A waste management facility known as a waste-to-energy plant burns garbage to create power. The role of waste-to-Energy plants in urban infrastructure is immense as they are substitutes for fossil fuels for generating electricity. Read here to understand more about them.
A study back in 2019 reported that nearly half of the country’s waste-to-energy plants were lying defunct. And the functioning plants were running at low capacity.
The government has now taken up the cause of waste-energy plants again to move towards garbage-free cities.
The Urban Development Policy is into three parts:
- The Smart City Mission is to modernize cities, e-governance, integrated command and control systems, and a network of CCTV cameras.
- The AMRUT mission is to modernize and rejuvenate physical infrastructure in cities, the RERA Act, setting up a metro network in more than 25 cities, and providing electric buses.
- To make cities clean so that it will be beneficial for the health of people living in cities, especially slum dwellers.
In this direction, we are moving forward through the construction of toilets and preparing waste-to-clean energy plants, solar rooftops, and LED lights.
Mountains of garbage are gradually decreasing as many plants have been set up for waste disposal, the gutter system has been streamlined and a scientific network has also been established for the collection of waste across the country.
Municipal and industrial solid trash is converted into power and/or heat for industrial processing at waste-to-energy or energy-from-waste plants.
The trash is burned at a high temperature in the energy plant, and steam is created as a result of the heat. After that, the steam powers a turbine to produce energy.
Burning rubbish not only generates power but also lessens the quantity of waste that would otherwise be buried in landfills. MSW is reduced in volume by burning by 80%. resulting in a variety of difficult-to-quantify societal and economic benefits.
Waste-to-Energy (WTE) technologies to recover the energy from the waste in the form of Electricity and Biogas/Syngas are:
Biomethanation is the anaerobic digestion of organic materials which is converted into biogas. Anaerobic digestion is a bacterial fermentation process that operates without free oxygen and results in biogas containing mostly methane (~60%), carbon dioxide (~40%), and other gases. Biomethanation has dual benefits. It gives biogas as well as manure as the end product.
- This technology can be conveniently employed in a decentralized manner for the biodegradation of segregated organic wet wastes such as wastes from kitchens, canteens, institutions, hotels, slaughterhouses, and vegetable markets.
Incineration technology is the complete combustion of waste (Municipal Solid Waste or Refuse derived fuel) with the recovery of heat to produce steam that in turn produces power through steam turbines.
- The flue gases produced in the boilers have to be treated by an elaborate air pollution control system.
- The resultant ash from the incineration of solid waste can be used as construction material after necessary processing while the residue can be safely disposed of in a landfill.
- This technology is well-established and has been deployed in many projects successfully at the commercial level in India to treat solid wastes like Municipal Solid Waste and Industrial solid Waste etc. and generate electricity.
Gasification is a process that uses high temperatures (500-1800 oC) in the presence of limited amounts of oxygen to decompose materials to produce synthetic gas (a mixture of carbon monoxide (CO) and hydrogen (H2)).
- Biomass, agro-residues, Segregated MSW, and RDF pellets are used in the gasifier to produce Syngas.
- This gas further can be used for thermal or power generation purposes
- The purpose of gasification of waste is to generate power more efficiently at lower power levels and also to minimize emissions hence it is an attractive alternative for the thermal treatment of solid waste.
Pyrolysis uses heat to break down combustible materials in the absence of oxygen, producing a mixture of combustible gases (primarily methane, complex hydrocarbons, hydrogen, and carbon monoxide), liquids, and solid residues.
- The products of the pyrolysis process are: (i) a gas mixture; (ii) a liquid (bio-oil/tar); (iii) a solid residue (carbon black).
- The gas generated by either of these processes can be used in boilers to provide heat, or it can be cleaned up and used in combustion turbine generators.
- The purpose of the pyrolysis of waste is to minimize emissions and maximize the gain.
