Curbing Climate change through Organics Diversion: Results of a National Survey Rathan Bonam, Dr. Shirley Thompson & Dr. Nicola Koper Natural Resources Institute, University of Manitoba Figure 1: Landfill Gas capture sites across Canada ABSTRACT To reduce greenhouse gas (GHG) and determine best practices for sustainable waste management the relationships between landfill gas, diversion rates, management methods and landfill characteristics were explored for 130 landfills across Canada. Significant GHG occur from Canadian landfills but methane recovery is only occurring at landfills using best management practices (high density, higher disposal fees, greater depth and higher diversion) but should be carried out at all landfills above a minimum size to reduce GHG. A linear regression analysis showed that landfill emissions are positively linearly correlated with landfill depth, density and organic waste and negatively correlated to waste diversion and disposal fee. Waste diversion's impact on GHG is significant enough for the nation to concentrate more on waste reduction, including composting and recycling programs to provide the long-term solution to reduce GHG production and waste generation. INTRODUCTION Canada’s high greenhouse gas (GHG) emissions per capita from solid waste disposal on land require that new strategies to reduce methane emissions including organic diversion and methane recovery. Canada has the second highest methane emissions per capita from solid waste disposal on land among the numerous countries in the United Nations Framework Convention on Climate Change Parties (UNFCC, 2003), due to burgeoning waste per capita, lack of widespread organic diversion and limited methane recovery. Landfill gas is basically made up of half methane and half carbon dioxide (CO 2), two potent greenhouse gases, as well as small amounts of hydrogen, oxygen, nitrogen, hydrogen sulphide and trace amounts of non-organic compounds and volatile organic compounds (Gardner et al. , 1993; Schumacher, 1983). In Canada, methane emissions account for approximately 12. 6% of Canada’s CO 2 equivalent (e. CO 2) GHG emissions with almost one-quarter (24%) arising from landfills (Canadian Electricity Association, 2002). Methane is typically generated during a 30 to 50 year period as waste undergoes anaerobic decomposition. Methane is the central concern for greenhouse gas emissions from landfills as it has 23 times the global warming potential of CO 2 (source ). However, the CO 2 produced from burning or aerobic decomposition of biomass, unlike methane, is deemed a sustainable cycle, as carbon in CO 2 is sequestered when the biomass regenerates (Environment Canada, 2003). Landfill gas recovery, organic waste diversion as well as other waste management aspects of 130 landfills were collected by a national survey to determine best management practices to reduce GHG. Municipal solid waste composition and quantity varies substantially by location and waste management systems (Bonomo and Higginson, 1988; Senior, 1990). In Canada, municipalities manage waste under provincial certificate of approvals. Municipalities and/or provinces are able to ban organics or require landfill gas capture – but few do. Only Ontario and Alberta are requiring landfill gas recovery of larger size landfills and only Nova Scotia and Prince Edward Island ban organics from landfills. The systematic recovery and utilization of landfill gas generated during anaerobic decomposition of municipal solid wastes both reduces GHG emissions and creates an alternative renewable source of energy to replace fossil fuel use (Pembina Institute, 2003; Smith et al. , 2001). If the methane was recovered from one tonne of waste it could produce approximately 1000 kilowatt hours (k. Wh), as one cubic meter of methane gas has an energy value of four to five k. Wh (Pembina Institute, 2003). Methane recovery of landfill gas represents one of the most cost effective means to reduce GHG emissions due to both fuel sales and credits from GHG reduction (Conestoga Rovers and Associates, 1999). In addition, the capture and use of landfill gas provides the ancillary benefits of limiting odours, controlling damage to vegetation, minimizing owner liability, reducing risk from explosions, fires and asphyxiation, and smog while providing a potential source of revenue and profit (Smith et al. , 2001). Despite its many benefits, methane recovery is essentially an “end of pipe” solution, which does not actively tackle the root cause of waste generation, unlike composting. Composting organic matter considers broader ecological issues such as resource-use efficiency, avoided ecological impacts, and improvements in soil stability, fertility and moisture-retaining properties (Smith et al. , 2001). Under aerobic conditions, methane is not produced in composting operations, however, usually some anaerobic decomposition occurs due to the incomplete aeration of compost. Source separated organic composting programs are uncommon outside of tbree provinces (Nova Scotia, Ontario and Prince Edward Island) and a few urban centres and only started to become popular across Canada in early 2000 (van der Werf and Cant, 2006). A