DoE Backs New Conversion Unit for Concentrating Solar Power Plants

In recent years, the U.S. Department of Energy has granted funds to a large number of research programs focused on lowering the cost of solar energy in the electrical grid. 

To that end, a research team based out of the Wisconsin Energy Institute has received a $2.6 million grant to design a new power conversion unit for concentrating-solar-power (CSP) plants.

The utility-scale power plants generate solar energy by reflecting and intensifying sunlight onto a small thermal receiver. The thermal solar energy is transferred into a fluid, usually supercritical steam or synthetic oil, which is used as a heat source for an electrical power generator. The research team will design two advanced power cycle units that transfer thermal energy into a supercritical carbon-dioxide fluid. This advanced power cycle has a higher thermal stability than the steam cycles currently used in CSP power generators, which results in a higher-efficiency energy conversion. Although it will be designed primarily for solar energy, the unit will also be compatible with nuclear, geothermal, and fossil energy sources.

To integrate this new power cycle, the research team will also have to develop a more efficient regenerator unit for converting thermal to mechanical energy. The new regenerator is expected to have better capabilities for internal heat transfer and energy storage than the recuperators currently used in CSP power plants. To further increase the regenerator's efficiency, the research team plans to design a pre-cooling system, which will release heat into the atmosphere at lower temperatures than current power cycles. With dry cooling capabilities, the system will not only reduce waste energy, but also minimize the amount of water used in the cooling process.

The members of the research team, led my University of Wisconsin-Madison professor Mark Anderson, will represent several universities, private companies, and national laboratories. Anderson and UW-Madison professor Greg Nellis will collaborate with members of the Colorado School of Mines, Sandia National Laboratories, the National Renewable Energy Laboratory, heat-transfer company CompRex, and chemical-process equipment company Flowserve. The team will test the new power units at a prototype facility in Alburquerque, New Mexico.