Advantages of waste-to-energy
- Waste-to-energy reduces reliance on fossil fuels, whose burning is a major source of Greenhouse Gas (GHG) emissions, and produces clean, dependable electricity from a renewable fuel source.
- It is a way to prevent waste from polluting the water bodies and air pollution.
- Waste-to-energy plants cause less air pollution than coal plants, but more than natural gas plants.
- It is carbon-negative: processing waste into fuel releases considerably less carbon and methane into the air than having waste decay away in landfills or the lake.
- Waste-to-energy plants use pollution control techniques like baghouses, scrubbers, and electrostatic precipitators to reduce the emission of air pollutants like nitrogen oxides, sulfur oxides, and particulates from the flue gases released to the atmosphere and to eliminate pollutants already present in the waste.
- Air pollution emissions can be greatly decreased by using high temperatures, efficient combustion, effective scrubbing, and effective controls.
Global data on WTE
Globally, Waste-to-energy generation is being increasingly looked at as a potential energy diversification strategy.
- Sweden has been a leader in waste-to-energy production over the past 20 years.
Municipal solid waste is expected to increase to approximately 2.2 billion metric tons by 2025.
MSW generation rates are influenced by several key factors:
- economic development
- degree of industrialization
Data collected by international organizations such as the World Bank and the United Nations suggest that the higher the degree of economic development and urbanization, the greater the amount of solid waste produced.
Income level (gross domestic product or GNP) and urbanization are usually correlated as well as disposable incomes and living standards.
As the levels of these factors increase, there is a corresponding increase in the generation of solid waste, with urban residents generating almost twice as much solid waste as rural inhabitants.
Waste reduction efforts are anticipated to produce a leveling of peak waste in OECD countries by 2050, East Asia and Pacific countries by 2075, and continued growth of waste in Sub-Saharan Africa.
Global waste generation is projected to possibly hit 11 million metric tons per day by 2100.
Waste-to-energy in India
The Ministry of new and renewable energy is promoting all the technology options available for setting up projects for the recovery of power in the form of Biogas/BioCNG/Electricity.
The energy can be generated from agricultural, Industrial, and urban wastes of renewable nature such as municipal solid wastes, vegetable, and other market wastes, slaughterhouse wastes, agricultural residues, and industrial/STP wastes & effluents.
The total estimated energy generation potential from urban and industrial organic waste in India is approximately 5690 MW.
To facilitate geographical mapping of the different types of waste availability and its energy generation potential across India, GIS Based Waste Mapping Tool has been developed under GEF–MNRE–UNIDO PROJECT.
Programme on Energy from Urban, Industrial, Agricultural wastes/Residues and Municipal Solid Waste
- To promote the setting up of projects for recovery of energy in the form of Biogas / BioCNG / Power from Urban, Industrial, and Agricultural Waste and Captive Power and Thermal use through Gasification in Industries
- To promote the setting up of projects for the recovery of energy from Municipal Solid Waste (MSW) for feeding power into the grid and for meeting captive power, thermal and vehicular fuel requirements.
- To promote Biomass Gasifiers for feeding power into the grid or meeting captive power and thermal needs of rice mills/other industries and villages.
The increase in environmental degradation causes catastrophic threats to health, safety, environment, and the destabilization of natural resources by the modern production process and their waste generations are quite alarming.
The piling of municipal solid waste (MSW) is of serious concern for every country and India is no exception to any of these issues.
Importantly, still, the municipal solid waste generated in the country is not fully disposed of with scientific methods for zero-waste systems, including energy waste.
Some of the core issues with waste management in India are present at the foundational level since most stakeholders, especially the state governments and local bodies, are heavily focused on the collection, transportation, landfilling, or dumping or burning on streets.
It is time to find scientific solutions with institutional networks at a decentralized method with community involvement.
Mostly, the Waste-to-energy plants have failed in India, but a step in the right direction is being taken to set up the defunct plants with compliance to NGT and environmental laws.
-Article written by Swathi Satish