gas is produced from the anaerobic decomposition of waste in landfills.
Methane is one of the main components of landfill gas--an odourless,
colourless gas generated by the anaerobic decomposition of degradable
organic waste. Although its composition can vary, landfill gas is
typically half methane and half carbon dioxide, with trace levels
of sulphur compounds and volatile organic compounds. Landfill sites
begin producing landfill gas in their first year, and can continue
producing for up to half a century.
Over the past decade, innovative technologies have been developed
to capture this gas by drilling
deep into landfill sites and pumping it out through a network of
pipes. The captured gas is
either flared or piped to nearby
facilities for use as fuel in heating buildings or generating
electricity. Burning landfill gas not only converts methane
to carbon dioxide, but also destroys most of its harmful components--which
can cause nuisance odours, stress on vegetation, smog, and a risk
of fire, explosion and asphyxiation. The methane produced by Canadian
landfill sites contains enough energy to heat more than 600 000
homes a year.
supports the utilization of landfill gas and has been working with
Canada, provincial departments and the private sector to raise
awareness of the energy potential of landfill gas by holding workshops
and publishing guidebooks on the subject, as well as supporting
research into new and innovative technologies. These include a new
cryogenic purification process
that can separate landfill gas into liquefied natural gas and high-purity
carbon dioxide, and the use of microturbines
to generate electricity on small landfill sites.
The increased availability of cost-effective and efficient technologies
has resulted in a 40-per-cent increase in landfill gas capture in
Canada since 1990. Today, nearly 300 000 tonnes of methane are recovered
at 42 sites across the country annually, reducing greenhouse gas
emissions equivalent to six megatonnes of carbon dioxide, the equivalent
of removing 1.4 million cars off the road. However, this still represents
just a quarter of the total landfill methane produced in Canada
About 70 per cent of the recovered gas is used as energy, most
of it at large-volume landfills located near major urban centres.
However, the potential also exists for many medium and small sites
to generate energy from landfill gas recovery projects.
Experts estimate that the volume of landfill methane captured
in Canada could be doubled within the next five years--significantly
decreasing Canada's greenhouse gas emissions, and reducing the impact
of human activity on global climate change.