Big Stone
Coal power plant · Grant County, South Dakota
Nameplate capacity
451 MW
Rank in South Dakota
#3
of 54 plants
In service since
1975
May 1975
Details
- Primary fuel
- Coal
- Technology
- Conventional Steam Coal
- Operator
- Otter Tail Power Co
- County
- Grant County
- Generating units
- 2
- Share of state capacity
- 5.88%
- Rank among coal plants in South Dakota
- #1 of 1
- EIA plant code
- 6098
Generating units
| Unit | Technology | Nameplate | Summer | Online | Status |
|---|---|---|---|---|---|
| 1 | Conventional Steam Coal | 450 MW | 478 MW | 1975 | Operating |
| D1 | Petroleum Liquids | 1.0 MW | 1.1 MW | 1975 | Standby/Backup: available for service but not normally used |
Nameplate is the maximum rated output; summer capacity is what the unit can reliably deliver on a hot day, which is typically lower.
Similarly sized plants in South Dakota
| Oahe | Hydro | 786 MW |
| Big Bend Dam | Hydro | 538 MW |
| Angus Anson | Natural gas | 406 MW |
| Astoria Station | Natural gas | 349 MW |
About this data
From EIA’s inventory of operable generators, May 2026 release. Capacity is nameplate — the maximum rated output of the equipment, not what the plant actually generates over a year, which depends on how often it runs. A 451 MW solar plant and a 451 MW nuclear plant have the same entry here and produce very different amounts of electricity.
“In service since” is the earliest in-service date among the units still listed, so a site rebuilt around newer equipment can read as younger than the site itself. All South Dakota power plants · What South Dakota actually generates