Introduction :- 

According to Ministry of New and Renewable Energy estimates, the solid waste generated from cities/towns in India has a potential to generate power of approximately 500 MW, which can be enhanced to 1,075 MW by 2031 and further to 2,780 MW by 2050.

Current Capacity: There are five municipal Waste to Energy plants operational in India, with a total capacity to produce 66.4 MW electricity per day, of which 52 MW per day is generated in Delhi.

Types of Technique at WtE :-

• Incineration It uses MSW as a fuel, burning it with high volumes of air to form carbon dioxide and heat. In a waste-to-energy plant that uses incineration, these hot gases are used to make steam, which is then used to generate electricity.
• Gasification is a process that converts organic or fossil fuel based carbonaceous materials into carbon monoxide, hydrogen and carbon dioxide. This is achieved by reacting the material at high temperatures (>700’C), without combustion, with a controlled amount of oxygen and/or steam. The syngas produced by gasification can be turned into higher value commercial products.
• Pyrolysis involves application of heat with no added oxygen in order to generate oils and/or syngas (as well as solid waste outputs) and requires more homogenous waste streams.
• Biomethanation is a process by which organic material is microbiologically converted under anaerobic conditions to biogas. It involves fermenting bacteria, organic acid oxidizing bacteria, and methanogenic archaea.

Need of Waste to Energy Plants :-

• Problems of unscientific Municipal Solid Waste (MSW) disposal: Only about 75- 80% of the municipal waste gets collected and out of this only 22-28 % is processed and treated and remaining is disposed of indiscriminately at dump yards. It is projected that by the year 2031 the MSW generation shall increase to 165 million tonnes and to 436 million tons by 2050.
• Harmful emission from Landfills: Organic decomposition of food waste mixed with municipal solid waste at landfill sites leads to high amounts of emissions which is also a public health issue.

Advantages of Waste to Energy (WtE) Plants :-

• Net Greenhouse Gas Reducer: Methane is a greenhouse gas which is mostly emitted from decomposing waste in landfills. WtE facilities avoid the production of methane while producing almost ten times more electricity from each ton of waste compared to landfills.
• Resource savings and recovery greatly expanded: Metals left in the municipal solid waste stream can be extracted from the ash resulting from incineration and the metals can be recycled.
• 24*7 Electricity: WTE facilities, unlike wind and solar, are capable of providing 24*7 renewable electrical power.
• Landfill usage and expansion greatly reduced: Waste to energy facilities typically reduce waste volumes by 90%. Fewer and smaller landfills are needed to process.
• Transportation of waste long distances can be greatly reduced with a waste to energy facility in a community, resulting in less air pollution.

Challenges :-

• Low Calorific Waste: Municipal waste in India is often not segregated properly. It has a very high biodegradable (wet) waste content ranging anywhere between 60 and 70 per cent of the total, compared with 30 per cent in the West. This gives our waste a high moisture content and low calorific value. In Delhi, for example, only 12 per cent of the waste can be thermally treated through incineration technologies. Also, Indian households have traditionally been recycling their waste such as paper, plastic, cardboard, cloth, rubber, etc. to kabadiwalas. This further lowers the calorific value of the waste.
•  High Toxic Waste: Incinerators develop toxic ash or slag, containing heavy metals and gas pollutants which are toxic (corrosive impact) and pollute underground water.
•  Expensive power: Compared to Rs 3-4 per kWh from coal and solar plants, WTE plants sell electricity at about Rs 7/kWh.
• Lack of Finance for Urban Local Bodies (ULBs) affects institutional capacity necessary for integrated management of municipal solid waste, which requires investments for WtE projects.
• Other Challenges include irregular and inadequate quantity of supply; non-payment of agreed fee and non-marketability of waste processed projects, including power.

Way Forward :-

• Improved MSW collection system: Separate collection and transportation of domestic waste (including trade & institutional waste), inert wastes such as street sweepings, silt from surface drains and Construction & Demolition wastes should be ensured by the municipal authorities.
• Encourage Private Partnership in building WtE plants as recommended by Task force on WtE (2014) headed by K Kasturirangan.
• Amendment to Electricity Act-2003 to include a provision for State Electricity Discoms to mandatorily purchase all power generated from municipal solid waste at a tariff decided through competitive bidding.
• Strict enforcement to ensure the waste is not mixed at the source of generation and then that the handling of waste is in unmixed streams.
• Alternative to WtE Plants: Since WtE technologies are being phased out in the West, they should not be allowed unless the waste offered meets the criterion specified by the Solid Waste Management Rules 2016. Other option could be explored like composting and bio-methanation.
• Role of urban local bodies (ULBs): Standing Committee on Energy report on Power Generation from Municipal Solid Waste suggested for increased grants to states and ULBs to maximise waste collection efficiency and also recommended to integrate ragpickers and kabadiwalas within the formal system.