WESTMINSTER - Scores of wells, made from 8-inch pipe, plunge deep into a hill in this Central Massachusetts town, searching for naturally occurring gas. It's no surprise that they find it.
The hill's lush green slopes cover a landfill, where tons of decomposing garbage belch methane gas. Once upon a time, the stinky byproduct was simply burned off. But today, it fuels a power plant generating enough electricity for 3,000 homes.
Waste Management Inc. of Houston, the nation's biggest landfill operator, just opened the squat, two-story plant this fall, piping methane from the landfill to drive two generators, each producing 1.6 megawatts of electricity. The plant, which has the capacity to quadruple the current electrical output, is the latest in Massachusetts to turn landfill gas into energy and part of a broader movement to reclaim methane from human and animal wastes.
More than 400 gas-to-energy plants now operate at US landfills, and that number has the potential to more than double, according to the Environmental Protection Agency. In Massachusetts, 17 gas-to-energy plants generate enough power for an estimated 60,000 homes, and at least three more landfills are candidates for new plants, according to state and federal environmental agencies.
Sewage is the feedstock for methane at the Deer Island treatment plant in Boston Harbor, where the gas is used to make one-fifth of the electricity consumed by the power-hungry treatment process. In Vermont, four dairy farms are tapping methane-producing cow manure to generate most of the electricity for 4,600 homes. Central Vermont Public Service, a Rutland utility, projects a dozen manure-to-energy plants will operate in the state by 2010 under a three-year-old program known as "Cow Power."
The program's motto: "Energy happens."
"People looked at us like we were crazy when we launched Cow Power," said Steve Costello, spokesman for Central Vermont Public Service. "But we've had no problem finding demand for the electricity produced by the farms."
Both environmental and economic factors are driving these methane mining efforts. Not only have sharp increases in fossil fuel prices made alternative energy economically competitive, but state and federal policies are creating a ready market for the power by requiring utilities to purchase electricity from renewable sources, which includes waste gases.
The Massachusetts House of Representatives, for example, recently passed energy legislation that would require new renewable sources to provide 15 percent of the state's electricity by 2020.
In addition, using these waste gases as fuel eliminates a particularly potent greenhouse gas that contributes to global warming, environmentalists said. Methane's effect on climate change is considered at least 20 times worse than carbon dioxide, the most common greenhouse gas.
"From a greenhouse perspective, it's very important that you capture methane," said Michael Stoddard, deputy director of Environment Northeast, a regional advocacy group. "But it's a win-win when you not only avoid emitting it, but convert it to something useful."
Landfills are the greatest source of man-made methane, accounting for about one-fourth of the gas released into the atmosphere by human sources, according to the EPA. Landfills create more methane than coal mining, chemical production, and natural gas- and oil-fired heat and power systems.
The landfill in Westminster, owned by the city of Fitchburg, is the fifth Waste Management facility in Massachusetts to host a gas-to-energy plant, and the first owned and operated by the company. Waste Management this summer launched a five-year program to build 60 gas-to-energy plants at its US landfills and generate 230 megawatts of electricity, enough to power about 230,000 homes.
That, of course, is just a tiny slice of the nation's electrical needs. The Pilgrim Nuclear Power Plant in Plymouth, for example, can generate nearly 700 megawatts alone. In New England, small projects such as gas-to-energy plants, account for less than 1 percent of electricity generation, according to ISO-New England, the company that manages the region's power grid.
Still, said Ellen Foley, the ISO-New England spokeswoman, gas-to-energy plants are "useful resources" in meeting the region's power demands. "It's fair to say every little bit helps," she said.
The Westminster plant, nestled at the foot of the landfill hill, will produce power at about the same cost as wind turbines, about 4 to 5 cents per kilowatt hour, but with one important advantage, said Thomas Murray, Waste Management's district manager for Eastern and Central Massachusetts. The power is steady, instead of intermittent.
About 100 wells recover the landfill gas, funneling it into a collection pipe that encircles the landfill below the surface. A powerful vacuum sucks the gas into the power plant, where impurities, primarily hydrogen sulfide and water, are separated from the methane.
The methane fuels two 2,300-horsepower engines, each driving a generator.
The current plant has room for two more engines and generators, and the site has enough space to double the size of the existing facility. If built out, the plant would be able to generate electricity for about 12,000 homes.
"This is just the beginning," said Murray. "It's only going to get bigger from here."
Robert Gavin can be reached at rgavin@globe.com.
