Waste to Energy Generation-Explained

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  • Recently, Karnataka Chief Minister laid the foundation stone for an 11.5 MW waste-to-energy plant.
  • This plant is expected to process 600 tonnes per day of inorganic waste.
  • Bengaluru generates close to 5,000 tonnes of waste daily, of which about 2,500 tonnes is organic, about 1,000 tonnes inert material (sweeping waste), and 1,500 tonnes inorganic.

Mains: GS III-

  • Environmental pollution & degradation
  • Science & Technology: developments & their applications & effects in everyday life.

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.
  • The decision of whether to turn waste into energy or to send it to a landfill depends on multiple factors, such as
    • Regulatory requirements
    • Economic factors
    • Public sentiment
    • Characteristics and availability of the targeted waste stream. 
Process and different methods of waste-to-energy generation

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

  1. Combustion Technologies
    • Mass-burn system
      1. Unprocessed Municipal Solid Waste is burned in a large incinerator with a boiler and a generator for producing electricity.
      2. The process of generating electricity in a mass-burn waste-to-energy plant has seven stages:
      • Waste is dumped from garbage trucks into a large pit.
        • A giant claw on a crane grabs waste and dumps it in a combustion chamber.
        • The waste (fuel) is burned, releasing heat.
        • The heat turns water into steam in a boiler.
        • The high-pressure steam turns the blades of a turbine generator to produce electricity.
        • An air pollution control system removes pollutants from the combustion gas before it is released through a smokestack.
        • Ash is collected from the boiler and the air pollution control system.
    • 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.
    • This process happens in the absence of oxygen in a sealed, oxygen-free tank called an anaerobic digester.
  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.
    • Using LFG helps to reduce odors and other hazards associated with LFG emissions.
  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.
    • Polycrack has the following advantages over the conventional approach of treating solid waste:
      • Pre-segregation of waste is not required.
      • It has a high tolerance to moisture hence drying of waste is not required.
      • Waste is processed and reformed within 24 hours.
      • It is an enclosed unit hence the working environment is dust-free.
      • Less area is required for installing the plant.
      • All constituents are converted into valuable energy thereby making it Zero Discharge Process.
      • The gas generated in the process is re-used to provide energy to the system thereby making it self-reliant and also bring down the operating cost.
      • A safe and efficient system with built-in safety features enables even an unskilled user to operate the machine with ease.
      • Low capital cost and low operating cost.
      • A fully automated system requires minimum manpower.

Best practices around the world
  • European Union
    • WTE facilities in the EU have long been viewed as a best practice and the most environmentally responsible method for treating post-recycled waste.
    • EU has enacted policies and legislation that promote or incentivize the use of WTE to manage post-recycled or residual waste.
    • Some EU nations, like Germany and Denmark, have gone as far as banning the landfilling of untreated waste.
    • The EU utilizes many different technologies to treat their waste streams, such as mixed waste processing with organics recovery and AD (also called mechanical biological treatment, or MBT).
    • Often, the residual streams from these technologies are further treated by a conventional WTE combustion facility to recover as much energy from the waste as possible.
    • It’s a common practice among cities and villages in the EU to use WTE facilities to provide district heating and electricity to the local community.
    • The architecture of many WTE facilities in the EU is more like a museum or government building than a waste disposal site or power plant. 
  • Japan
    • Similar to the EU, Japan has a long history of developing and operating WTE facilities.
    • As an island nation with limited space for landfills, Japan has very regimented and aggressive recycling programs that emphasize the two Rs (Reduce and Reuse).
    • The Japanese Ministry of Environment also considers the recovery of energy and resources by WTE a key component of their responsible waste management practices.
    • Japan’s limited natural resources have made the reuse of ash residues from WTE facilities critical to construction.
  • North America
    • As landfill space was growing scarcer, along with concerns about energy security post-9/11, there was renewed interest in WTE in North America.
  • Helps in waste management
    • With the increasing population and growing consumerism, tonnes of waste is generated.
    • This waste needs to be scientifically managed and should be utilized for energy generation.
  • Ensures energy security
    • Energy generated from waste can add to the energy basket of the country and reduce dependence on imports.
  • Environmental conservation
    • Unscientific management of waste by burning leads to air pollution and leaching from landfills leads to water pollution.
    • This can be avoided by generating energy from waste in a scientific manner.
  • Can provide Baseload Power
    • The most familiar renewable energy resources such as wind and solar can only provide power if the sun is shining or the wind is blowing.
    • WTE projects can actually provide baseload power that is used to serve consumers and the grid no matter the time of day or if the sun is shining or not.
    • Baseload power is essential when intermittent resources like solar and wind become more prevalent.
  • Can reduce Use of Landfills
    • WTE projects reduce waste volumes by approximately 90%, which results in fewer landfills and reduces dependency on unscientific landfills.
    • This ends up protecting our natural resources and land dramatically.
  • WTE projects have Multiple Revenue Streams
    • Waste-to-energy projects produce byproducts like biochar, which has multiple applications and fetches good prices.
  • WTE facilities are Net Greenhouse Gas Reducers
    • WTE facilities avoid the productions of methane and end up producing up to 10 times more electricity than landfill gas projects.
    • By generating electrical power or steam, WTE facilities avoid carbon dioxide (CO2) emissions from fossil fuel-based electrical generation.
  • Reduce fire accidents
  • Solution to recover value from inorganic waste
    • The recovery of ferrous and nonferrous metals from the municipal solid waste by waste to energy is more energy-efficient than production from raw materials.
  • Not All WTE Projects are Clean and Green
    • Waste-to-energy projects would seem to be green and clean because they turn trash into power or gas.
    • However, some projects require long hauling of trash to bring to the actual incineration facility.
    • This actually leads to much more emissions from the trash haulers than alternatives.
    • Burning municipal waste does produce significant amounts of dioxin and furan emissions to the atmosphere as compared to the smaller amounts produced by burning coal or natural gas.
  • Costly WTE technology
    • As the technology is still in the development stage, its cost is high for general usage.
  • The relatively cheap cost of landfills and inexpensive fuel
    • WTE facilities may be uneconomical as there are cheapest alternative sources like a landfill.
    • Also, the revenue generated might be fluctuating due to volatile prices.
  • Lack of proper technology
    • Over the last decade, several Indian cities have been trying to set up such plants but a good demonstration model is yet to be established.
  • Huge variation in type of waste
    • Technology suppliers are international organizations who struggle with the change in the quality and nature of waste generated in Indian cities. 
    • A few plants in India have stopped operations for this reason.
  • Lack of proper collection and segregation at source
    • Since segregation at the source doesn’t happen in the city, the collected waste material needs to be processed to generate energy.
Way forward
  • Need of public and private investment
    • Government need to incentivize WTE facilities
    • Private companies can be encouraged to invest through CSR funds
  • Proper waste management
    • Waste should be properly segregated and pre-treated to make waste management easy and obtain maximum value.
  • Increase awareness on need for WTE generation
    • Citizens must be made aware of the benefits of generating energy from waste.

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