to nitrogen oxides (NO or N0 2). This also provides reactive nitrogen to the atmosphere, and with subsequent wet or dry deposition, can nitrify and denitrify. The IPCC provides guidelines for these emissions and estimates that 1% of NH 3 -N or N O x - N emitted to the atmosphere will eventually be converted to N 2 0 . However, they also provide low and high estimates of 0.2 and 2% respectively. Thus, emission factors for gaseous emissions of ammonia or nitrogen oxides are similar to the emission factor for wastewater-nitrogen. It is not important how reactive nitrogen gets out of the landfill, only how much reactive nitrogen gets out. 2 It is important to note that in 1999 Vancouver City Council approved the expenditure of $5.4 million to upgrade this landfill gas collection system and thereby improve this collection efficiency (Henderson and Underwood 2000). 40 Composting The composting of food and yard wastes will result in N 2 0 either during the process itself or by the future nitrification and denitrification of reactive nitrogen leaving the composting process in the form of ammonia emissions, nitrate or organic matter. The available research has demonstrated the existence of N 2 0 emissions during the composting process. This is likely N 2 0 leakage during the nitrification and denitrification of reactive N in the organic wastes. Researchers have observed a conversion of N to N 2 0 ranging from 0.00005 to 2.2% and the findings are summarized in Table 2-4. T a b l e 2 - 4 : R e v i e w o f N i t r o u s O x i d e E m i s s i o n s f r o m C o m p o s t i n g N 20-N Loss Compost & Method (% of Initial TKN)f Researcher Dairy Cow Litter - Static Piles 0.00005 - 0.0005 Sommer and Dahl(1999) Yard Waste - Turned Windrow 0.5 Hellebrand(1998) Food & Yard Waste - Tunnel and Static Pile 0.2-0.4 Schenk et al. (1997) Wastewater Sludge & Wood Ash - Aerated Static Piles 0.7* Czepiel etal. (1996) Yard Waste - Turned Windrow 1.2 Ballestero et al. (1996) Bedding & Horse Manure - Turned Windrow 2.2 (after 60 days) Ballestero et al. (1996) Swine Feces & Cardboard - Aerated & Turned In-Vessel 0.1 Kuroda et al. (1996) Not given 0.5-0.8 Hellmann (1995) from Hellebrand(1998) * data provided in the research paper was adapted to determine this value f TKN = Total Kjeldahl Nitrogen (ammonia-N + organic-N) The above research documented immediate N 2 0 losses during composting, but this is not the complete picture. Additional N 2 0 generation is possible from the reactive nitrogen frequently lost during composting, and from the reactive nitrogen contained in finished compost. Nitrogen losses in the form of ammonia occur during composting when C:N ratios are below 20:1 and "the available carbon is fully utilized without stabilizing all of the nitrogen." (NRAES 1992) In addition, finished compost is typically land applied as a soil conditioner, where the reactive nitrogen is free to nitrify and denitrify. As a result, actual N 2 0 losses may be greater than demonstrated by these studies. For the N 2 0 emissions from yard waste composting to be considered a net GHG emission, it would have to be human-induced emissions. In other words, it would have to be N 2 0 emissions which would not have occurred naturally without human interference. There are two possibilities when this could occur: (1) yard trimmings which contain anthropogenic N fertilizer (i.e., yard waste resulting from fertilizer applications), and (2), when the human-induced accelerated composting process increases the emission of N 2 0 over and above the rotting/decomposition of organic waste which would otherwise occur in nature. While it is a simple concept that any N 2 0 emission from anthropogenic 41 reactive N should be considered a GHG emission, it is difficult in reality, to differentiate between natural and anthropogenic yard waste nitrogen. It is even more complicated to assess the second possibility. In fact, this author has been unsuccessful in finding any scientific research on either of these issues. As a result of these complexities, two assumptions are used in this report: that only 50% of yard waste nitrogen is anthropogenic and that composting does not impact N 2 0 emissions which would otherwise occur in nature. By making these assumptions, this research states that only half of the N 2 O emissions resulting from the composting of yard waste can be considered as anthropogenic GHG emissions. The IPCC methodology does not yet consider composting as a N 2 O source; agriculture is