FAQs

Seminoe Pumped Storage will provide Wyoming with an important, versatile, and economical tool for supporting reliable power supply and grid stability. As the state and region modernizes its electrical system and transitions to greater reliance on variable and intermittent resources, like solar and wind energy, energy storage is becoming critically important. Detailed socioeconomic studies and analyses are being conducted. Preliminary estimates are described below.

Development (2020-2025):

-Income from lodging, gas, dining and other local spending by project development support staff.

-Employment of local expertise in project development support wherever possible.

Construction (2026-2030): -

Approximately 300-500 full-time construction jobs for a period of 5 years, with the significant indirect economic benefits that come with local spending.

Operation (2030-):

-An expected 18-24 permanent full-time jobs in the Rawlins area, with the indirect economic benefit to the community that those jobs bring.

Water need will vary across the different project phases.

-Construction: requirement estimated to be 200 to 500 acre-feet per year for five years.

-Initial Fill: 10,000 acre-feet

-Evaporation Makeup: estimated 200-300 acre-feet per year for the life of the project.

Black Canyon Hydro, on behalf of the Seminoe Pumped Storage project, is engaging with existing water rights holders at the Seminoe Reservoir to negotiate a water supply agreement for the initial fill volume as well as ongoing water rights to replenish evaporation losses.

The Seminoe Reservoir has a capacity of 1,017,289 acre-feet. At 10,000 acre-feet, the Seminoe Pumped Storage project is approximately 1% of the volume of the existing Seminoe Reservoir.

During construction, there would be significant activity at the upper reservoir site. This would primarily involve earth-moving activity. Underground activity would consist primarily of tunneling. Mitigation of construction-related impacts will be subject to rigorous regulatory and licensing review by the FERC and under the NEPA process for the project. An existing road to the upper site, accessed off Kortes Road, will need to be improved for construction access. Any other road improvements needed to minimize dust, etc. will be made per applicable requirements. It is anticipated that the majority of heavy equipment required for construction will be transported in an initial mobilization to the reservoir work area and remain there for the duration of the construction phase. This will help to isolate construction activities to the immediate vicinity of the project and minimize excessive disruptions to the community. After construction, the project would produce no emissions, noise or light pollution, and traffic would be minimal, limited to required maintenance activities. The upper reservoir dam, will not be visible from most public vantage points. In terms of visual impact of the project structures, the lower intake structure will be near the bottom of the Seminoe Reservoir and will not be visible. Visual simulations of other project facilities will be created as part of the preparation of the FERC license application in 2022. The primary traffic to the project would be during crew changes for staffing the powerhouse, which would be accessed from Seminoe Road. Visits to the upper reservoir site would be minimal.

The project plans to interconnect to PacifiCorp’s transmission system via a new transmission line that will run approximately 30 miles to PacifiCorp’s Aeolus Substation near Medicine Bow. The 500kV line will use lattice towers and is planned to run parallel to two existing transmission lines.

Black Canyon Hydro does not anticipate any impact to most activities on Seminoe Reservoir. It is not anticipated that the project will have any impact on fishing or boating. The potential effects on ice fishing due to small fluctuations in water level are being studied.

The new upper reservoir will be subject to significant daily fluctuations in water levels. For safety reasons in particular, it will not be usable for recreation purposes.

The upper reservoir is located within sage grouse General Habitat Management Areas (GHMA). Most of the proposed transmission line route is located within sage grouse Priority Habitat Management Areas (PHMA). Protection of sage grouse and their habitat is a high priority for Black Canyon Hydro, residents, and state and federal permitting agencies. Field surveys commenced in spring 2021 and will be further undertaken to get an up-to-date and accurate understanding of sage grouse habitat and leks in the vicinity of the project. Any resulting constraints, conditions, or mitigation measures will inform the next steps of project development. Given the relatively small footprint of the project, Black Canyon Hydro believes that the project will be compatible with existing state and federal resource management plan requirements to protect sage grouse and sage grouse habitat in the project vicinity.

Water need will vary across the different project phases.

-Construction: requirement estimated to be 200 to 500 acre-feet per year for five years.

-Initial Fill: 10,000 acre-feet

-Evaporation Makeup: estimated 200-300 acre-feet per year for the life of the project.

Black Canyon Hydro, on behalf of the Seminoe Pumped Storage project, is engaging with existing water rights holders at the Seminoe Reservoir to negotiate a water supply agreement for the initial fill volume as well as ongoing water rights to replenish evaporation losses.

The Seminoe Reservoir has a capacity of 1,017,289 acre-feet. At 10,000 acre-feet, the Seminoe Pumped Storage project is approximately 1% of the volume of the existing Seminoe Reservoir.

The project is intended to serve customers and utility loads in Wyoming and the surrounding region. The energy storage capacity of the Project will enhance the value of abundant, but intermittent, Wyoming wind.

Pumped storage hydro is the best established form of energy storage used around the world, and is the most economical for long duration of energy storage. It also has the longest useful life (80+ years). As the cost of chemical energy storage (batteries) has come down, utilities have begun using them for energy storage, and this use is expected to increase significantly. Utilities’ interest in the better-established technology of pumped storage continues, however, because of the substantial advantages that it retains over battery storage. These advantages include:

-Lower cost at longer duration (anything longer than 6 hours)

-A much longer lifespan (80+ years for pumped storage vs. 10-20 years for batteries)

-Unlike batteries, no degradation of efficiency or storage capacity for pumped storage no matter how frequently the plant is cycled or how deep the discharge is (i.e., how low the water level gets in the upper reservoir).

As with all energy storage facilities, there is an efficiency loss in the round-trip cycle of pumping and generating. Newer pumped storage plants like Seminoe Pumped Storage are expected to have a round-trip efficiency of 78-80%. This round trip efficiency is slightly lower than for a battery energy storage system.

To house the construction workforce, a wide range of options, including temporary worker-camps, use of mobile housing units, and available housing in Rawlins, Casper, and surrounding cities will be considered. The project team will work closely with local government on development and implementation of the workforce housing plan.