Abstract: Every year, about 5.5 crore (55 million) tonnes of municipal solid waste (MSW) and 3,800 crore (38 billion) litres of sewage are generated in the urban areas of India. It is expected to increase rapidly in the future as more people migrate to urban areas and as incomes increase, consumption levels are likely to rise, as are rates of waste generation. The need of the hour is to focus on reducing the waste production by reusing and recycling of existing waste.
Author: Rivisha Porwall
ENERGY FROM WASTE
Every year, about 5.5 crore (55 million) tonnes of municipal solid waste (MSW) and 3,800 crore (38 billion) litres of sewage are generated in the urban areas of India. generation in India is expected to increase rapidly in the future as more people migrate to urban areas and as incomes increase, consumption levels are likely to rise, as are rates of waste generation. The need of the hour is to focus on reducing the waste production by reusing and recycling of existing waste. Organic waste has significant portion in overall waste generation in industrial/urban/ agricultural sector and therefore it can be used for energy generation.
India has had a long involvement with waste to energy creation by using anaerobic digestion and biogas technologies. Waste water treatment plants in the country have been established which produce renewable energy from sewage gas. Also, wastes from the distillery sector are on some sites converted into biogas to run in a gas engine to generate onsite power.
INDIA world’s 3rd largest renewable energy producer with 38% of energy capacity installed in the year 2020 (136 GW of 373 GW) coming from renewable sources. Renewable energy generation in GW in 2019-2020 shows a significant contribution of biomass energy-
|Total utility power||1,385|
|% Renewable power||21.25%|
Biomass is plant-based material used as fuel to produce heat or electricity. India has an ideal environment for biomass production with suitable tropical location, sunshine and rains
- Sources of biomass-
a. Municipal solid waste
b. Forestry residuals
c. Agricultural residuals
e. Industrial residuals
f. Animal residuals
Biogas is a biofuel which is produced from the decomposition of organism . The rejected organic solids from biogas plants can be used after Torrefaction in the existing coal fired plants to reduce coal consumption.
Synthetic methane (SNG) generated using electricity from carbon neutral renewable power or Bio CNG can be used to produce protein rich feed for cattle, poultry and fish economically by cultivating a bacteria culture with tiny land and water foot print. The carbon dioxide gas produced as a by product from these bio protein plants can be recycled in the generation of SNG. Similarly, oxygen gas produced as by product from the electrolysis of water and the methanation process can be consumed in the cultivation of bacteria culture.
1. SOURCES OF WASTE-
1.1. Industrial Waste
1.2. Commercial Waste
1.3. Domestic Waste
1.4. Agricultural Waste
2. CATEGORY OF WASTE-
2.1 Inorganic waste: All waste from non-biological origin (plastic, rubber).
2.2 Organic waste: All waste of biological origin (plant, animal).
2.2.1 Biodegradable organic waste can be broken down in simpler molecules by microorganism. It comprises of argo-residue, food processing rejections, municipal solid waste, waste from poultry farms, cattle farm slaughter houses, dairy, sugar, distillery, paper, oil extraction plant, starch processing and leather industries.
2.2.2 Non-Biodegradable organic Waste have a very low degradation rate. This primarily includes woody plants, Cardboard, cartons, containers, wrappings, pouches, discarded clothing, wooden furniture, agricultural dry waste, bagasse, rice husk.
Waste to Energy (WTE)
Before proceeding to waste to energy techniques, we need to consider processing of waste under two waste handling processes to make the WTE techniques more efficient. These processes are –
1. Waste segregation
Conventionally, it is the separation of wet waste and dry waste. The purpose is to recycle dry waste easily and to use wet waste as compost. Importantly, waste segregation should be based on the type of waste and the most appropriate treatment and disposal, ideally divided into dry waste, wet waste, plastic waste, e-waste, domestic sanitary waste, and domestic hazardous waste.
1. Waste that gets landfilled reduces considerably
2. Lower levels of air and water pollution
3. Easier to apply different processes to the waste, like composting, recycling and incineration.
4. Cheaper to dispose of because it does not require as much manual sorting as mixed waste
5. Fulfilment of legal obligations
6. Protection of human health and the environment
1. One way to practice waste segregation is to ensure there is awareness and proper explanation of the process of the same.
2. Institutions should make it as easy as possible for their staff to correctly segregate their waste by proving labelled accessible bins.
3. Municipal corporations should ensure source segregation of garbage at door-to-door level.
Recycling of waste product helps in processing waste or used products into useful or new products. Examples-
1. Biodegradable waste can be decomposed and converted into organic matter with the help of Composting (action of bacteria and fungi) and Vermicomposting (action of red worms). This manure is known as vermicompost.