national survey of composting in Canada found that 135 municipalities have curbside composting programs, reaching 17 million people (van der Werf and Cant, 2006). All of these 135 municipalities have yard waste composting and 40% of these have source separated organic programs. Nova Scotia’s landfill ban on organics contributed to Nova Scotia reducing its waste disposal rate to half of other provinces, with an overall 56% diversion rate from landfills (Betts, 2007). Halifax’s rates of organic diversion at 68% almost reaches that of EU, where organic diversion rates are above 80% for Austria, Belgium (Flanders), Germany, Switzerland, Luxembourg, Italy, Spain (Catalonia), Sweden and the Netherlands (ECN, 2007). These countries all have country-wide policies that require source separation of organics or ban organics from landfills. van der Werf and Cant (2006) considered that it was feasible to divert 50% of Canada’s organic waste or 2. 9 million tonnes/year through composting. The Scholl Canyon model is applied to estimate the energy potential of Brady Road Landfill. This simple model is widely used in the landfill gas industry in Canada and the United States, particularly for landfills with greater than one million tonnes of waste in places (Environment Canada, 2003; US EPA, 1996). However, it has never been used as a management tool to compare different waste management options. This model is consistent with Environment Canada and IPCC climate change protocols for calculating GHG emissions. The Scholl Canyon model assumes that after a lag time of negligible duration, during which anaerobic conditions are established and the microbial biomass are built up and stabilized, the gas production rate is at its peak (Schumacher, 1983). This model is an exponential decay model dependent on factors that affect biodegradation rates (e. g. , age of waste, moisture content, etc. ) used to estimate methane generation from landfills but has not been applied to compare waste management options. BC METHOD 1. Surveyed 300 landfills regarding waste and landfill gas. 2. Analyzed data descriptively and by province to determine how waste management differs by province. 3. Determined relationships after meeting linear regression assumptions (required logging landfill emissions, density of waste, waste diverted, current waste, waste capacity, organic content, recycling and composting) at the 0. 05 probability level defining significance with S-Plus statistical software version 7, between: - waste management practices and measured methane emissions; - waste management practices and diversion; and - determination of what is important to model emissions. The statistical model “Y = ß 0 + Xi 1 ß 1 + Xi 2 ß 2 + Xi 3 ß 3 + Xi 4 ß 4 + e” assumed a linear relationship between the following variables (where “e” is an observational error, β 0 (intercept) and βn (slope)) Independent Variables: Xi 1 = Waste diverted in 2005 from the landfill (log) [Tonnes] Xi 2 = Total current waste (log) – [Tonnes] Xi 3 = Organic waste disposed in 2005 (log) – [Tonnes] Xi 4 = Depth of the waste placed in the landfill – [Meters] Xi 5 = Disposal fee/tipping fee of the landfill – [Dollars] Dependent variable: Y = Measured landfill emissions in 2005 (log) – [Kilo Tonnes] All these five independent landfill variables were not correlated either positively or negatively with each other (considering r>0. 6). All variables followed a normal distribution. 4. Determined whether actual methane emissions and modelled emissions could benefit from other factor 5. Determined GHG savings from recycling and composting based on the overall GHG releases through the life cycle of a number of materials which form a considerable part of the MSW waste stream. AB 7 2 7 0 QC 10 ON 10 2 12 NS 1 National Summary 52 Operational Projects (67 MW and 4, 234, 814 million BTU) 1 30 Active sites 22 Closed sites RESULTS National Survey Results: The response rate was 43% (i. e. 130 landfills with 97 being active) and 52/52 or 100% landfills of the gas capturing systems in place. The findings in Table 1 shows that many provinces have limited waste capacity. Many landfills are trying to extend the life of their landfill by increasing density, depth, disposal fee and increase diversion. The total amount of landfill gas recovered in both closed and open landfills is 52 landfills (314 kt of methane) and of that 215, 800 or 60% of the landfill gas recovered is from landfills that continue to receive waste. Those recovering methane are larger landfills with better management, that is greater density, increased depth, higher diversion rates and more expensive disposal fees. The contrast between all of Alberta’s landfills for diversion and depth compared to the one recovering methane reflects that this alternative is municipally driven and not a result of provincial policies and programs. Approximately one-third (32%) of the landfills recovering methane plan to close within five years. Seventeen active landfills had waste composition data from audits which we compiled to find that the organic composition in landfills ranged from 41% to 100%. The average organic composition was 63% – including wood, food, garden and non-food