The world”s first commercial concentrated solar power (CSP) plant located near Seville, Spain, employs molten salt as the heat transfer fluid, an innovative technology that allows for the continuous generation of electricity 24 hours a day for many months throughout the year.
The 19.9-megawatt (MW) Gemasolar power plant utilizes a central tower receiver with thermal storage capabilities. Due to the molten salt storage design, the CSP plant is capable of energy production for up to 15 hours without sunlight, helping to avoid fluctuations in the region”s power supply.
Managed by Torresol Energy, a joint venture between SENER (the leading Spanish engineering and construction company) and Masdar (Abu Dhabi”s future energy and clean technology company), the Gemasolar station incorporates 2,650 large, sun-tracking heliostats (mirrors) to focus sunlight on the top of a centrally located tower. Utilizing molten salt as the heat transfer fluid at temperatures in excess of 500 C (932 F) makes it possible to generate super-heated steam at higher pressures, which significantly boosts the plant”s efficiency.
Seven specially configured vertical turbine pumps (VTPs) are capable of sustaining temperatures up to 600 C (1,100°F) and generating pressures up to 100 bar (1,450 PSI). Materials of construction for these high-process temperatures include stainless steel alloys to minimize thermal growth and forestall shaft deflection. These pumps, supplied by Flowserve are designed for heat dissipation and include Flowserve dry gas fluid sealing systems to specifically handle the molten salt. Low pump submergence allows the liquid level to be drawn down further in the storage tanks for greater energy generation. These specially adapted VTPs may be deployed in pump lengths up to 20 meters (65 feet).
Located in the Andalucia region of Spain, the power plant supplies electricity to 25,000 homes and is expected to reduce carbon dioxide emissions by more than 30,000 tons annually.