A $10 million grant will help Pueblo become home to a battery storage system designed to hold four days worth of solar- and wind-generated energy to be built on the site of Xcel Energy's soon-to-close Comanche 3 power plant east of Pueblo.

Breakthrough Energy Catalyst has agreed to commit $20 million to help the utility fund the Pueblo project and a second at a retiring coal plant in Minnesota, according to Kevin Coss, senior media relations representative with Xcel Energy. Breakthrough Energy formed in 2015 to help finance new solutions for a zero-carbon economy, including long-duration energy storage.

The Comanche 3 coal-fired power plant in Pueblo is slated to close Dec. 31, 2030, which will mark an end to the use of coal power plants in Colorado. If approved by regulators, the battery storage system construction could employ 15 to 20 workers and would go online as soon as 2025.

The new battery storage system is being designed by Form Energy, a Massachusetts-based company that makes the batteries. The batteries use iron, instead of lithium, so they are less expensive to make because iron is more readily available.

Pueblo's 10-megawatt storage site would feature a bunch of individual containers holding iron-air battery technology inside them, Coss said.

"It would be covering a 5-acre site and as part of that 5 acres there is a substation which collects and distributes that energy," Coss said. "The energy would be coming from nearby solar (farms.)"

More Comanche news: New energy storage facility could be coming to Pueblo under pilot plan

Why longer-term renewable energy storage is vital

The storage project will help Xcel maximize the use of renewable energy while maintaining the reliability of the electric grid. The batteries will allow Xcel Energy to store renewable energy such as solar and wind when it is being produced and then later distribute the energy during periods of lower production.

"This is like a pilot-scale system, so one of the intents is to see how well it works," Coss said. "The batteries generally bring the most value through charging and discharging from renewable resources, particularly when those renewables would otherwise be curtailed."

Most existing battery technologies provide less than eight hours of energy storage. Form Energy’s iron-air batteries can store 100 hours of energy at costs competitive with conventional power plants.

The batteries also will strengthen the grid during normal weather variability, as well as save energy for use during extreme weather events such as severe winter storms and polar vortex events.

“Innovative, long-duration energy storage technologies are crucial to achieving 100% carbon-free electricity,” said Bob Frenzel, chairman of Xcel Energy, in a press release. “This grant 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.”

The Breakthrough Energy Catalyst grant is the first partnership the agency has forged with a utility.

“Long-duration storage will be a critical part of creating a clean, affordable and reliable grid, so we’re proud to play a role making these groundbreaking, first-of-a-kind, utility-scale projects possible,” said Mario Fernandez, head of Breakthrough Energy Catalyst, in a press release. “By investing in clean energy storage solutions, Xcel Energy is laying the groundwork for a net-zero future that’s affordable and keeps the lights on regardless of the weather, and these projects will help accelerate our journey there.”

Xcel Energy also plans to use provisions in the federal Inflation Reduction Act, such as renewable energy tax credits, to further reduce the cost to build the new battery storage facilities.

Xcel already has partnered with Lightsource BP to build its second solar farm in Pueblo. Sun Mountain Solar will include 640,000 solar models on 1,700 acres southeast of the Bighorn Solar farm, which provides power for the EVRAZ Rocky Mountain Steel Mill.

More Comanche news: Pueblo committee forms to study energy strategies for when Comanche plant closes

Chieftain reporter Tracy Harmon covers business news. She can be reached by email at tharmon@chieftain.com or via Twitter at twitter.com/tracywumps.

This article originally appeared on The Pueblo Chieftain: Pueblo's renewable energy storage project gets $10 million boost