100 Hours of Storage: Unpacking the Iron-Air Battery Deal That Changes Everything
Xcel Energy announced a deal to supply a new Google data center in Pine Island Minnesota with renewable energy. The utility said it was committed to ensuring that new large loads do not negatively affect other ratepayers and that this Clean Energy Accelerator Charge (CEAC) would help meet that commitment, with 1,400 MW of wind and 200 MW of solar.
The CEAC also includes a $50 mn investment in Xcel’s Capacity Connect program, a unique effort in which it will develop and own up to 200 MW of distributed storage assets, with between 1 and 3 MW of storage at local commercial, industrial, and institutional sites.
Storage is also part of the huge Google deal, with a technology at a scale the world has never seen before: iron air batteries from Form Energy, with 300 MW at 100 hours of duration, totaling 30,000 MWh. This single project represents a little over 50% of the entire battery energy storage duration installed across the U.S. in 2025.
Iron is abundant and it’s cheap, but it has taken the company many years to get to this point, manufacturing, testing and validating the technology.
Form bought and rehabilitated an old steel mill in W Virginia – with annual output of 500 MW when fully built out. The Google deal will take 60% of one year’s capacity.
Unlike lithium-ion batteries, that typically operate at 90% round trip efficiencies, losing 10% of the energy during each cycle, or pumped hydro that often sits in the mid 70% range, Form has a low 40% RTE.
Nonetheless, 100 hours of duration, if delivered reliably, at low cost, and in enormous quantities, has the potential to be a game changer in integrating more variable wind and solar to decarbonize the grid and meet the huge demand from data centers.