Anaerobic technology harnessed fully by using different techniques: Review

In today's energy demanding life style, there is need for new sources of energy which are renewable as well as eco-friendly because the climate change is one of the biggest challenges for mankind. Many countries initiated production and distribution of several renewable energy technologies to solve the energy problem in rural areas. In India, the per capita energy consumption is 400 KWH per annum, while 350 kgoe per capita primary commercial energy consumption and about 80% of total rural energy consumption comes from non-commercial energy like firewood, agricultural waste, dry cow dung cakes. Among several technologies the anaerobic digestion technology, has been proved to be viable and emerged as a promising technology because biomass is available as domestic resources in India (biomass availability in India is of 150 million MT per annum), require less capital investment and per unit production cost as compare to other renewable energies. The another major issue is to reduce the emission of greenhouse gasses and this could be solved by anaerobic digestion technology (1 kg biomethane is equivalent to the reduction of 25 kg CO2) with various advantages like; replace the fossil fuels, reduce or eliminate the energy footprint of waste treatment plants, reduce methane emission from landfills, replace the industrially produced chemical fertilizers etc. Recent life cycle assessment studies have demonstrated that biogas derived methane (biomethane) is one of the most energy efficient and environmentally sustainable way of replacement of fossil fuels in both heat and power generation. In anaerobic digestion other than its merits, certain constraints are also associated with it. Most common among these are the low gas production in winter, low gas production from agricultural residues, large hydraulic retention time and digester design etc. Therefore, need of different techniques to remove its various limitations to achieve optimized gas production and helpful for rural areas. This paper reviews the various techniques, which could be used to solve the constraints occur during the gas production and harnessed fully anaerobic technology.