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Stillwater, NV – triple hybrid geothermal and solar plant

Stillwater, NV – triple hybrid geothermal and solar plant Stillwater hybrid geothermal-solar plant, Nevada (source: Enel, video screenshot)
Alexander Richter 7 May 2021

Enel Green Power operates the unique triple hybrid Stillwater geothermal power plant in Nevada that combines geothermal, solar PV and solar thermal.

Enel Green Power operates a unique geothermal power plant in Stillwater in Churchill County, about 60 miles/ 90 km from Reno, in the state of Nevada. We previously reported on the plant and its hybrid character utilising both solar energy and geothermal energy to produce clean electricity.

In an overview, the company shares details about the actual triple hybrid nature of the plant. The Stillwater plant consists of a 33 MW geothermal power plant, a 26 MW dc photovoltaic solar power plant, a 27 MW dc photovoltaic plant and a 2 MW solar thermal plant.

The plant complex is the first in the world to combine the continuous capacity of medium enthalpy geothermal resources binary cycle geothermal power with solar PV and solar thermal. The Stillwater hybrid facility is an award-winning power plant that has been paving the way for hybrid solutions at other sites around the world.

“[The plant] showcases the pioneering technology innovation of Enel Green Power that is making us so successful in working with governments and business partners around the world to tackle environmental issues and climate change through renewable energy,” said Enel CEO Francesco Starace, when the plant was inaugurated in 2016 – as we reported.

It produces around 241,000 MWh annually saving around 97,000 tons annually.

In addition, research findings between March and December 2015 confirm that the combination of a 2 MW solar thermal facility with a 33.1 MW geothermal plant increased overall output at Stillwater by 3.6% compared with production from geothermal only. These findings were bolstered by the results of a study of the integration of geothermal and solar thermal. This is the first time empirical data from a commercial hybrid plant validates a theoretical hybrid model. This work was performed under the framework of the Cooperative Research and Development Agreement (CRADA) with the National Renewable Energy Laboratory (NREL) and Idaho National Laboratory (INL), under the oversight of the U.S. Department of Energy Geothermal Technologies Office.

The Stillwater plant began operation in 2009 with the completion of the geothermal plant. Since then, the site has served as a hub of innovation for Enel Green Power (EGP). Making the most of its international reach, resources and partners, EGP looked to its own diverse renewable portfolio and the most advanced facilities in the world for more resourceful and innovative ways to maximise plant operations and output.

In 2012, the company added a 26.4 MW solar PV unit to the geothermal plant at the time one of the largest PV systems of its kind in the United States. In 2015, the company developed a solar thermal system to operate in conjunction with the existing Stillwater geothermal power station. By combining three renewable sources at the same location for the first time, EGP was able to fully capitalise on already installed assets, creating a more efficient and productive overall plant.

Source: Enel Green Power, Enel