Types of Landfill Gases

As organic wastes break down in a landfill, the bacterial by-products produce gases. The gases produced depend on several factors, including size, depth, age and chemical environment of the landfill. The type of garbage also plays a role. The gases produced in landfills are often a combination of several gases.

Methane

• Methane is found naturally in the environment as well as being emitted from landfills. It is potentially flammable and explosive, especially if confined in a small spaces. It typically accounts for 45 to 60 percent of the gasses produced by landfills. Landfills are the largest methane producers in the United States.

Carbon Dioxide

• Carbon Dioxide usually makes up 40 to 60 percent of the gas emitted from American landfills. Though C02 occurs naturally, its increasing concentration in the atmosphere makes this gas an important factor in the process of climate change. It is known as a "greenhouse gas."

Sulphides

• Sulphides are what give the landfill its rotten smell. Because of the strong smell that sulphides cause, we would expect that they accounted for a considerable amount the total gas emitted by landfills. However, sulphides account for up to 1 percent of landfill gases. This category of gases includes: hydrogen sulphide, dimethyl sulphide and mercaptans.

Other Gases

• Other gases produced by landfills include nitrogen, oxygen, ammonia, hydrogen and carbon monoxide. Except for nitrogen, which accounts for 2 to 5 percent of landfill gases, these gases account for 1 percent or less. Another set of gases, non-methane organic compounds (including trichloroethylene, benzene and vinyl chloride), are also sometimes found.