Northfield Mountain
Franklin County, Massachusetts · EIA plant ID 547 · Operator: FirstLight Power Resources, Inc. - MA
Nameplate1,168MWSummer 1,168 MW
Generators4in service
Net generation-324GWh12 mo to Aug 2026
Capacity factor—not meaningful for storage
Heat rate—thermal plants only
First online1972
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) |
|---|---|---|---|
| 2001 | -552.2 | — | — |
| 2002 | -512.4 | — | — |
| 2003 | -393 | — | — |
| 2004 | -386.7 | — | — |
| 2005 | -329 | — | — |
| 2006 | -371.3 | — | — |
| 2007 | -579.9 | — | — |
| 2008 | -460 | — | — |
| 2009 | -370.8 | — | — |
| 2010 | -156.1 | — | — |
| 2011 | -296.6 | — | — |
| 2012 | -206.7 | — | — |
| 2013 | -222.3 | — | — |
| 2014 | -309.7 | — | — |
| 2015 | -313.8 | — | — |
| 2016 | -349.1 | — | — |
| 2017 | -339.8 | — | — |
| 2018 | -292.7 | — | — |
| 2019 | -272.6 | — | — |
| 2020 | -262.2 | — | — |
| 2021 | -273.5 | — | — |
| 2022 | -270.3 | — | — |
| 2023 | -181.1 | — | — |
| 2024 | -270.9 | — | — |
| 2025 | -284.6 | — | — |
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 | Hydroelectric Pumped Storage | PS | 292 | 292 | Feb 1973 | Operating | — | coming soon |
| 2 | Hydroelectric Pumped Storage | PS | 292 | 292 | Oct 1973 | Operating | — | coming soon |
| 3 | Hydroelectric Pumped Storage | PS | 292 | 292 | Jul 1973 | Operating | — | coming soon |
| 4 | Hydroelectric Pumped Storage | PS | 292 | 292 | Nov 1972 | Operating | — | coming soon |
Owner / operator
Operator: FirstLight Power Resources, Inc. - MA. Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
| FirstLight Power Resources, Inc. - MA | 100.0% | 1,168 MW |
Nearby plants
Within 80 km.
| NFM Solar Power LLC | 2 MW | 0.2 km |
| Erving CSG | 1 MW | 0.8 km |
| French King Solar LLC | 5 MW | 2.3 km |
| Kearsarge Gill | 2 MW | 6.7 km |
| Erving Paper Mills | 6 MW | 7 km |
| Turners Falls | 6 MW | 7.4 km |