NCT backs HVDC over battery storage for Barmer solar evacuation

At its 30th meeting, the National Committee on Transmission (NCT) approved high-voltage direct current (HVDC) technology to evacuate 6 GW of solar power from Barmer in Rajasthan to South Kalamb in Maharashtra. The committee rejected battery energy storage system (BESS) as an alternative following a cost analysis by the Central Transmission Utility of India Ltd (CTUIL).

The proposal had been under discussion for months as the Central Electricity Authority (CEA) directed CTUIL to examine the long-term cost-effectiveness of BESS compared to HVDC. CTUIL prepared a comparative assessment of three options: a 24,000 MWh BESS, a ±800 kV line-commutated converter (LCC) HVDC system, and a ±600 kV voltage source converter (VSC) HVDC system.

The capital cost of the BESS system was estimated at Rs 597.21 billion, while the VSC HVDC option stood at Rs 360.44 billion. The LCC HVDC system emerged as the least-cost solution at Rs 249.74 billion. These figures were based on net present value calculations at a discount rate of 9.25 per cent, using April 2025 BESS bid data from GUVNL as a reference.

The BESS option, despite offering faster deployment and grid flexibility, was found significantly more expensive. Grid-India, which had earlier supported BESS for its grid stability benefits, acknowledged the cost competitiveness of LCC HVDC in this case. It noted that the HVDC project was already agreed upon in regional planning forums and that its implementation could proceed under the tariff-based competitive bidding (TBCB) route.

The approved scheme includes setting up a new 400/220 kV substation at Barmer-II, ±800 kV HVDC terminals at Barmer-II and South Kalamb, a 900 km HVDC bipole line, and associated EHVAC infrastructure. The project will be executed by RECPDCL with an implementation timeframe of 54 months.

In the same meeting, the NCT also took note of a delay in another approved transmission scheme.

The 1×500 MVA, 400/230 kV ICT augmentation at Tuticorin-II GIS substation has been paused following a directive from CTUIL. The scheme, approved in the NCT’s 28th meeting on 6 March 2025, was to be implemented by POWERGRID under the Regulated Tariff Mechanism (RTM).

The ICT was designated as an Associated Transmission System (ATS) for three generators that had sought connectivity at Tuticorin-II. These applicants were expected to submit their consent for implementation and furnish their share of cost via the second Connectivity Bank Guarantee (Conn-BG2).

Conn-BG2 is a financial instrument required under General Network Access (GNA) rules to ensure that generators are financially responsible for dedicated transmission assets built for them.

CTUIL informed the committee that unless the applicants submit their consent and Conn-BG2 within the defined timeframe, their connectivity could be revoked and the transformer augmentation may be scrapped. POWERGRID has been asked to keep the project on hold until further communication.