the main human-induced source and wastewater treatment is indirectly considered because of the anthropogenic fertilizer component of wastewater. However, it is likely that composting will be included in the future. I n c i n e r a t i o n Limited research has demonstrated that emissions of nitrous oxide occur during the incineration of municipal solid waste and wastewater sludge. This research was compiled by de Soete (1993) for an IPCC Workshop and is adapted for use in Table 2-5: T a b l e 2 - 5 : R e v i e w o f N i t r o u s O x i d e E m i s s i o n s f r o m I n c i n e r a t i o n Waste - Facility Temperature (°C) N 2 0 Emission (g N20/tonne waste) R e s e a r c h e r * Municipal refuse - Stepgrate 780-880 11-43 Yasuda et al. (1992) Municipal refuse - Stepgrate 780-980 40-220 Yasuda et al. (1992) Municipal refuse - Fluidized Bed 830-850 14-123 Yasuda et al. (1992) MSW - 5 stokers (20-400 tpd) not given 26-270 Watanabe et al. (1992) MSW - 3 fluidized bed not given 97-293 Watanabe et al. (1992) MSW-rot. kiln (120 tpd) not given 35-165 Watanabe et al. (1992) Wastewater sludge - rotary grate 750 227 Yasuda et al. (1992) Wastewater sludge - fluidized bed 770-812 580-1528 Yasuda et al. (1992) Wastewater sludge - rotary grate 838-854 684-1508 Yasuda et al. (1992) Wastewater sludge - rotary grate 834-844 275-886 Yasuda et al. (1992) Wastewater sludge - rotary grate 853-887 101-307 Yasuda et al. (1992) * As quoted in de Soete (1993) - unable to acquire primary reference The data presented in Table 2-4 demonstrate the limited and highly variable research on the N 2 O emissions resulting from waste incineration. Examples of emission estimates for municipal solid waste incineration which are being used are as follows (Environment Canada 1997a; USEPA 1999; USEPA 1998): • Environment Canada National Inventory 160 g N20/tonne waste incinerated • U.S. EPA National Inventory 30 g N20/tonne waste incinerated • U.S. EPA MSW Analysis 130 g N20/tonne waste incinerated 42 Though the research is uncertain, the data in Table 2-4 suggest three key points: 1. both the combustion of solid waste and sludge result in the formation of N 2 O , 2. wastewater sludge combustion, which generally has a higher N content than MSW, may result in greater N 2 0 emissions, and 3. increasing the combustion temperature during sludge incineration may decrease N 2 O formation. Both solid waste and wastewater sludge incineration have been demonstrated to result in the thermal formation of nitrous oxide. While the emissions from MSW incineration range between 11 and 293 g of N20/tonne of waste, the emissions from wastewater sludge incineration range from 101 to 1528 g of N20/tonne of waste. This may be an indication that sludge, which generally has a higher N content than MSW, may result in greater N 2 O formation and therefore emissions. Is thermal N 2 O formation a function of nitrogen content? Research has also demonstrated N 2 0 formation during the fluidized- bed combustion of coal, and two excellent review papers on this subject are Johnsson (1994) and Wojtowicz et al. (1994). This is important, because N 2 O formation during coal combustion has been found to "originate mainly from the nitrogen present in the carbonaceous fuel (fuel-N) (Wojtowicz et al. 1994)." Also, recent research on MSW incineration has found a correlation between N 2 O formation and the N content of wastes incinerated (Tanikawa et al. 1995). In addition, experiments with the incineration of sewage sludges and various coals found that the sludges yielded higher N 2 O emissions, and it was concluded that this was due to the higher nitrogen contents offering a greater potential for N 2 O formation. Therefore, the formation of N 2 O may likely be the conversion of part of the reactive nitrogen in the combusted material to N 2 O gas. Does increasing the combustion temperature during sludge incineration cause a reduction in thermal N 2 O formation? While the results of Yasuda et al. (1992) are variable, the N 2 O emission was lowest, 101-307 g/tonne, when the temperature was 853-887 °C. An exception to this was the result of 227 g/tonne at a temperature of 750 °C. Clearly, the only conclusion that can be derived from these results is that future research is greatly required. However, the decrease in N 2 O formation with an increased combustion temperature has been conclusively demonstrated in coal research (Wojtowicz et al. 1994; Pels et al. 1994). Unfortunately, as N 2 0 formation decreases, the formation of NO increases, in fact the sum of fuel nitrogen conversions "was found to be remarkably constant" over a range of temperatures.