Friday, AUGUST 22, 2025 |
Photo – Map of proposed Pumped Storage Project – Courtesy rPlus Hydro
Officials with the Seminoe Pumped Storage Project clarified recent statements made by the county commissioners.
The Utah-based energy development company, rPlus Hydro, is planning to construct a pumped storage facility at Seminoe Reservoir. rPlus Hydro Managing Director of Hydro Strategy Matthew Shapiro said the plan calls for the construction of a 13,000-acre-foot artificial lake atop Bennett Mountain. When electricity is plentiful, water will be pumped 1,000 feet uphill from the lower Seminoe Reservoir into the higher storage lake. When energy is in high demand, Shapiro explained, the water will flow downhill through an underground hydroelectric turbine, generating power.
The first pumped hydroelectric storage systems were built in Europe in the 1890s. However, the technology is relatively uncommon here in the United States, with the majority of the facilities being built between 1970 and 1990.
Managing Director of Hydro Strategy Shapiro said pumped storage is a quick and easy way to support the country’s electrical grid, and Seminoe Reservoir is an ideal place for such a facility.
Unlike conventional hydroelectric powerplants, pumped storage facilities do not require the construction of a dam. Instead, Shapiro said electricity is generated in a large underground powerhouse. The same turbines are used to pump water back into the upper reservoir.
Shapiro said the Seminoe Pumped Storage Facility will be capable of generating up to 900 megawatts of electricity, roughly the same power output as the coal-fired Dave Johnston Power Plant in Glenrock, Wyoming.
Water levels at Seminoe Reservoir will fluctuate as water moves between it and the upper storage basin. Shapiro said the upper lake is designed to hold 13,000 acre-feet, though only 10,000 acre-feet will be actively cycled while the facility is operating. Because the upper basin is much smaller than Seminoe, the Director of Hydro Strategy said the impact on the reservoir will be small.
At the June 2024 announcement meeting in Sinclair, rPlus Energies Program Manager Lars Dorr said the water level of the Seminoe Reservoir will change by 6 to 18 inches when the facility is operating.
Shapiro said rPlus Hydro has conducted extensive studies to assess the potential impact of the pumped storage facility on the downstream ecosystem, including the Blue-Ribbon fishing habitat known as Miracle Mile. Shapiro said the studies show that the project will have little to no effect.
When the facility is operating, Shapiro said water temperatures in Seminoe Reservoir will be continuously monitored. If temperatures drift outside normal ranges, the facility will be shut down until they return to normal.
Once construction is complete, the facility will transmit electricity across 25 miles of newly built transmission lines to the Aeolus substation near Medicine Bow. Shapiro said the power can then be sent wherever it’s needed.
However, Shapiro said rPlus Hydro has not yet found a buyer for the electricity produced by the Seminoe Pumped Storage Facility, which is required before construction can begin.
At their August 19th meeting, the Board of Carbon County Commissioners stated that rPlus Hydro had not signed an agreement with PacifiCorp, owners of the Aeolus substation, to route power generated by the Seminoe Pumped Storage Facility to the grid. Shapiro confirmed the Board’s comments, adding that rPlus had applied for access to the substation, but later withdrew the application. The Director of Hydro Strategy said the company intends to reapply at a later date.
Also, during the August 19th meeting, County Attorney Ashley Davis said rPlus has stated that building the pumped storage facility will impact tourism at Seminoe Reservoir for five years. Shapiro responded to the County Attorney’s comments by saying construction will not prevent people from accessing the popular recreation area.
On July 14th, Wyoming Industrial Siting Administrator Jenny Staeben informed the Board of Carbon County Commissioners that rPlus Hydro had not reached out to the Industrial Siting Council for a construction permit and may be under the mistaken assumption it does not require one. All construction projects in Wyoming with an estimated build cost exceeding $253 million must obtain a permit from the Industrial Siting Council before beginning construction. With an estimated price tag of over $3 billion, the Seminoe Pumped Storage Project falls under the scope of the ISC.
rPlus Hydro Managing Director of Hydro Strategy Matthew Shapiro said his company has been in contact with the Industrial Siting Council since the project’s inception and is well aware this project requires a permit.
Last fall, the Federal Energy Regulatory Commission, or FERC, accepted the final license application for the Seminoe Pumped Storage Project and held public comment meetings in Casper and Rawlins. The next step is for FERC to finalize its environmental impact report. Shapiro said after another round of public comment meetings, he hopes FERC will approve the project by next spring.
If all the permits are acquired and a customer can be found to purchase the electricity generated by the Seminoe Pumped Storage Facility, Shapiro said construction could begin in 2028. The Managing Director of Hydro Strategy said the project is the best way to meet the state’s increasing power demands.
When completed, Shapiro said the pumped storage facility is estimated to generate up to $10 million a year in tax revenue and employ approximately 30 people.
