What is biogas?
Methane is the main constituent of what is popularly known as biogas. A
colourless, odourless, inflammable gas, it has been referred to as sewerage gas,
klar gas, marsh gas, refuse-derived fuel (RDF), sludge gas, will-o'-the-wisp of
marsh lands, fool's fire, gobar gas (cow dung gas), bioenergy, and "fuel of
the future." The gas mixture produced is composed roughly of 65 per cent
CH4, 30 per cent CO2, and 1 per cent H2S. A thousand cubic feet of processed
biogas is equivalent to 600 cubic feet of natural gas, 6.4 gallons of butane,
5.2 gallons of gasoline, or 4.6 gallons of diesel oil. For cooking and lighting,
a family of four would consume 150 cubic feet of biogas per day, an amount that
is easily generated from the family's night soil and the dung of three cows. In
addition, rural housewives using the biofuel are spared the irritating smoke
resulting from the combustion of firewood, cattle dung cakes, and the detritus
of raw vegetables (Figure 1).
Figure. 1. The Attributes of Biogas as a Fuel vs.
the Disadvantages of Wood (Source: Bio-Gas Newsletter, August