06/28/2026
This is very exciting technology for long term
Energy storage of days, not hours
An iron-air battery project that stores electricity using nothing but iron and air is coming to Massachusetts in 2028 — and it promises to deliver long-duration grid storage at a fraction of the cost of lithium. New battery storage projects in Massachusetts are targeting lower power costs and reduced peak demand through a combination of short and long-duration storage technologies, with the most significant being a 400 megawatt-hour iron-air battery installation planned for 2028. Developed by Form Energy, iron-air batteries store electricity by oxidizing iron — essentially controlled rusting — when discharging, and reverse the process using electricity when charging, cycling between rust and iron indefinitely using only the most abundant metal on Earth and the oxygen in ordinary air.
Iron-air batteries cannot charge and discharge as quickly as lithium-ion cells, making them unsuitable for applications requiring rapid power response. But for long-duration grid storage — storing surplus renewable electricity for 100 hours or more and releasing it slowly during extended periods of low wind or solar generation — iron-air batteries offer a cost profile that lithium-ion simply cannot match. Iron is one of the cheapest industrial materials on Earth. Air is free. The raw material cost of an iron-air battery is a small fraction of an equivalent lithium-ion system, and the technology does not degrade through charge cycles the way lithium electrode chemistry does.
Massachusetts is an ideal proving ground for long-duration storage because the state's aggressive renewable energy targets are increasingly creating the multi-day storage challenges that lithium-ion's four-hour discharge window cannot address. Extended periods of cold, calm, cloudy New England winter weather can suppress both solar and wind generation simultaneously for days at a time, creating precisely the grid stress scenario that a 100-hour iron-air battery is purpose-built to solve.
Source: Interesting Engineering, June 2026