Waste to Energy

Why in News?

  • Recently, The Kerala government notified the State’s first Waste-To-Energy project in Kozhikode. The planned facility is anticipated to be built in two years and generate around 6 MW of power.
  • Kozhikode has a population of around 6.3 lakh and generates about 300 TPD of waste. Of this, around 205 TPD is biodegradable and 95 TPD is non-biodegradable.
  • There are apprrox.100 waste-to-energy projects around the country but only a handful of them are operational, thanks to several production and operation challenges.

Waste-to-Energy Projects-

  • Waste to energy projects use non-recyclable dry waste to produce electricity and ease the Solid Waste Management (SWM) burden.
  • Solid waste in India is 55-60% biodegradable organic waste, which can be converted into organic compost or biogas; 25-30% non-biodegradable dry waste; and about 15% silt, stones, and drain waste.
  • Of the non-biodegradable dry waste, only 2-3% –involving hard plastics, metals, and e-waste is recyclable.
  • The remainder contains low-grade plastic, rags, and cloth that can’t be recycled.
  • This fraction of the non-recyclable dry waste is the most challenging portion of the current SWM system; the presence of these materials also decreases the efficiency of recycling other dry and wet waste.
  • Waste-to-energy plants use this portion to produce power. The waste is combusted to generate heat, which is converted into electricity.

Waste-to-Energy Technologies-

  • Biological Treatment Technologies (BTT)- BTT are designed and engineered for natural biological processes working with the organic rich fraction of Municipal Solid waste. These treatments are divided into two different processes-
  • The aerobic process or composting (in the presence of oxygen) and the anaerobic process (in the absence of oxygen).
  • Thermal Treatment Technologies- The thermal treatment of hazardous waste includes pyrolysis, gasification, and incineration techniques, depending upon the nature of the waste and the end-product application.
  • Pyrolysis is the heating of an organic material, like biomass, in the absence of oxygen. Biomass pyrolysis is generally conducted at or above 500 °C, giving enough heat to deconstruct the strong biopolymers.
  • Gasification is a process that converts organic or fossil-based carbonaceous materials at high temperatures (>700°C), without combustion, with a controlled amount of oxygen or steam into carbon monoxide, hydrogen, and carbon dioxide.
  • Incineration is a rapid oxidation process, which is used to convert VOCs (Volatile Organic Compounds) and other gaseous hydrocarbon pollutants to carbon dioxide and water.
  • Torrefaction converts biomass in the absence of oxygen at a temperature of 200–300°C to produce torrefied materials, bio-oils, bio-char, etc.

Challenges Related to Such Plants-

  • Low Calorific Value- The low calorific value of solid waste in India due to inappropriate segregation. The calorific value of mixed Indian waste is approx. 1,500 kcal/ kg, which is not suitable for power generation.
  • The calorific value of segregated and dried non-recyclable dry waste is much higher, at 2,800-3,000 kcal/kg, sufficient to generate power. Though, segregation should be streamlined to ensure the waste coming to the facility has this calorific value.
  • High Costs of Energy Production- The cost of generating power from waste is approx. Rs 7-8 per unit, while the cost at which the States’ electricity boards purchase power from coal, hydroelectric, and solar power plants is around Rs 3-4 per unit.
  • Improper Assessments- Various waste-to-energy projects have failed because of improper assessments, high expectations, erroneous characterisation studies, and other on-ground conditions.

Various Related Initiatives-

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