Gemasolar Solar Power Plant - With stainless steel core
Torresol Energy of Spain switches to stainless steel in a core part of a revolutionary solar power process. Technology supplier and co-owner SENER turns to Outokumpu for stainless expertise.
Images of Gemasolar. Courtesy of Torresol Energy
Solar power technology is about to take a major leap forward: the Gemasolar Concentrating Solar Power plant, under construction by Torresol Energy in Sevilla, Spain, promises to outdate conventional processes. The plant features technological breakthroughs in solar heat reception and storage systems.
Gemasolar incorporates 2,650 heliostats - tracking reflectors - situated around a central tower. They concentrate the sun's rays onto a receiver placed at the top of the tower, which is capable of absorbing 95 percent of the heat energy. Molten salts acting as the working fluid are passed through the receiver and become heated, to be used to generate water vapor for steam turbines that drive electric generators.
With 17 megawatts of nameplate power, Gemasolar will generate enough electricity to power 30,000 homes. This renewable energy project will annually offset 30,000 metric tons of carbon dioxide emitted into the atmosphere.
As the first commercial central tower-heliostat plant in the world, Gemasolar will be fitted with a heat storage system where the hot molten salts are stored in special tanks at temperatures exceeding 500°C. This system will allow Gemasolar to operate for up to 15 hours without solar radiation.
Gemasolar will feature extraordinary energy efficiency, more than double that of conventional solar power technology, accomplishing this with only two-thirds of the investment required for older technology. Hailing Gemasolar as the most advanced technological venture in solar energy to date, Torresol Energy remains true to its commitment to making solar power increasingly affordable and accessible.
The new technology has been developed by SENER, a Spanish engineering and technology group and 60% owner of Torresol Energy.
To be able to build the innovative hot salts tanks for the heat storage system, SENER needed a tank material able to handle the task. Stainless steel was that material without question, owing to its ability to withstand elevated temperatures. SENER specified a standard heat resistant grade, 347H (EN 1.4550), but needed more information about the behavior of this grade at the operating temperatures of the tanks.
Many years of cooperation with Outokumpu in a range of technology projects prompted SENER to contact Outokumpu's Spanish sales and technical team for the materials expertise they needed. Outokumpu specialists provided SENER with information about the grade's behavior at 550 °C and above, the corrosion and stress relief tests to be applied, and welding procedures - even alternatives to 347H.
Outokumpu's early and deep involvement in the Gemasolar project was instrumental for Outokumpu to secure the stainless steel supply for the hot salts tanks, consisting of 347H plates. The contract for the fabrication of the largest tank, 23m in diameter and 14m high, went to the Barcelona-based tank fabricator Emypro. This tank continues successful cooperation between Emypro and Outokumpu in building many industry-leading storage tanks in Spain in recent years.
Gemasolar under construction. The foundations of the cold and hot molten salts tanks next to the central tower are in place. Courtesy of Torresol Energy
Gemasolar Solar Power Plant: Based on central tower receiver, heliostats and molten salts storage technology. Located in Sevilla, Spain. Nameplate power 17 MW. Completion in 2011.
Developed by: Torresol Energy Investments S.A., see http://www.torresolenergy.com, jointly owned by SENER Grupo de Ingeniería of Spain (60%) and MASDAR, Abu Dhabi Future Energy Company (40%)
Technology provider: SENER
Hot salts tank fabricators: Main tank by Emypro S.A. of Spain, other fabricators to be named.
(Sourced from http://www.outokumpu.com/)