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Waste-to-Energy (Municipal Solid Waste)

Energy from municipal solid waste

Municipal solid waste (MSW), often called garbage, is used to produce energy at waste-to-energy plants and at landfills in the United States. MSW contains biomass (or biogenic) materials like paper, cardboard, food waste, grass clippings, leaves, wood, leather products, and other nonbiomass combustible materials like plastics and other synthetic materials made from petroleum.

In 1960, the average American threw away 2.7 pounds of trash per day. Today, the average American throws away about 4.4 pounds of trash every day. Of those 4.4 pounds, about 34% is recycled or composted, and about 13% is burned and converted to energy. The rest, about 53%, is discarded, mostly into landfills. About 85% of household trash is material that will burn, and about 61% of that is biogenic—material that is made from biomass (plant or animal products).

Waste-to-energy plants make steam and electricity

MSW is burned at special waste-to-energy plants that use the heat to make steam to generate electricity or to heat buildings. In 2013, there were about 80 waste-to-energy plants in the United States that generated electricity or produced steam. These plants burned about 30 million tons of MSW in 2013, and generated nearly 14 billion kilowatthours of electricity, about the same amount used by 1.3 million U.S. households in 2013. The biogenic material in MSW contributed about 52% of the energy from MSW that was burned in electricity-generating waste-to-energy facilities. Many large landfills also generate electricity by using the methane gas that is produced as biomass decomposes in the landfill.

Waste-to-energy is a waste management option

Producing electricity is only one reason to burn MSW. Burning waste also reduces the amount of material that would probably be buried in landfills. Burning MSW reduces the volume of waste by about 87%.

Last updated: January 11, 2017

How waste-to-energy plants work

Waste-to-energy plants burn municipal solid waste, often called garbage or trash, to produce steam in a boiler that is used to generate electricity.

image showing how Waste-to-Energy Plants work

The process of generating electricity in a waste-to-energy plant has seven stages:

  1. Waste is dumped from garbage trucks into a large pit.
  2. A giant claw on a crane grabs waste and dumps it in a combustion chamber.
  3. The waste (fuel) is burned, releasing heat.
  4. The heat turns water into steam in a boiler.
  5. The high-pressure steam turns the blades of a turbine generator to produce electricity.
  6. An air pollution control system removes pollutants from the combustion gas before it is released through a smoke stack.
  7. Ash is collected from the boiler and the air pollution control system.

Think of municipal solid waste as a mixture of energy-rich fuels. In 100 pounds of waste, more than 85 pounds can be burned as fuel to generate electricity. Those fuels include paper, plastics, and yard waste. One ton of municipal solid waste burned in waste-to-energy plants in the United States in 2013 generated about 481 kilowatthours (kWh) of electricity, the amount of electricity used by about 16 U.S. households in one day.

In a waste-to-energy plant, 2,000 pounds (one ton) of garbage is reduced to 300–600 pounds of ash.

Trash burned around the world

Many countries use waste-to-energy plants to capture the energy in waste. The use of waste-to-energy plants in some European countries and Japan is relatively high, in part because those countries have little open space for landfills, and they have few energy resources.

Last updated: January 11, 2017