The National Committee on Transmission recently deliberated on the feasibility of battery energy storage systems (BESS) as a non-wire alternative to conventional power transmission lines to address challenges arising from renewable energy curtailment and grid imbalances.

Along with grid-forming inverters, BESS can be planned as a transmission asset and built through the tariff-based competitive bidding (TBCB) route to avoid issues such as a lack of buyers for standalone storage or off-solar hours peak power.

Expert member on the committee, S.R. Narasimhan, drew attention to the recent amendment to the Terms and Conditions of Tariff Regulations for the 2024-29 period, under which a generating station or transmission asset under section 62 of the Electricity Act can install an energy storage system at its power project or substation.

These regulations provide a technical and commercial framework for such an energy storage system. Extending this logic, the battery energy storage asset can be executed quickly through TBCB in lieu of transmission, with minor modifications to the bidding documents.

In Rajasthan, 6 GW of solar capacity can be safely evacuated with a battery storage system installed at Bikaner. The Central Transmission Utility had earlier highlighted the issue of matching load generation during solar hours and an almost 25-55 GW surplus in the 2030-31 timeframe. On the other hand, there has been a serious capacity crunch during non-solar hours from the summer of 2022 to the present.

The transmission system can be completely avoided as battery storage would address both these constraints simultaneously, Narasimhan argued.

He also noted that a detailed cost analysis indicates that the BESS-based approach is more economical than the conventional AC transmission system, even after accounting for battery replacement costs. The model also generates substantial revenue through energy arbitrage and ancillary services, resulting in net economic benefits and reduced overall system cost.

In addition to cost advantages, battery storage would improve grid stability by providing rapid frequency response and reactive power support, reducing reliance on additional grid equipment, minimizing renewable curtailment, and addressing peak-demand challenges.

Considering the delays in transmission projects, assuming 100% certainty about new transmission schedules may not be prudent. As of date, 11 GW of renewable energy connected to the interstate transmission system is already experiencing 90-95% curtailment (4.5 GW in Rajasthan and 6.5 GW in Gujarat) due to delays in commissioning the planned transmission system.

The battery storage alternative can be the answer because it can be commissioned quickly in phases.

Mercom recently reported that about 11.5 GW of solar and wind power was curtailed in Rajasthan alone since January this year.

This January, a discussion paper by the Grid Controller of India proposed that all new BESS installations of 50 MW and above should incorporate grid-forming capability, especially when located in weak-grid or remote areas.