WASHINGTON - The U.S. Department of Energy (DOE) announced that it will provide up to $60 million for concentrating solar power (CSP) projects that focus on advanced thermal energy storage or heat transfer fluids. The DOE funding will go toward both new research and development projects and demonstrations of technologies already under development. DOE anticipates that 10 to 25 industries or academic institutions will be selected to receive this funding, which will be distributed over the next five years. With a mandatory private industry cost share of 20 percent for research and development, and a 50 percent cost share for demonstrations, more than $75 million could be invested in these projects.

CSP systems collect thermal energy by absorbing and concentrating energy from the sun. Today’s largest systems employ either arrays of parabolic mirrors, which focus the sun’s heat on an absorber tube carrying a heat transfer fluid, or “heliostats,” which are flat mirrors that focus the sun’s heat on a thermal absorber mounted to the top of a “power tower,” through which a heat transfer fluid is pumped. The parabolic mirrors can also be replaced with linear Fresnel reflectors. In all those cases, the thermal energy captured by the heat transfer fluid is used as a heat source for a boiler, which generates steam to drive a turbine. Dish-shaped mirrors generally focus the sun’s heat on a heat engine, but they can also employ a thermal absorber through which a heat transfer fluid is pumped.

Heat transfer fluids with the capacity to store a lot of thermal energy can be combined with thermal energy storage systems to allow such CSP systems to continue operating after the sun has set, helping to meet peak power demands on hot summer evenings. Thermal energy storage also helps CSP plants to operate continuously on partly cloudy days. Because of these advantages, inexpensive thermal energy storage is considered a key technology for making CSP systems cost-competitive by 2020.

Publication date: 05/19/2008