waste and paper and textiles. Table 1: National Survey Findings for 130 landfills organized by Province Average Total Landfill Waste Province Depth (m) disposed in 2005 Current Waste (tonnes) Table 2: Characteristics of 28 of 30 active LFG projects by Province Waste Average % Waste Capacity Density Disposal diverted (tonnes) (kg/m 3) Fees ($) 12 15 15 20 20 22 20 Waste Province Disposed diverted in 2005 NS (1) 1, 443, 681 22, 674, 427 102, 054, 139 1, 287, 247 25, 898, 000 53, 800, 000 281, 447 3, 287, 849 22, 775, 000 275, 324 1, 520, 699 10, 045, 760 3, 911, 351 64, 234, 313 155, 156, 327 33, 376 148, 400 371, 000 4, 821, 571 105, 315, 590 196, 313, 230 25 65 61 64 63 100 50 750 20 500 900 750 730 725 700 900 13 29 22 16 54 6 65 Table 3: Statistical Model of important factors related to methane emissions Log (2005 Measured Methane Emissions) = - 5. 6703 + 0. 6776*log (Current waste) + 0. 0111*Depth of waste + 0. 5003*log (Organic waste disposed) – 0. 2871*log (Waste Diverted in 2005) + 0. 0035*Disposal fees. Value Std. Error T value -5. 6703 0. 8138 -6. 9678 0. 6776 0. 1565 4. 3287 0. 0111 0. 0049 2. 2553 0. 5003 0. 1311 3. 8168 -0. 2871 0. 1111 -2. 5843 0. 0035 1. 0115 5, 390 QC (10) 4, 751, 289 6% 192, 458, 548 934 24 44 141, 180 ON (10) 1, 715, 671 11% 67, 968, 776 893 20 64 39, 390 AB (1) 250, 000 44% 13, 500, 000 850 43 42 4, 170 BC (6) 1, 387, 247 28% 65, 300, 000 850 15 65 25, 680 8, 261, 978 24% 342, 827, 324 860 25 66 215, 800 Graph 2: Correlation of Actual Emissions to Scholl Canyon methane model and depth Graph 3: Greenhouse emissions saved by composting and recycling including saving embodied energy in products 0. 0169* Disposal waste 115 0. 0009* Waste Diversion (log) 20 0. 0344* Organic waste (log) 780 0. 0003* Depth of waste 3, 600, 000 0. 0000* Waste in Place (log) 29% Pr(>|t|) (Intercept) 157, 771 Waste Average Disposa Total LFG Capacity Density Depth l Fees captured ($) (tonnes/yr) (tonnes) (Kg/m 3) (m) Total (tonnes) AB BC NB NS ON PEI QC Average/ Total Note: 22 landfill gas recovery collected from closed landfill Graph 1: Waste Composition from audits of 17 landfills across Canada 0. 3228 Residual standard error: 0. 2928 on 23 degrees of freedom Multiple R-Squared: 0. 824, F-statistic: 20. 6 on 5 and 23 degrees of freedom The p-value is 0. 0000001242 *Statistically significant at 0. 05 CONCLUSION Greenhouse gas emissions from landfills dictates that Canada needs a strong policy to reduce organics and require methane recovery for medium and large landfills. The variation across the country and within provinces in waste management practices and methane recovery show the lack of an overall Canadian or provincial policy. Provinces across Canada should adopt the best practices that only a few provinces have adopted. Regarding landfill gas recovery, Ontario recently required larger landfills to recover methane. All other provinces should make it a requirement of all landfills above a minimum size. The method to estimate methane emissions should consider depth of waste to improve accuracy. Regarding composting, both Prince Edward Island (PEI) and Nova Scotia banned organics from landfill. PEI’s diversion rate is 54% and Nova Scotia is 30%. Other provinces have no source separation of organics programs and divert waste through user-pay systems. Banning organics reduce GHG: a linear regression analysis showed that landfill emissions are positively linearly correlated with landfill depth, capacity and organic waste and negatively correlated to waste diversion and disposal fee. In addition, organic diversion would help resolve the crisis of closing landfills by extending the life of landfills. Further, best practices to extend landfill life include deep landfills, higher disposal fees and more diversion practices. Deeper landfills are more economical for infrastructure of liner, reduced land-base and higher methane recovery in deeper wells. Waste diversion's impact on GHG is significant enough for the nation to concentrate more on waste reduction, including composting and recycling programs to provide the long-term solution to reduce GHG production and waste generation. ACKNOWLEDGEMENTS The authors are grateful to Environment Canada for supporting this survey. REFERENCES • • • Canadian Electricity Association (CEA). (2002). Joint Study to Reduce GHG Emissions at City Landfills. Ottawa: CEA. Gardner, N. , B. Manley and J. Pearson. (1993). “Gas Emission from Landfills and their Contributions to Global Warming”. Applied Energy, 44: 165 -174. Smith, A. , K. Brown, S. Ogilvie, K. Rushton and J. Bates (2001). Waste Management Options and Climate Change. Final Report to the European Commission. Amsterdam: AEA Technology Environment. Schumacher, M. M. (1983). Landfill Methane Recovery. Park Ridge, NJ: Noyes Data Corporation. Statistics Canada. (2002, 2000, 1998, 1996, 1995, 1994). Waste Management Industry Survey, Business and Government Sectors, Catalogue No. 16 F 0023 XIE. United Nations Framework Convention on Climate Change. (2003). Article 2: Objective. http: //unfccc. int/essential_background/convention/background/items/1353. php. (accessed on June 15, 2007).
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