Making something useful out of smelly old garbage sounds like making a silk purse out of a sow’s ear. But with modern engineering, the waste in landfills can be used to generate electricity.
The simplest and most popular way to make electricity from garbage uses the naturally occurring methane gas that solid waste gives off as it decomposes. By the end of this month East Kentucky Power Cooperative (which supplies electricity to 16 distribution co-ops in the Bluegrass State) will begin generating electricity at the first three plants in Kentucky to use this technology.
Getting rid of household garbage and other solid wastes is a huge problem. In the United States about 2,500 landfills accept solid waste, with hundreds of others shut down because they’re already full.
Garbage in landfills gives off methane, even 30 to 50 years after closing. Methane gas smells bad and is explosive, so many landfill operators simply burned it off in a continuous, controlled flare through the end of a pipe. Although this helps control odor and reduce the danger of explosions, burning the methane day and night wastes energy. Why not use it?
Ralph Tyree, manager of non-traditional power projects for East Kentucky, explains how the co-op will convert methane into electricity.
“These new power plants built right next to the landfill site collect the gases that occur naturally in the buried waste through a series of wells. The gas is withdrawn from the landfill using a vacuum. As the gas moves through a grid of pipes, some of the moisture is removed, and it travels through yet another pipe where the gas can either be burned as a flare, sometimes necessary during routine maintenance, or sent over to the generating station. In the generating station the gas is compressed, cooled, more moisture removed, and finally sent to the engines that turn the generators to make electricity.”
East Kentucky’s new landfill gas-to-electricity generating stations cost about $4 million each to build, and produce electricity at a comparable cost to coal-fired plants.
The new plants are located at the Bavarian Landfill in Boone County in northern Kentucky, the Laurel Ridge Landfill in Laurel County in southeastern Kentucky, and the Green Valley Landfill in Greenup County in northwestern Kentucky.
“Each building is about 5,000 square feet,” Tyree explains, “and we’ve used the same basic design and layout for each one. This modular design helps us save money during the construction phase as well as with operator training.”
Altogether, the three plants will generate enough power for more than 6,000 homes, roughly 10 megawatts. While that is a tiny share of East Kentucky’s 2,500-megawatt peak demand, company spokesman Kevin Osborne points out that when these new plants begin operating at the end of the month, East Kentucky will become one of the leaders in the southeastern United States in providing renewable energy.
The U.S. Environmental Protection Agency encourages the construction of these kinds of generating plants through its Landfill Methane Outreach Program. Nationally, about 330 solid-waste landfills recover and burn landfill gases to generate electricity or heat, while hundreds of others continue to simply flare the gas.
Tyree notes that East Kentucky continues to evaluate other sites in Kentucky. It is looking for landfills with at least 20 years’ worth of methane to justify the initial investment. So far, about 20 sites possibly meet their criteria.
“These first three landfill gas projects are not just demonstration projects,” says Tyree. “Our co-op has a continuing, long-term commitment to this kind of project. We’ll be offering tours at the landfill generating plants…to help people understand what an important role this new technology will play in meeting the electricity demands of the future.”
To find out more about generating electricity from landfill gas, visit the Web site: www.epa.gov/outreach/lmop/products/factsheet.htm
Next month: Wind Power