Even if its precise definition isn’t at the tip of your tongue, most everyone gets the general drift of what is meant by the term biogas — there’s biology involved, and the result is gas. One might guess it’s the funk in the air aboard the bus carrying the sauerkraut-eating team home after a weekend competition. Others would say biogas is cow belches, or the rotten-egg stink-bubbles that swarm to the surface when your foot sinks into swamp ooze.

Those are all examples of biogas, which is composed primarily of methane, CH4, at concentrations ranging from 50% to 60 %. Methane is highly combustible, and can be used in place of natural gas for heat or to run internal-combustion engines for the generation of electricity and other applications. Formed by microbes under anaerobic conditions, it is a greenhouse gas twenty-eight times more potent than carbon dioxide at trapping heat in Earth’s atmosphere. The fact that it can be useful if harnessed but dangerous if released is why we need to trap biogas given off by landfills, manure pits, and someday, maybe even cow burps. » Continue Reading.