ArcelorMittal’s XCarb vehicle led the energy storage technology producer's latest round, which has been upsized from $200m and which includes Eni Next.

Form Energy, a US-headquartered developer of grid-scale energy storage systems, completed a $240m series D round on Tuesday led by steel producer ArcelorMittal’s XCarb fund.

XCarb provided $25m for the round’s first close last month, and the round also featured energy utility Eni’s Next fund.

Perry Creek Capital, NGP Energy Technology Partners, Coatue, Temasek, Energy Impact Partners, Breakthrough Energy Ventures (BEV), Prelude Ventures, The Engine, Capricorn Investment Group and Macquarie Capital filled out the investors with TPG Rise Climate and The Rise Fund.

Formerly known as Baseload Renewables, Form Energy has created a system built around a rechargeable iron-air battery capable of providing electricity for some 100 hours at a fraction of the cost of lithium-ion batteries.

The technology is used to store surplus energy from renewable power plants, allowing them to supply energy across multiple days even in less beneficial conditions. It plans to jointly develop ion materials with ArcelorMittal for use in its systems.

Mateo Jaramillo, Form Energy’s co-founder and chief executive, said, “We are very pleased to welcome ArcelorMittal and TPG Rise Climate to our investor group.

“This is a critically important and exciting time at Form Energy and we look forward to collaborating with our diverse coalition of leading investors as we accelerate development and prepare for commercialisation to meet the urgency of demand for scalable climate solutions.”

The round lifted the company’s overall funding to $367m, $9m coming in a 2018 series A round featuring petroleum supplier Saudi Aramco, BEV, Prelude Ventures, Macquarie Capital and existing investor The Engine.

Eni Next, The Engine, BEV, Prelude Ventures, Macquarie Capital and Capricorn Investment Group, provided $40m in series B funding for Form Energy in 2019.

Coatue Management led Form Energy’s $76m series C round in November 2020, investing with Eni Next, BEV, Prelude Ventures, The Engine, Capricorn Investment Group, Macquarie Capital, Energy Impact Partners, NGP Energy Technology Partners and Temasek.