Big Stone
Grant County, South Dakota · EIA plant ID 6098 · Operator: Otter Tail Power Co
Nameplate451MWSummer 479 MW
Generators2in service
Net generation1,640GWh12 mo to Aug 2026
Capacity factor39%gas/coal/oil units, summer MW
Heat rate10,283Btu/kWhfossil units, electric fuel, HHV
First online1975Runs as baseload
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), gas/coal/oil units. Each year uses that year's EIA-860 ratings; the hollow dot is the latest 12 months.
Heat rate by year
Electric fuel MMBtu × 1000 ÷ net MWh (Btu/kWh, HHV), fossil units only; CT + CA counted as one combined-cycle block.
Annual data table
| Year | Net GWh | Capacity factor | Heat rate (Btu/kWh) |
|---|---|---|---|
| 2001 | 3,462 | — | — |
| 2002 | 3,119.5 | — | — |
| 2003 | 3,282.6 | 82.3% | 10,584 |
| 2004 | 3,477.7 | 86.9% | 10,764 |
| 2005 | 2,846.7 | 70.5% | 10,607 |
| 2006 | 3,174 | 77.0% | 10,366 |
| 2007 | 2,520.9 | 61.1% | 10,583 |
| 2008 | 3,575 | 84.8% | 10,693 |
| 2009 | 3,101.4 | 73.6% | 10,767 |
| 2010 | 3,169.2 | 76.1% | 10,824 |
| 2011 | 2,459.4 | 59.0% | 11,029 |
| 2012 | 2,830.4 | 67.8% | 10,918 |
| 2013 | 2,854.8 | 68.5% | 10,822 |
| 2014 | 2,692.6 | 64.6% | 10,980 |
| 2015 | 1,498.7 | 36.0% | 10,881 |
| 2016 | 2,084.3 | 50.0% | 10,311 |
| 2017 | 2,064.6 | 49.7% | 10,317 |
| 2018 | 2,343.3 | 56.4% | 10,227 |
| 2019 | 2,619.1 | 63.0% | 10,233 |
| 2020 | 1,650.1 | 39.6% | 10,317 |
| 2021 | 1,640.6 | 39.5% | 10,274 |
| 2022 | 1,876.7 | 45.0% | 10,280 |
| 2023 | 1,566.6 | 37.6% | 10,333 |
| 2024 | 1,565.7 | 37.3% | 10,344 |
| 2025 | 2,029.6 | 48.4% | 10,267 |
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 | Conventional Steam Coal | ST | 450 | 477.6 | May 1975 | Operating | — | coming soon |
| D1 | Petroleum Liquids | IC | 1 | 1.1 | May 1975 | Operating (Standby / backup) | — | coming soon |
Owner / operator
Operator: Otter Tail Power Co. Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
| Otter Tail Power Co | 53.9% | 243 MW |
| NorthWestern Energy - (SD) | 23.4% | 106 MW |
| Montana-Dakota Utilities Co | 22.7% | 102 MW |
Nearby plants
Within 80 km.
| State Auto Insurance | 2 MW | 12.4 km |
| Valley Queen Cheese | 5 MW | 13.5 km |
| Crowned Ridge Wind Energy Center | 200 MW | 30.5 km |
| Dakota Range Wind | 304 MW | 41.1 km |
| Dakota Range III Wind Project | 154 MW | 46.6 km |
| Crowned Ridge Wind II Energy Center | 201 MW | 46.7 km |