Landfill gas

Landfill gas is a mix of different gases created by the action of microorganisms within a landfill as they decompose organic waste, including for example, food waste and paper waste. Landfill gas is a type of biogas, which is approximately forty to sixty percent methane, with the remainder being mostly carbon dioxide. Landfill gas often contains nitrogen gas that is pulled in from the atmosphere during collection. Trace amounts of non-methane volatile organic compounds (VOCs), siloxanes, and hydrogen sulfide comprise the remainder (<1%). These trace gases include a large array of species, mainly simple hydrocarbons.

Landfill gases have an influence on climate change. The major components are CO₂ and methane, both of which are greenhouse gases. Methane in the atmosphere is a far more potent greenhouse gas with a global warming potential of 27 over a one-hundred year period. Landfills are the third-largest source of methane in the US.

Because of the significant negative effects of these gases, regulatory regimes have been set up to monitor landfill gas, reduce the amount of biodegradable content in municipal waste, and to create landfill gas utilization strategies, which include gas flaring or capture for electricity generation.