July 14, 2023
By JOHN FITZGERALD WEAVER

Former US coal plant to host 100-hour iron-air battery

The Minnesota Public Utilities Commission (PUC) has approved Form Energy’s 10 MW/1 GWh iron-air long-duration storage facility for Xcel Energy.

Image: Form Energy

PUC has approved Form Energy’s construction of a 10 MW/1 GWh iron-air long-duration energy storage facility for Xcel Energy. It is scheduled to be built on the site of the former Sherburne County Generating Station, which is a coal-fired generating plant on the banks of the Mississippi River. The project will replace a facility previously capable of delivering over 2.2 GW of coal-generated power.

Xcel plans to start construction in mid-2024, aiming to bring the site online by mid-2025. The project proposal submitted to PUC has been largely redacted, concealing many details, including specific cost information, from the public. This is somewhat ironic, given the “public” nature of the utilities commission.

The filing does disclose that the project’s location on a brownfield/coal site qualifies it for an additional 10% tax credit adder under the US Inflation Reduction Act. The filing also implies that the project might also be eligible for a 10% domestic content tax credit adder, as Form Energy has expressed commitment to ensuring their product’s qualification. In a recent development, Form Energy announced the establishment of a factory in West Virginia.

According to a different Minnesota PUC docket, a white paper from Form Energy (Docket No. ET-2/RP-22-75), prepared as part of the slower-progressing Cambridge Energy station, provides insights into the cost inputs for the financial modeling tools (see table below). Form Energy estimates the cost of iron-air energy storage hardware, under the “All-in Capital Cost,” to be between $1,700 and $2,400 per kW, with operating costs of $19/kW per year.

Although the hardware costs are two to three times higher due to its unique nature (100-hour battery capacity), Form Energy projects the operating costs to be less than half of those for eight-hour lithium-ion batteries.