Energy.gov

This article is part of the Energy.gov series highlighting the “Top Things You Didn’t Know About…” Be sure to check back for more entries soon.

9. Concentrating solar power (CSP) technology involves using mirrors, sometimes in the hundreds of thousands, to reflect sunlight and collect solar heat to generate electricity. A single CSP plant can generate enough power for about 70,000 homes -- making it a major player of the utility-scale solar market. For more CSP technology basics, watch our video Energy 101: Concentrating Solar Power.

8. Legend has it that the Greek scientist, Archimedes, first made use of concentrated sunlight by employing the reflective properties of bronze shields to set fire to Roman ships during the battle of Syracuse in 212 BC. While experimental recreations have proved such a feat is possible, much doubt still surrounds this story.

7. There are four types of demonstrated CSP technologies. Parabolic trough and linear Fresnel systems focus sunlight onto a linear receiver. The other two technologies -- dish/engine and power tower -- focus sunlight to a point. All of these technologies involve converting sunlight into thermal energy for use in a heat-driven engine.

6.  How can solar-generated electricity be consistently available when the sun doesn’t shine around-the-clock? The answer lies in thermal energy storage -- the ability to store the sun’s heat in the form of thermal energy for use when the sun isn’t shining. By incorporating thermal energy storage systems, the cost of power from a CSP plant can actually be reduced and can provide solar power on demand -- even when it’s cloudy or at night. More details on thermal storage in this SunShot Podcast.

5. The Solar One project near Barstow, California, operated between 1982 and 1986, demonstrating that large-scale concentrating solar power tower systems were viable. In 1996, the Energy Department upgraded the plant and renamed it Solar Two. As the world’s first large-scale molten salt power tower facility, Solar Two demonstrated the potential of thermal energy storage systems at scale for the first time. Molten salt thermal energy storage technology is now widely commercialized in the CSP industry and molten salt power tower technology is currently being deployed at a global scale.

4. More than 520 megawatts (MW) of CSP plants currently operate in the United States. Five new CSP plants under construction will soon increase the total CSP capacity in the United States to 1.8 gigawatts (GW). These new CSP plants will provide enough electricity for more than 330,000 homes. Check out our interactive map of America’s CSP plants -- both up-and-running and under-construction.

3. In a CSP system, oil-based heat transfer fluids move thermal energy from the solar receiver to the power block, where the heat is used to drive a turbine that generates electricity. Today’s heat transfer fluids can only get so hot, limiting efficiency and increasing costs. The Energy Department is funding research projects to develop new heat transfer fluids that can operate at incredibly high temperatures -- up to 2,350 degrees Fahrenheit.

2. The Energy Department’s SunShot Initiative has set aggressive targets to lower the cost of CSP by the end of the decade. Among the technological breakthroughs being explored to achieve this goal is an Energy Department-supported project led by General Atomics. The company has demonstrated in the lab -- and is now in the process of scaling up for demonstration -- a method for storing the thermal energy produced by a CSP system in chemical bonds. This energy could then be transported to less sunny regions of the country for use as clean electricity.

1. The CSP supply chain is overwhelmingly domestic. In other words, most, if not all, materials necessary to build a CSP plant can be found and manufactured here in the United States -- creating job opportunities and driving economic growth.  As an example, the supply chain for Abengoa’s Solana project that is currently under construction covers 27 states and 90 U.S. companies.