Abengoa Solar is to develop a new solar-power tower technology thanks in part to a grant from the US Department of Energy (DOE).
The technology comprises a heliostat field of movable mirrors oriented according to the position of the sun to reflect solar radiation, which is then concentrated onto a receptor located on the upper part of the tower. The heat generated is then transferred to a salt fluid, which is used to create steam that drives a turbine.
The new tower system that the company is developing with the DOE grant will operate at higher temperatures than its existing system, allowing it to produce more energy from the same size power plant. It will also incorporate a thermal storage system to allow it to operate for periods when the sun isn’t shining.
Abengoa is currently the only company with a full-scale operational power tower. Last September, the company unveiled its PS20 20MW solar plant, the largest commercial solar tower plant in the world, located in Sanlúcar la Mayor, Seville.
That system forms part of a number of solar-power systems under construction in that region of Spain, including towers, solar troughs, photovoltaic panels and Stirling technology-based dishes. When completed in 2013, the total output from all the systems will be 300MW.
But Abengoa Solar isn’t the only company to be awarded a grant from the DOE to work on the technology.
The department is also providing a grant to eSolar, which plans to design, build and test a Concentrating Solar Power (CSP) plant with multiple, modular towers instead of one central tower and receiver.
Once again, using reflective mirrors, the sun’s radiation will heat a liquid salt within each receiver. A molten salt transport system will then move the high-temperature fluid to a molten-salt steam generator that produces electricity. Like the Abengoa Solar system, the eSolar plant will also feature a thermal storage system.
For its part, Pratt & Whitney Rocketdyne plans to advance the current state-of the art in solar-power tower plant design. Also armed with a DOE grant, the company will explore new materials for the central power tower receiver, as well as develop its own thermal storage system and integrate it into the design of the CSP plant.