From waste to energy to pollution Premium

How thermal plants and waste-to-energy plants intensify Delhi air pollution

Delhi remains the most polluted city in India, as of December 20. Air pollution in the capital is over 17 times the limit prescribed by the World Health Organization, according to official data. Particulate matter (PM2.5) can go deep inside the lungs, causing respiratory illnesses. Air toxicity also results in increased incidences of cancer and miscarriages.

The fight against pollution remains unsuccessful despite efforts by the government and interventions by the Supreme Court. Air pollution in Delhi mostly originates from human activities such as burning coal; petrol, diesel, and gas; biomass in industries; and coal-based power plants. Kitchen smoke, vehicular emissions, large-scale construction activity, firecrackers, and the burning of residual crops also vitiate the air. Although many of the major sources of pollution are active throughout the year, the worsening of air quality during winter happens due to temperature inversion. Heavier winds prevent pollutants from scattering and keep them concentrated closer to the ground.

The recommendations for pollution mitigation largely range from promoting crop diversification in the neighbouring States to transforming the transport sector. Only a few reports dwell sufficiently on the role that thermal plants and waste-to-energy plants play in intensifying air pollution. According to the Centre for Research on Energy and Clean Air, thermal plants emit sulphur dioxide at levels 240 times higher than stubble burning. “While stubble burning receives heavy penalties, coal-fired power plants operate with repeated compliance extensions,” the report states.

The guidelines of the Ministry of Environment, Forest and Climate Change require coal-based power plants to install flue-gas desulfurization systems, which can reduce their annual sulphur dioxide emissions by more than 60%. However, the Union Power Ministry has been seeking an extension of the deadlines. The Central Electricity Authority has already missed two deadlines and has asked for time till 2035.

Besides coal power plants, Delhi’s four waste-to-energy (WtE) plants located in Ghazipur, Narela, Okhla, and Tehkhand are also major sources of pollution. These plants burn garbage to produce steam that runs turbines to generate electricity. This is seen as a solution to the mounting garbage crisis. While WtE plants in Delhi generate electricity, they also produce bottom ash and fly ash. The bottom ash that remains after combustion comprises about 20-30% of the original waste volume. Hailed as a green solution to the city’s mounting garbage crisis, waste-to-energy incinerators are like open pit garbage fires that billow toxic particulate matter and gases.

The New York Times published an article on November 9, 2024, focusing on the Timarpur-Okhla WtE plant, commissioned in 2012. The paper found that the plant’s fly ash contains cadmium that is four times higher than the Environmental Protection Agency’s permissible limits and 10 times the legal amount of dioxins, a notorious toxic substance. The plant does not follow any ecological norms in handling fly ash, causing air and water contamination, despite public concerns over health and environmental impacts. No clear guidelines against WtE plants have been issued under the Graded Response Action Plan, a set of emergency measures that kick in to prevent further deterioration of air quality once it reaches a certain threshold.

Modern incinerators have primary and secondary burn chambers and controlled burners designed for efficient burning with the lowest possible emissions. The newest generation plants elsewhere in the world use stoker technology, and others use advanced oxygen enrichment technology. Several treatment plants worldwide use relatively novel processes such as direct smelting. It is unclear if the plants in Delhi use any filters or scrubbers to prevent the pollutants from escaping.