Waste to Energy (WTE) is a term used to designate various technologies that convert non-recyclable waste into usable forms of energy including heat, fuels, and electricity through a variety of processes such as combustion, gasification, pyrolization, anaerobic digestion, and landfill gas recovery. WTE generates clean and reliable energy from a renewable fuel source and thus reducing the dependency on fossil fuels.
Sewage, faecal sludge, industrial, biomass and municipal solid waste find their way into land and water bodies without proper treatment and thus causing severe water, air, and soil pollution. These problems caused by solid and liquid wastes can be substantially lessened through the adoption of environment-friendly waste to energy technologies that will allow the treatment and processing of wastes before their disposal.
“The World is changed by your example, not by your Opinion” – Paulo Coelho
The term WTE is frequently used in specific reference to incineration that burns completely combusted waste at ultra-high temperatures allowing for energy recovery. Modern incineration facilities use pollution control equipment to prevent the release of emissions into the environment. Currently, incineration is the only WTE technology that is economically viable and operationally feasible at a commercial scale.
A safe and secure waste management hierarchy is employed for energy recovery from waste materials. The conversion of non-recyclable waste materials into electricity and heat generates a renewable energy source, reduces carbon emissions by compensating the need for energy from fossil sources, and reduces methane generation from landfills.
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According to the Ministry of New and Renewable Energy (MNRE), India has the potential of generating energy in the range of 1500-2000 MW from urban waste and about 1300 MW from industrial waste.
Nearly 55 million tonnes of municipal solid waste and 38 billion litres of sewage are generated every year in urban areas of India. Industries also share a major portion of the total waste generation and it is estimated to increase 1-1.33 % annually.
This has significant impacts on the amount of land needed for waste disposal, economic costs of collecting and transporting the waste, and environmental concerns of increased waste generation levels.
Waste to Energy (WTE) Technologies
Incineration is the major technological option under this category but it has limitations when it comes to emission characteristics. Thermal degradation of waste takes place at high temperatures that result in complete oxidation of waste but at the same time increased levels of carbon emissions.
The main technological options under this category include pyrolysis and gasification. This process involves high temperature driven decomposition of organic matter to produce either heat energy, fuel oil, or gas. They are useful for wastes containing a high percentage of organic non-biodegradable matter and low moisture content.
Bio-methanation and fermentation are the importation technologies of energy generation from waste using biochemical conversion. This involves enzymatic decay of organic matter by microbial action to produce methane gas, alcohol, etc. These methods are preferred for wastes having a high percentage of organic, biodegradable matter, and a high level of moisture content, which aids microbial activity.
Electrochemical Conversion: This WTE technology is at a nascent stage in India and worldwide
This WTE technology refers typically to microbial fuel cells (MFCs), which are developed to trap the energy from wastes where the reduction-oxidation machinery of immobilized microbial cells is catalytically exploited for the accelerated transfer of electrons from organic wastes to generate electricity and bio-hydrogen gas. However, this technology is at a nascent stage in India and worldwide.
“We can reduce carbon emissions and replace Fossil fuels using robust and effective WTE Technologies”
Nearly all-biodegradable waste is biomass having a biological origin. Plants formed this biodegradable matter using atmospheric CO2 and hence the CO2 emissions from combustion can be taken out if these plants are regrown. Energy generation from biomass part of the waste is considered as renewable energy whereas non-biodegradable matter contributes to non-renewable energy.
Thermal WTE technologies are associated with an increased percentage of carbon emissions to the atmosphere and thus enhancing the carbon footprint. Current research work in these technologies focuses on the elimination of CO2 emissions and residue. We can be accountable towards nature and reduce the carbon levels in the atmosphere by being aware of our carbon footprint and ways to reduce it.
“Let’s reduce our Carbon Footprint; Save Energy, Live Green.”
Carbon footprint is the number of greenhouse gases- predominantly carbon dioxide- released into the atmosphere by particular human activity. It can be an extensive measure or be applied to the activities performed on an individual level to society or even to an entire nation. It is usually calculated as tons of CO2 emitted per year.
It is a number that can be supplemented by tons of CO2-alike gases including methane, nitrous oxide, and other greenhouse gases. These gases are considered a major contributor to climate change and global warming around the world.
A number of methods can work in reducing the carbon footprint that includes using energy-efficient electrical appliances, minimal use of private transportation, eating local and seasonal fruits and vegetables, planting a large number of trees, investing in sustainable and clean sources of energy like solar, wind, employing efficient methods for waste matter utilization, etc.
We can calculate the carbon footprint on an individual level by simple methods and start shrinking it by making slight changes in our lifestyle.
References: Chinwan et al., Journal of Basic and Applied Engineering Research, Vol. 1, Number 10, 2014.