Wednesday, September 12, 2007

Targeting Methane: Turning Landfill Gas Into Electricity

Most of us love wind (unless we own a house on Nantucket), but let's not forget about the much less glamorous landfill gas, which offers a cheap source of power that puts to use what is now a nuisance gas. Landfills are already there, so using the gas presents far fewer problems with NIMBYism or people worried about their views.

According to these EPA numbers, we are currently exploiting about half the landfill gas potential in the U.S.:

As of December 2006, approximately 425 landfill gas (LFG) energy projects were operational in the United States. These 425 projects generate approximately 10 billion kilowatt-hours of electricity per year and deliver 230 million cubic feet per day of LFG to direct-use applications.

Of the 2,300 or so currently operating or recently closed MSW landfills in the United States, about 400 have LFG utilization projects. We estimate that approximately 560 additional MSW landfills could turn their gas into energy, producing enough electricity to power over 870,000 homes.

Comment: Burning methane produces CO2, but it counts as a renewable energy source since it is basically recycling carbon that was absorbed by (now decomposing) plants and animals. Targeting methane produces a double benefit first by preventing the methane emissions and second by using the methane as a substitute for non-renewable energy sources like coal.

Here are a few back-of the-envelop calculations: Generating 10 billion kWh of electricity from coal would produce more than 10.26 million metric tons of carbon emissions (assuming 2.3 lbs of CO2/kWh).

Using LFG to power another 870,000 homes--roughly another 9.5 billion kWh--would prevent another 9.7 million metric tons of emissions.

In 2006, methane emissions from landfills decreased by 20 million metric tons. If we were to take complete advantage of this resource, we could reduce methane and non-renewable emissions by about 60 MMT of CO2 equivalent--or about 5% of the total emissions from the residential sector (1197 MMT).

In contrast, according to industry numbers, wind currently generates about 17 billion kWh and prevents about 19 million tons of CO2 emissions each year.


Anonymous said...

You are probably interested on that web software for landfill design, which includes a landfill gas calculation tool based on EPA's LandGEM v3.02:

A short description and video about about this software you can find here.

Foto Unik said...

Dear Friend,
U have great article's. Im from Indonesia, Please visit our new "Landfill Gas for electricity" project on Indonesia. and give us your opinion :

Best Regards,