Delhi generates over 9,600 tonnes of municipal solid waste (MSW) per day and this continues to grow with the increasing population and the rise of consumerism in the city. Further, the waste is not segregated at source despite the amended MSW rules of 2016, which could have made waste management easier.
The waste is transported to four landfills in Delhi – Okhla, Bhalswa, Ghazipur and Bawana. These “graveyards of waste” present a grim picture of waste management in the city. The lack of alternatives has led to an overuse of these landfills. As a result, their height is almost twice the permissible levels but they continue to be used beyond their operational period.
Last year in September, two people lost their lives and several were left injured when the Ghazipur landfill collapsed. Following the horrific accident, Delhi authorities have been seriously looking at ways to resolve the waste crisis in the city. However, the development of new landfills, which would require large swathes of land, is not a financially viable option given the skyrocketing rates in Delhi. Even the vacant Bhatti mines were looked at as a potential landfill site. However, the idea was shelved by the National Green Tribunal on environmental grounds
Narela-Bawana WtE plant
The ideal solution for clearing the mess in the city is behavioural change. But looking at the current status of waste segregation in Delhi, this seems to be a distant dream.
Another reasonable alternative to get rid of the large volumes of waste is waste-to-energy (WtE) plant generation, which is being explored in the city. In this regard, a tender was released by North Delhi Municipal Corporation (NDMC) in 2009 for the construction of a state-of-the-art landfill and a 24 MW WtE plant at Narela, with a capacity to handle 4,000 tonnes of solid waste per day. Ramky Enviro Engineers Limited, a Hyderabad-based waste management company, won the tender by quoting a tariff of Rs 7.03 per kWh and started the construction in 2010. However, the construction was delayed due to a dispute between the developers and NDMC on predetermined contractual agreements. The project was finally commissioned in 2017 and now runs at full capacity. However, due to the delay, the project cost escalated from the planned Rs 4.48 billion to Rs 6.5 billion.
The facility comprises a scientifically engineered landfill, the first in Delhi, which prevents toxic water to seep into the ground and traps harmful gases (methane) that are released from the waste. The solid waste is collected door-to-door from households in Rohini and Civil Lines and transported to the landfill, where it goes through a material recovery facility. This facility reclaims valuable metals and other recyclables that have a higher opportunity cost. The facility also sorts organic waste, which is sent for composting. The waste is further segregated to obtain refuse-derived fuel (RDF), which is burned at over 1,000 °C to generate electricity. A toxic by-product called fly ash is generated during the burning of the waste, but the amount of this by-product is less than 20 per cent of the input waste and is carefully dumped in the landfill.
Points of debate
The dual construction of the landfill-cum-WtE plant in Delhi is an innovative and environment friendly source of renewable energy generation. It can serve as a model for similar plants in other cities. Some critics of the WtE plant say that the same amount of solar energy could be generated on the land at a much lower cost without the release of toxic fly ash. They forget that the primary objective of such a plant is to curb the impact of the endless waste generated. Meanwhile, several solar modules with toxic materials like silicon, cadmium and copper are dumped in landfills, which could also be effectively disposed of through WtE generation.
That said, WtE plants do generate toxic fly ash. However, careful dumping of the product and immediate sale to cement companies can put this controversy to rest. Also, the risks associated with irresponsible dumping on exhausted landfills are much greater than the impact of the toxic by-product.