Waste-to-energy plants could sustainably dispose of municipal solid waste, while generating electricity. Management of solid waste or garbage has three elements:
- Segregation of biodegradable or wet waste from dry waste at source.
- Once segregation is achieved, municipal governments can use wet waste to produce compost and biogas in biomethanation plants.
- The dry waste, after removing recyclable elements, should go to waste-to-energy plants: This will reduce the volume of waste that remains to be sent to landfills.
About waste-to-energy plants:
A number of waste-to-energy plants are coming up in urban India using
- Refuse Derived Fuel (RDF)-based combustion or conversion technologies such as pyrolysis and gasification.
There is a great deal of confusion about what the different technologies entail, and also apprehension about the potentially damaging impact of waste-to-energy plants on the environment in general, the quality of air in particular, and consequently, on public health. There are also questions about whether these plants are financially viable.
Incineration-based waste-to-energy plants rely on mass burning of municipal solid waste, which involves complete combustion of miscellaneous waste materials into ash. The latter is also true of RDF combustion-based plants. Depending on what is being combusted (and this is a huge challenge to determine with municipal solid waste), the gases generated may contain dioxins and furans, which are toxic and can be lethal. These plants therefore need to put in place emission control filters of a very high standard to check the release of harmful gases into the atmosphere.
Singapore uses incineration with due environmental precautions in managing its municipal solid waste after recycling 60 per cent of its waste (among the highest rates in the world). Japan and a number of European countries also rely on incineration, with due precaution, as they try to minimise the waste that needs to go to landfills. The United States had a long free run with incineration plants, but thanks to the environmental movement, there has been a significant tightening of regulations with respect to emissions since the 1970s. The abundance of land in the US led to greater recourse to landfills. But incineration plants are making a comeback and with these, so is the need for vigilance on emissions.
The innovations in waste-to-energy technologies worldwide have been focusing on pyrolysis, gasification and plasma gasification, which can deliver cleaner emissions but are considerably more expensive. These technologies involve heating of solid waste at very high temperatures in an oxygen-controlled environment, such that the thermal reactions produce synthesis gas (or syngas) which has the advantage that it can be burned directly or transported through pipelines and/or tankers for use in electricity generation, refining, chemical and fertiliser industries. While syngas can be scrubbed and converted into a clean energy source, the technologies are expensive, compromising the commercial viability of plants based on conversion technologies.
Pollution control boards set up by the government of India and state governments were expected to provide technical assistance and keep a check on the emissions/environmental footprints of waste-to-energy plants. Unfortunately, they have not kept pace with the rapidly evolving technology in the field of pollution control and were not able to check routine defaulters. Recognising the need for a more empowered body that could enforce adherence to environmental regulations, the National Green Tribunal was set up in 2010, as an independent judicial body under an act by the Parliament of India. As a judicial body in charge of supervisory jurisdiction over all environmental matters, NGT has, in many cases, prodded the pollution control authorities and catalysed action from State Pollution Control Boards/Municipalities, especially in waste management. It has been setting the rules of the game and putting the weight of legal compensation and enforcement behind its rulings. Hopefully, NGT will receive full support from the Central Pollution Control Board in its quest for scientific evaluations of the environmental impact of waste-to-energy plants.
The level of subsidy required to make waste-to-energy plants financially viable presents another set of problems. These plants involve significant capital investment and the cost of energy produced is higher than from the grid, unless there are government subsidies. Considering their contribution to resource recovery and saving on the energy cost of transportation, which would otherwise be incurred to haul waste to a landfill, there is a good case for subsidising these plants.
It is also important to emphasise that electricity generation from waste is not the most efficient way of generating electricity. It is a way of resource recovery from municipal solid waste and should be considered as a by-product of waste management. Enthusiasts sometimes speak of waste-to-energy as a solution to our energy problem — this is not correct. However, if implemented to global emission standards, it could be a pathway to scientific and sustainable disposal of municipal solid waste, given the scarcity of urban land in the country, while also generating some much needed electricity.