SolarReserve has completed a 540-foot solar power tower, the centerpiece of its 110-megawatt Crescent Dunes solar thermal power plant that will use molten salt storage to help it supply power day -- and night.
SolarReserve still has to install the 10,000 billboard-sized sun-tracking mirrors or heliostats necessary to concentrate sunlight onto the massive tower at the site of the solar plant in Tonopah, Nevada. The power plant, which is expected to come online by December 2013, will be the largest of its kind in the world, according to the company. Crescent Dunes has secured a 25-year power purchase agreement with NV Energy and will provide electricity for 75,000 homes. Check out the time lapse video provided by SolarReserve below.
The critical component of the Crescent Dunes project is its molten salt storage. The reflected sunlight is directed onto a large heat exchanger called a receiver, which is located on the tower. Molten salt -- not oil like other concentrated solar power plants -- is within the receiver and absorbs heat from concentrated sunlight, reaching up to 1,000 degrees Fahrenheit. The molten salt flows down the piping inside the tower and into a thermal storage tank, where the energy is stored until electricity is needed.
When the utility needs power -- again, at day or night -- the high-temp molten salt flows into a steam generator, which drives a turbine to produce electricity. The cooled molten salt is then piped back into a cold salt storage tank and eventually back up to the receiver to start the whole process over again. According to the company, its technology has the ability to store energy for 10 to 15 hours. In other words, the solar power plant will be able to provide a continuous supply of power.
Variability is among the biggest problems with solar-generated power, which the SolarReserve project and others like the Gemasolar plant in Spain are designed to solve. When the sun sets, the renewable power source drops off and that can create problems for grid operators trying to maintain a steady electricity supply. Without access to solar power, the utility will switch over to natural gas- or coal-fired power plants.