Biogas produced from the natural degradation of organic material in landfills. It must be clarified that landfill gas is not the same as natural gas or methane. Landfill gas is about 40-60% methane, with the remainder being mostly carbon dioxide (CO2). Landfill gas also contains varying amounts of nitrogen, oxygen, water vapor, sulfur and a hundreds of other contaminants — most of which are known as “non-methane organic compounds” or NMOCs. Therefore, burning landfill gas through combustion engines or turbines emits more pollution than burning natural gas.