United Power pushes ahead on battery storage

Colorado’s second largest cooperative 313.34 megawatt-hours of storage at six locations across its service territory

Preparing for its plans to become an independent utility, United Power has announced an agreement with Ameresco to install eight sets of batteries at strategic locations across the electrical cooperative’s service territory in northern Colorado.

The agreement calls for 78.3 megawatts/313.34 megawatt-hours of battery storage.

(Storage duration is the amount of time storage can discharge at its power capacity before depleting its energy capacity. For example, a battery with 1 MW of power capacity and 4 MWh of usable energy capacity will have a storage duration of four hours. – For more information, see this explainer from NREL, “Grid-Scale Battery Storage.”)

These batteries, explained Mark Gabriel, chief executive of United Power, are “essential to a resilient and responsive power system.” The batteries will enable United to balance its daily power needs and incorporate local renewables more efficiently.

Gabriel said batteries have become very competitive thanks to funding provided by the Inflation Reduction Act and tax credits that cover 30% to 50% of the costs.

United serves nearly 110,000 meters in its service territory on metro Denver’s northern side. That territory extends from the foothills west of Arvada to the proliferating housing tracts around Firestone and Brighton and to the oil-and-gas fields of Weld County.

In late 2018, United became the first utility in Colorado to have a storage battery. Installed behind the utility’s office between Longmont and Firestone, the Tesla batteries (see photo above) have 4 megawatt-hours of storage. It also has a smaller battery installation at its headquarters in Brighton.

In November 2022, that capacity was finally surpassed in Colorado by the 15 megawatt-hour capacity installed in conjunction with a solar project for Holy Cross Energy. In June, Xcel Energy added battery-storage that dwarfed that of Holy Cross. Next Era Energy Resources described the capacity of the battery storage for the Thunder Wolf Energy Center as 100 megawatts. See also: “Colorado’s newest biggest battery.”

As for United, it currently gets nearly all of its electricity from Tri-State Generation and Transmission. That contract ends in 2050. However, United wants out and expects to be out by May 1, 2024.

The major remaining hurdle is figuring out how much it must pay Tri-State and its remaining 41 members to leave them whole. The formula for determining those costs is expected to be ruled upon by FERC later this year.