An energy technology pioneer backed by the likes of Bill Gates, Jeff Bezos and Richard Branson unveiled the site for the first factory to build ‘iron-air’ batteries that are claimed as a breakthrough in long-duration storage of wind and solar power.

Form Energy – which claims its technology can store massive amounts of renewable energy for days at a time at costs far below other alternatives – will build a $760m debut plant in Weirton in the US state of West Virginia, the company said.

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 company 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.

A rendering of a large Form Energy iron-air battery facility. Photo: Form Energy

The issue of prolonged slumps in wind output has been a live one in Europe over recent weeks, with the phenomenon widely known as ‘Dunkelflaute’ – a German word meaning dark doldrums – putting variability of renewables in the spotlight.

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”.

Recharge reported in 2020 that Minnesota-based utility Great River Energy was planning to build a 1MW/150MWh grid-connected demonstration storage plant using Form Energy’s secret battery technology – providing 1MW of output for 150 hours straight – as it closes all but one of its fossil-fuel power plants.

The West Virginia battery plant will be up and running in 2024, said Form Energy CEO and co-founder Mateo Jaramillo, who previously helped build up Tesla’s energy storage business.

“After a year-long nationwide site selection process that started with identifying over 500 candidate locations across 16 states, it became abundantly clear that Weirton, West Virginia – a historic steel community that sits on a river and has the rich heritage and know-how to make great things out of iron – is the ideal location for our first commercial battery production factory,” Jaramillo said.