The New Nation - Internet Edition

Biogas is a renewable alternative fuel, which is produced by breaking down organic matter by a process of microbiological activity. Basically this means that rotting municipal waste, food waste or sewage (both human and animal) is turned into gas by means of "anaerobic conversion" in a digester or fermentation of biodegradable materials such as biomass, manure or sewage, municipal waste, and energy crops. This type of biogas is comprised primarily of methane and carbon dioxide. The other principle type of biogas is wood gas which is created by gasification of wood or other biomass. This type of biogas is comprised primarily of nitrogen, hydrogen, and carbon monoxide, with trace amounts of methane. Organic matter such as switchgrass can be grown specifically for biogas production. The gases methane, hydrogen and carbon monoxide can be combusted or oxidized with oxygen. Air contains 21% oxygen. This energy release allows biogas to be used as a fuel. Biogas can be used as a low-cost fuel in any country for any heating purpose, such as cooking. It can also be utilized in modern waste management facilities where it can be used to run any type of heat engine, to generate either mechanical or electrical power. Biogas is a renewable fuel and electricity produced from it can be used to attract renewable energy subsidies in some parts of the world. Methane within biogas can be concentrated to the same standards as natural gas, when it is, it is called biomethane. If the local gas network permits it the producer of the biogas may be able to utilize the local gas distribution networks. Gas must be very clean to reach pipeline quality, and must be of the correct composition for the local distribution network to accept. Carbon dioxide, Water, hydrogen sulfide and particulates must be removed if present. If concentrated and compressed it can also be used in vehicle transportation. Compressed biogas is becoming widely used in Sweden, Switzerland and Germany. It is generally accepted that Biogas gives an average of 95% carbon dioxide reduction (well to wheel) in comparison to diesel, as well as 80% lower nitrous oxide emissions. Plus, it also has zero particulate emissions. Some people even argue that biogas actually reduces carbon emissions by more than 100 per cent. This is because the organic waste that is converted into gas would normally be responsible for putting methane into the atmosphere. Production of biogas therefore actually lowers the need for landfill and allows gas capture at sewage works.

Krishna Chandra Das

Sontosh, Tangail