Waste-to-energy (WtE) or energyfrom-waste (EfW) is the process of generating energy in the form of electricity or heat from the primary treatment of waste. WtEis a form of energy recovery. Most WtE processes produce electricity or heat directly through combustion, or produce a combustible fuel commodity, such as methane, methanol, ethanol or synthetic fuels.
Technologies for the generation of energy from MSW
THERMAL CONVERSION: The process involves thermal degradation of waste under high temperature. In this complete oxidation of the waste occurs under high temperature. The major technological option under this category is incineration. But incineration is less preferred these days because of emission concerns.
THERMO-CHEMICAL CONVERSION: This process entails high temperature driven decomposition of organic matter to produce either heat energy or fuel oil or gas. It is useful for wastes containing high percentage of organic non-biodegradable matter and low moisture content. The main technological options under this category include Pyrolysis and Gasification.
BIO-CHEMICAL CONVERSION: This process is based on enzymatic decomposition of organic matter by microbial action to produce methane gas, alcohol, etc. The major technological options under this category are anaerobic digestion (bio-methanation) and fermentation. Of the two, anaerobic digestion is the most frequently used method for waste to energy, and fermentation is an emerging option.
Current status of WtE techniques in India
Recovering energy out of the waste produced is a complicated, yet, resourceful method. India has always been lagging in this field owing to several reasons namely the lack of policyframework, technological advancements, infrastructure, sustainable planning and insufficient funding sources. Yet, the nationhas not stopped trying and is still constantly experimenting toextract energy out of its enormous pile of waste.
Chandigarh has witnessed installation of a (Refuse-derived fuel) RDF plant with a capacity of 500 TPD of MSW to produce pellets and other solid fuel. But today, the plant is rarely operated and lies dormant. However, it is being retrofitted with MSW drying systems to reduce moisture in the final RDF.
The first large scale waste incineration plant was set up at Timarpur, New Delhi in 1987, by Miljotecknik volunteer, and Denmark. It has a capacity of 300 TDP and cost Rs 250 million. The plant was out of operation within 6 months which forced Municipal Corporation of Delhi to shut it down. The latest development in the same direction is the setup of another incineration plant at Okhla landfill site, New Delhi. It is designed to generate 16 MW of electricity by combusting 1350 TPD of MSW.
Telangana and Andhra Pradesh have installations of quite a few RDF plants at Hyderabad, Guntur and Vijayawada. The Hyderabad plant was commissioned in 1999 near Golconda dumping ground. It has a capacity of 1000 TPD but received only 700 TPD of waste until in use. It produced around 210 TPD of fluff and pellets, and was also to generate power of about 6.6 MW. The Vijayawada plant handled 500 TPD of MSW to generate 6 MW of power. Currently none of these plants are in use.
Gujarat is one of the frontrunners in using renewable sources of energy in India. The state has effectively started using waste to energy techniques as well. Anaerobic digestion is used by Kanoria Chemicals Ltd., Ankleshwar to generate 2 MW of power. Similarly, Anil Starch Products Ltd., is producing 4800 m3 of biogas per day using anaerobic digestion process. A 0.5 MW capacity power plant has been set up at the sewage treatment plant in Surat. Many other such small scale plants exist in Gujarat. Apart from biomethanation, RDF is also practiced in Gujarat, with Rajkot leading the effort.
Maharashtra is another leader in WtE projects. Maharashtra Energy Development Agency (MEDA) is constantly inviting potential investors to invest in this process. Thus, they have been successful in implementing many plants and pilot projects in Mumbai, Pune, Nashik, etc. Western Paques, Pune, has already completed testing biogas production using anaerobic digestion. The results reveal that 150 t/day of MSW produces 14,000 metric cube of biogas with methane content of 55%–65%. It has the potential to generate 1.2 MW of power. In the same direction Pune Municipal Corporation has taken a step forward to develop a MSW biomethanation plant that serves in managing the waste as well as generating power. The plant has been operational since November 2009. Apart from this, an incineration plant was put up at BARC, Trombay to burn institutional waste. In addition, one RDF plant at Deonar, Mumbai, owned by Excel India was set up in early 90’s to process garbage into pellets. However, the plant is not in operation since a few years now. The landfill site at Gorai, Mumbai had been tapped in 2008 for capturing and flaring landfill gas (LFG).
According to Ministry of New and Renewable Energy (MNRE) estimates, there exists a potential of about 1460 MW of energy from MSW.
While talking to Urban Update, Director General of Carbon Mine of India and Former Advisor of Environment and Forest Ministry, Dr Srikanta K Panigrahi said, “In India either we have no policy for waste to energy or if it exists there is no execution of these policies. Failure of waste to energy plants in India is all due to the carelessness of government. Before setting up the plants we need to take some steps into consideration like location, availability of raw material, economic feasibility; also we should try a different technology if one is not working. But we are not doing anything, we are simply mixing all the waste together and we are throwing it in a common place”. He further added, “We have asked government to establish independent waste to energy authority which can look after the policies introduced. We should bring a right policy and proper planning. Western countries are successfully using the technology but most of this technology is not relevant in India.”
India has tried quite a few things until now to extract energy from the waste generated, but has often met with failures. Ten aerobic composting projects in 1970s, a WTE project in 1980s, a large scale biomethanation project, and two RDF projects in 2003, have all met with failure. Large scale biomethanation has failed owing to the absence of source separation. A major plant in Lucknow to produce six MW of electricity failed due to
However the same process has shown huge success on small scale, using kitchen waste, market waste, restaurant waste, etc. India has a total of five RDF processing plants, all of which have encountered operational problems due to lack of proper financial and logistical planning. Two RDF plants have already been shut down. The initial failures of WtE technologies have turned people against the technology, which has turned out to be a key barrier in development today.
Giving the example of Delhi, Chitra Mukherjee, Head of Programmes and Operation of Chintan Environmental Research and Action group said, “When you set up a WtE Plant, it releases harmful fumes in to the air. Residents near the WtE plant keep on complaining of the fumes which is basically ash and it keeps on collecting on their windows and cars. Delhi is already polluted without any WtE plant and despite that you are setting up more. There are so many petitions against Okhla Plant already.”
She added, “In western countries their monitoring standards are very stringent so it is easy for them to regularly check on pollution caused by WtE plants. But in India we have no equipment for monitoring or to take samples (Acc. to DPCC). Monitoring of each sample costs Rs 60000. Pollution standards are not being met, so concept of WtE is not successful in India.” There are no faults as such in the technology. The mistakes rather are happening in the execution. So right now what India requires is an integrated system of waste management comprising separation of waste and then the treatment of each component accordingly. Each site and the local conditions need to be analyzed thoroughly and solutions have to be designed accordingly. Only then would it be possible to make WtE work in India.