Recent advances in solar power technology include use of liquid molten salt as both the energy collection and the storage mechanism in a solar thermal power plant (see OWOE: How do solar thermal power plants generate electricity?
). Concentrated solar energy heats a mass of molten salt to between 500 and 1000 degrees Fahrenheit. The heated salt is stored and can be used at any time to boil water for steam to generate electricity. This solves a major technological issue for solar power and allows the utility to continue to generate electricity from sunlight, even after dark. It also allows the solar plant to be used as a dispatch resource for the electrical grid. Thus, when the grid operator must quickly ramp-up power to handle a problem, the solar plant can be used rather than the traditional gas or coal plant.
Figure 1 ishows the the process diagram for a CSP plant using molten salt. Figure 2 shows the 110 MW Crescent Dunes Solar Energy Project
located near Tonopah, Nevada, which was the first CSP plant in the world to incorporates such a storage system. It consists of a single 540-foot tall tower and approximately 174,000 heliostats. Enough salt is used to provide 10 hours of full load storage for grid stability and reliability. See Videos 1 and 2 for more information on the Crescent Dunes project and molten salt technology. The Crescent Dunes plant successfully synchronized with the grid in October 2015. Unfortunately, due to a number of design flaws, the plant only generated electricity sporadically, and in October 2019 NV Energy, the project's sole customer, terminated its contract on the basis of the project having "failed to produce". After a bankruptcy reorganization, the plant was restarted in July 2021. Outside the US molten salt CSP plants have been built and are operating successfully. The Noor Quarzazate power station
in Morocco is the largest CSP plant in the world
with a total of 510 MW capacity. It has the ability to store up to 8 hours of electricity.