Waste to Energy Generation-Explained

Context:

• 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.

Relevance: 
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. 

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.

• 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.

• 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.