Switch on, smoke off: Reducing emissions from diesel generator sets

Diesel generator (DG) sets, used for power backup across residential, commercial, and industrial sectors, are prominent hyperlocal sources of air and noise pollution throughout India. The current study estimated that a total of 14.7 lakh DG sets, with a capacity of over 5 kVA and a cumulative capacity of 2,72,576 MVA, were operational in India in 2022. These DG sets contributed to 42 Gg of particulate matter with a diameter of 2.5 µm (PM2.5), 23 Gg of black carbon, and 877 Gg of nitrogen oxides (NOX) in India. Additionally, older and poorly maintained DG sets tend to emit significantly more than regular ones and were termed as super-emitters in this study.

Many districts in Rajasthan, Uttar Pradesh, West Bengal, and Maharashtra show high PM2.5 emissions, driven by high installed capacities of DG sets and frequent power cuts. The top 10 districts with the highest PM2.5 emissions from different categories of DG sets are ranked in Table 3. Patna (Bihar), Gautam Buddha Nagar (Noida), Bengaluru Urban (Karnataka), Mumbai City (Maharashtra), and North 24 Parganas (West Bengal) have the highest PM2.5 emissions from almost all categories of DG sets and the highest total PM2.5 emissions from all types of DG sets.

Promoting reliable and cost-effective alternatives, including solar, newer DG sets like CPCB IV+ with stringent emission controls, gas-based solutions, and RECDs, is key to reducing DG set use and mitigating air pollution, till grid reliability improves and the need for DG sets is minimised.

Broader policy (e.g. a national scrappage policy for outdated/super-emitter units) and economic support (e.g. financial incentives for rooftop photovoltaic systems incorporating battery storage or for the purchase of CPCB IV+ DG sets) is necessary to scale these measures and effectively reduce air pollution.