Xcel plans to replace Colorado power plant in Pueblo with renewable energy battery system

Xcel Energy recently announced its intent to construct a long duration energy storage system at the site of a coal-fired power plant in Pueblo. 

Once operational, the system in Colorado "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 renewable production," according to Xcel in a press release. 

Construction is tentatively set to begin late next year. 

The move is part of a settlement Xcel reached with Pueblo County Commissioners in July 2022. In that deal, Xcel agreed to further accelerate the decommissioning of the Comanche Generating Station. The plant is now scheduled to shut down in 2031, nine years earlier than its previously negotiated closing and 39 years before its originally scheduled end of service, according to Xcel. 

The company also committed to the evaluation of renewable technologies to replace the coal plants capacity and keep employees in the community. 

In exchange, Pueblo County agreed to absorb 10 years of property tax payments to account for acceleration of the Comanche plant's retirement date. 

Xcel plans a nearly identical project in Minnesota where it will replace the retiring Sherburne County Generating Station in Becker with another battery storage system.

Xcel's plans were bolstered by a grant of up to $70 million from the U.S. Department of Energy. The grant was awarded to both the Colorado and Minnesota projects. 

Xcel's was one of nine LDES projects awarded federal grant money. The company also received another $20 million from a private renewable energy investment firm. 

The LDES systems will be comprised of iron-air batteries built by Form Energy of Massachusetts. Both will have 10 MW/1,000 MWh capacity. 

"Our batteries complement the function of lithium-ion batteries," Form Energy states on its website. "For scale, in its least dense configuration, a one megawatt system comprises half an acre of land. Higher density configurations would achieve [greater than[ 3 MW/acre."

Per Xcel, most existing battery technologies serve fewer than eight hours of energy storage; Form Energy's iron-air batteries deliver electricity for up to 100 hours. 

"The long duration energy storage systems will strengthen the grid against day-to-day and week-to-week variability of renewable energy," the company stated in its press release.

The Pueblo project still needs to be approved by the Colorado Public Utilities Commission.