One of the biggest problems with solar energy is that the sun doesn’t shine 24 hours a day.
This means that unless users are only planning on using electricity when the sun is shining, some form of energy storage system is required. Since storing excess electricity in rechargeable batteries isn’t really practical for large-scale solar power plants, another storage system is needed. U.S. utility-scale solar project developer SolarReserve has now received approval for the first solar power plant in California that uses molten salt technology to store the sun’s thermal energy as heat so it can generate electricity when needed, at any time of the day or night.
The Rice Solar Energy Project is designed as a solar power tower, with thousands of tracking mirrors (heliostats) focusing concentrated sunlight on a receiver that sits at the top of a central tower to collect the thermal energy. Whereas most solar power towers use this thermal energy to heat water into steam to power a turbine, SolarReserve’s system uses the thermal energy to heat molten salt to store the energy. The molten salt is a mixture of sodium nitrate and potassium nitrate that is non-flammable and non-toxic and is an efficient and inexpensive energy storage medium.