(Pels et al. 1994) Nitric oxide is also of environmental concern due to its contribution to acid rain and photochemical smog. In contrast, the study by Tanikawa et al (1995) was unable to find a correlation between N 2 O emission and temperature during MSW incineration, while sludge incineration experiments by Werther et al (1994) found that increasing the freeboard temperature lead to a decrease in N 2 0 without a consequent increasing of NOx emissions. It is important to remember that NOx is a future source of N 2 0 emissions; this reactive nitrogen is short- lived in the lower atmosphere and is returned to terrestrial ecosystems in the form of HNO3 and NO3 where it is then available for denitrification. Could solid waste and sludge incineration provide an effective means of performing clean denitrification? If the potential exists, the consequent increases in NOx emissions must be contended with. 43 2.5.6 Summary When nitrogen leaves farms as food products leave the farm it switches responsibility; no longer is it the responsibility of agriculture, the waste management community and municipalities take over. In addition, the nitrogen in yard wastes is assumed in this study to be partially anthropogenic in origin, and are therefore in excess of natural processes. Therefore, any immediate or future nitrous oxide emissions during landfilling, composting or incineration of these wastes must be considered as anthropogenic interference of the global N 2 0 cycle. 2.6 RECYCLING ANALYSIS The collection, processing and subsequent marketing of recyclable materials in the GVRD is an inherently complicated system. Several brokers exist and compete for market share throughout the various municipalities. Some municipalities provide their own curbside collection of blue-boxes while others have contracted this collection out to private industry. Blue-box recycling, either at single- or multi-family residences, may be managed by municipal crews, one company or a number of companies. The collection of recyclables at commercial buildings are typically managed by a number of different firms. Increasing the complication, once the recyclables are at the brokers, these materials are processed and marketed to a myriad of potential factories or mills for reuse into new products. The recycling of paper products illustrates this complexity. Once collected by one of the several methods, paper products can be shipped to mills across North America, and increasingly, recycled paper is shipped overseas to Asia. Similar systems are in place for other recyclable materials. In fact, the destinations of the collected recyclables rapidly change in response to the fluctuating markets for these materials. Brokers, as private enterprises, endeavour to maximize their revenues while concurrently minimizing the expenses incurred as a result of the necessary transportation. Recyclables collected in the GVRD could be delivered to the factories or mills in the region (or within British Columbia) which are designed to handle these materials but recycled paper could also be sent to the Eastern United States. Conversely, recycled paper is imported into Canada from cities in the U.S. to supply the local Newstech Recycling facility (Pers. comm. Pat Martin). This material is transported a great distance; likely requiring a substantial energy outlay and generating greenhouse gas emissions from transportation and handling requirements. Collaboration with GVRD representatives identified early on in this project that it would be necessary to simplify the complicated and rapidly changing recycling system. Rather than assess the plethora of potential fates for recyclables, it was deemed appropriate to simplify the system by assuming a single recycling facility depot and a single final destination for each type of recyclable. However, this research is performed to assess this pathway in the greater industry context. Concurrent to this, an invesigation is also conducted on the ramifications of manufacturing an equivalent product using virgin materials. This research is necessary to ascertain the greenhouse gas benefits or liabilities 44 of recycled vs. virgin manufacturing. The analysis of manufacturing using virgin or recycled materials is ceased when the convergence point (as discussed in Section 1.3.4) is reached. This investigation is not concerned with t