The Eni and Saudi Aramco-backed energy storage technology developer has raised series C financing to push its total funding past the $120m mark.

Form Energy, a US-based grid-scale battery developer backed by corporates Saudi Aramco and Eni, has raised more than $70m of series C funding from undisclosed investors, Reuters reported on Friday.

Founded in 2017, Form Energy is developing sulphur-based battery storage systems for renewable forms of electricity such as wind and solar that fluctuate more than conventional power plants due to changes in weather.

The aqueous air batteries are designed to store energy for up to 150 hours, according to Form Energy, potentially representing a far longer duration than the lithium-ion batteries currently used in storage systems.

The company closed a $40m series B round in August 2019 led by renewable power producer Eni’s corporate venturing arm, Eni Next, and backed by The Engine, Breakthrough Energy Ventures, Capricorn Investment Group, Prelude Ventures and Macquarie Capital.

Oil and gas supplier Saudi Aramco had joined The Engine, Breakthrough Energy Ventures, Prelude Ventures and Macquarie Capital in a $9m series A round for Form Energy that closed in May 2018, following $2m in seed capital from The Engine the previous year.