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Garbage In, Power Out

Landfills, which house garbage for eternity, are increasingly becoming power plants

Atish Patel /Reuters

Landfills are the ultimate symbol of waste. They are the repository of stuff that was produced but that is no longer needed, or that has been discarded, or that was built to be obsolete, or that was never used in the first place. For those in the resource world, every ton of junk that goes into a landfill represents wasted energy.

But today, many landfills are actually quite productive places. Aside from producing odors and mountains of trash, they increasingly produce power.

Garbage actually produces quite a punch. It can be incinerated to create heat and power electricity-making turbines. That’s what Sweden does, to great effect. In 2012, the Scandinavian country’s 32 waste-to-energy plants accounted for about 8 percent of the country’s electricity supply. In the U.S., waste-to-energy is a much smaller industry. There are 84 plants sprinkled among 23 states with a combined capacity of 2,700 megawatts—about the size of two very large coal-fired plants.

But that doesn’t mean that the U.S. doesn’t use landfills—and the material in them‚—to produce energy. When garbage decomposes in landfills, it releases so-called “landfill gas,”—i.e. methane that had been trapped in the organic, plastic, and other materials that everybody threw out. In recent decades, landfill operators have started capturing that gas in ever-rising quantities, and then using it to generate electricity. Waste Management, the large disposal company, has turned its landfills into a fleet of power producers. It notes that at 130 of its sites the company collects enough gas to make “over 550 megawatts of electricity, which is enough to power more than 440,000 homes.” The company also converts the gas into a liquid fuel that can run vehicles in its fleet. According to the U.S. Energy Information Administration, in 2012, some 256 million cubic feet of landfill gas was used to generate electricity. That year, landfill gas accounted for 9,800 gigawatts of electricity generation, up more than 90 percent from 2003.

There’s another way that landfills are being used to create energy. One of the downsides of landfills is that it is difficult to do anything with them once they have served their purpose. When they are full, many landfills are capped—covered with asphalt or concrete. Then just sit there, lying fallow. Precisely because of the materials that are underneath them, it is generally impossible to build houses, or school, or malls or offices on top of them.

But the relatively flat surfaces—and the lack of competing uses—make landfills excellent good candidates for fields of solar panels. This increasingly popular method of generating electricity requires large, contiguous open spaces that are not surrounded by obstacles like buildings that shade the sun’s rays. And so there has been a boom in placing solar fields on top of landfills.

Massachusetts has been a pioneer in this area, approving dozens of large-scale projects to place solar panels on landfills, in towns like Marshfield, Acton, and Brookfield.

The practice is spreading. At the end of October, the first landfill solar field in New York State was completed. Covering 13 acres of a landfill no longer in use in West Nyack, it has a generating capacity of 2.36 megawatts. To the south, in New Jersey, workers in September broke ground on what is likely to be the largest landfill solar plant in the country—a 10 megawatt plant covering 40 acres in the massive Parklands landfill, south of Trenton.

One person’s trash is another person’s cash, the old saying goes. We might coin a new one: one person’s garbage is another person’s wattage.