NTPC flags thermal plant damage from flexible ops for renewable integration

NTPC says flexible and two-shift operations for renewable integration are causing wear and failures in thermal units, prompting the power ministry to review plant stress and grid needs

State-owned power generator NTPC Ltd has raised serious concerns over damages caused to its thermal power plants due to flexible and two-shift operations required for integrating renewable energy (RE) capacity into the grid.

 

In a meeting chaired by the power secretary last May, the company stated it was already experiencing high boiler tube leakages (BTLs), frequent flame failures, and a significant increase in generator and turbine failures over the past three years.

 

“Repeated ramp-ups and ramp-downs are accelerating wear and reducing the lifespan of thermal units,” NTPC said, adding that, therefore, it is not in a position to support two-shift operations. This finds mention in the draft report of a committee set up by the power ministry on the issue.

 

The company highlighted that 692 BTLs were reported fleetwide from 2021-22 to September 2025, apart from 10 instances of flame failure. It underscored that 11 of the 15 BTL events at Farakka thermal power plant were attributed to fatigue failure, overheating, and weld joint failure.

 

After the meeting, the power secretary asked the Central Electricity Authority (CEA) and Grid-India to thoroughly examine the potential damage to the country's thermal plant fleet before considering the implementation of two-shift operations. The power ministry also set up the committee on "Wear & tear, O&M and plant lifespan implications due to flexible operation".

 

The committee's mandate was to examine the potential damage to thermal power plants on account of flexible operation and also to assess the impact of two-shift operations on generating units.

 

According to the draft report, Grid-India informed that on May 31, 2025, despite backing down the national thermal fleet to 58 per cent and curtailing nearly 10 gigawatt (Gw) of solar generation through emergency down dispatch, system frequency still rose to 50.48 Hertz, posing a serious concern for safe and secure grid operation.

 

NTPC had submitted operational and technical data from two of its power plants — 39-year-old Farakka Unit-2 (210 megawatt, or Mw) and 13-year-old Jhajjar Unit-3 (210 Mw) — to the committee in October last year. The data covered outage categorisation, ramping behavior, and operational events during flexible operation.

 

"NTPC submitted that the data reflects increased mechanical and thermal stresses experienced by plant components due to flexible operation at 55 per cent minimum technical load (MTL)," the report said.

 

The committee said in the draft report that NTPC’s analysis correlates all failures to flexible operation, ignoring other dominant causes such as frequent startups and shutdowns, suboptimal O&M (operation and maintenance) practices, improper preservation or forced cooling, coal quality deviation, and human and procedural errors.

 

According to the draft report, around 70 per cent of the observed issues were not due to flexible operation, but related to ageing, poor coal quality, or operational disturbances. "It was, therefore, concluded that while flexibility introduces some additional thermal stress, the existing conservative operations have not shown measurable degradation directly attributable to low-load running," it said.

 

The panel concluded the data shared by NTPC is limited to two units and cannot be extrapolated to the entire NTPC fleet. "Based on available data and empirical evidence, it is confirmed that no significant damage has been observed that can be attributed directly to low-load operation (at 55 per cent MTL and conservative ramp rates). The principal sources of accelerated wear and tear remain improper startup or shutdown procedures, human and procedural errors, poor combustion management, etc.," the report said.

 

Considering high ash content in Indian coal, and after five years of successful multiple pilot study and tests, the CEA notified flexible operation regulation in 2023 regarding 40 per cent MTL of coal-fired power plants to be achieved phase-wise by 2030.

 

According to the CEA, enabling two-shift operations and operation at lower MTL below 55 per cent is crucial to avoid renewable curtailment and ensure secure grid management. The committee discussed in the meeting that running a unit at 40 per cent load is operationally less damaging compared to repeated reserve shutdown (RSD) cycles.

 

Achieving India’s target of 500 Gw of RE capacity and 50 per cent non-fossil energy by 2030 is contingent upon significantly enhancing grid flexibility through a combination of flexible thermal operation (40 per cent MTL), two-shift operation, battery energy storage systems (BESS), and pumped storage project.