Utah company advances pumped storage project in Wyoming

The 900-megawatt power plant would provide renewable electricity even when there was no wind or sun

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

Salt Lake City-based rPlus Hydro announced Thursday that it has submitted its final application to the Federal Energy Regulatory Commission to build a 900-megawatt pumped-storage project north of Rawlins, Wyo.

Pumped storage projects act as giant batteries. Wyoming has added wind and solar farms in the area, and these farms would provide the energy to pump water uphill from a lower reservoir to an upper reservoir.

Then when the energy is needed, the process is reversed. The water flows from the upper reservoir through an underground hydroelectric turbine to the lower reservoir, where it produces electricity on demand.

Dubbed the Seminoe Project, the project would use the existing Seminoe Reservoir north of Rawlins, Wyoming as the lower reservoir. An upper reservoir would be built 1,000 feet higher in the mountains near Seminoe. When full, the upper reservoir can deliver 900 megawatts of power for up to 10 hours, enough to power thousands of homes. It takes 12 hours of available wind or sun to fully charge, but its cycles are dependent on wind and sun availability. It is intended as a backup for those sources that can record after the wind has stopped and the sun has gone down.

“This project will help to extract all the values ​​of the wind, solar and transmission lines,” said Luigi Resta, President of rPlus Hydro. For the four-year-old company, which is backed by real estate and development company Gardner Group, it is the first project to reach the final application phase.

Two major transmission lines are under construction near the project. One is the Gateway South Line that PacifiCorp is building from southeastern Wyoming to Mona, Utah. The other line, the Transwest Express line, will run from Wyoming to the Intermountain Power Plant near Delta, where it can be connected to another transmission line to Southern California.

These lines give the project access to multiple electricity providers who could be potential customers for the electricity. That includes Rocky Mountain Power’s customers in Utah, but it could include other systems as far away as California.

It’s a $2.5 billion project that is expected to be operational by 2031. The cost will ultimately be borne by the electricity customers using the electricity, although the federal government can cover up to half the cost through the Inflation Reduction Act, Resta said.

With the filing this month, the environmental analysis will begin, including the writing of an Environmental Impact Statement. Three federal agencies are involved, and the process could take more than two years. The existing Seminoe Reservoir is operated by the US Bureau of Reclamation. The upper reservoir would be built on Bureau of Land Management land, and the Federal Energy Regulatory Commission oversees all power plant development in the country.

Resta said the company conducted preliminary research to determine there were no environmental or cultural resources that would prevent construction. The environmental analysis includes a public comment period.

There are currently 43 licensed pumped storage projects in the country, most of them east of the Mississippi. This would be the first in Wyoming. Utah has no licensed pumped storage projects, although several are proposed.

As more solar resources come online, the need for storage becomes more acute. The so-called “duck curve” describes the problem when energy suppliers have to shut down other sources when the sun is shining and then have to start up the other sources again when the sun goes down. Pumped storage can provide on-demand electricity that comes online quickly when the sun goes down.

Tim Fitzpatrick is a renewable energy reporter for The Salt Lake Tribune, a position funded by a grant from Rocky Mountain Power. The Tribune retains overall control of editorial decisions independent of Rocky Mountain Power.