We are currently at a point where solar and wind are cheaper than fossil fuels. What we have not solved yet is the problem of intermittency.

Lithium-ion batteries do provide an efficient solution to tackle that issue, but their storage capacity only lasts for six hours. Now, a new technology using rust is looking to extend that storage capacity for up to 100 hours.

The innovation is the work of Form Energy, a Massachusetts-based start-up that has developed a rechargeable iron-air battery. The technology has been around since 1968 when NASA first started toying with it.

However, it was never commercialized due to technical problems with its components. Form Energy has spent years fine-tuning the technology to make it viable and efficient.

The firm now believes it can provide low-carbon energy every day of the year to populations around the world. Talk about a worthy goal! The company's iron-air batteries can store large amounts of energy and release it over a period of four days.

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