NTPC Green Energy, a subsidiary of major state-owned power producer NTPC announced in a regulatory filing the start of commercial operation of 165MW of generation capacity at Khavda-II, a solar PV plant complex in Gujarat.
Also known as Gujarat Hybrid Renewable Energy Park, the complex will comprise a total of nearly 5GW of solar generation across Khavda-I and Khavda-II, with a 130MW phase of Khadva-I recently achieving the start of commercial operation in January.
Alongside this, NTPC Green Energy’s own subsidiary, NTPC Renewable Energy, is seeking to deploy a 100MWh vanadium redox flow battery (VRFB) long-duration energy storage (LDES) system at the Khavda hybrid park.
Flow batteries store energy in tanks of liquid electrolyte, with separate power stacks. This means that, unlike lithium-ion (Li-ion) batteries, where the energy and power are both within the cell, flow batteries enable the decoupling of energy and power.
What this means in effect is that the energy capacity of a flow battery can be scaled up simply by increasing the size of the electrolyte tanks, lowering the cost of increasing the system’s duration.
The company announced that it would be tendering for the large-scale non-lithium battery system in November last year. Earlier this month (7 February), NTPC Renewable Energy issued an invitation for bids (IFB) for an engineering, procurement and construction (EPC) package for the VRFB’s development and delivery on a turnkey basis.
The output of the facility is listed at 16.7MW, meaning that at 100MWh, the VRFB will have a 5.9-hour discharge duration at maximum rated output. It will be integrated with the solar plant through a 33kV pooling substation.
In the document’s explanation of scope of work, NTPC Renewable Energy said specifications should include detailed explanations of guaranteed annual battery energy storage system (BESS) degradation, round trip efficiency (RTE) including auxiliary power consumption and other metrics.
Bidders must apply for the entire project capacity, with the asset to be designed for an expected 25-year lifetime, with the bidder taking on the first ten years of operations and maintenance (O&M).
The move follows an initial tender for a 3MWh, 5-hour duration VRFB system (600kW output) held in June 2024 by parent company NTPC. Deployed at an NTPC R&D centre in Greater Noida, Uttar Pradesh, the contract was awarded in September 2024 to India-headquartered flow battery manufacturer Delectrik, which co-developed the system with Rays Power Infra.
That system was paired with a microgrid at the NTPC Energy Technology Research Alliance (NETRA) R&D hub.
NTPC is also testing another potentially scalable non-lithium technology—the CO2 Battery from Italian tech company Energy Dome—piloting a 20MW/160MWh system at one of its thermal generation plants in Bijapur, Karnataka.
Energy Dome is partnering with Indian company Triveni Turbines on the project, while NETRA will assess the project. The CO2 Battery stores energy in compressed carbon dioxide gas, which is liquified during charging and evaporated during discharging.
“As a public-owned enterprise, [NTPC’s vision is] quite linked to the strategy and the wider vision of India, which is that they don’t necessarily see lithium-ion as the panacea,” Ben Potter, Energy Dome chief operating officer (COO), said in an interview with ESN Premium last year.
