Renewables realism: BESS and India's path to round-the-clock supply

India's renewable energy sector added a record 44.5 GW of capacity in 2025, pushing total non-fossil fuel capacity past 253 GW. Yet these figures mask a fundamental constraint: when the sun sets and the wind dies down, the power disappears.

Energy storage remains the missing link between ambitious capacity targets and a reliable electricity supply. Battery energy storage systems (BESS) are no longer a distant aspiration — India expects installations to surge nearly tenfold from 507 MWh in 2025 to around 5 GWh in 2026.

The challenge extends far beyond simply adding batteries to the grid. Even though outside of wind applications, charging is fairly predictable for renewables, heating and high cell temperatures are a challenge in Indian climatic conditions, which result in degradation.

Commercial cells typically reach end-of-life at 80 per cent capacity retention after 2,000-plus cycles at optimal temperatures – this also depends on the materials (battery chemistry) used – but harsh operating conditions, common in India, can reduce this significantly.

Globally, the shift to 24×7 carbon-free electricity procurement is accelerating. BloombergNEF projects that under its Net Zero Scenario, renewables will enable 73 per cent of emissions abatement needed by 2050, with battery storage playing a critical role in matching hourly electricity demand with clean supply. Asia-Pacific's share of global emissions has nearly doubled since 1990 to 47 per cent in 2021, driven largely by the power sector.

More than $5 billion was invested in BESS in 2022, according to a McKinsey analysis — almost a threefold increase from the previous year. In a 2023 report, the consultancy projects the global BESS market to reach between $120 billion and $150 billion by 2030.

This reflects the fact that without a storage infrastructure that can cycle reliably for 10-15 years, round-the-clock renewable power remains theoretical.

Bengaluru-based e-TRNL Energy, founded in 2021 by technologists from IIT Bombay and IIT Roorkee, has developed what it describes as a chemistry-agnostic cell manufacturing approach. The technology reorients current flow within prismatic cells, shortening the path electrons travel from negative to positive terminals.

In conventional cylindrical formats like 18650 or 21700 cells, current flows in a spiral pattern, covering roughly ten times the necessary distance. This extended path generates heat and resistance, limiting performance. The redesigned architecture, which the company terms 3D Electrode Architecture, spreads current over a larger surface area while minimising travel distance and hence heat generation.

In the context of BESS, it’s worth pointing out that such systems have batteries heating up in closed, tight spaces (containers), which would otherwise need forced external cooling – adding to the costs of using them. eTRNL’s approach is applicable across current lithium-ion chemistries and future sodium-ion variants, potentially offering manufacturing flexibility as battery chemistry evolves.

Extended cycle life matters acutely for grid-scale storage, where replacement costs and downtime directly affect economics. If e-TRNL's cells can maintain 80 per cent capacity beyond conventional lifetimes under India's temperature extremes, the technology could improve the business case for battery storage projects.

India's Union Budget 2026 removed customs duties on lithium-ion batteries for grid storage applications, signalling policy support, but deployment still hinges on demonstrating long-term reliability at a commercial scale.

eTRNL raised Rs. 7.5 crore in pre-seed funding in 2024 and is working toward commercialisation. Translating laboratory performance to manufacturing at the gigawatt-hour scale presents considerable hurdles—battery startups globally have struggled with this transition.

Production consistency, supply chain integration, and sustained performance across thousands of cycles in real-world conditions will determine whether the technology can compete with established manufacturers like CATL, LG Energy Solution, and Samsung SDI.

India's renewable energy strategy depends on solving the storage equation. The government has set a target of meeting 4 per cent of electricity demand through energy storage by 2030 — approximately 200-250 GWh of grid-scale capacity. Current installations fall far short. Projects such as the Adani group's large battery system in Gujarat and Rajasthan's solar-plus-storage initiatives represent progress, but financing remains challenging, particularly for low-tariff bids.

Battery technology alone will not unlock 24×7 renewables. Grid modernisation, transmission infrastructure, and policy frameworks for treating storage as a grid asset all require parallel development. Yet an improved cell design that extends lifetimes and reduces costs would address a fundamental bottleneck.

If e-TRNL Energy's architecture delivers on its promise at scale, it could contribute to making round-the-clock renewable power commercially viable — not through revolutionary breakthroughs, but through incremental engineering improvements that compound over billions of charge cycles.