South Portland ESS, LLCPlanned
Cumberland County, Maine · EIA plant ID 64616 · Operator: South Portland ESS, LLC
10 MW planned (Batteries), first expected Dec 2027 · EIA-860M
Nameplate—MWSummer — MW
Generators0in service
Net generation—GWh12 mo
Capacity factor—not meaningful for storage
Heat rate—thermal plants only
First online—
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.
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 | 10 | 10 | planned Dec 2027 | Planned | — | coming soon |
Owner / operator
Operator: South Portland ESS, LLC. Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
Nearby plants
Within 80 km.
| Regional Waste Systems | 13 MW | 3.6 km |
| Larson | 5 MW | 4.2 km |
| Westbrook Energy Center Power Plant | 564 MW | 5.2 km |
| BWC Beech Ridge Brook, LLC | 5 MW | 6.3 km |
| Cape Gas Turbine | 35 MW | 6.6 km |
| MEVS Waterhouse | 2 MW | 6.8 km |