Most Canadian cities do not have diversion programs in place for organic materials and this is contributing to increases in the gases that cause global warming, say University of Manitoba researchers Shirley Thompson and Rathan Bonam.
In a recent survey the team looked at 132 landfills across the country in conjunction with Environment Canada.
“Despite recycling programs, waste amounts going to landfills are increasing, as are the greenhouse gases (GHGs) from waste created by decomposing organic material,” says Dr. Thompson, National Resources Institute, University of Manitoba. “When organic waste goes to landfills it creates methane gas, and our findings show this increases Canada’s greenhouse gases by four per cent.”
Thompson found only 12 per cent of total household waste, or 1.7 tons, was diverted by recycling and composting programs in 2005. The other 88 per cent of all waste goes directly to landfills. Diversion is when resources in waste are re-used.
One diversion option is to ban organic materials from landfills and offer subsidized composting programs, she says. As organic matter decays in landfills it generates methane gas, one of the greenhouse gases that includes carbon dioxide and nitrous oxide. Canadians generate about seven megatons of organics each year, with 66 per cent of it ending up in landfills. The typical Canadian landfill generates 40 to 60 per cent methane gas which has 23 times the global warming potential of carbon dioxide.
The study found only 6.1 per cent, or 831,335 tons of organic matter was composted, which in itself resulted in a decrease of 7.3 kt in methane emissions, according to International Protocol for Climate Change calculations. When organics are composted aerobically they do not produce methane and are considered part of a sustainable cycle. In a landfill the organic material decomposes anaerobically.
Thompson, who recently presented her findings at an international conference on GHGs, says if more cities encouraged diversion with green box programs where organic matter and paper could be composted it would help Canada reach its Kyoto targets and reduce global warming.
She adds that the best strategy, however, is when organics composting is combined with the recovery of methane from landfills. Recovered methane can be converted into gas for electricity or heating, a plan currently under consideration at Winnipeg’s Brady Road landfill. The study found that 52 out of an estimated 800 active and closed landfills in Canada actually recover methane. To make methane recovery initiatives more affordable for municipalities, Thompson suggests incentives to help pay for capital costs and income from utilizing gas energy.
“If we applied targets to individual sectors such as waste, transportation, other industries, and subsectors such as landfills, we could reach the Kyoto goals, which are set at a six per cent reduction by 2012,” Thompson says. But she warns any initiatives would need to be aggressive, citing how many European countries have done so only by achieving rates of diversion at 80 per cent and higher.
“A long lead time is required for organic diversion to result in a significant reduction in methane emissions, as historical waste in anaerobic landfills emits methane for 30 to 50 years,” she explains. “Significant organic diversion requires strong government regulation to ban organics from landfills in each province across Canada.”
Thompson identifies Prince Edward Island, British Columbia and Nova Scotia as “star” provinces. The Halifax Regional Municipality (HRM), for instance, banned organics in landfills and reduced organic waste by 67 per cent. The HRM organics green cart is collected from households and accepts all food scraps, sawdust, wood shavings, yard waste and many paper products.