The Department of Energy (DOE) released a report on May 21 highlighting progress at five concentrating solar power (CSP) projects in the southwestern U.S.

In the report, “2014: The Year of Concentrating Solar Power,” three DOE-supported technologies are featured: parabolic trough, power tower, and thermal storage. The DOE has helped finance the large-scale deployment of CSP technology through its Loan Programs Office (LPO). LPO provides loan guarantees for projects that deploy innovative technologies that have been demonstrated but are not yet commercial.

The five CSP projects featured in the report are all expected to be fully operational by the end of 2014. When online, they will provide a combined 1.26 GW of capacity, nearly quadrupling the previous CSP total in the U.S.

CSP uses mirrors to direct and concentrate sunlight onto a receiver from which a heat transfer fluid carries the thermal energy to a power block to generate electricity. When deployed with thermal energy storage, CSP can produce electricity on demand, which makes it a more flexible option than some other renewable resources.

The five projects profiled in the report are: Crescent Dunes (Tonopah, Nev.)Genesis (Blythe, Calif.); Ivanpah (Ivanpah Dry Lake, Calif.)Mojave (near Barstow, Calif.); and Solana (near Gila Bend, Ariz).

Three of the projects—Crescent Dunes, Genesis, and Mojave—utilize parabolic trough technology, which captures the sun’s energy using giant “U” shaped mirrors to heat a special fluid contained in a receiver pipe. The other two projects—Ivanpah and Crescent Dunes—utilize power tower CSP systems. Power towers use numerous large, flat, sun-tracking mirrors (known as heliostats) to focus sunlight onto a receiver at the top of a tall tower. In either case, steam is generated, which is used in a conventional turbine generator to produce electricity.

The third technology—thermal storage—adds flexibility, because it allows solar facilities to generate electricity for hours after the sun has stopped shining. A typical storage system uses molten salt as a heat transfer medium, because it retains heat so well. The Solana and Crescent Dunes projects both use this type of technology.

In addition to the five projects covered in the report, the DOE also announced today that it has awarded $10 million to six new research and development projects. All of the projects are developing thermochemical energy storage systems designed to store the sun’s energy at high densities in the form of chemical bonds for use in utility-scale CSP facilities.

The winners were: Colorado School of Mines ($1,008,511); Pacific Northwest National Laboratory ($2,906,415); Sandia National Laboratory ($3,450,000); Southern Research Institute ($836,697); University of Florida ($791,200); and University of California, Los Angeles ($1,182,788).

“By improving energy storage technologies for concentrating solar power systems, we can enhance our ability to provide clean and reliable solar power, even when the sun is not shining,” said Energy Secretary Ernest Moniz.

For more on the state of energy storage, see “The Year Energy Storage Hit Its Stride” and “Balancing Renewables with Li-ion Energy Storage” in the May issue of POWER.

Aaron Larson, associate editor (@AaronL_Power, @POWERmagazine)