India’s push to integrate 500 GW of non-fossil fuel capacity by 2030 is increasing the need for greater flexibility from conventional power plants. With solar generation creating a strong “duck curve,” net power demand can fall sharply during the day before rising rapidly in the evening. In some cases, the midday drop has reached nearly 82 GW, while evening demand requires steep increases in generation. This has made thermal power plant flexibilization an important requirement for maintaining grid stability.

To assess how frequent cycling and reduced-load operation affect coal-fired power plants, the Central Electricity Authority (CEA) constituted an expert committee with participation from NTPC, GRID-INDIA, BHEL, Damodar Valley Corporation (DVC), and technical consultants. The committee examined the operational and mechanical challenges associated with running thermal units at lower loads and through daily startup and shutdown cycles.

During the discussions, NTPC raised concerns about operating coal-fired units at 40% Minimum Technical Load (MTL) and adopting two-shift operations. The company reported several problems across its fleet, including boiler tube leakages, flame failures, thermal fatigue, and distortion of rotor casings. According to NTPC, repeated cycling could increase stress on major equipment and reduce plant life.

However, an empirical assessment carried out by the CEA and Intertek produced a more nuanced finding. The study examined operational data from NTPC’s Farakka Unit-2, which is around 39 years old, and Jhajjar Unit-3, which is about 13 years old. The analysis found no measurable direct degradation when the units operated steadily at 55% MTL with conservative ramp rates.

The committee found that more than 70% of reported equipment outages and damage were linked to factors other than steady low-load operation. These included natural equipment aging, operational mistakes, variations in coal quality, and the use of unblended high-ash coal.

BHEL also highlighted that the greatest equipment stress generally occurs during rapid load changes, uncontrolled startups, and poor operating practices rather than during stable part-load operation. The company noted that many thermal plants are currently being flexibilized without adequate modernization of their control systems, which could increase equipment fatigue and accelerate life consumption.

The committee therefore recommended the use of advanced control upgrades, artificial intelligence-based combustion optimization, and real-time equipment stress monitoring to reduce operational risks. Such technologies could help operators manage flexible operation while protecting critical plant components.

Two-shift operation was identified as a potential solution for older thermal power units during periods of low renewable demand. The CEA identified 151 thermal units aged 35 years or more, representing a combined capacity of about 34.5 GW, as potential candidates. The committee estimated that converting these units for two-shift operation could provide nearly 24 GW of virtual storage capacity.

The estimated capital expenditure for this conversion is between ₹30,200 crore and ₹37,750 crore. This is significantly lower than the estimated ₹1,75,500 crore required to create an equivalent BESS capacity.

The committee also recommended exempting eligible two-shifting peaking units from mandatory FGD installation, noting that their planned shutdown during solar-generation hours could reduce their average emissions.

Other recommendations include rotating flexible operation among groups of thermal units instead of relying strictly on Merit Order dispatch, introducing stabilization blocks between ramps, expanding CERC compensation mechanisms for additional O&M expenses of up to 5%, and deploying predictive monitoring systems.

The committee further emphasized greater use of hydro, gas, and energy storage resources for fine balancing. These measures are aimed at reducing renewable energy curtailment, which has exceeded 23 GW on peak solar-generation days, while ensuring that thermal plants can provide the flexibility required for India’s increasingly renewable-heavy power system.