Ples I

Geothermal power plant in California, United States of America. Approximate location 37.6455, -118.9096.

GeothermalCaliforniaUnited States of America

Ples I is a 15 MW geothermal power plant in California, United States of America. It is operated by Ormat Nevada Inc. Based on reported annual generation of 82 GWh, it can supply roughly 23,542 homes. It ranks #4136 of 9,833 United States of America power plants by installed capacity. Commissioned in 1991, it is around 35 years old — long-established. As a non-combustion source, it has no direct CO₂ emissions from generation. In context, geothermal supplies about 0.4% of United States of America's electricity; the national grid averages 384 gCO₂/kWh (43.0% low-carbon) (2025).

15MW installed capacity
82GWh reported / yr
23,542homes powered
1991commissioned (~35 yrs)

Plant data: WRI Global Power Plant Database (CC BY 4.0), id USA0010479.

Reported generation trend

2013: 100 GWh20132014: 94 GWh20142015: 89 GWh20152016: 87 GWh20162017: 96 GWh20172018: 86 GWh20182019: 82 GWh2019100 GWh

Annual generation (GWh), WRI Global Power Plant Database (CC BY 4.0).

Owner

Operated by Ormat Nevada Inc. All plants by this company →

Local climate & thermal context

This geothermal plant taps underground heat to raise steam that drives a turbine. It sits in a warm-summer Mediterranean climate (Köppen Csb) — Northern Hemisphere, latitude 37.6°N — which shapes how much energy it can produce and how its output varies through the year.

5.6°Cannual mean temp
4,490heating degree-days (base 18°C)
0cooling degree-days (base 18°C)
2,440 melevation

Monthly mean temperature

J: -4 °CJF: -2 °CFM: 0 °CMA: 3 °CAM: 7 °CMJ: 12 °CJJ: 16 °CJA: 16 °CAS: 12 °CSO: 7 °CON: 2 °CND: -2 °CD16 °C

Heating degree-days here run 83% above the median power plant in this dataset — a proxy for how much extra energy heated equipment must replace through its surfaces in winter.

Climate heat-demand index: 90/100 — this site sits in the top third of the power plants we cover by heating degree-days.

In colder climates, uninsulated hot equipment (boilers, turbines, valves, steam lines) loses proportionally more heat to ambient air — exactly the loss Inzonex modular insulation is designed to cut.

Climate normals: WorldClim 2.1 (1970–2000 monthly normals, 10 arc-min, CC BY 4.0); zone: Köppen-Geiger world climate classification (Kottek et al. 2006, 0.5° grid). Degree-days & heat-demand index computed by PowerAtlas — a modelled heat-demand proxy, not a measured site figure.

How it compares & nearby plants

The #56 largest geothermal power plant of 65 in United States of America by capacity.

United States of America has 65 geothermal power plants in this dataset, together about 3,889 MW of capacity.

Nearby power plants

Location

Coordinates 37.6455, -118.9096 from WRI Global Power Plant Database (CC BY 4.0). View on OpenStreetMap.

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