Key Differentiator
100-hour duration; iron/water/air chemistry; non-flammable; <1/10th cost of Li-ion per kWh; FEOC compliant; no thermal runaway risk; Made in USA
150MWh
1.5MW
—
6,000
25yr
—
Data Confidence
Founded 2017. HQ: Somerville, MA. $800M+ total funding (GE Vernova, Breakthrough Energy, T. Rowe Price). Factory: 550K sq ft Weirton, WV (former Weirton Steel site). 300+ employees at factory. First pilot: 1.5MW/150MWh with Great River Energy, Cambridge MN (operational late 2025). Pipeline: 14 GWh. Upcoming: 10MW Xcel Energy (2026), 15MW Georgia Power (2026), 8,500MWh Lincoln ME (2027-28). DOE support. Reversible rusting process. Modules ~washer/dryer size, ~30 cells each, grouped in shipping container enclosures. >3 MW/acre at highest density. UL 9540A tested—exceptional results. Not a Li-ion competitor—complementary for multi-day storage gaps.
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