Transcript Gas Emissions at Brady Road Landfill in Canada

Waste Management Options to Curb Climate Change:
Gas Emissions at Brady Road Landfill in Canada
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Sarayut Tanapat , Shirley Thompson , Cheryl Corman , Tony Kuluk
1) Natural Resources Institute, University of Manitoba, 70 Dysart Road, Winnipeg, Manitoba R3T 2N2, 2) Manitoba Hydro P.O. Box 815 Winnipeg, Manitoba R3C 2P4, 3) City of Winnipeg, Solid Waste Division, Winnipeg, Manitoba R3E 3P1
ABSTRACT
METHODS
Part of the strategy to meet Kyoto targets in Canada and Manitoba is to curtail emissions of greenhouse gas from
landfills. Canada’s target is to reduce greenhouse gases to 6 percent below 1990 levels by 2008 to 2012, with the province
of Manitoba promising to curb greenhouse gases at almost four times that rate.
The Scholl Canyon model is generally used to estimate greenhouse gases produced at landfills which is useful to
determine the cost-effectiveness of implementing methane recovery programs. However, this model also has utility for
comparing different waste management options for greenhouse gas production by using site-specific data for Winnipeg’s
Brady Road Landfill, as we demonstrate in this paper. The Brady Road landfill will generate methane at rates from 1000 to
6000 standard cubic feet per minute (scfm) in 2050, with rates varying depending on the parameters of the model and
diversion rates.
RESULTS AND DISCUSSIONS
dL/dt = kLo Σ ri ei – ki ti
where:
Lo is total volume of methane ultimately to be produced (ft3/lb);
n is number of years considered;
ti is time from placement year 2000 as i to (years);
ki is greenhouse gas production constant applied to each year; and,
ri is a ratio of the tonnage of all previous years accumulated to the landfill’s maximum capacity of landfill*.
*The expected total site capacity is estimated at about 50 million tones of total waste. A fraction of total landfilled refuse (ri) is obtained from the amount of refuse
deposited each year between 1973 and 2000 divided by the expected site capacity of 50 million tones (i.e. r (1973) 30,000/50,000,000). This assumes the same rate of
garbage disposal by assuming that any reduction in waste per person would be nullified by population growth in Winnipeg, without incorporating composting
programs.
INTRODUCTION
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CAA, Lo=170; K=0.05
AP-42 (Wet), Lo=100; K=0.04
AP-42 (Dry), Lo=100; K=0.02
Environment Canada, Lo=165; K=0.006
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CAA, 25% Biowaste Diversion, Lo=170; K=0.05
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AP-42 (Wet), 25% Biowaste Diversion, Lo=100; K=0.04
AP-42 (Dry), 25% Biowaste Diversion, Lo=100; K=0.02
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ACKNOWLEDGEMENTS
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AP-42 (Wet), 50% Biowaste Diversion, Lo=100; K=0.04
AP-42 (Dry), 50% Biowaste Diversion, Lo=100; K=0.02
Environment Canada, 50% Biowaste Diversion, Lo=165; K=0.006
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Graph 4: Estimated Landfill Gas Generation Potential with 75% Waste Division
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Thus it is possible and lucrative to harvest biogas through methane recovery and, at the same time, reap other resources
through composting. To turn Brady Road Landfill’s powder keg of methane, which is presently an explosion and fire risk, into a
goldmine, methane recovery and/or composting should be considered. The question being asked here is not whether composting is
better than methane recovery. Rather the question is whether composting and recovering methane are compatible so that maximum
Landfill gas recovery is an innovative way to reduce the emissions and create an alternative renewable source of energy
through the systematic recovery and utilization of biogas generated during anaerobic decomposition of municipal solid wastes.
However, landfill gas recovery and flaring gas is essentially an “end of pipe” solution, which reduces only one of the impacts of
landfilling biodegradable waste without tackling the root cause of waste generation. Broader ecological issues include: resource
use efficiency, avoided ecological impacts and improvements from using compost in soil stability, fertility and moisture-retaining
properties.
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Graph 3: Landfill Gas Generation Potential with 50% Waste Division
Brady Road landfill clearly will emit substantial amounts of methane under any waste management option. Brady Road is an
active site with filling projections into the next century, which would provide a stable consistent source of energy and/or compost.
The utility of the Scholl Canyon model in comparing different waste management scenarios has been demonstrated. The Scholl
Canyon provides practical information for management decision-making that when converted to Kilowatt per Hour (kW-hr)
potential for electrical generation or British Thermal Unit (BTU) for low- grade fuel for heating can provide estimates for potential
annual revenue. For example, at 1,000 scfm methane generation the annual revenue for heating fuel is expected to be over one
million dollars in 2001 Canadian dollars [5].
recovery of resources can occur. Clearly they are.
