Metal-air batteries: Impact and additionality

Could week-long batteries finally retire backup gas plants?

What this tab covers The impact and additionality lens: what it displaces on the grid, who gains and who bears the burden along the supply chain, and what happens at end of life.

Multi-day iron-air storage is one of the few battery options aimed at replacing gas plants kept for rare low-renewable weeks. It is still pre-commercial at utility scale, and India's interest lies mainly in aluminium-air.

Grid decarbonisation versus fossil displacement

Favourable

Lithium-ion shifts solar by a few hours; a 100-hour store can cover multi-day weather events, the role now played by gas peakers and coal reserves. That makes iron-air potentially high-additionality, but only once systems run at scale. The first utility system, 1.5 MW / 150 MWh at Great River Energy's Cambridge, Minnesota, peaking plant, was originally due by end 2025; in Oct 2026 MIT Technology Review put it at 2027. The Georgia Power project was agreed in 2023 at 15 MW / 1,500 MWh, when Form said it could come online as early as 2026; no start of operation had been reported by late 2026.¹²³¹⁵

Great River Energy system 1.5 MW / 150 MWh; target slipped from end 2025 to 2027¹¹⁵ Georgia Power project 15 MW / 1,500 MWh³ Duration versus lithium-ion 100 h vs about 8-12 h nameplate²

Just transition and local community impact

Mixed

Form's factory is on the former Weirton Steel site in West Virginia, a coal and steel state, with 2 GWh a year of capacity. In India, IOC Phinergy (Indian Oil and Phinergy of Israel) has been preparing aluminium-air manufacturing, with Hindalco agreeing to make aluminium plates and recycle used aluminium, a model framed around cutting battery imports. Aluminium smelting is energy-intensive, so the carbon benefit depends on the power used in smelting and recycling.¹⁶⁷¹⁶

Form factory capacity 2 GWh a year¹

Circular economy and end of life

Favourable

Iron and steel are among the most recycled materials, and Form says its batteries are designed with abundant and recyclable raw materials. Aluminium-air depends on recycling by design: used aluminium goes back to the smelter to make new plates, which Hindalco has agreed to do in India. Zinc-air button cells are a small but dispersed waste stream covered by EU portable battery collection rules.³⁶⁷

Sources

15 Climate Tech Companies to Watch 2026: Form Energy (6 Oct 2026) MIT Technology Review, 2026
100-hour LDES battery technologies from Form, Noon and Ore: how do they compare? (cites Form presentations and a LinkedIn commentator) Energy-Storage.news, 2025
Form Energy signs definitive agreement for 100-hour iron-air BESS with Georgia Power Energy-Storage.news, 2023
Indian Oil's aluminium-air battery manufacturing JV readies itself for manufacturing rollout Autocar Professional, 2023
Hindalco, Phinergy and IOP partner on revolutionary aluminium-air batteries for EVs and energy storage (press release, 18 Jul 2022) Hindalco Industries, 2022
Cambridge Energy Storage Project (project page) Great River Energy, 2025
Iron-air US LDES startup Form Energy secures US$750 million Series G financing (Aug 2026) Energy-Storage.news, 2026