Biogas PlantBiogas plants produce a high calorific value gas which similar to natural gas and do this using the anaerobic digestion process. Biomass is digested in plants ranging from the size which might serve one house or a small farm up to much larger plants which tend to be highly complex and take a variety of feedstocks from various sources.A biogas plant normally comprises two main components, including: * a digester (or fermentation tank) * and, a gas holder (like a gasmometer as used for coal gas and natural gas). The feature which distinguishes these plants from composting which is the other form of digestion, is that the biogas plant reaction takes place in the absence of any oxygen. The gas contains up to 70 percent methane and 30 percent carbon dioxide. Fermentation is a normally a reasonably robust process when the biomass is kept within a certain pH value range. However, care is needed during operation to ensure that the pH range is maintained within limits or the biological process will be inhibited and gas production will reduce.  For reliable production of biogas in most plants the operator of the plant must be well trained,
and select the right combination of feeds. He must be aware that if fermentation materials are fed into the
plant which are excessively dilute, or too highly concentrated, either of these will result in a low biogas
production rate, and this will be the result of low fermentation activity. Segregation of the input to ensure that at all times, a suitable combination of nutrients is present in the feed to the process. This is of utmost importance for smooth running of the biogas plant. Success of biogas plants depends a great deal on proper segregation of, for example, kitchen waste from large pieces of material grit and dust which can be present choke and fill up the plant. Biogas production provides a public health benefit beyond that of any other treatment in managing the rural health environment of developing countries. Because the heat and biological action in the process especially in high temperature digestion is very good at reducing pathogen content, plus other disease vectors, and also kills many weed seeds. Anaerobic digesters can also be fed with specially grown energy crops such as silage for dedicated biogas production. Substrate composition is a major factor in determining the methane yield and methane production rates from the digestion of biomass. The biogas can also be used for heat production as steam or hot water. The evaporation plant uses the surplus heat out of the energy production for the concentration of the digester effluent up to a dry matter content where it is suited for drying (drier plant) or composting. RenewableAnaerobic digestion is a renewable energy source because the process produces a methane and carbon dioxide rich
biogas suitable for energy production helping replace fossil fuels. Especially in such situations where there
are few (or no) consumers on the farm that need electricity, the farmer earns money by selling the surplus
electricity. See the panel below to anser this question!
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