New Delhi, May 18 -- India is scrambling to solve a growing clean-energy paradox: the country is adding renewable power at record pace, but lacks the storage capacity needed to use that energy when the sun sets and wind generation drops. To bridge that gap, the Union government is preparing a financial support scheme for long-duration energy storage (LDES) technologies, according to three people aware of the discussions. The proposed scheme-part of the government's 'India Battery Storage Vision 2047'-is being worked out by the ministries of power and heavy industries, and is expected to be rolled out by fiscal year 2028 (FY28) under the administrative control of the power ministry, the people said on condition of anonymity. The push comes as policymakers increasingly acknowledge that India cannot fully leverage its rapidly expanding renewable-energy capacity without large-scale storage infrastructure. Unlike battery energy storage systems (Bess), which typically store electricity for one to four hours, LDES technologies can supply power for eight hours or more. These include pumped hydro storage, flow batteries, compressed air energy storage (CAES), and sensible heat storage. A viability gap funding (VGF) mechanism for LDES is currently being worked out, one of the officials said, adding that the government could also consider interest subvention support to improve liquidity access and accelerate adoption. "High reliance on short-duration storage could reduce energy security, increase system costs, and limit the feasibility of achieving 100% green power penetration," another official said, adding that long-duration storage is critical for optimal integration of renewable energy, "thereby achieving energy transition in the true sense". The first official added that the high cost of storage and lower technological maturity compared with lithium-ion battery systems have so far delayed large-scale deployment of LDES technologies. "There has been consideration for support to these new-age technologies for a long time now, but commercial viability has been a concern," the first person said. "Now it is high time these technologies are promoted and implemented at scale." Alongside financial incentives, the power ministry is preparing a broader policy framework to accelerate LDES adoption. This includes creating a technology-agnostic definition for LDES, incorporating storage targets into the National Electricity Plan (NEP) and Energy Storage Obligation (ESO) framework, and developing a national deployment roadmap. Pilot projects are also being planned to test LDES technologies across different grid conditions and establish commercial use cases. The policy push comes amid an aggressive renewable-energy expansion drive. India has added 178.88 gigawatts (GW) of renewable-energy capacity over the past five years, taking clean energy's share in the country's installed power capacity to 51.5%, data from Central Electricity Authority showed. Another around 100GW is expected to be added by 2030. However, India's storage infrastructure has failed to keep pace with the rapid expansion of renewable generation capacity, limiting the grid's ability to absorb and dispatch green power efficiently during non-solar and low-wind hours. According to estimates from the CEA's NEP 2023, India would have required about 47GWh of battery storage capacity by FY27 to support renewable integration, but only 795 megawatt hours (MWh)-predominantly short-duration Bess-has been installed so far. Queries emailed to the Union ministries of power and heavy industries remained unanswered till press time....