They eat dead plants and animals, causing them to rot or decay. Even though this natural process is slowed in the artificial environment of a landfill, a substance called methane gas is still produced as the waste decays. New regulations require landfills to collect methane gas for safety and environmental reasons. Methane gas is colorless and odorless, but it is not harmless. The gas can cause fires or explosions if it seeps into nearby homes and is ignited.
Landfills can collect the methane gas, purify it, and then use it as an energy source.
Methane, which is the same thing as natural gas, is a good energy source. Most gas furnaces and gas stoves use methane supplied by natural gas utility companies. The city landfill in Florence, Alabama recovers 32 million cubic feet of methane gas a day. The city purifies the gas and then pumps it into natural gas pipelines. Today only a tiny portion of landfill gas is used to provide energy.