Capturing the sun: Solar project quadruples its battery storage to keep lights on in Utah

Billion-dollar Green River Energy Center will have one of the nation’s largest battery installations

(rPlus Energies) Workers for Sundt Renewables install solar panels at the Appaloosa solar project near Cedar City, which recently started generating power. The same company will install the Green RIver Energy Center, which will include Utah's largest lithium battery array.

This story is part of The Salt Lake Tribune’s ongoing commitment to identify solutions to Utah’s biggest challenges through the work of the Innovation Lab.

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A Utah company is taking a big step to address the limiting factor of solar energy: sunsets.

rPlus Energies, the clean energy company backed by Utah real estate developer Gardner Group, has announced a major expansion of the Green River Energy Center, a solar project it is installing in Emery County in the shadow of the state’s big coal plants.

The company isn’t adding more solar panels. Instead, it’s quadrupling the amount of lithium batteries at the site so that it can store more energy from the panels and dispatch it in the middle of the night.

The project’s battery array will be able to store 1,600 megawatt hours of electricity, four times the original 400 megawatt hours. It also is doubling the power that the project can generate from the batteries, rising from 200 megawatts to 400 megawatts. That allows the batteries to deliver a lot of power over a couple of hours or less power over eight hours or more.

The expansion raises the Green River price tag to roughly $1 billion. It was made possible by a $460 million investment in rPlus from Connecticut-based Sandbrook Capital.

Theresa Foxley, chief of staff for rPlus, said she has been “highly focused” on bringing in Sandbrook’s funding to help not just Green River but also other rPlus projects. Sandbrook has invested more than $4 billion in clean energy projects, much of it in Europe.

“We believe rPlus has built one of the strongest development, construction and operations teams in North America, as evidenced by their advanced portfolio of high-quality projects,” said Sandbrook co-founder and partner Carl Williams in a statement. “Sandbrook’s investment in rPlus underscores our commitment to accelerating the decarbonization of the U.S. grid in partnership with entrepreneurs who embody environmental stewardship, innovation and grit.”

Where the clean energy goes

Green River’s clean energy is bound for PacifiCorp and will serve the 80% of Utahns who get their power from Rocky Mountain Power (a PacifiCorp subsidiary) when it opens next year. The center is less than a 20-mile drive from the Hunter power plant and less than 40 miles from the Huntington plant, currently Rocky Mountain’s biggest power sources in Utah. By locating near the plants, the solar/battery project can more easily connect to major transmission lines.

Utah's largest solar farm and battery project will sit on 3,200 acres north of Moore in Emery County.

“After a decadelong, successful partnership, this milestone project marks the third contracted collaboration between rPlus and PacifiCorp,” said Luigi Resta, rPlus president and CEO. “We appreciate PacifiCorp’s diverse and forward-thinking energy vision, and we look forward to contributing to Emery County’s rich energy history.”

Just last month, power started flowing from another rPlus solar project in Utah. The Appaloosa Solar 1 project near Cedar City began delivering up to 200 megawatts to PacifiCorp, but it is committed to one customer: Meta, the parent company of Facebook and Instagram.

rPlus also built the 80-megawatt Graphite Solar project in Carbon County, which began operation in 2022. That power is also sold to Meta through PacifiCorp.

rPlus also is developing a 900-megawatt “pumped storage” project in Wyoming. The Seminoe project will create a new reservoir uphill from the existing Seminoe Reservoir northeast of Rawlins. When there is an excess of wind power in Wyoming, it can be used to pump water from Seminoe to the upper reservoir. It then can be released to generate power when needed. That is still in the early stages and no power agreements have been signed with utilities.

Utah’s largest solar installation, the Faraday project near Fairfield, will be 673 megawatts when it is completed next year. That project, which is more than a $1 billion, is funded by Excelsior Energy Capital. Its power is committed to Meta through an agreement with PacifiCorp.

At 400 megawatts, Green River will be one of the largest battery installations in the country. The largest is the 750-megawatt battery array at Moss Landing, Calif., on Monterey Bay.

Battery power

Virtually all U.S. utilities are pursuing battery storage. More than 300 utility-scale battery facilities are expected to be operating by the end of 2025. Of the five biggest battery installations coming on line this year and next, four are in Texas, ranging from 433 to 621 megawatts.

All of these projects are eligible for significant tax benefits for clean energy developers. The federal Inflation Reduction Act, passed in 2022, extended the investment tax credit, which covers up to 30% of the cost of the project. The tax advantages grow if the project uses domestically sourced suppliers for the batteries and panels.

Foxley said the company is still negotiating with suppliers.

The contractor for the project is Sundt Renewables, a part of Sundt Construction, a legendary 132-year-old Southwestern firm that built the original University of Arizona buildings in Tucson and the Manhattan Project facilities at Los Alamos, N.M.

About 500 people will be employed during construction, but only a handful of workers will be required to operate it once it is built.