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The Scholl Canyon model is used to estimate the landfill gas that could be
recovered at the landfill, comparing methane generation emissions under different
waste management strategies. Different input parameters including greenhouse
gas production constants from US EPA[1] upper and lower limits for both wet and
dry climates and Environment Canada [2] parameters specific for the climate of
Manitoba are applied to deal with uncertainties regarding gas generation. The
advantages of paper recycling and composting over landfilling for greenhouse gas
management depends on the efficiency with which the landfill is assumed to
control biogas emissions [3] and ranges from 50 to 280 kg CO2 equivalencies per
tonne of municipal solid waste.
Graph 2: Estimated Landfill Gas Generation Potential with 25% Waste Diversion
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Landfill Gas Generation Rate (scfm)
As landfill gas accounts for over 5 percent of overall greenhouse gases in
Canada, waste management must be a component of any climate change
reduction plan. As Brady Road Landfill in Winnipeg is the largest single point
source in Manitoba of greenhouse gas and the largest landfill that is unmanaged
for greenhouse gas in Canada it is important site for developing a waste
management plan that considers climate change. Presently, Brady Road Landfill
is operated by the City of Winnipeg without: composting (other than yard waste),
flaring of methane or recapturing of methane gas for energy. Although a blue box
recycling program for paper and cardboard is in place the majority of paper waste
is landfilled. The recovery rate in 2000 was 34 percent, which declined from 41
percent in 1998 and 42 percent in 1996 (City of Winnipeg Waste Composition
Study, 2000). The need for a waste management plan at Brady Road Landfill is
clear. To determine the best option to reduce greenhouse gases different options
including composting and methane recovery need to be considered.
Landfill Gas Generation Rate (scfm)
Graph 1: Landfill Gas Generation Potential at Brady Road Landfill
Figure 1: Showing Brady
Road landfill in Winnipeg,
Manitoba, Canada
CONCLUSIONS
L is amount of gas left to generate per unit weight of refuse (ft3/lb);
Composting promises to reduce the methane generation significantly, particularly if government and community
support result in substantive diversion rates. If composting resulted in diversion rates as high as 50 or 75 percent as well as
harvesting rich soil it would still result in a lucrative landfill gas recovery from Brady Road Landfill at the lower rate of
1000 scfm. Thus, landfill gas recovery and composting programs are indeed compatible to maximize resource recovery
and have great promise to turn Brady Road landfill from a powder keg of methane, which is presently a fire and explosion
risk, into a goldmine.
Winnipeg
Landfill gas generation rates could be as high as 5800 scfm or as low as 3800 according to Graph 1 if no composting programs
are put in place. Composting programs would have a dramatic decrease in methane (see Graph 2 to 4). In 2050 landfill gas
production would amount to 1000 scfm, in the best case scenario where 75 percent of waste is diverted which is one-sixth the
upper range of 5800 scfm if no waste diversion occurs. As the recycling rate for paper, which is easier to divert than compost, is
presently less than 40 percent in Winnipeg, even with blue box curb side pick-up, it is expected that the diversion rate for
composting would be at the lower rate of 25 percent. At 25 percent there would still be approximately 2000 to 4000 scfm in 2050.
The Scholl Canyon model is employed for the purposes of evaluating landfill gas production rates over time under four different strategies for waste
management options, namely: 1) constant waste generation, 2) 25 percent waste diversion from composting and paper recycling, 3) 50 percent waste
diversion, 4) 75 percent waste reduction. This approach assumes that after a lag time of negligible duration, during which anaerobic conditions are
established and the microbial biomass is built up and stabilized; the gas production rate is at its peak. Therefore, the gas production rate is assumed to
decrease as the organic fraction of the refuse diminishes. The equation governing the model is [4]:
REFERENCES
CAA, 75% Biowaste Diversion, Lo=170; K=0.05
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This study was supported in part by a grant from Manitoba Hydro. The authors are also grateful to the Alumni Association Inc.
of the University of Manitoba for the financial assistance.
AP-42 (Wet), 75% Biowaste Diversion, Lo=100; K=0.04
1)
US Environmental Protection Agency (US EPA). 2001. Evaluating Landfill Gas Potential. Proceeding of Landfill Methane
Outreach Program, Training Workshop, Sao Paulo, Brazil. June, 26, 2001.
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2)
Levelton, B. 1991. Inventory of Methane Emissions from Landfills in Canada. Ottawa: Environment Canada.
2000
3)
Smith, A., Brown, K., Ogilvie, S., Rushton, K., and Bates, J. 2001. Waste Management Options and Climate change. Final
Report to the European Commission. Amsterdam: AEA Technology Environment.
4)
Schumacher, M. M. 1983. Landfill Methane Recovery. Noyes Data Corporation, Park Ridge, NJ, USA.
5)
Manitoba Hydro. 2003. Energy Matters Insights News Releases Electrical Links. Report of Manitoba Hydro.
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AP-42 (Dry), 75% Biowaste Diversion, Lo=100; K=0.02
Environment Canada, 75% Biowaste Diversion, Lo=165;K=0.006
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