Solar power plants in the Mojave Desert

Insolation in the Mojave Desert is among the best available in the United States, and some significant population centers are located in the area. This makes the Mojave Desert particularly suitable for solar power plants.

Solar One was a pilot solar-thermal project east of Barstow, which was upgraded to Solar Two before decommissioning in 1999.

File:Usgs mojave desert.jpg

Extent of Mojave Desert. Green square is the area of a survey made by the USGS which covers 25,000 square miles.

Solar One

Solar One was a pilot solar-thermal project in the Mojave Desert just east of Barstow, California. It was the first test of a large scale thermal solar power tower. Solar One was designed by the Department of Energy (DOE), Southern California Edison, LA Dept of Water and Power, and California Energy Commission. It was located in Daggett, California, which is about 10 miles east of Barstow (see Solar One article for details).

Solar Two

Aerial view of the Solar Two facility.

In 1995 Solar One was converted into Solar Two, by adding a second ring of 108 larger heliostats around the existing Solar One, making a total of 1926 heliostats with a total area of 82,750 m². This gave Solar Two the capability of redirecting the equivalent of 600 suns and the ability to produce 10 megawatts of power.

Solar Two used molten salt as an energy storage medium instead of water or oil. This helped in energy storage during interruptions in sunlight due to clouds and night time. The Solar Two project demonstrated the ability of solar molten salt technology to provide long-term, cost effective thermal energy storage for electricity generation (see Solar One article for details).

Solar Two was decommissioned in 1999, and was converted by the University of California, Davis, into an Air Cherenkov Telescope in 2001, measuring gamma rays hitting the atmosphere.

Solar Electricity Generating Systems

Sketch of a Parabolic Trough Collector

Solar Energy Generating Systems (SEGS) is the name given to nine solar power plants in the Mojave Desert. SEGS I-VII are located at Kramer Junction, and SEGS VIII and IX are at Harper Lake and Barstow respectively. The SEGS power plants were commissioned between 1984 and 1991.

The installation uses parabolic trough solar thermal technology along with natural gas to generate electricity. The facility has a total of 400,000 mirrors and covers 1,000 acres (4 km²). The plants produce 354MW, making the system the largest solar plant of any kind in the world.

Nevada Solar One

Nevada Solar One has a 64 MW generating capacity and is located in Boulder City, Nevada. It was built by the U.S. Department of Energy (DOE), National Renewable Energy Laboratory (NREL), and Solargenix Energy.

Nevada Solar One uses parabolic troughs as thermal solar concentrators, heating tubes of liquid which act as solar receivers. These solar receivers are specially coated tubes made of glass and steel which were designed and produced by Schott Glass. About 19,300 of these four meter long tubes are used in the newly built power plant. Nevada Solar One also uses a technology that collects extra heat by putting it into phase-changing molten salts. This energy can then be drawn at night.

Solar thermal power plants designed for solar-only generation are ideally matched to summer noon peak loads in prosperous areas with significant cooling demands, such as the south-western United States. Using thermal energy storage systems, solar thermal operating periods can even be extended to meet base-load needs.

Stirling Solar Dish

A parabolic solar collector concentrating the sun's rays on the heating element of a Stirling engine. The entire unit acts as a solar tracker.

Stirling Energy Systems in conjunction with utility company Southern California Edison is erecting a 500 megawatt, 4,600-acre (19 km²), solar power plant to open in 2009. This will be the first commercial application of the Stirling Solar Dish. A different technology from the more familiar solar panel, the dish concentrates solar energy by the use of reflective surfaces and by the use of the Stirling heat engine to convert the heat into electricity.

Stirling Energy Systems have announced another agreement with San Diego Gas & Electric to provide between 300 and 900 megawatts of electricity.

Land use issues

Solar thermal power plants are big and seem to use a lot of land, but when looking at electricity output versus total size, they use less land than hydroelectric dams (including the size of the lake behind the dam) or coal plants (including the amount of land required for mining and excavation of the coal). While all power plants require land and have an environmental impact, the best locations for solar power plants are on land, such as deserts, for which there might be few other uses.

See also

• deployment of solar power to energy grids
• list of solar thermal power stations
• renewable energy commercialization
• solar power
• solar thermal energy

External links

• Nevada Solar One video
• Ten facts about solar thermal power
• Huge Solar Plants Bloom in Desert