-
Feb 14, 2007 9:08 am US/Mountain
-
Digg |
Facebook |
E-mail
|
Print
How Do You Make Power Out Of Garbage?
by Alan Gionet
DENVER (CBS4) ―
Across the acres of artificially created hills at the Denver-Arapahoe disposal site and the old Lowry landfill, there's opportunity to create electric power out of trash. But how would it work?
"This one's ready to go," says Steve Derus, landfill district manager.
He's talking about the ripening trash buried down to 100 feet below where we walk on one of the hills. Perforated pipes reach down through the trash and a vacuum helps suck up methane gas. Right now that gas goes to a 1,500 degree blast furnace where it's burned off because methane is a greenhouse gas.
"The energy's wasted," says Derus.
Waste Management, which operates the site under contract with Denver, has other methane burning plants at other landfills. They don't generate a great deal of electricity and even the one proposed for both the Lowry and Denver-Arapahoe site would create only about three megawatts.
That's tiny compared to modern coal burning and even wind plants, some of which can produce hundreds of megawatts of electricity. But the methane plant could produce enough to power about 3,000 homes.
A great deal of the 8,000 to 12,000 tons of garbage currently dumped every day at the Denver-Arapahoe disposal site consists of food and paper. Once the oxygen works its way out of the soil after trash is dumped, anaerobic bacteria take over.
They eat the organic waste and produce mostly methane gas and carbon dioxide. The plan calls for a plant to take the mixture recovered from pipes drilled down into the trash and process it. The methane would be separated from the carbon dioxide and other gases. The water would be drained out and cleaned.
The gas is also filtered and pressurized. Then it's piped to a bank of turbines and generators that burn it for electricity. The plant is hooked into the power grid and three megawatts would be added to the power supply.
The drawback is that landfills don't release methane forever. In fact the plant would likely operate for only 20 years. But the gas supply is essentially free.
(© MMVII CBS Television Stations, Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)