99 Islands
Cherokee County, South Carolina · EIA plant ID 3272 · Operator: Duke Energy Carolinas, LLC
Nameplate12MWSummer 15 MW
Generators4in service
Net generation31GWh12 mo to Dec 2025
Capacity factor23%hydro units, summer MW
Heat rate—thermal plants only
First online1910
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), hydro 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.
Heat rate applies to fuel-burning (thermal) units only.
Annual data table
| Year | Net GWh | Capacity factor | Heat rate (Btu/kWh) |
|---|---|---|---|
| 2001 | 25.4 | 30.2% | — |
| 2002 | 29.4 | 27.9% | — |
| 2003 | 63.2 | 60.1% | — |
| 2004 | 53.4 | 50.6% | — |
| 2005 | 38.9 | 37.0% | — |
| 2006 | 5.6 | 6.7% | — |
| 2007 | 37.6 | 44.6% | — |
| 2008 | 33.7 | 40.0% | — |
| 2009 | 62.4 | 74.2% | — |
| 2010 | 69.9 | 83.1% | — |
| 2011 | 50.7 | 60.3% | — |
| 2012 | 49.6 | 58.8% | — |
| 2013 | 91.6 | 108.9% | — |
| 2014 | 78.8 | 93.7% | — |
| 2015 | 61.4 | 48.7% | — |
| 2016 | 45.2 | 35.7% | — |
| 2017 | 50.6 | 28.9% | — |
| 2018 | 83.3 | 48.5% | — |
| 2019 | 67.6 | 50.8% | — |
| 2020 | 80.3 | 60.2% | — |
| 2021 | 61.2 | 46.0% | — |
| 2022 | 45.3 | 34.1% | — |
| 2023 | 62.1 | 46.6% | — |
| 2024 | 36.5 | 27.3% | — |
| 2025 | 31.3 | 23.5% | — |
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 Hydroelectric | HY | 3 | 4.2 | May 1910 | Operating | — | coming soon |
| 2 | Conventional Hydroelectric | HY | 3 | 3.4 | May 1910 | Operating | — | coming soon |
| 3 | Conventional Hydroelectric | HY | 3 | 4.2 | May 1910 | Operating | — | coming soon |
| 4 | Conventional Hydroelectric | HY | 3 | 3.4 | May 1910 | Operating | — | coming soon |
| 5 | Conventional Hydroelectric | HY | 3 | 2.4 | May 1910 | Retired Dec 2018 | — | coming soon |
| 6 | Conventional Hydroelectric | HY | 3 | 2.4 | May 1910 | Retired Dec 2018 | — | coming soon |
Owner / operator
Operator: Duke Energy Carolinas, LLC. Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
| Duke Energy Carolinas, LLC | 100.0% | 12 MW |
Nearby plants
Within 80 km.
| Cherokee Falls | 4 MW | 6 km |
| Broad River Energy Center | 985 MW | 9.1 km |
| Cherokee County Cogen | 118 MW | 11.8 km |
| Mohea Solar Energy Center, LLC | 5 MW | 13.5 km |
| Gaston Shoals | 5 MW | 15.2 km |
| Mill Creek (SC) | 799 MW | 15.4 km |