Landfills, with the tendency to belch noxious greenhouse gases, have long gotten a bad rap from environmentalists.
But now several clean-power technology companies believe waste can be a source of environmentally friendly energy.
FlexEnergy, an Irvine company, showed off a pilot generator Thursday that converts previously unusable methane gas seeping from a Riverside County landfill into 100 kilowatts of electricity. That could be used to help run the sprawling landfill operations or light up more than 100 homes.
The company envisions its generators being installed at many of the country's 2,300 currently operating or recently closed landfills. Trash in municipal solid-waste landfills produced 22% of all methane emissions nationwide in 2008, second only to the amount produced by animals as they digest food, according to the Environmental Protection Agency.
Riverside County's Lamb Canyon Landfill could produce up to 1.5 megawatts — enough to power 1,500 homes — if more of FlexEnergy's units are installed, the company said.
The project is the latest in a move to use landfills to produce electricity. At more than 500 landfills in the U.S. — 74 in California — methane already is being converted into electrical power.
But the Flex Powerstation technology is the first to use a low-emission process to deal with landfill methane, which can hover in the atmosphere for years, according to the company. Many dump operators deal with the gas by burning it up using flares, a technique that often releases more pollutants such as nitrous oxide and carbon monoxide.
Most waste-to-energy technologies can function only when gas with high methane content is available. But the methane levels degrade as landfills age, making those generators less efficient and shorter-lived than the Flex Powerstation, the company said. Even using gas with a small percentage of methane, the FlexEnergy option is still able to produce power.
On top of government stimulus funding, the company has picked up $13 million in venture capital investment over the 10 years it has been working on the technology. It attracted $7 million of that in the last two years, from RNS Capital and Costa Mesa-based Sail Venture Partners.
Next up for the company: working with the Department of Defense. FlexEnergy has identified hundreds of sites run by the U.S. Army that could use generators and is installing a system at Ft. Benning in Georgia in February, said Chief Executive Joe Perry.
The company's standard 250-kilowatt unit will sell for about $800,000, he said. Southern California offers a landfill marketplace worth $300 million, but Perry is also eyeing wastewater treatment plants, oil drilling sites and coal mines as potential customers.
"Methane is in multiple markets and multiple industries that are pollution sources that we can turn into energy sources," he said.
Other companies are also using landfills for eco-friendly applications.
BlueFire Ethanol Fuels Inc., also of Irvine, is slogging through the permitting process for a refinery in Lancaster that would convert organic waste into 3.7 million gallons of cellulosic ethanol each year to serve as an alternative to gasoline.
The plant would use grass trimmings, food scraps and paper that would otherwise be chucked into the landfill next door. BlueFire already has a $40-million grant from the Department of Energy to build another factory in Southern California.
And at the Toland Road Landfill northeast of Camarillo, the Ventura Regional Sanitation District is also turning piles of decomposing garbage into a source for power.
Starting in August 2009, nine microturbines that run on methane and other landfill gases have been generating 2.25 megawatts, which is enough to power more than 2,000 homes. Southern California Edison gets about 1.5 megawatts from the project. The remainder of the energy runs the rest of the landfill's operations, including machinery that superheats waste to destroy pathogens.
But some projects are encountering resistance.
After residents raised worries about air quality and health issues, the Los Angeles County Sanitation Districts pared back plans at the Palos Verdes landfill to upgrade an older, steam-powered generator with newer methane converters.
But the project is now two years behind schedule, and with dropping methane levels, it may have become too expensive to proceed, said supervising engineer Mark McDannel. He said he might have to scrap half or all of the proposal by the end of the year.