India’s Green Transition is Missing Long-Duration Energy Storage (LDES)

Context

India’s electricity demand is rising rapidly, with peak demand touching 270.8 GW in May 2026. Although India is expanding renewable energy, the existing energy storage roadmap focused mainly on Battery Energy Storage Systems (BESS) and Pumped Hydro Energy Storage (PHES) may not be sufficient to ensure reliable electricity during prolonged periods of low solar and wind generation. The article argues that Long-Duration Energy Storage (LDES) could become the missing pillar of India’s green transition.

Highlights

• The 2024 Long-Term National Resource Adequacy Plan targets 60 GW of BESS and 94 GW of PHES by FY2035-36, providing average discharge durations of 4 hours and 6 hours, respectively.
• LDES technologies can store electricity for 8 hours to several days, enabling renewable energy to be used during periods of prolonged low generation.
• Several LDES technologies are at different stages of development, including flow batteries, thermal energy storage (TES), compressed air energy storage (CAES), hydrogen-based storage, and iron-air batteries.
• PHES remains the most mature technology but requires two water reservoirs at different elevations and suitable topography, limiting deployment.
• India has identified 106.8 GW of PHES projects by 2035-36, of which 11.6 GW is under construction.
• India has also launched a 160 MWh Carbon Dioxide battery storage system at NTPC Kudgi, Karnataka, which stores energy using phase change between liquid and gas CO₂.

Concepts

Long-Duration Energy Storage (LDES)

Technologies capable of storing electricity for 8 hours to several days, allowing renewable energy generated during surplus periods to be supplied when generation is low.

Battery Energy Storage Systems (BESS)

Electrochemical battery systems designed mainly for short-duration storage, typically providing around 4 hours of electricity.

Pumped Hydro Energy Storage (PHES)

Stores surplus electricity by pumping water to an upper reservoir and generating power by releasing it through turbines when demand increases.

Compressed Air Energy Storage (CAES)

Stores energy by compressing air into underground spaces such as salt caverns or depleted gas fields, releasing it later to generate electricity.

Flow Batteries

Electrochemical batteries with long operational life (20 – 40 years) and discharge durations of 8 – 12 hours, though currently more expensive than lithium-ion batteries.

Way Forward

• Incorporate LDES into the Ministry of Power’s National Energy Storage Systems Promotion Policy.
• Include LDES-specific planning in future grid planning exercises by estimating technology requirements under different weather and geographical conditions.
• Establish a clear regulatory classification for LDES to unlock investments.
• Provide targeted policy support, including subsidies and viability-gap funding, to improve commercial viability.
• Develop business models and market mechanisms, such as multi-use contracts and grid service frameworks, to generate stable revenue.
• Build domestic manufacturing capacity, identify suitable use cases, and strengthen research, pilot projects, skill development and cross-sector coordination for LDES deployment.