Around 14 billion pounds of waste plastic is dumped in the ocean waters annually. For every phytoplankton there is 6 multiples more plastic per unit weight and nearly 50 times more than zooplankton- the life forms acquiring key positions in the functioning of marine life. Hunderds of thousands of seabirds and many more terrestrial and aquatic animals perish due to ingestion of plastic and its products. The data only speaks of plastics. Other wastes such as organic wastes are produced everyday globally. Wouldn’t it be astounding and at the same time resourceful if somehow the waste generated could be used for harnessing energy or at least not injure Mother Earth? Waste recycling techniques and waste to energy plants do the same.
Who thought that the need of a substitute for elephant ivory to make golf balls would lead to the invention of plastics? Almost every human in every part of the world uses plastic. Waste is generated inevitably in everyday life. Farm waste and organic waste proves to be a vital source of energy for example, cow dung being rich in nitrogen, phosphorus and potassium is utilised as an excellent source of manure, besides it is also used to generate methane and other combustible gases which have a tremendous potential for thermal energy generation. The leftover dung after treatment has traces of essential nutrients needed for plant growth. Energy recovery from waste uses processes of combustion, gasification, pyrolization, anaerobic digestion and landfill gas recovery. Many waste to energy plants burn waste that is not fit or efficient to be recycled. The energy generated is usually in the form of steam, electricity or hotwater. The reuse and recycling of waste is the foremost step in waste disposal. Any waste not passing the standards for recycling and reuse are incinerated or operated on to be used for other purposes or at least minimize pollution. Even when waste is segregated before incinerating, it has some traces of metals, which are recycled and the leftover ash, composed primarily of gravel or sand is stored for a certain period before using it in road construction and other purposes.
In some countries buses function on hydrogen produced from waste. Though incineration has its plus points they are not plenty and the process is still not perfected. Gasification is preferable over it in which the waste is turned into a synthetic gas or ‘syngas’- the process being more economical and eco-friendly. The synthetic gas can be converted into a wide variety of end products such as electricity, diesel fuel, hydrogen fuel or ethanol depending on what’s the most valuable at that time. In gasification, no toxic gases are generated. These plants are more favourable as the companies are paid by the government to take the garbage and they profit even more by turning the same trash into expensive products, thus providing such plants with twin benefits- a clever way to earn and at the same time conserve the environment.
Pyrolysis on the other hand involves thermal decomposition of waste at extreme temperatures (540°C- 1000°C) in anaerobic conditions, producing materials that are combusted again in the next chamber. Pyrolysis plants are profitable and have their own set of advantages for instance they improve energy density and ensure economical transportation.
Anaerobic digestion is yet another way where bacteria break down organic matter in absence of oxygen- the process performed on cow dung. Other organic wastes such as animal excreta, restaurant and cafeteria food wastes, crop residues, leftover products from fast food generation companies can also be codigested with cow dung.
The process of fermentation involves producing energy from organic substances composed of lipids, carbohydrates and proteins. Here, carbon dioxide and alcohol are produced- both having appreciable thermal energy potential. Besides this, Mechanical Biological Treatment (MBT) is also in effect. Landfill gas recovery is process of extracting methane from solid wastes in landfills. A landfill has the potential and ability of producing gases for more than 50 long years!
There are about 186 waste to energy plants in India that cater the needs of growing population and energy demands. The global waste to energy market was valued at $35.5 billion in 2019 and is expected to reach about a whopping $50.1 billion by 2027. The inclination of consumers to more efficient WTE( Waste to Energy) techniques boosts the process of flourishing WTE. The COVID-19 pandemic has slowed down the functioning of many plants and industries in many fields due to imposition of lockdowns in almost all the countries. As a result the WTE and recycling plants too are badly affected and hit hard. The total energy generation in India from waste is approximately 5960 MW(Megawatts).
The processes to convert waste to energy go on developing and invention of new processes is a must. We have to ensure that the waste should reach the WTE and recycling plants and not find itself floating in waters and lying on roads and footpaths. It is upon us to hold up and brace the government and other organisations that promote environmental conservation. ‘A stitch in time saves nine’-they say. There still is time. Amidst growing global warming and climate change a thin ray of hope is still seen. We, the people have to make sure that it too doesn’t die. Proper guidance and inculcation of good manners in children, developing a sense of sympathy and live towards the environment in their innocent and growing minds is a must. Active participation in cleaning programmes and other activities promoting environmental preservation can be done. After all it is up to us to envision an earth 50 years from now- lush green, still with earthlings, clean water and fresh air, still containing life or a dark one with no sign of life, not a single drop of water and polluted, toxic air.