India’s CEA committee urges deeper flexibility in coal power to support rising renewables, backing two-shift operation for 151 ageing units that could provide 24 GW of flexible capacity and about 27 GW of virtual storage.
It finds limited direct evidence that 55% load operations cause major damage, but stresses better compensation, monitoring, and merit order reform, while critics demand stronger long-term evidence on plant life impacts.
India’s coal-fired power fleet may have to operate much more flexibly as renewable energy expands, but the transition will require changes in how plants are dispatched, compensated and operated, says a new Central Electricity Authority (CEA) committee report.
The recent report of the CEA Committee on Wear & Tear, O&M and Plant Lifespan Implications due to Flexible Operation and Analysis of 2-shift Operational Data comes at a time when India is increasingly relying on coal plants to back down during solar hours and ramp up in the evening. The report states that on some days, the difference between maximum demand and minimum net demand has reached around 82 GW, while national ramping requirements typically range between 250-300 MW per minute. The panel says deeper thermal flexibility, two-shift operation and storage will be needed to integrate increasing renewable generation.
One of the report’s most important findings is that the relationship between flexible operation and equipment damage is more complicated than simply attributing failures to low-load operation.
CEA and Intertek analysed operational data from two NTPC units, the 39-year-old Farakka Unit-2 and 13-year-old Jhajjar Unit-3. Neither unit had operated below 55 per cent minimum technical load during normal conditions. The observed ramp rates were generally conservative.
The panel found no significant damage that could be directly attributed to operation at 55 per cent load or conservative ramping. Around 70 per cent of the observed issues were attributed instead to ageing, poor coal quality or operational disturbances. It also noted that frequent start-ups and shutdowns, human and procedural errors and combustion-related issues can be significant sources of damage. Importantly, the statistical analysis available to the committee could not conclusively establish a correlation between failures and flexible operation.
The report also highlights an important distinction raised by BHEL which says equipment deterioration can have three components: historical ageing and O&M practices, stress associated with grid balancing requirements such as Automatic Generation Control (AGC) and Security Constrained Economic Dispatch (SECD), and additional damage arising specifically from the current flexible operating regime. Establishing this distinction is essential if generators are to be compensated fairly for flexibility-related costs.
The strongest new proposal is perhaps the committee’s endorsement of two-shift operation for older coal plants.
CEA has identified 151 coal-based generating units, totaling around 34.5 GW and aged 35 years or more, as potential candidates for two-shift operation by 2030. The committee estimates that these units could provide around 24 GW of flexible power, effectively creating about 27 GW of virtual storage, after suitable retrofits and accounting for availability and auxiliary consumption.
The basic operating model is straightforward: plants would shut down during the peak solar generation period and restart during the evening demand peak. The committee argues that this could be particularly suitable for older, largely depreciated plants, where the economics of retrofitting for two-shift operation may be more attractive.
Data from Tuticorin Thermal Power Station suggests that shutdown and start-up costs are around 29.4 paise per kWh, while increased O&M costs are around 16.7 paise per kWh. Depending on retrofit expenditure, the total tariff impact estimated by CEA ranges from about 62 to 80 paise per kWh.
The committee estimates that retrofitting the identified 151 units could cost roughly Rs 30,200 crore at Rs 200 crore per unit, substantially below its estimate for equivalent battery storage capacity.
The report also raises a potentially significant question around Merit Order Dispatch (MOD). CEA recommends that the burden of flexibility should be shared across a pool of suitable plants rather than repeatedly imposed on the same units. It recommends avoiding consecutive ramp-up and ramp-down of the same plants, rotating ramping responsibilities and providing stabilisation periods between changes in ramp direction.
The committee explicitly says that MOD “may be reviewed, if necessary” to accommodate this approach. It also proposes the introduction of ramping and stable-load blocks and suggests that hydro, gas, pumped storage and batteries should increasingly be used for fine balancing rather than relying exclusively on thermal plants.
This is important because a purely static merit-order approach can repeatedly expose the same plants to cycling, even when other technically suitable units are available.
Apart from what the report mentions, there is much more MOD reform can offer in terms of providing incentives that could reward flexibility and efficiency. The idea here would be to move beyond the consideration of cost as the only parameter for dispatch.
The panel also recognises that flexibility needs increased compensation. It recommends expanding the existing CERC compensation mechanism for operation at 55 per cent minimum technical load to cover incremental O&M costs of up to 5 per cent, in addition to compensation for auxiliary power consumption, station heat-rate degradation and increased oil consumption.
The report also calls for better operational monitoring, including systems for thermal-stress and boiler-tube-leakage prediction, coal-quality monitoring, combustion optimisation and improved load forecasting. It stresses the need for operator training and better operating procedures.
