1st largest plant in Massachusetts · 116th nationally
Mystic Generating Station is a natural gas power plant in Massachusetts with a nameplate capacity of 1,744 MW. It generates roughly 1.3M MWh per year — enough to power about 124,422 average U.S. homes.
Its capacity factor of 9% reflects intermittent or peaking operation. At 884 lb CO₂/MWh, its emission rate sits above the national grid average of roughly 800 lb/MWh.
Ghost bars are each month's theoretical maximum (1,744 MW nameplate × hours in the month). Filled bars are actual net generation reported to EIA Form 923. The gap between them is capacity factor made visible.
| Plant Name | Mystic Generating Station |
|---|---|
| Operator | Constellation Mystic Power Llc |
| City | Charlestown |
| County | Middlesex County |
| State | Massachusetts |
| ZIP | 02129 |
| Coordinates | 42.39080, -71.06750 |
This plant highlighted in navy-ringed pin; other generators within 25 miles shown as fuel-colored dots.
| ID | Technology | Fuel | Capacity | Status | Online |
|---|---|---|---|---|---|
| 7 | Petroleum Liquids | Residual Oil | 617 MW | Retired | 1975 |
| ST85 | Natural Gas Fired Combined Cycle | Natural Gas | 315 MW | Retired | 2003 |
| ST96 | Natural Gas Fired Combined Cycle | Natural Gas | 315 MW | Retired | 2003 |
| GT81 | Natural Gas Fired Combined Cycle | Natural Gas | 279 MW | Retired | 2003 |
| GT82 | Natural Gas Fired Combined Cycle | Natural Gas | 279 MW | Retired | 2003 |
| GT93 | Natural Gas Fired Combined Cycle | Natural Gas | 279 MW | Retired | 2003 |
| GT94 | Natural Gas Fired Combined Cycle | Natural Gas | 279 MW | Retired | 2003 |
| 4 | Petroleum Liquids | Residual Oil | 156 MW | Retired | 1957 |
| 5 | Petroleum Liquids | Residual Oil | 156 MW | Retired | 1959 |
| 6 | Petroleum Liquids | Residual Oil | 156 MW | Retired | 1961 |
| GT1 | Petroleum Liquids | Distillate Oil | 14.2 MW | Retired | 1969 |
| CO₂ | 577.3k metric tons |
|---|---|
| SO₂ | 3 metric tons |
| NOₓ | 37 metric tons |
| CO₂ Rate | 884 lb/MWh |
Annual totals and CO₂ rate reported by EPA eGRID for 2023. Reference averages are approximate U.S.-wide figures from the same dataset.
| NERC Region | NPCC |
|---|---|
| Balancing Authority | Iso New England Inc. |
Natural gas plants are the workhorse of the modern grid. Combined-cycle units achieve very high efficiency and can ramp up and down quickly to balance variable renewables. They emit roughly half the CO₂ per MWh of coal and far less of other pollutants, but they still release upstream methane during fuel extraction.