The Centre for Science and Environment (CSE) has said that India needs to make its coal-fired power plants more flexible to accommodate the rapid growth of renewable energy and maintain grid stability.
This comes after CSE released a new report on coal flexibilisation noting that India has rapidly expanded renewable power capacity while coal remains the backbone of its electricity system, creating growing challenges in balancing supply and demand as solar and wind generation fluctuate.
“We are not talking about renewable vs coal here. We are talking about renewable and coal, and about how to integrate the two,” CSE Director General Sunita Narain said at a national dialogue on coal flexibilisation.
“The task is not to replace coal, but to displace it,” she said.
CSE released two reports at the event examining how coal-fired power plants and thermal power purchase agreements could be reformed to support India’s energy transition.
The reports, titled Flex to Fix: Deciphering India’s Coal Flexibilisation Challenge for RE Integration and Beyond Baseload: Reforming Thermal PPAs for India’s Energy Transition, call for changes to plant operations, equipment and regulatory frameworks to enable coal units to respond more quickly to fluctuations in renewable generation.
India reached 50% non-fossil-based installed power capacity in November 2025, five years ahead of its original 2030 target, according to CSE.
But the rapid expansion of renewable energy, particularly solar power, has increased variability in the electricity system. Solar capacity has risen 3.5-fold over the past six years to more than 160 gigawatts, CSE said.
“The growth and transformation that India’s power sector is witnessing has meant that we must work towards greater flexibility in the grid,” Narain said.
“Enhancing the flexibility of the existing coal fleet can play a role in balancing the system and enabling greater integration of renewable energy.”
Managing a changing power system
Coal flexibilisation involves allowing thermal power plants to reduce or increase electricity generation more rapidly depending on grid requirements.
When solar and wind output is high, coal plants can lower generation, while during periods of weak renewable output or higher demand they can ramp up production.
CSE programme manager Parth Kumar said this would require upgrades to plant equipment and control systems, as well as changes to maintenance, fuel management and operator training.
Plants would also need to operate safely at lower loads and withstand more frequent start-ups and shutdowns, he said.
GRID-India recorded multiple instances in 2024 when grid frequency breached the 49.9-50.05 hertz threshold, with CSE saying over-injection by thermal generators increased the risk of instability.
The challenge is expected to grow as renewable energy accounts for a larger share of India’s electricity generation.
Cost-effective flexibility
CSE said coal flexibilisation could provide a relatively low-cost way of improving system flexibility while battery storage and other technologies are scaled up.
India currently has about 3 gigawatt-hours of operational battery storage against a target of 34.72 GWh, according to the report.
Without coal flexibilisation, an additional 184.4 GWh of battery storage could be required, potentially increasing system costs, CSE said.
The estimated impact of coal flexibilisation on electricity tariffs ranges between 0.272 rupees and 0.457 rupees per kilowatt-hour, depending on the technology, age and condition of individual plants.
“Flexibilisation offers a low-cost, technically feasible solution that can be deployed immediately,” said B.C. Mallick, principal chief engineer at the Central Electricity Authority.
CSE said experiences from China, Chile and Germany also show that greater flexibility in coal generation can support higher renewable energy penetration while delivering additional emissions reductions.
Policy support needed
CSE called for detailed assessments of individual coal units to determine their technical readiness, potential equipment damage and compensation requirements.
It also urged central and state governments to provide comprehensive tariff mechanisms covering equipment life consumption, testing and training costs.
The organisation recommended financial incentives for plants that meet flexibility targets, including preferential treatment in merit-order dispatch or lump-sum payments.
It also called for a review of the Central Electricity Authority’s coal-flexibilisation rollout, with priority given to efficient plants with better heat-rate and emissions performance.
“Flexibilisation is the bridge between today’s coal-dependent system and a future renewable-dominant grid,” said Nivit Yadav, programme director at CSE.
“Without redressal and correction in implementation and regulatory alignment, India risks undermining the hard-won gains of its renewable energy transition.”
The dialogue brought together officials and representatives from the Central Electricity Authority, Central Electricity Regulatory Commission, GRID-India, Bharat Heavy Electricals, NTPC, Torrent Power, academia and civil society to discuss reforms needed to integrate renewable energy while keeping electricity costs manageable for consumers.
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