In developing countries like India, the energy needs of rural poor are mostly met with by burning firewood. Traditional methods of cooking are very unhealthy for the cook, as they emit a lot of smoke. Also the heat released in burning is not efficiency utilized. Indian energy scientists have come up with smokeless (Chulhas) stoves specially designed for Indian conditions. These ‘Chulhas’ are smokeless, permit shorter cooking time and there is also saving of fuel.
1) Smokeless Chulhas:
The fuel in smokeless ‘chualhas’ is renewable. Wood and straw are packaged solar energy that is used by plants as they grow. In the process, they absorb carbon dioxide from the air and thus help reduce green house effect. When plants parts are burnt as fuel, the carbon dioxide is released again but it will be reabsorbed in an endless cycle as long as trees keep growing and fields are replanted.
The improved ‘chulha’ has invoked tremendous response and positive action from all concerned. Nearly 3,000 villages, either an improved ‘chulha’ or a biogas plant is used for cooking food. A trained work force of more than 50,000 persons, mainly women, was created to work as master craftsmen for constructing the improve chulhas.
2) Gobar Gas:
Another alternative is biogas, also known as gobar gas. Gobar gas, which is largely methane, can also be generated from wood and straw, in specially built digesters. These can be afforded by any farmer who owns two to three cattle heads. The dung is collected and diluted with water along with straw, wood shavings or other agriculture or abattoir residues.
The range of raw materials that can be digested in gobar gas digesters in fact very wide, kitchen wastes, human night soil, piggery refuse, waste newspapers, city sewage. Almost any natural organic matter you can think of can be digested to produce gobar gas (methane) which is collected in the dome above the digester, from where it is taken to the kitchen through pipes and burnt in gas burners for cooking.
Its other benefits include reduction of indiscriminate felling of trees for fuel, improvement in sanitation, reduction in the incidence of eye disease among village women and easy and efficient cooking. One of the greatest merits of gobar gas is its versatility. It can be used for cooking, lighting and power generation, running refrigerator, or tube well pumps sets.
Another advantage of biogas digester is that the material left over after digestion, which is known as spent slurry, is a good fertilizer, rich in NPK (nitrogen, phosphorus, and potassium). The spent slurry, if applied to fields, is known to increase yields because along with the NPK it contains significant number of bacteria beneficial to the crops.
There is only one difficulty with biogas digesters; their efficiency goes down during winters when the atmospheric temperature is low and the need for energy is acute. However, in tropical countries like India, this may not pose a serious problem. Moreover, this problem can be tackled by using initial traces of gas coming from the dome in heating the digester itself.
The Government of India provides subsidy and extends technical know-how for installation and running of the gobar gas digesters. In view of the large social benefits of biogas energy, the National Projects on Biogas Development (NPBD) was taken up the promotion of biogas production in the country.
3) Energy from City Sewage:
The city sewage treatment plants use anaerobic digestion units for extracting methane from human nightsoil, which is in the form of sludge. The gas generated from the sludge is called sludge gas, which like biogas consists largely of methane. The Department of Non-Conventional Energy Sources has supported setting up sewage-based biogas plants in Uttar Pradesh, Madhya Pradesh and Delhi.
One large size urban waste recycling plant is already operating at Okhla, Delhi. The plant comprises 15 digesters connected to 15 gas collectors. The total gas generation from the plant is about 0.6 million cubic feet per day having a heat value of 700-800 “BTU” per cubic foot (equivalent to 500-570 cal per m3). The gas is about 50 percent cheaper than the LPG gas. Another such projects has been commissioned, recently at Pandraune in UP. Plants are under construction at Ayodhya in UP, Eshaopur in Delhi, and at Bhopal in MP. In Jabalpur, Municipal Corporation is setting up a garbage-based power plant which will generate 7 MW electricity daily.
Many bioorganic wastes are released as by-products by distilleries in India. A new technology for waste recycling and disposal has been introduced for the first time in the country by a distillery in Gujarat. The technology, simultaneous with the treatment of 45,000 litres of waste, will generate energy equivalent to that given by 10 tonnes to coal every days. The fuel is generated from the waste after fermenting the ash with yeast in a suitable culture medium. The 10 million-litre capacity distillery can get 50 percent of its fuel requirement from recycling its own waste. If all the 150 distilleries in the country adopt the technology there could be a saving of Rs.30 crores or 50,00,000 tonnes of coal annually. This will also result in an environmentally safe disposal of wastes!
Similarly, National Environmental Engineering Research Institute has installed digestion units at Nagpur. The Commission for Additional Resources of Energy has set up its units, one each at Chandigarh, Hyderabad, Bhopal, Ahmedabad, Lucknow and Guwahati.
Plants are being made for setting up sewage gas plants in the riverside towns like Varanasi, Allahabad, Agra, Kanpur and Bangalore. The Department of Non-Conventional Energy Sources has been active in preparing plants for depolluting the Ganga.
4) Solar Energy:
Biogas is a cheap and efficient fuel and its feedstock is renewable. More recently, other renewable sources for energy generation are being explored. Systematic efforts, for example, are being made to tap solar energy for meeting the demands of our rural poor. It is a decentralized energy system, which can to meet versatile needs of the Indian masses. Solar cooking, water heating, water desalination, space heating, crop dying, etc. are some of the modes of thermal conversion. Efforts are on to economically develop solar collectors for high temperature applications. More than 380 solar water heating systems are operating in the country. More than 1,000 large capacity water heating systems are under installation.
Solar energy can also be converted into electrical energy. Solar panels concentrate large amounts of light energy on photovoltaic cells, which charge the batteries that serve as a source of electricity. This electricity can be used to run pumps, street lighting systems or even refrigerators. More then 160 solar photovoltaic pumps have been installed in the rural areas providing water for drinking and irrigation. Solar photovoltaic street lighting systems have been provided by Government of India in more than 150 villages on experimental basis. Installed in the remote villages, also know as Urjagrams, far from power lines, solar energy makes electricity available to people who would otherwise not be able to dream to thermal of thermal or hydel electrical energy.
5) Wind Energy:
Another renewable alternative source of energy is wind energy. Wind energy holds promise for systematic utilization. The maximum exploitable potential has been estimated at about 3.2 x 108 J/Year. It can be converted into mechanical and electrical energies and would be particularly useful in remote areas. Wind energy can be made to run turbine to generate electricity. According to Indian Meteorological Department, average annual wind density of 3kWh/m2/day (read as kilowatt-hours per square metre per day) is prevalent at a number of places in Peninsular and Central India. In some areas, the densities are higher than 10 kWh/ m2/day during winter when energy requirements are very acute and 4 kWh/m2/day for 5-7 months in a year. At present, this energy is being used to upwell groundwater at four locations in Ajmer in Rajasthan. DNES has installed 924 wind pumps throughout the country. Wind electricity generators at appropriate locations (like Ladakh) are envisaged with aggregate capacity of 2 MW (Megawatts), for lighting and pumping water in additional to devising charging of batteries.