2007年VOA标准英语-Modern Landfills Can Turn Garbage into Clean En

As long as there are people on the planet, there will be garbage.  The rubbish often piles up in landfills that produce a harmful greenhouse gas called methane 1.  VOA's Stephanie Ho reports solid waste managers have been working to turn this methane into something good -- namely, clean energy.

A mountain of garbage looks awful. And it is worse than it looks -- and smells.  Those tons of decomposing 2 trash are producing methane gas.

Garbage being dumped at a landfill



If allowed to seep 3 out into the environment, methane contributes significantly to global warming. Yet it is not all bad. If captured correctly, methane can generate electricity. 

The Environmental Protection Agency says about 400 landfills in the United States have methane power plants.  One of them is the Frey Farm Landfill, run by a local government authority in Lancaster County, Pennsylvania. The E.P.A. considers it a model landfill for the way it pipes methane to a private plant that generates enough electricity for about 4,000 homes.

Gary Platt is the plant's operator. "They bring the garbage in and after the garbage is compacted into the landfill, we draw wells,” he explains. “Wells go down, we put perforated pipe down the center of it, which collects all the methane from the garbage."

The gas plant also produces steam that a local dairy uses to pasteurize its milk and clean its equipment.  The dairy's executive vice 4 president, John Cox, points to the old diesel 5-fueled boilers 6 the dairy used to use. "We estimate that we're going to save 220,000 gallons [833,000 liters] of diesel fuel a year, by purchasing steam from this methodology."

Lancaster County's partner is a local energy company called PPL Energy Services.  PPL business manager Steve Gabrielle says the Frey Farm project is only financially feasible for his company right now because of the government tax credits. "If electric energy prices continue to increase, there might be more of a reason to do these projects without the tax incentives 7."

Back at Frey Farm Landfill, waste management official Jim Warner says the site will accept trash for more than a decade. "You see, eventually that will be filled, this whole area will be filled in the year 2019.  There will be a nice big circle 80 feet higher [24.5 meters]."

Capturing methane energy after a landfill is capped



The landfill will continue generating methane gas long after it is full.  The problem then -- what to do with the land?

According to Jim Warner, Executive Director of Lancaster County Solid Waste Management Authority, "Once a landfill, always a landfill, for the most part."

Because the waste settles as it decomposes 8, a landfill is not an ideal place to build homes.  But Warner says the government is exploring other ways to generate energy at the site, using wind and the sun.

"That's one benefit of the landfill, it is open space,” says Warner. “And that is something you need to develop solar projects -- open space to capture the sun.  Right now we have a nice sunny day.  We could be capturing some of this solar energy."

And if they do, they will help the United States, and the rest of the world, meet an ever-growing demand for energy.