Enel Green Power’s geothermal power station at Stillwater Nevada is truly remarkable. It was primarily a geothermal power station of 33 MW capacity until 2011 when a 26 MW PV plant was paired to it. And now the company has decided to add solar thermal power generation to the mix.
Plans are underway to add 17 MW CSP to the power station. What is interesting is that CSP will be integrated with the geothermal loop at a process level. The Stillwater geothermal plant, consisting of two binary-cycle units, will be integrated with the parabolic trough CSP system so that they contribute to the same turbines. The hybrid plant will combine the continuous generating capacity of geothermal power with daytime peak generation from the solar thermal component. The proposed setup reduces a lot of overlapping costs, even the PV plant utilizes the same sub station and power evacuation system.
SkyFuel is supplying the parabolic trough solar field that will be integrated into the heating loop of the Stillwater geothermal plant. The CSP portion will be able to generate approximately 3 million kWh/year, to be added to the power currently being generated by the existing hybrid plant. The energy produced will be sold to NV Energy, through the existing 20-year Power Purchase Agreement (PPA). CSP can extend the life of the geothermal reservoir by reducing the need to drill additional production wells or relocate injection wells. The coupled geothermal reservoirs can in some sense act as a storage for CSP.
Combining several renewable power generation technologies also increases zero-emission output as well as making it possible to rely on the same infrastructures, such as electrical interconnection lines, thereby further reducing environmental impact.