New Delhi: Can India’s coal-fired thermal power plants operate flexibly to support rising renewable energy without accelerating wear and tear or shortening plant life? A draft report prepared by a committee of the Central Electricity Authority (CEA) on wear and tear, operations and maintenance (O&M) and plant lifespan implications due to flexible operation suggests that low-load operation at 55 percent minimum technical load (MTL), under conservative ramp rates, has not led to significant damage — but it also records strong and divergent views from utilities and manufacturers. The document remains under consultation.
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The committee notes that “no significant damage has been observed that can be attributed directly to low-load operation (at 55 percent MTL and conservative ramp rates).” It further states that “approximately 70 percent of the observed issues were not due to flexible operation, but related to ageing, poor coal quality, or operational disturbances.”
At the same time, it acknowledges that flexible operation increases thermal cycling and that plant components experience stress particularly during start-up, shutdown and tripping events.
The draft underscores that damage accumulation is primarily linked to cyclic events rather than steady low-load operation. Citing modelling studies, including the USAID–Intertek “Cost of Cycling” analysis, the report notes that a single poorly executed start-up can cause multiple thermal cycles in critical components. It emphasises that improper O&M practices, forced cooling, human error and poor coal quality contribute substantially to equipment stress.
The implication is that operational discipline and technical retrofits may matter more than the absolute load level. The committee reiterates that 40 percent MTL — already notified by CEA in 2023 following pilot studies — is technically achievable with appropriate control systems and OEM consultation. However, it also calls for further pilots and data validation.
The report lays out contrary positions from key stakeholders. NTPC has argued that operating below 55 percent load is not technically feasible in many cases due to high ash coal quality and design constraints. It has expressed concern that repeated ramp-ups and cyclic operation accelerate wear, reduce equipment life and increase boiler tube leakages.
NTPC informed the committee that 692 boiler tube leakages were recorded between FY22 and September 2025, attributing many of these to flexible operations.
MAHAGENCO has stated that two-shift operations may be more damaging than continuous low-load operation at 40 percent MTL , while Adani Power has indicated that steady operation at 55 percent MTL is manageable, but impacts arise during frequent cyclic loading.
Bharat Heavy Electricals Limited (BHEL), for its part, has taken a nuanced position. The manufacturer observed that “damage cannot be solely attributed to flexible operation” and that many units were already operating near failure thresholds. It also noted that flexible operation does consume additional life but can be mitigated through retrofits, improved controls and component upgrades.
A key recommendation of the draft is to conduct a structured pilot on two-shift operations, particularly on older 210 MW units that are more than 35 years old. The committee observes that non-availability of nominated pilot units has delayed progress in assessing viability, life consumption and tariff implications. NTPC has sought exemption from such trials and has not nominated units for the pilot so far .
The outcome of this pilot is expected to inform any compensation framework for flexible operation.
Internationally, coal-fired units in countries such as Germany, Japan, Denmark and Australia have demonstrated minimum technical load levels as low as 30–40 percent, supported by advanced control systems and retrofits. In the United States, cycling capability has been enhanced in several plants to support renewable integration.
However, most of these plants operate on low-ash coal, typically between 5-20 percent ash content, compared with Indian domestic coal, which often has ash content in the range of 30–45 percent. High ash affects combustion stability, slagging, fouling and heat transfer characteristics, which, utilities argue, complicates deep load reduction.
The draft acknowledges that coal quality and design legacy must be factored into flexibility assessments, and that imported coal blends and design modifications may influence achievable MTL.
The committee makes it clear that further technical validation, OEM consultation and pilot-based evidence are required before final conclusions can be drawn.
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While the draft leans toward the view that steady low-load operation at 55 percent — and potentially 40 percent with retrofits — does not inherently cause major damage, it also recognises stakeholder concerns around cyclic stress, life consumption and cost recovery.
