Alternative Energy

Garbage buried in airless pockets deep inside landfills, the organic matter in these great mounds of waste is consumed by bacteria that give off gas rich in methane, increasingly used to generate electricity and heat. Landfill methane in New York , New Jersey and Connecticut powers generators that produce a total of 169 megawatts of electricity; the methane also provides 16.7 million cubic feet of gas daily for heating and other direct uses.

Methane production depends on the type of garbage, organic-laden municipal solid waste is the best producer — how old and how tightly bundled it is, the quantity and, especially, weather conditions. Landfills in dry, hot climates produce less; those in steamy, rainy places do best because moisture hastens the decomposition that produces methane.Landfill gas is about 50 percent methane and 50 percent carbon dioxide. Trace ingredients include hydrogen sulfide, which has a noxious odor. Collection systems and flaring largely eliminates odors from these ingredients. Methane itself is odorless.

Landfill methane becomes a greenhouse gas at least 20 times more potent than carbon dioxide if not captured, when it rises into the atmosphere. Capturing methane is a global housekeeping benefit as well as an important alternative energy niche, energy production from landfill methane, while desirable, will go only a short way toward meeting overall energy needs.