The committee has also called for detailed, plant-specific studies and tests before deeper flexibility is implemented, recognising that the measures required will vary by unit and by the degree of flexibilisation.
The report notes that the CERC order directing two-shift pilot projects also provides for incentives during the pilot period. However, the committee itself does not lay out a new, broad incentive package for plants that provide flexibility; its main emphasis is on cost compensation, better dispatch and sharing of operational stress.
The committee’s conclusions, however, are not without dissent.
NTPC has questioned whether the available evidence is sufficient to draw definitive conclusions about the long-term consequences of deep flexibilisation and two-shift operation. Its concern is particularly because the committee’s analysis of damage is based on only two units, neither of which had operated below 55 per cent under normal conditions.
The power utility has argued that some consequences of cycling and two-shift operation may not become visible during a short pilot. In its comments, it pointed to the possibility that impacts on plant life and forced outages could emerge only after around two to three years. It also questioned whether short-duration trials could therefore provide a reliable assessment of long-term damage.
Reiterating GRID India’s argument, NTPC also argued for retaining a uniform 55 per cent minimum technical load and bringing intra-state and regional independent power producers under mechanisms such as SCUC, SCED and ancillary services to optimise dispatch. Additionally it also raised concerns about the effects of Indian coal characteristics on deep part-load operation.
Views of Intertek recorded in the report also mention that in the absence of sufficient actual operating data and comprehensive long-term studies, particularly for supercritical units, a conclusive assessment of the extent of flexibility-related damage cannot yet be made.
The answer, therefore, may not be to choose between “flexibilise” and “do not flexibilise”, but to build a much stronger evidence base while flexibility is scaled up.
Interestingly, several of the committee’s recommendations converge with proposals made by the Centre for Science and Environment (CSE) in its recent Flex to Fix report.
CSE had recommended structured baseline unit-wise health assessments of thermal units before retrofitting, specifically to distinguish legacy wear and tear from flexibility-induced damage, the need of which was clearly highlighted in the committee’s report. CSE’s recommendations also called for compensation mechanisms to cover mandatory training, workforce upskilling and costs incurred during trial and testing periods. The committee report recognises and reiterates the need for training, detailed testing and pilot studies to build evidence on the impacts of flexible operation.
The Delhi-based think tank had further proposed reforming MOD including how it could enable incentives such as preferential treatment in MOD for units that meet flexibility targets. The committee report also considers rethinking of MOD towards increasing the ambit of flexibility among generating units.
There is also convergence on the need to reconsider how coal units are prioritised under the flexibilisation phasing plan. CSE’s Flex to Fix had recommended that the existing CEA phasing plan be reviewed through an evidence-based assessment of heat-rate and emission performance, the greater utilisation of efficient and low-emission supercritical and ultra-supercritical units, the suitability of older and inefficient plants for two-shift or limited peak-support roles, and the technological limits of different thermal technologies. CSE had argued that greater utilisation of efficient, lower-emission assets could reduce the overall emissions impact of flexibilisation, while expensive retrofits of units beyond 30 years of age may not always be justified given their remaining operational life and reliability risks. It had also highlighted differences in minimum technical-load constraints, start-up times and oil consumption across thermal technologies, recommending that technological limits, start-up economics and real-time emission profiles be formally assessed before restructuring the overall phasing plan.
The committee report reflects this principle of differentiated treatment, calling for unit-specific studies and testing to determine appropriate flexibility measures and recommending feasibility studies for smaller, older units for two-shift operation, taking into account their technical constraints, reliability, potential life consumption and retrofit costs.
The overlap is significant. Together, these recommendations point towards a more evidence-based approach to coal flexibility, where technical performance, operational constraints and economic implications are considered alongside the broader need for fleet-wide flexibility.
The CEA report moves the flexibility debate beyond the question of whether coal plants should flex. The more immediate question is now how to do it without unnecessarily shortening plant life, distorting dispatch or leaving generators with unrecovered costs.
That will require properly designed pilots, longer-term monitoring, transparent attribution of damage, plant-specific health assessments and a compensation framework that captures the actual cost of flexibility. It will also require dispatch rules that distribute cycling more rationally across the fleet.
The fact that CEA has identified 151 older units for possible two-shift operation which shows the prioritisation of this approach but the absence of adequate pilot participation from utilities, including NTPC, also shows that more work is required to achieve consensus.
Several of the issues in the CEA committee report were already highlighted in CSE’s Flex to Fix. Since India has been envisioning to flexibilise its coal fleet since past several years, while counterparts like China have already flexibilised more than 300 GW of their fleet, it is high time that India moves beyond pilots, reaches consensus and delivers implementation on this before the challenges of growing renewables and the grid intensify.