Biogas

Biogas is a mixture of gases produced when organic materials are decomposed in anoxic conditions by anaerobic bacterial action. Methane is produced by certain bacteria during the final stage of such processes.

Biogas largely consists of methane (CH₄) and carbon dioxide (CO₂), with the proportion of methane varying between 40% and 70%, and carbon dioxide accounting for 30-60%. The gas mixtures produced in biogas reactors also contain small concentrations of nitrogen and hydrogen sulphide. Landfill gases also typcially contain traces of chlorine and flourine compounds. The unpleasant odours associated with biogases are due to the presence of sulphurous gases.

Environmentally friendly energy

Biogas is a renewable energy source which nevertheless closely resembles non-renewable fossil natural gas in its chemical makeup. Methane is a major ingredient in both gases. But from the point of view of the greenhouse effect biogas is a preferable option, since it originates from renewable sources of organic biomass which would release carbon dioxide into the atmosphere even if they were not used to generate energy.

This means that burning biogas does nod add carbon dioxide to the atmosphere. Like wood energy and energy crops it is a climate-friendly form of energy production.

Methane is a much more potent greenhouse gas than carbon dioxide, so from the point of view of climate protection it is well worth capturing and exploiting the methane that would otherwise escape into the atmosphere from landfill sites as the organic materials inside the landfill decompose.