What comes next, coast to coast.
Proposed pumped storage developments in upstate New York and the Southern Sierra Nevada, extending our portfolio to the east coast grid.
Ashokan Pumped Storage
- Power options
- 700–2,000 MW
- Head
- 594 ft
- Upper reservoir
- 226 acres · 25,558 acre-ft
- Interconnection
- 230 kV · Hurley Av. Sub.
- Units
- 5 × 560 MW
About the project
Located in upstate New York using the Ashokan reservoir, the project proposes the construction of an upper reservoir with a total area of 226 acres and a volume of 25,558 acre-ft in the surrounding area. The proposed interconnection uses 230 kV transmission lines linking the new substation with the existing Hurley Av. Substation.
Generation options
| Option | Generation time (h) | Power (MW) | Head (ft) |
|---|---|---|---|
| Option 1 | 6 | 1,200 | 594 |
| Option 2 | 4 | 2,000 | 594 |
| Option 3 | 12 | 700 | 594 |
Estimated pipe lengths (Option 1)
| Element | Diameter (ft) | Length (mi) |
|---|---|---|
| Headrace tunnel | 47 | 0.38 |
| Vertical shaft | 42 | 0.09 |
| Horizontal tunnel | — | 2.64 |
| Penstocks | 27 | 0.04 |
| Tailrace tunnel | 50 | 0.55 |
Equipment
To supply 1,200 MW and 2,000 MW when necessary (pumping 1,680 MW and 2,800 MW, respectively), the project requires 5 new pump-turbine generator-motor sets, each with a nominal rating of 560 MW. Longer-duration storage is possible, but could affect the Ashokan Reservoir level beyond the proposed 2 ft maximum.
Environmental approach
The area lies near Catskill Park, an extensive forest and wild area. All necessary measures have been taken to avoid interfering with the wilderness: the proposed upper reservoir is located away from natural areas, and the connections between reservoirs run underground so as not to interfere with the landscape — an eco-friendly solution.
Isabella Pumped Storage
- Capacity
- 2,000 MW
- Lower pool
- Existing Isabella Reservoir
- Upper pool
- Southern Sierra Nevada
- Interconnection
- SCE or PG&E grid
About the project
The proposed Isabella Pumped Storage Project would be located 40 miles northeast of Bakersfield, California, in Kern County. The project envisions a 2,000 MW pumped storage plant using the existing Isabella reservoir as the lower pool and a new reservoir in the Southern Sierra Nevada Mountains as the upper pool. The project would operate in a closed loop — aside from evaporation and percolation losses, the project's water would stay within the system.
Existing Isabella Reservoir dams
| Dam | Crest elev. (ft) | Height (ft) | Crest length (ft) | Completed | Composition |
|---|---|---|---|---|---|
| Main Dam | 2,633 | 185 | 1,695 | 1953 | Earthen |
| Auxiliary Dam | 2,635 | 100 | 3,160 | 1953 | Earthen |
Powerhouse
The powerhouse location will depend on the upper reservoir alternative. The approximate floor level would be between 200 ft and 300 ft below ground level. The cavern will be stabilized with high-strength projected concrete (shotcrete), with steel formwork and concrete as necessary. Tentative powerhouse dimensions are 500 ft long, 125 ft wide, and 150 ft high. Adjacent to the powerhouse, the transformers chamber cavern — also stabilized with shotcrete — would measure roughly 165 ft long, 60 ft wide, and 50 ft high. Generating/pumping units, electrical switchyards, interconnecting transmission lines, and other appurtenant facilities complete the project.
Interconnection
The project is expected to have a rated capacity of 2,000 MW and would interconnect with the existing Southern California Edison (SCE) or Pacific Gas and Electric (PG&E) transmission grid to provide energy storage for renewable resources. Other electrical utilities in California are expected to be interested in the project.