Landfill gas is created by the decomposition of organic residues in waste. Landfill gas consists mainly of methane, which contributes to the greenhouse effect if it is released into the environment. By extracting landfill gas from the landfill site, this emission is prevented and the energy can be utilized. The landfill gas can be used to generate sustainable electricity and heat, but its efficiency is limited. Use as natural gas or vehicle fuel results in a much higher yield. Landfill gas can be upgraded to natural gas quality, just like biogas.
The composition of the landfill gas depends on the waste deposited. An additional cleaning step for capture of the chlorine-fluorine compounds may be necessary.
Because a large landfill cannot be sealed as easily as a digester, more nitrogen is present in the gas. If there is too much nitrogen to achieve the required gas quality, the nitrogen must be removed.
In 2008 we developed a PSA nitrogen removal technique that makes it possible to upgrade landfill gas to H gas quality.