What Happened
- 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.
Static Topic Bridges
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.
- 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).
Connection to this news: 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.
- 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.
Connection to this news: 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.
- 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.
Connection to this news: 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.
- 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.
Connection to this news: 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.
Key Facts & Data
- 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).