Seminoe Reservoir

Seminoe Reservoir, located about 30 miles outside of Rawlins, is a popular summer recreation site for boaters and fishermen. The reservoir has been identified by the federal government as an ideal location for pumped storage of energy.

RAWLINS — As renewable energy is integrated into the grid, developers say a project at Seminoe Reservoir will address energy storage needs in the Western United States.

“Wyoming has traditionally been an energy exporter, but the forms of energy that it has been exporting are changing,” said Matthew Shapiro, CEO of rPlus Hydro. “The tremendous wind resource is going to be used across more than one state, and it is going to be exported to Utah and the Pacific Northwest.

“But it needs a battery. It needs storage, because wind is only available when it is blowing, just like solar is only available when the sun is shining.”

rPlus Hydro is continuing work on plans for a 900-megawatt pumped hydro energy storage project at Seminoe Reservoir which, once complete, would provide 10 hours of storage capacity. The project also is aimed at efficient usage of transmission lines being built to deliver wind energy to market.

Environmental, biological and cultural studies on the Seminoe Pumped Storage Project are underway, along with technical engineering and design.

A draft license application will be filed with the Federal Energy Regulatory Commission (FERC) in the first quarter of 2022. The project also requires a special permit from the Bureau of Reclamation and a right of way from the BLM, among other permits. rPlus Hydro hopes to secure the FERC license in 2024, with construction happening from 2025-2029.

“Next year is going to be a big year for the project,” Shapiro said, adding that PacifiCorp also is reviewing an application to integrate energy stored into the grid.

Developers say the project, representing an investment of more than $2 billion, will help diversify the economy of Carbon County.

“We will be preparing an economic impact study as part of license preparation, but typically in our estimations, we are seeing that a project like this would require 400 to 500 full-time construction jobs for a period of four years,” Shapiro said.

Those jobs will most likely be in heavy construction, earth moving, tunneling and road maintenance. After construction, there will be 30-35 full-time permanent employees at the facility.

“There is also the indirect impact of having workers spend money in a given area,” Shapiro said.

Shapiro approached the Carbon County Board of Commissioners with the plan in August and said he plans to update the community again soon.

“We want the community to understand the project, and we do plan on providing the commissioners an update soon,” he said.

Pumped hydro energy storage, or simply “pumped storage,” is a form of large-scale energy storage that shifts water between two reservoirs at different elevations. As utilities retire conventional generation and rely more heavily on wind and solar energy, the need for energy storage is growing dramatically, according to rHydro.

Pumped storage is the “most established and most economical form of bulk energy storage available today,” the company says, and pumped storage plants have an operational lifespan of more than 75 years.

Seminoe Reservoir was previously identified in studies by the federal government as an ideal location for pumped storage. The project involves building a new upper reservoir 1,000 feet in elevation above Seminoe and connecting that reservoir with the existing reservoir through underground tunnels. The primary surface features would be the upper reservoir and a project transmission line.

The new reservoir would be about 100 acres in size and hold about 10,000 acre-feet of water. This is equivalent to about 1% of the full volume of Seminoe Reservoir.

Other than the initial fill, the project would consume no water except for what is needed to replenish evaporation loss

Stantec Inc., an engineering firm with offices in northern Colorado and Cheyenne, will conduct a detailed feasibility study for the Seminoe Pumped Storage Project into 2022. Stantec will identify and analyze the alternative intake and outlet structure types for the project and will identify the location and type of upper reservoir to complete the pumped storage scheme above Seminoe Reservoir.

Additionally, the firm will plan and perform a geotechnical investigation that will support the feasibility design of the underground facilities, identify pump-generating equipment, identify routing for a transmission line that will lead to nearby grid interconnection, evaluate project constructability and provide an opinion on probable construction cost.

“We need large-scale proven solutions like hydro pumped storage to address the energy storage needs in the United States,” said Mario Finis, executive vice president for Stantec’s Energy & Resources business. “Stantec is privileged to partner with rPlus Hydro in studying the feasibility of this project, which will play a critical role in increasing grid reliability and increased generation from clean renewable energy sources.”

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