According to reports, Biogas is a form of renewable energy produced from organic matter through a biological process. It is typically derived from anaerobic digestion or fermentation processes and can be produced from a diverse range of organic feedstocks including biomass, sewage, agricultural waste, certain industrial wastes (e.g. from the food & beverage manufacturing sector) and municipal waste.
Renewable energy from biomass is one of the most efficient and effective options among the various other alternative sources of energy currently available. The anaerobic digestion of biomass requires less capital investment and per unit production cost as compared to other renewable energy sources such as hydro, solar and wind. Furthermore, renewable energy from biomass is available as a domestic resource in the rural areas, which is not subject to world price fluctuations or the supply uncertainties as of imported and conventional fuels.
In India, energy demand from various sectors is increased substantially and the energy supply is not in pace with the demand which resulted in a deficit of 11,436 mw, which is equivalent to 12.6 per cent of peak demand in 2006. The total installed capacity of bioenergy generation till 2007 from solid biomass and waste to energy is about 1,227 mw against a potential of 25,700 MW.
The bioenergy potential from municipal solid waste, crop residue and agricultural waste, wastewater sludge, animal manure, industrial waste which includes distilleries, dairy plants, pulp and paper, poultry, slaughter houses, sugar industries is estimated. The total potential of biogas from all the above sources excluding wastewater has been estimated to be 40,734 Mm3/year.
In India, biogas has been traditionally based on dairy manure as feedstock and these `gobar’ gas plants have been in operation for a long period of time, especially in rural India. In the last two-three decades, research organisations with a focus on rural energy security have enhanced the design of the systems resulting in newer efficient low cost designs such as the Deenabandhu model.
The Deenabandhu model is a new biogas-production model popular in India. (Deenabandhu means `friend of the helpless.’) The unit usually has a capacity of two to three cubic metres. It is constructed using bricks or by a ferrocement mixture. In India, the brick model costs slightly more than the ferrocement model; however, India’s ministry of new and renewable energy offers some subsidy per model constructed.
In India, Nepal, Pakistan and Bangladesh, biogas produced from the anaerobic digestion of manure in small-scale digestion facilities is called gobar gas; it is estimated that such facilities exist in over 2 million households in India, 50,000 in Bangladesh and thousands in Pakistan, particularly North Punjab, due to the thriving population of livestock. The digester is an airtight circular pit made of concrete with a pipe connection. The manure is directed to the pit, usually straight from the cattle shed. The pit is filled with a required quantity of wastewater. The gas pipe is connected to the kitchen fireplace through control valves. The combustion of this biogas has very little odour or smoke. Owing to simplicity in implementation and use of cheap raw materials in villages, it is one of the most environmentally sound energy sources for rural needs.
To create awareness and associate the people interested in biogas, the Indian Biogas Association was formed. It aspires to be a unique blend of nationwide operators, manufacturers and planners of biogas plants, and representatives from science and research. The association was founded in 2010 and is now ready to start mushrooming. Its motto is `propagating biogas in a sustainable way’. In Pakistan, the Rural Support Programmes Network is running the Pakistan domestic biogas programme, which has installed 5,360 biogas plants and has trained in excess of 200 masons on the technology and aims to develop the biogas sector in Pakistan.
Similarly, the Chinese had experimented the applications of biogas since 1958. Around 1970, China had installed 6 million digesters in an effort to make agriculture more efficient. During the last few years, the technology has met high growth rates. This seems to be the earliest development in generating biogas from agricultural waste.
So, what’s the bottomline? Biogas technology provides an alternate source of energy in rural India and is hailed as an archetypal appropriate technology that meets the basic need for cooking fuel in rural areas. Using local resources, i.e. cattle waste and other organic wastes, energy and manure are derived. Realisation of this potential and the fact that India supports the largest cattle wealth led to the promotion of national biogas programme in a major way in the late 1970s as an answer to the growing fuel crisis.
(The writer is a faculty of Indian Institute of Technology, Mandi)