Black Mesa BESS
Elmore County, Idaho · EIA plant ID 66326 · Operator: Idaho Power Co
Nameplate40MWSummer 40 MW
Generators1in service
Net generation-3GWh12 mo to Aug 2026
Capacity factor—not meaningful for storage
Heat rate—thermal plants only
First online2024
The 12-month figures include preliminary EIA-923 months, which EIA revises. Final data runs through Dec 2025.
Monthly net generation
EIA-923, all units at the plant. Net of station use; storage can go negative.
FinalPreliminary
Capacity factor by year
Net MWh ÷ (summer MW × hours), primary-fuel units. Each year uses that year's EIA-860 ratings; the hollow dot is the latest 12 months.
No capacity factor available.
Heat rate by year
Electric fuel MMBtu × 1000 ÷ net MWh (Btu/kWh, HHV), fossil units only; CT + CA counted as one combined-cycle block.
Heat rate applies to fuel-burning (thermal) units only.
Annual data table
| Year | Net GWh | Capacity factor | Heat rate (Btu/kWh) |
|---|---|---|---|
| 2025 | -3.2 | — | — |
Generators
EIA-860 (annual) with EIA-860M updates through Sep 2026. EIA-923 reports generation by plant, prime mover and fuel, not by unit, so unit-level output isn't shown.
| Gen ID | Technology | Prime mover | Nameplate MW | Summer MW | Online | Status | Planned retirement | OEM / model |
|---|---|---|---|---|---|---|---|---|
| 1 | Batteries | BA | 40 | 40 | Sep 2024 | Operating | — | coming soon |
Owner / operator
Operator: Idaho Power Co. Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
| Idaho Power Co | 100.0% | 40 MW |
Nearby plants
Within 80 km.
| Black Mesa Solar, LLC | 40 MW | 0.1 km |
| Bliss | 75 MW | 9 km |
| High Mesa | 40 MW | 12.2 km |
| Tuana Springs | 17 MW | 13.5 km |
| Cassia Wind | 8 MW | 13.8 km |
| Cassia Gulch | 19 MW | 13.9 km |