Solar power towers are the new trend in thermal power plants. Instead of rows of curved mirrors focusing sunlight onto miles of black tubing, power towers use Heliostat (sun-tracking) mirrors to focus light on a central tower. As first conceived, that “power tower” would contain water that when heated, creates steam to spin a turbine and generate electricity. Two new solar power towers set to be built by SolarReserve will make one major improvement: instead of using water in the tower, they use molten salts.
The advantage of molten salt is its high heat capacity, allowing it to get much hotter during the day and retain much of that heat throughout the night. The result is a clever form of solar energy storage that could help transform solar into a base-load, on-demand power source. SolarReserve is introducing the concept to the desert Southwest. A 100-megawatt plant will be built in Nevada under a power purchase agreement (PPA) with NV Energy. A second, 150-MW power tower will come as part of a deal with Pacific Gas & Electric (PG&E). (more…)