Example
Methane concentration affects energy content and the quantity available for destruction.
The catch
A single sample may miss changing conditions over time.
Related terms
Methane, Anaerobic decomposition, Anaerobic digestion, Biogas, Biomethane, Composting
In more depth
Gas composition, explained.
Gas composition tells an operator what is happening underground as well as how much fuel is in the pipe. Field analysers on landfill gas report the main components, chiefly methane and carbon dioxide, plus any oxygen and nitrogen. Laboratory tests add trace compounds such as hydrogen sulphide and siloxanes, which corrode or foul engines.
Oxygen and nitrogen are the warning signs. Their presence usually means air is being drawn in through the cover or a well is drawing too hard. That can disturb the microbes that produce methane and raise the risk of underground fires. For carbon accounting, state whether proportions are by volume or by mass and whether the gas was dried before analysis, because the conversion to tonnes depends on both.