Bill Gates backed 'Rust battery' to be tested in Minnesota

Energy storage costs with these massive-scale batteries are a tenth compared to lithium-ion packs which aren't great at multi-day storage.
Ameya Paleja
Artist's illustration of how the energy storage solution looks like at scale
Artist's illustration of how the energy storage solution looks like at scale

Form Energy 

A new battery technology that uses the rusting process to store energy will soon be tested in Minnesota. Developed by Form Energy, a startup backed by Bill Gates Breakthrough Energy Ventures, the demonstration battery is being built at a 10 MW scale and will go online in 2025, Recharge News reported.

As the world looks to renewable sources of energy to move away from fossil fuels, it also needs large-scale energy storage solutions to tide over the intermittency of renewable power generation.

Companies like Tesla have jumped in to offer massive storage solutions but lithium-ion batteries are expensive at those scales. Moreover, lithium-ion batteries are not suitable for long-term storage or staying charged up for prolonged periods of time.

When the sun is shining and the wind is blowing, grid-connected batteries do not have to kick in for days. In such a scenario, a slower storage solution works better and this is where the rust battery fits perfectly.

The Rust Battery

Form Energy's alternative to massive lithium-ion packs is a washing machine-sized modular unit that uses the reversible process of rust formation to store and release energy.

During the charging process, the battery converts iron oxide or rust into metallic iron and releases oxygen as a by-product. When discharging, the oxygen reacts with metallic iron and leads to iron oxide formation, releasing energy. The reaction does not happen instantly like in a lithium-ion battery but at a massive scale is sufficient to support the requirements of the grid. It is also referred to as an Iron Air battery.

A full discharge cycle can take up to 100 hours or roughly four days, which can help tide over bad weather conditions as well. Moreover, the cost of building the battery and storing energy is almost a tenth of using the lithium counterpart, making it an attractive proposition going forward.

Demonstrator at Minnesota

Earlier this year, Form Energy set up a manufacturing facility in West Virginia and has now secured the regulatory clearance to test a 10MW/1,000MWh demonstration-scale system at a facility in Minnesota.

Form Energy's battery demonstrator will be set up over five acres (two hectares) of land in Becker, Minnesota. The site is close to the 710 MW solar plant that is under construction from Sherco Solar and will be built in collaboration with Xcel Energy, a power company.

Historically, Xcel Energy has used coal-fired power plants to supply energy to its customers but is now replacing them with renewable sources. The construction of the energy storage solution is expected to begin next year and the facility will go online by 2025.

Xcel is confident that once Form Energy's batteries are online, it will be able to provide its customers with energy at rates that are comparable to when it was providing coal-fired power but without the associated emissions.

The Rust battery offers a low-cost way to store renewable energy in an environmentally friendly manner. Once the life of the battery is complete, the iron can be used for downstream processes as scrap iron has been for centuries together.

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