India is one of the most promising environmental markets in Asia and offers significant opportunities for Renewable Energy Sector . The total environmental technologies and services market in India is expected to grow to US$9 billion by 2010. The hazardous waste technologies and services component – estimated at over US$223 million in 2006 – is likely to grow by 7 per cent annually until 2010. Presently about 960 million tones of solid waste are being generated annually in India From industrial, mining, municipal, agricultural and other processes, of these approximately 350 million tones are organic wastes from agricultural sources; 290 million tones are inorganic waste of industrial and mining sectors and 4.5 million tones are hazardous in nature.

Solid waste generated in India’s largest cities exceeds 100,000 MT/day (approximately 36.5 million tons annually), most of which is disposed of in landfills (94 per cent). In many centers the collection, transportation and disposal of municipal wastes are carried out in unhygienic ways that poses serious risks for carriers, people working or scavenging in dumping areas, and to others living nearby. Ground water in dumping areas is highly contaminated. Deteriorating sanitary conditions and waste management problems are being exacerbated by the growing concentrations around waste sites of unskilled, unemployed and poorly educated people who have migrated from rural areas. This estimation is based on the structured data base prepared for 299 Class I cities and 36 Class II cities as part of “National Master Plan for Development of Waste to Energy in India” being taken up under UNDP/GEF assisted Project on “Development of High Rate Biomethanation Processes”. The study concluded that 17(6%) cities have generation rate in excess of 1000 TPD, and 80 cities (26%) generate 150 to 1000 TPD. The balance 202 cities (68%) individually generate less than 150 TPD. The municipal solid waste (MSW) generation ranges from 0.25 to 0.66 kg/person/day with an average of 0.45 kg/person/day. In addition, large quantities of solid and liquid wastes are generated by industries. Most of the wastes generated find their way into land and water bodies, without proper treatment, emitting gases like Methane (CH4), Carbon Dioxide (CO2), etc, resulting in bad odor, air and water pollution, as well as increase in the emission of green house gases. This problem can be significantly mitigated through adoption of environment-friendly waste-to-energy technologies for treatment and processing wastes before disposal. It not only reduces the quantity of wastes, but also improves its quality to meet the required pollution control standards, besides generating substantial quantity of energy.
Electricity can be produced by burning "municipal solid waste" (MSW) as a fuel. MSW power plants, also called waste to energy (WTE) plants, are designed to dispose of MSW and to produce electricity as a byproduct of the incinerator operation.
The term MSW describes the stream of solid waste ("trash" or "garbage") generated by households and apartments, commercial establishments, industries and institutions. MSW consists of everyday items such as product packaging, grass clippings, furniture, cloths, bottles, food scraps, newspapers, appliances, paint and batteries. It does not include medical, commercial and industrial hazardous or radioactive wastes, which must be treated separately.
MSW is managed by a combination of disposal in landfill sites, recycling, and incineration. MSW incinerators often produce electricity in WTE plants. The US Environmental Protection Agency (EPA) recommends, "The most environmentally sound management of MSW is achieved when these approaches are implemented according to EPA's preferred order: source reduction first, recycling and composting second, and disposal in landfills or waste combustors last.

Technology for Treatment of MSW Various technological options are available for setting up of waste-to energy projects. Some of these are described below.
Anaerobic Digestion/Biomethanation: In this process, the organic fraction of the waste is segregated and fed into a closed container (biogas digester). In the digester, the segregated waste undergoes biodegradation in presence of methanogenic bacteria and under anaerobic conditions, producing methane-rich biogas and effluent. The biogas can be used either for cooking/heating applications, or for generating motive power or electricity through dual-fuel or gas engines, low-pressure gas turbines, or steam turbines. The sludge from anaerobic digestion, after stabilization, can be used as a soil conditioner. It can even be sold as manure depending upon its composition, which is determined mainly by the composition of the input waste.
Combustion/Incineration In this process, wastes are directly burned in presence of excess air (oxygen) at high temperatures (about 800 ºC), liberating heat energy, inert gases, and ash. Combustion results in transfer of 65%–80% of heat content of the organic matter to hot air, steam, and hot water. The steam generated, in turn, can be used in steam turbines to generate power.
Pyrolysis/Gasification Pyrolysis is a process of chemical decomposition of organic matter brought about by heat. In this process, the organic material is heated in absence of air until the molecules thermally break down to become a gas comprising smaller molecules (known collectively as syngas).
Gasification can also take place as a result of partial combustion of organic matter in presence of a restricted quantity of oxygen or air. The gas so produced is known as producer gas. The gases produced by Pyrolysis mainly comprise carbon monoxide (25%), hydrogen and hydrocarbons (15%), and carbon dioxide and nitrogen (60%). The next step is to ‘clean’ the syngas or producer gas. Thereafter, the gas is burned in internal combustion (IC) engine generator sets or turbines to produce electricity.
Landfill Gas recovery The waste dumped in a landfill becomes subjected, over a period of time, to anaerobic conditions. As a result, its organic fraction slowly volatilizes and decomposes, leading to production of ‘landfill gas’, which contains a high percentage of methane (about 50%).It can be used as a source of energy either for direct heating/cooking applications or to generate power through IC engines or turbines.
Plasma arc Plasma arc technology is a relatively new technology for disposal of wastes, particularly, hazardous and radioactive wastes. This technology is now being seen as an attractive option for disposal of MSW as well