Waste-to-Energy

Waste-to-Energy

Subject – Environment

Context – Bandhwari landfill: Waste-to-energy plant will pollute environment, residents protest expansion

Concept –

• Waste-to-energy or energy-from-waste is the process of generating energy in the form of electricity and/or heat from the primary treatment of non-recyclable waste or the processing of non-recyclable waste into a fuel source.
• It is a form of energy recovery.
• Search for waste disposal solutions and the desire for alternative energy sources were the forces behind the genesis for this industry in the late 1970s, early 1980s.
• The Timarpur Okhla Municipal Solid Waste Management plant, a private-public partnership project of the Jindal ITF Ecoplis and Municipal Corporation of Delhi (MCD) is India’s first waste-to-energy plant.

There are different types of waste-to-energy systems or technologies:

1. Combustion Technologies
   • Mass-burn system: Unprocessed Municipal Solid Waste is burned in a large incinerator with a boiler and a generator for producing electricity.
   • Modular Systems
     • Modular Systems burn unprocessed, mixed MSW.
     • They differ from mass-burn facilities in that they are much smaller and are portable.
     • They can be moved from site to site.
   • Refuse Derived Fuel Systems – Refuse derived fuel systems use mechanical methods to shred incoming MSW, separate non-combustible materials, and produce a combustible mixture that is suitable as a fuel in a dedicated furnace or as a supplemental fuel in a conventional boiler system.

2. Gasification
   • It is a process that converts any material containing carbon—such as coal, petroleum, or biomass—into synthesis gas (syngas) composed of hydrogen and carbon monoxide.
   • The syngas can then be burned to produce electricity or further processed to produce vehicle fuel.

3. Pyrolysis
   • Pyrolysis is defined as a process of temperature decomposition of organic material in the absence of oxygen.
   • It involves a change in chemical composition.

4. Incineration
   • Incineration is a thermo-decomposition process where the components present in the waste stream are ionized into harmless elements at a higher temperature in the presence of oxygen.

5. Anaerobic digestion
   • Anaerobic digestion is the process by which organic matter such as animal or food waste is broken down to produce biogas and biofertilizer.

6. Landfill gas (LFG) recovery
   • It is the process by which methane gas is collected from solid waste deposited in a landfill.
   • Instead of escaping into the air, LFG can be captured, converted, and used as a renewable energy resource.

7. Torrefaction
   • The torrefaction technology involves heating straw, grass, sawmill residue, and wood biomass to 250 degrees Celsius – 350 degrees Celsius.
   • This changes the elements of the biomass into ‘coal-like’ pellets.
   • These pellets can be used for combustion along with coal for industrial applications like steel and cement production

8. Polycrack technology
   • It is the world’s first patented heterogeneous catalytic process that converts multiple feedstocks into hydrocarbon liquid fuels, gas, carbon, and water.
   • The process is a closed-loop system and does not emit any hazardous pollutants into the atmosphere.
   • The combustible, non-condensed gases are re-used for providing energy to the entire system and thus, the only emission comes from the combustion of gaseous fuels.
   • This process will produce energy in the form of light diesel oil which is used to light furnaces.