2. Plastic waste is being converted into smaller polymer for pyrolysis and cement bricks for construction.
3. Non-recyclable waste uses in the construction of road and sidewalks.
1. Recycling helps in controlling air, water, and land pollution.
2. It also uses less energy.
3. Recycling helps in conserving natural resources and energy.
3.WASTE TO ENERGY TECHNOLOGY
To recover the energy from the waste in the form of Electricity and Biogas/Syngas, here are the technologies to use:
1. Bio methanation
1. BIO METHANATION
1. It gives biogas
2. It also gives manure
1. The biogas can be burned to produce heat for thermal application industries and cooking
2. The biogas can be burnt in a gas engine to produce electricity
3. The biogas can be cleaned to produce BioCNG used as a vehicle fuel.
20-25kgs of Cattle dung can generate about 1m3 of biogas and further 1m3 of Biogas has potential to generate 2 units of electricity or 0.4kgs of BioCNG.
1. Steam can be used to produces power through steam turbines.
2. The resultant ash from incineration of solid waste can be used as construction material.
1. The flue gases produced in the boilers have to be treated by an elaborate air pollution control system to reduce gaseous pollutants
2. The residue need to be disposed off in a landfill.
https://images.theconversation.com/files/Gasification works by feeding Biomass, agro-residues, Segregated MSW and RDF into a unit a pot, where it goes through the process fluidization (heat, oxygen, steam) which converts the waste into a mixture of hydrogen, methane, carbon monoxide and carbon dioxide, also called syngas.
1. Syngas can be used to generate thermal or power.
1. Sustainable technology
2. Cuts utility expenses for heating or electricity
3. Significantly reduce dependency on landfills
4. Lowers the operating budget for solid waste management services
1. The gas can be used in boilers to provide heat
2. It can be cleaned up and used in combustion turbine generators
3. Plastic waste can be converted to diesel
1. Minimize emissions of gases
2. Maximize the gain
From one kilogram of waste plastic, we can either produce 850 ml of diesel or 700 ml of petrol or 500 ml of aromatic products.
Reasons for failure of waste to energy plants in India
Calorific value is the amount of heat or energy produced when waste is burnt. The ideal calorific value for WTE plants is 1,900-3800 kcal/kg. However, India’s waste calorific value is 1,411–2,150 kcal/kg. Our waste composition has significant amount of biodegradable and organic waste with 70-80 per cent of water in it. Now, to burn it one will need more fuel, which will be impacting the environment more as it will be creating more emissions.
2. To Be Effective, WTE Plants Required Only Segregated Waste
WTE plants should get the waste that is segregated into non-biodegradable, non-reactive and non-recyclable. The mixed waste requires an additional fuel to burn the waste, which makes the plants economically very unviable.
3. Electricity Produced by WTE Plants Is Negligible
Incineration seems an easy option to get rid of waste but the electricity that it produces is very negligible. These are very expensive plants with very less ROI and they need a lot of monitoring and are required to meet environment norms.
4. WTE Plants Impacting Health Of The Environment And Residents
Ideally for WTE plants the bottom ash shouldn’t be more than 20 percent but plants in INDIA have as high as 40 percent. Adding to this, Environmental Impact Assessment (EIA) norms states that such plants should be located no nearer than 300 meters from residences and industries to minimise impact of explosion
- Indore is undertaking an initiative to convert waste into energy with an aim to deal with wet waste and at the same time reduce the city’s dependence on fossil fuel which causes air pollution. The Waste-to-Energy plant installed by IMC converts wet waste into 95 per cent pure biogas called Methane which is further converted into CNG (Compressed Natural Gas).
- There are various technologies for processing dry and wet waste like composting, bio-methanation, RDE, pyrolysis, gasification and waste to energy etc.
- Plastic waste from the city is successfully collected and is being sent to the plastic waste treatment facility where it is converted into diesel.
2.ART OF LIVING: Scaling up the projects
Initiative I – Recycling solid waste and Preventing water pollution
A composting machine set up in Dakshin Eshwar Kali temple in West Bengal that could handle 500 kg waste takes only 7 days to decompose. Process-
1. Segregation of collected waste
2. Waste treatment of floral/wet waste in the composting unit
3. Selling The organic compost
4. Sustainability Sales of compost used to make the project sustainable
Initiative II – Manage kitchen waste and save cost on labour and transport.
Swachh Composting Plant has been set up in a residential colony- NDMC Nursery Raja Bazaar, Sector-4, Gole Market New Delhi. The plant will dispose of 1000 kg waste every day and produce 300 kg of organic compost without using any chemical treatment.
3.PLASTIC TO ENERGY
- Plastic waste takes years to decompose and harms the environment severely. For this purpose, A plant in Prayagraj, Uttar Pradesh has been set up to take 2 quintals of plastic waste and convert it to 1,200 litres of fuel.
- A plant to convert plastic to diesel is set up in Indian Institute of Petroleum (IIP) of Council of Scientific and Industrial Research in Dehradun, Uttarakhand. The right combination of catalysts helped in turning these molecules into hydrocarbons like diesel and petrol. The final products in liquid form, which is gasoline or diesel or aromatics.