Retired coal sites to be transformed into multi-day iron-air batteries

American storage technology company Form Energy is set to deploy two 10MW/1,000MWh multi-day iron-air battery storage systems at two retiring coal plant sites in Minnesota and Colorado.

Form Energy signed a definitive agreement with US utility Xcel Energy late last week which would see two Xcel subsidiaries each deploy a 10MW/1,000MWh iron-air system.

Xcel Energy–Minnesota will deploy at the retiring Sherburne County Generating Station in Becker, Minnesota, while Xcel Energy–Colorado will deploy its system at the Comanche Generating Station in Pueblo, Colorado.

Both projects are expected to be online as early as 2025, though are nevertheless still subject to regulatory approvals in their respective states.

“We’re on track to reduce our electric system carbon emissions 80% by 2030 and to deliver carbon-free electricity by 2050,” said Bob Frenzel, chairman, president and CEO of Xcel Energy.

“As we build more renewable energy into our systems, our partnership with Form Energy opens the door to significantly improve how we deliver carbon-free energy so that we can continue to provide reliable and affordable electric service to our customers well into the future.”

Form Energy’s iron-air batteries are based around what the company bills as some of the safest, cheapest, and most abundant materials on the planet – low-cost iron, water, and air.

Capable of storing electricity for 100 hours at system costs competitive with traditional power plants, the batteries consist of cells filled with thousands of iron pellets.

Through a controlled process that exposes the iron to air, creating rust, before removing the oxygen so as to revert the rust to iron, the process allows the battery to be charged and discharged.

Credit: Form Energy

To ensure the viability of Form Energy’s technology on Xcel Energy’s grid, the two companies conducted an extensive modelling on Form Energy’s modelling tool for power grid, Formware.

The modelling helped Xcel Energy validate how the multi-day storage would enhance its ability to integrate large amounts of variable renewable energy sources on its system.

Moreover, the modelling further showed that Form Energy’s battery technology will strengthen the grid against normal day-to-date, week-to-week, and season-to-season weather variability, in addition to extreme weather events such as winter storms and polar vortex events.

“Xcel Energy operates across some of the richest wind-resource areas in North America,” said Mateo Jaramillo, CEO and co-founder of Form Energy.

“We’re very pleased to work with the Xcel Energy team to maximize use of its renewable generation by providing a technology solution that will ensure their customers benefit from reliable and cost-effective service year-round.

“This partnership highlights Xcel Energy’s commitment to ensuring grid resiliency and reliability, energy security, and access to low-cost clean energy when and where it is needed – every day of the year.”