Investors in Form Energy’s Series D round included Bill Gates and Jeff Bezos-backed Breakthrough Energy Ventures.

Secretive but high profile battery technology startup Form Energy has collected a $240 million Series D funding round that included Breakthrough Energy Ventures as an investor. Breakthrough is backed by investors such as Bill Gates and Jeff Bezos. Form Energy’s first commercial product is a rechargeable iron-air battery capable of storing electricity for 100 hours. (CNBC)

The D round was led by the decarbonization XCarb innovation fund of the global steel manufacturer ArcelorMittal (AMS: MT).

How it works

The battery uses iron, air and water to recharge and produce power at costs competitive with legacy power plants. It is claimed to solve the critical problem of inexpensively storing power from renewable sources – for use when these sources are down for reasons such as nightfall and bad weather. It is also a valuable resource as a grid backup.

“Iron-air batteries are the best solution to balance the multi-day variability of renewable energy due to their extremely low cost, safety, durability, and global scalability,” the company says on its website. The battery is said to store energy at less than 1/10^th the cost of the lithium-ion battery technology.

Based on the principle of “reversible rusting,” the battery charges and discharges by converting iron back and forth into rust.

Thousands of these batteries are contained in power blocks. Tens to hundreds of these power blocks, contained in an environmentally-protected enclosure, can be hooked up to the grid. A one-MW system would need about an acre of land, depending upon the density of the blocks.

Pilot project

According to Recharge News, Form Energy is working on a 300MW pilot project for Minnesota-based Great River Energy which will likely be commissioned in 2023.

When announced in 2020, it was a 1 MW, grid-connected storage system capable of delivering its rated power continuously for 150 hours.

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Images credit: Form Energy