Casey Toth - newsobserver.com
The Durham County Landfill has 66 wells that extract methane from the decomposing rubbish. Each well is protected from the weather by a box. A similar landfill in Apex will turn trash to energy by next year.
The South Wake landfill in Apex entombs waste from all over the county to the grinding roar of earth movers and the scream of wheeling seagulls. In its brief four years of operation, this 179-acre burial ground has reached a critical mass sufficient to convert gag-inducing garbage into something more palatable: green energy.
By next year, the county's castoffs will arise from this methane-blazing abyss to be reborn as electricity. In the humid warmth below, microscopic bacteria feast in a compost-rich heaven of plenty, metabolizing half-eaten meals, unopened junk mail and worn-out socks into combustible gas.
The gas will be vacuumed out of this putrefied stew and fed to 18 diesel generators - long-haul truck engines, to be exact. The electricity will be generated by Industrial Power Generating Co., headquartered in Richmond, Va., and resold by Ingenco to a local electricity provider that will deliver the current to local wall outlets.
The South Wake landfill methane-to-power project will be one of the largest in North Carolina, joining about two dozen others in operation, including a 3-year-old methane-to-electricity project in Durham. The N.C. Utilities Commission registered the $4.3 million South Wake green energy project last month.
South Wake's colossal bacteria colony will take two to three decades to nibble its way through the rubbish, leaving behind a mass of compost and some indigestible hulks, like bicycle wheels and wrenches and ball-point pens.
"It takes a long time for it to decompose," said Dave Palumbo, Ingenco's senior vice president of development.
Ingenco won the South County contract through a bid to pay Wake County $17.7 million over 15 years. The company outbid Novartis, which wanted to use the gas for its vaccine plant in Holly Springs.
As the state's population booms, creating mountains of waste as a byproduct, some estimate that in less than five years a dozen more landfills in the state will boost their methane output to levels that justify connecting electric generators. Until then, landfills typically flare or vent the methane to prevent deadly explosions, like the 1969 blast in Winston-Salem that alerted authorities to the dangers of gas buildup.
In that accident, methane migrated from a landfill into the basement of an armory. Someone lit a cigarette and the gas exploded, killing three men and injuring five others.
One of the last such accidents happened in Charlotte in 1994. A 33-year-old woman lost a soccer ball in a ground hole at a municipal soccer field built on a former landfill. When she flicked a lighter inside the hole, she was seriously burned in a methane explosion.
"It's just like a natural-gas well-head," said Ryan Hennessy, president of operations for Cary-based Methane Power, which runs the Durham facility.
Today, landfill gas is vented or burned not just for safety reasons, but also because methane is considered a potent greenhouse gas when allowed to escape into the atmosphere.
Slated for 9.5 megawatts, the South Wake project will never approach the enormity of a landfill methane plant in Sampson County. That facility is slated to expand to 25.6 megawatts by 2025, which would make it one of the five biggest projects in the nation that use landfill methane to generate electricity.
Methane gas is similar to natural gas, except it doesn't require drilling or fracking or pipelines. Unlike natural gas or oil, methane is in endless supply as long as humans generate garbage.
"It's some of the best (fuel), from a value standpoint," said James McLawhorn, who directs the electric division of the Public Staff, the state's consumer agency in utility rate cases.
Power for 5,900 homes
But the energy potential of landfill methane is puny in scale compared to fossil fuel deposits. The South Wake project will produce just enough electricity for about 5,900 homes when it reaches full capacity in 2022, assuming it produces at maximum capacity.
The trash-sourced methane can also be sold as a gas for heating, cooking or industrial processes, rather than electrical generation. Charlotte-based Enerdyne, which operates 10 landfill gas projects in the state, sells the methane from the North Wake landfill to a nearby pharmaceutical company, Covidien. The North Wake landfill closed in 2008, several months after South Wake began accepting trash.
In Asheville, the company sells the gas to a wastewater treatment plant and in Henderson to a food processing company.
The gas output depends on the quality of the trash, impurities in the gas, the moisture content of the landfill - factors that encourage the bacteria to work harder.
"Your worst day is when you overbuild and you don't have enough gas," said Bill Brinker, Enerdyne's founder and owner. "Then you have a very expensive asset to look at."
