California has just approved a new solar project that could revolutionize how we use energy from the sun – namely because it will be able to keep producing electricity even after night falls. SolarReserve’s Rice Solar Energy Project will end up looking a lot like the solar thermal tower above but will have a secret weapon hidden underneath – molten salt. Since the salt will be able to reach temperatures over 1000 degrees Fahrenheit and retain most of the heat it collects during the day, the plant will have the ability to keep churning out juice long after the sun goes down. It will be the first project in California to use the savory technology to store and distribute energy.
SolarReserve’s technology is based on the solar power tower model that uses hundreds of mirrored heliostats in a two square mile field to focus heat on a tower that collects thermal energy. Generally a solar power tower simply uses the energy to heat water and sends power to the grid through a steam generator, but SolarReserve has created a unique technology that allows that power to be stored efficiently and released as needed. Held within the solar power tower is a reserve of salt that is heated to a molten state by the thermal energy the heliostats create. The molten salt is then pumped into a reserve tank and maintains close to all of its original heat. When needed, the heat can be pumped through a steam generator that sends electricity to the grid.
SolarReserve is using technology that has been around the block – most of the components for their solar power projects are readily available and the new elements like the molten salt and loop system are inexpensive. Together, the depth of research into solar power towers and the price of molten salt allows SolarReserve to provide power at a lesser cost than traditional coal or natural gas. Plus, unlike solar power towers with no storage system — or inefficient ones — this renewable energy system can throw electricity into the grid 24 hours a day, even when the sun isn’t shining. The Rice Solar Energy Project already has a 25-year power purchase agreement with Pacific Gas & Electric, will employ 500 skilled workers and was approved in record time — just under 13 months. SolarReserve is hoping to begin construction toward the end of 2011.