Solar Power Plants (with Photovoltaic and Thermal Energy Systems) now can generate power all the day 24 hours time, both in sunlight using photovoltaics and/or direct solar temperature collectors, and in dark using the stored heat energy. BrightSource Energy has become the latest solar thermal power company to develop a heat energy storage system for generating power when the sun isn’t shining. The company says the technology can lower the cost of solar power and make it more reliable, helping it compete with conventional sources of electricity. BrightSource Solar Thermal Energy Systems generate power the same way as traditional power plants – by creating high temperature steam to turn a turbine. However, instead of using fossil fuels or nuclear power to create the steam, BrightSource uses the sun’s energy.

Solar Thermal Power Plant Heat Energy Storage SystemSolar thermal systems use mirrors to focus sunlight, generating temperatures high enough to produce steam to drive a turbine. One of the advantages of the solar thermal approach, versus conventional photovoltaics that convert sunlight directly into electricity, is that heat can be stored cheaply and used when needed to generate electricity. In all solar thermal plants, some heat is stored in the fluids circulating through the system. This evens out any short fluctuations in sunlight and lets the plant generate electricity for some time after the sun goes down. But adding storage systems would let the plant ride out longer periods of cloud cover and generate power well into, or even throughout, the night. Such long-term storage could be needed if solar is to provide a large share of the total power supply.

BrightSource’s SolarPLUS combines the company’s high-efficiency LPT solar thermal technology with proven two-tank molten-salt storage. In BrightSource’s SolarPLUS plants, a portion of the steam produced in the boiler is directed to a heat exchanger, where molten salts are further heated to a higher temperature, thus efficiently storing the heat energy for future use. Later, when the energy in storage is needed, the heat stored in the molten salts is used to generate steam to run the steam turbine. The benefits of BrightSource’s SolarPLUS thermal power plants include:

  • Extending the production of electricity into later parts of the day and after the sun sets when it is most valued by utilities.
  • Reducing the cost of renewable power for utilities’ customers by increasing a plant’s capacity factor and offering higher efficiencies than competing solar thermal power plants.
  • Providing utilities with greater operational flexibility to shape production to meet changing utility customer demand.
  • Offering utilities and grid operators additional operational and market value, by providing balancing and shaping capabilities, as well as ancillary services to support a reliable grid.