From Trash To Energy

ECO-VISTA LANDFILL’S METHANE FUELS GENERATORS

 Gary Thomas with Multicraft Contractors inspects a gas-powered electrical generator Tuesday that uses methane from the Waste Management landfill in Tontitown to produce electricity.The generators can produce enough electricty to power about 4,000 homes when they go online this fall.
Gary Thomas with Multicraft Contractors inspects a gas-powered electrical generator Tuesday that uses methane from the Waste Management landfill in Tontitown to produce electricity.The generators can produce enough electricty to power about 4,000 homes when they go online this fall.

— One pile of trash plus five tugboat engines is about to equal a lot of electricity.

Construction should be complete this fall on a power-generation plant at Waste Management’s Eco-Vista landfill in south Tontitown. The four-megawatt plant, fueled by methane collected from within the trash heap, produces enough electricity to power about 4,000 homes.

“We have to destruct the methane one way or another, and this way we make money off it,” said Jay Maruska, project manager for Waste Management’s renewable resources division. “It makes more sense than just burning it off.”

For several decades, methane gas created by decomposition in landfills was collected through piping systems and destroyed by a flare, a constantly burning flame similar to a super-size Bunsen burner, said Kirby Thompson, landfill manager. In recent years, landfill owners have started directing the methane to burn in generators.

Early systems used turbine engines, but newer versions use modified 16- or 20-cylinder diesel engines. Five Caterpillar engines — originally designed to drive tugboats — burn methane and spin generators, each of which produce 800,000 kilowatts an hour, said Steve Cochrane, project manager for T.V. John Construction, the contractor installing the plant.

The power will be sold to utility companies and pumped into the regional electrical distribution grid.

The idea has been under consideration since Waste Management purchased Eco-Vista in 2003, Thompson said. The 110-acre landfill puts out about 1,500 cubic feet of methane each minute from 11 million cubic yards of trash. The landfill takes in about 450,000 tons of trash each year from Washington, Benton and Madison counties.

The plant also happens to be in an area where Ozarks Electric Cooperative needed additional power, said Keith Kaderly, manager of marketing and energy services for the cooperative.

“Four megawatts isn’t a huge impact for our grid, because we can run as much as 255 megawatts at peak power, but it’s in a good spot,” Kaderly said. “With the growth in that area, we needed more supply there.”

The plant will represent the biggest alternative-fuel electricity supply in the Ozarks system, Kaderly said. A few solar installations pump power into the grid, but they’re all individual homes and put out negligible power, he said.

Once it goes online in November, the $8 million facility will join about 60 similar generators on other Waste Management landfills around the country, Maruska said. Other landfill companies are also moving toward recycling methane for power, he said.

“We’re producing methane pretty constantly, and we knew how big a generator we could support on the gas flow from the pile,” he said. “Utility companies love these kind of generators because the power output is very consistent.”

The landfill will continue to use a flare to burn any excess methane the generators can’t burn, Thompson said.

Dirty diapers and empty takeout boxes are just one of many ways to produce power, Kaderly said.

“It might sound a little weird at first, but in terms of alternative energy sources, it makes a lot of sense,” he said. “Every little bit helps.”

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