Biogas consists of two types of gas – methane (CH4) and Carbon Dioxide (CO2). Biogas comes out of a biological decomposition process, starting when organic material is heated in a anaerobic environment (with oxygen). Normally we talk about a mesophilic process, which happens at 37 – 42° C or a thermophillic process, which happens at 52 – 56° C. However, biogas is also produced from 20°C to 56°C.
The useful part of the biogas is the methane. Methane has a calorific value at almost the same as natural gas and can be used with the same purpose. Biogas can be used as fuel in a gas furnace producing heat or in a engine/generator plant producing electricity and heat.
The biogas is upgradeable through a upgrade plant. Here the CO2 is removed from the biogas, so that the methane is the only thing left. Methane is then transferable to the existing natural gas network and can be used for the same purposes as natural gas.
Biogas is considered CO2 neutral as the only CO2 released comes from the plants that are added to the plant in the form of manure, energy crops and waste products. However, you can say that by burning and making use of the biogas, the methane and nitro that would have been released in the manure is no longer harming the environment. As these gasses are up to 35 times more harmful to the atmosphere than CO2.