EEI and its member companies regard long-duration energy storage as a key enabler for a resilient clean energy future. At Xcel Energy, plans are underway to incorporate long-duration energy storage technologies at two retiring coal-based power plants.

The projects—which will be placed at the Comanche Generating Station in Pueblo, Colo., and the Sherburne County Generating Station in Becker, Minn.—will be 10 megawatt/1,000megawatt-hour iron-air battery systems developed by Form Energy. Breakthrough Energy Catalyst also is involved with the projects and has agreed to commit $20 million in contingent grant funding.

“Innovative long-duration energy storage technologies are crucial to achieving 100-percent carbon-free electricity,” said Xcel Energy Chairman, President, and CEO Bob Frenzel. He added that the grant funding will “accelerate adoption of this promising new technology, which allows us to provide higher percentages of renewable energy while still providing affordable electric service to our customers.”

Long-duration—or multi-day—energy storage offers similar benefits to more traditional storage technologies: It helps to maximize the integration of renewable energy and maintain reliability, particularly during periods of high demand or lower renewable production. Electric companies utilize for 93 percent of all energy storage technologies deployed today. Yet, many current technologies store energy for eight hours or less. Multi-day storage will allow companies to manage their renewable energy reserves more strategically and will help to bolster reliability and resilience.

In July, Xcel Energy received regulatory approval for its Minnesota long-duration storage project. Construction will start in the second quarter of 2024, with the battery system expected to come online as early as 2025.

Xcel Energy also has recently received a grant of up to $70 million from the U.S. Department of Energy to reduce the cost of these types of projects and plans to use provisions in the Inflation Reduction Act, such as renewable energy and storage system tax credits, to further drive down iron-air battery costs.

“Multi-day battery storage has the potential to help us better harness the renewable energy we generate while ensuring the grid remains reliable for our customers,” said Bria Shea, regional vice president, regulatory policy for Xcel Energy–Minnesota. “We look forward to bringing this system online … and learning more about the role it can play in our larger effort to reach 100-percent carbon-free electricity.”