New battery technology backed by the likes of Bill Gates, Jeff Bezos and Richard Branson is set for a pioneering outing at one of America’s largest solar plants.

Power group Xcel Energy said it received the green light from Minnesota regulators for a 10MW/1,000MWh demonstration scale system using ‘iron-air’ technology from Form Energy to provide multi-day storage of green electricity.

Form Energy has over the last few years attracted an array of high-profile investors including Breakthrough Energy Ventures – itself backed by Microsoft billionaire Gates, Amazon tycoon Bezos and Virgin founder Branson – along with the likes of steel giant ArcelorMittal.

The Minnesota project – due online in 2025 – will be located near Xcel’s Sherco Solar project, which plans to expand to more than 700MW, and “help maximise the company’s use of renewable energy and maintain grid reliability through extreme temperatures and weather,” the operator said.

“Multi-day battery storage has the potential to help us better harness the renewable energy we generate while ensuring the grid remains reliable for our customers,” said Bria Shea, regional vice president, regulatory policy for Xcel Energy–Minnesota.

Form Energy is billing its scalable, modular technology as the answer to one of the biggest challenges facing the energy transition – how to store renewable energy for long enough periods to compensate for prolonged high demand, or low wind and solar generation, timescales beyond the range of lithium-ion batteries that can do the job for shorter durations.

The only solution currently on the table is to keep relying on gas or even coal-fired plants to step in when needed to fill the gaps.

Form Energy has revealed relatively few details of its technology except to say it is based on “some of the safest, cheapest, and most abundant materials on the planet — low-cost iron, water, and air”.

It claims the iron-air technology will be able to “store electricity for 100 hours at system costs competitive with legacy power plants. The company’s pioneering multi-day battery will reshape the electric system to reliably run on 100% low-cost renewable energy, every day of the year”.

Form Energy said in 2021 that its battery modules “will produce electricity for one-tenth the cost of any technology available today for grid storage”.