Coal-fired plants’ inflexibility jeopardises India’s clean energy push: Can an incentive scheme work?
India's coal-fired power plants operate with a structural inflexibility: they cannot ramp down below approximately 55% of their installed capacity (their "minimum technical load"), even when solar and wind generation is plentiful and demand is low.
This inflexibility is causing significant renewable energy curtailment — India curtailed 2.3 TWh (terawatt-hours) of solar power between May and December 2025, and peak curtailment reached 23 GW at points during May–November 2025.
The "duck curve" problem — where mid-day solar surplus and evening demand peak create a rapid ramp requirement — is intensifying as solar capacity grows.
The Central Electricity Authority (CEA) has proposed a phased roadmap to enable coal plants to operate at 40% minimum technical load by 2030, down from the current 55%.
An incentive scheme is being explored to compensate coal plants for the operational costs and mechanical stress associated with increased ramping and lower minimum loads.
This issue is central to India's ability to achieve its 500 GW non-fossil capacity target by 2030 while maintaining grid stability.
India's 500 GW Renewable Energy Target — NDC and Energy Transition Context
India's renewable energy targets are embedded in its Nationally Determined Contributions (NDCs) under the Paris Agreement and form the backbone of its energy transition strategy.
Key Details
- India's updated NDC (2022): Achieve 500 GW of non-fossil fuel installed electricity capacity by 2030; generate 50% of cumulative electric power from non-fossil sources by 2030; reduce emissions intensity of GDP by 45% from 2005 levels by 2030.
- Current status (2025-26): India's total installed power capacity has crossed 5.05 lakh MW (505 GW); renewable energy (solar + wind + hydro + biomass) accounts for approximately 200+ GW.
- Solar target: India aims to reach 280 GW of solar by 2030; capacity additions have accelerated significantly through the PM-KUSUM, rooftop solar, and large-scale solar park schemes.
- International Solar Alliance (ISA): India co-founded the ISA (with France) at COP21, 2015 — headquartered in Gurugram; aims to mobilize $1 trillion for solar deployment in sunshine-rich member countries.
- India has committed to net zero emissions by 2070 at COP26 (Glasgow, 2021).
If coal plants cannot flex down to absorb rising solar and wind generation, large volumes of cheap renewable electricity must be curtailed — directly undermining the 500 GW target and making clean energy investments economically unviable.
The Duck Curve and Grid Flexibility Challenges
The "duck curve" is a graphical representation of the imbalance between electricity demand and renewable energy supply, especially solar, during different times of day. It is a critical concept in power system planning as renewable penetration increases.
Key Details
- Shape: Net demand (total demand minus renewable generation) dips sharply during mid-day (solar peak) and then requires a steep ramp up in late afternoon/evening — creating a duck-shaped curve.
- Challenges posed: (1) Over-generation and curtailment during mid-day; (2) Steep ramp requirements in the evening requiring fast-response capacity; (3) Frequency management stress on the grid.
- Solutions: Battery Energy Storage Systems (BESS), pumped hydro storage, demand-side management (shifting loads to daytime), increased transmission interconnections, flexible gas/hydro backup, and — crucially — reducing the minimum technical load of coal plants.
- India's grid operator: POSOCO (Power System Operation Corporation) — manages the national grid; recently merged into NLDC (National Load Despatch Centre).
- Must-run status: Renewable energy plants are designated "must-run" under grid regulations — their output cannot be curtailed by load despatch centres except for grid security reasons. Coal plants do not have must-run status but their minimum load limits prevent further reduction.
India curtailed 23 GW at peak and 2.3 TWh of solar in 2025 precisely because of the duck curve effect — coal plants hitting their 55% minimum load floor during low-demand mid-day periods, leaving no room for solar absorption. Reducing coal plant minimum load to 40% is the central policy response.
Coal in India's Energy Mix — A Structural Dependency
India's coal dependence is both a developmental reality and a climate challenge. Understanding the structural role of coal in India's power sector is essential for GS3 energy policy questions.
Key Details
- Coal accounts for approximately 70% of India's total electricity generation (by units, not capacity).
- India has the world's 4th largest coal reserves (approximately 361 billion tonnes, Geological Survey of India).
- Coal India Limited (CIL): World's largest coal producing company by output; a Maharatna PSU; produces approximately 80% of India's domestic coal.
- Thermal Power Plants (TPPs): Most are designed as baseload plants — intended to run at constant high loads (70–90% plant load factor). Ramping capability is limited by boiler design, turbine stress, and fuel characteristics.
- Minimum Technical Load (MTL): The lowest generation level at which a thermal plant can operate without tripping. Currently ~55% for most Indian coal plants; reducing to 40% requires technical upgrades and operational protocol changes.
- Supercritical and Ultra-Supercritical technologies: More flexible and efficient than subcritical boiler technology; new plants being built at supercritical specifications — better suited for flexible operation.
- India plans to pause new coal plant approvals after 2035, but existing capacity will continue operating for decades.
The incentive scheme under discussion would compensate coal plant operators (most are state utilities or NTPC subsidiaries) for the financial and mechanical cost of flexing down — acknowledging that coal plants bear an operational burden to enable renewable integration that the current electricity market pricing does not compensate.
Energy Storage and Grid Balancing — Policy Responses
Beyond coal flexibility, India's clean energy push requires a comprehensive storage and grid balancing strategy.
Key Details
- Battery Energy Storage Systems (BESS): CEA has a target of 51.5 GW/208 GWh of battery storage by 2032. The first large-scale BESS tender (4 GWh) was floated by SECI in 2023.
- Pumped Hydro Storage (PHS): Currently ~4.7 GW installed; CEA target of 18.8 GW by 2032 from identified sites.
- Demand Flexibility: Rajasthan Electricity Regulatory Commission (RERC) notified Demand Flexibility (DF)/DSM Regulations, 2026 — mandates DISCOMs meet Demand Flexibility Portfolio Obligations (DFPO), starting 0.25% of peak demand in 2026-27, rising to 2% by 2029-30.
- Green Hydrogen: Intended to serve as long-duration storage and industrial decarbonization; National Green Hydrogen Mission (2023) targets 5 million tonnes per year production by 2030.
- Transmission: Green Energy Corridors Phase I and II — dedicated transmission lines linking renewable-rich states (Rajasthan, Gujarat, Tamil Nadu, Andhra Pradesh) to demand centres.
Coal flexibility and storage are complementary solutions. Until sufficient BESS and pumped hydro capacity is built (requiring years and trillions in investment), reducing coal plant MTL from 55% to 40% is the lowest-cost, fastest-available lever to absorb more renewable generation and reduce curtailment.
- India's renewable curtailment (May–Dec 2025): 2.3 TWh of solar power.
- Peak renewable curtailment: 23 GW (May–November 2025).
- Current coal plant minimum technical load (MTL): ~55% of installed capacity.
- CEA target MTL by 2030: 40% of installed capacity.
- India's 500 GW non-fossil capacity target: By 2030 (NDC, updated 2022).
- India's total installed power capacity (2025-26): >5.05 lakh MW (505 GW).
- Coal's share in India's electricity generation: ~70% by units.
- Coal India Limited: Maharatna PSU, ~80% of India's domestic coal production.
- India's coal reserves: ~361 billion tonnes (4th largest globally, GSI).
- BESS target (CEA): 51.5 GW / 208 GWh by 2032.
- Pumped hydro target (CEA): 18.8 GW by 2032.
- India's net zero commitment: 2070 (COP26, Glasgow, 2021).