Energy may be produced from solid waste in two ways: (1) generate methane from anaerobic decomposition of the waste and burn it (landfill-gas-to-energy, or LFGTE)or (2) burn the waste directly (waste-to-energy, or WTE).The heat generated by either method can be used to produce steam, which impinges on a turbine rotor connected to a generator to produce electricity. LFGTE produces about 215 kWh electricity/ton of waste, and WTE produces roughly 600kWh/ton of waste. The average output of a large power plant is 1GW, which is enough to supply the annual residential energy consumption of a city of roughly 800,000 people.
(a) The current rate of municipal solid-waste generation in the United States is approximately 413 million tons per year. If all of it were used for energy recovery, how many 1GW power plants could LFGTE supply? How many if WTE is used?
(b) A municipality trying to decide between LFGTE, WTE, and a natural gas-fired combustion turbine has called you in as a consultant. Use information in the sources cited below to summarize the pros and cons of each choice.
A useful source of information regarding LFGTE is the U.S. EPA Landfill Methane Outreach Program, www.epa.gov/lmop/; the Waste-to-Energy Research and Technology Council at Columbia University provides useful information on WTE, www.seas.columbia.edu/earth/wtert/; and information on natural gas can be obtained from the U.S. Energy Information Administration,
www.eia.doe.gov/oil_gas/natural_gas/info_glance/natural_gas.html.