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Local resident questions Excel/Connexus iron‑air battery plans, says federal grant pulled and technical claims questionable
Summary
At open forum, a Big Lake resident criticized iron‑air battery storage projects involving Excel and Connexus, saying federal grant support was pulled and outlining concerns about charging efficiency, cycle life and unrealistic performance claims.
At the Sherburne County Board of Commissioners' open forum, Brett Collier of Big Lake questioned the technical and financial merits of proposed iron‑air battery storage projects tied to Excel and Connexus.
Collier said the federal government withdrew $770 million in grant funding for the broader program of battery storage projects in Minnesota and Colorado. He described the technology as being marketed as a “proof of concept” but said developers appeared to be moving directly into production, with multiple installations planned across several states.
On technical claims, Collier said the proposed 10‑megawatt iron‑air systems were advertised to deliver 10 megawatts for 100 hours. He told the board he calculated that charging the systems would require roughly 2.63 times more input energy than the output delivered, and that using solar panels to charge the batteries would take many days to reach full capacity. He asserted the batteries would provide only about 16 cycles per year and might reach only approximately 100 cycles of useful life before replacement — conclusions he said made the lifetime economics unfavorable compared with other storage technologies.
Collier offered to email the board links and additional material for their consideration. County officials did not take action on the matter during the meeting.
