Solar Energy Generating Systems (SEGS) is the largest solar energy generating facility in the world. It consists of nine solar power plants in California's Mojave Desert, where insolation is among the best available in the United States. SEGS I–II (44 MW) are located at Daggett, SEGS III–VII (150 MW) are installed at Kramer Junction, and SEGS VIII–IX (160 MW) are placed at Harper Lake.[1] NextEra Energy Resources operates and partially owns the plants located at Kramer Junction and Harper Lake.
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The plants have a 354 MW installed capacity, making it the largest installation of solar plants of any kind in the world.[1] The average gross solar output for all nine plants at SEGS is around 75 MWe — a capacity factor of 21%. In addition, the turbines can be utilized at night by burning natural gas.
NextEra claims that the solar plants power 232,500 homes and displace 3,800 tons of pollution per year that would have been produced if the electricity had been provided by fossil fuels, such as oil.[2]
The facilities have a total of 936,384 mirrors and cover more than 1,600 acres (6.5 km2). Lined up, the parabolic mirrors would extend over 229 miles (370 km).
As an example of cost, in 2002, one of the 30 MW Kramer Junction sites required $90 million to construct, and its operation and maintenance cost is about $3 million per year (4.6 cents per kilowatt hour).[3]
The installation uses parabolic trough solar thermal technology along with natural gas to generate electricity. 90% of the electricity is produced by the sunlight. Natural gas is only used when the solar power is insufficient to meet the demand from Southern California Edison, the distributor of power in southern California.
The parabolic mirrors are shaped like a half-pipe. The sun shines onto the panels made of glass, which are 94% reflective, unlike a typical mirror, which is only 70% reflective. The mirrors automatically track the sun throughout the day. The greatest source of mirror breakage is wind, with 3000 typically replaced each year. Operators can turn the mirrors to protect them during intense wind storms. An automated washing mechanism is used to periodically clean the parabolic reflective panels.
The sunlight bounces off the mirrors and is directed to a central tube filled with synthetic oil, which heats to over 400 °C (750 °F). The reflected light focused at the central tube is 71 to 80 times more intense than the ordinary sunlight. The synthetic oil transfers its heat to water, which boils and drives the Rankine cycle steam turbine,[4] thereby generating electricity. Synthetic oil is used to carry the heat (instead of water) to keep the pressure within manageable parameters.
The SEGS power plants were built by Luz Industries,[4][5] and commissioned between 1984 and 1991. After Luz Industries bankruptcy in 1991 plants were sold to various investor groups as individual projects and expansion including three more plants was halted.
Kramer Junction employs about 95 people and 45 people work at Harper Lake.
| Plant | Year built |
Location | Net turbine capacity |
Field area |
Oil temperature |
Gross solar production of electricity (MWh) |
|
|---|---|---|---|---|---|---|---|
| (MW) | (m²) | (°C) | 1996 | average 1998–2002 | |||
| SEGS I | 1984 | Daggett | 14 | 82,960 | 307 | 19,900 | 16,500 |
| SEGS II | 1985 | Daggett | 30 | 165,376 | 316 | 36,000 | 32,500 |
| SEGS III | 1986 | Kramer Jct. | 30 | 230,300 | 349 | 64,170 | 68,555 |
| SEGS IV | 1986 | Kramer Jct. | 30 | 230,300 | 349 | 61,970 | 68,278 |
| SEGS V | 1987 | Kramer Jct. | 30 | 250,500 | 349 | 71,439 | 72,879 |
| SEGS VI | 1988 | Kramer Jct. | 30 | 188,000 | 391 | 71,409 | 67,758 |
| SEGS VII | 1988 | Kramer Jct. | 30 | 194,280 | 391 | 70,138 | 65,048 |
| SEGS VIII | 1989 | Harper Lake | 80 | 464,340 | 391 | 139,174 | 137,990 |
| SEGS IX | 1990 | Harper Lake | 80 | 483,960 | 141,916 | 125,036 | |
| Sources: Solargenix Energy,[6] KJC Operating Company,[7] IEEE,[8] NREL[9] | |||||||
SEGS VIII and SEGS IX, located at , are the largest solar power plants individually and collectively in the world.[10] They were the last, the largest, and the most advanced of the nine plants at SEGS, designed to take advantage of the economies of scale. Construction of tenth plant is same locality was halted because of bankruptcy of Luz Industries, construction of approved eleventh and twelfth plants never started. Each of all three planned plants had 80 MW of installed capacity.[11]
This location () receives an average of 340 days of sunshine per year, which makes it an ideal place for solar power generation. The average direct normal radiation (DNR) is 7.44 kWh/m²/day (310 W/m²),[7] one of the best in the nation.
SEGS I and II are located at .
In February 1999, a 900,000-US-gallon (3,400 m3) therminol storage tank exploded at the SEGS II (Daggett) solar power plant, sending flames and smoke into the sky. Authorities were trying to keep flames away from two adjacent containers that held sulfuric acid and sodium hydroxide. The immediate area of 0.5 square miles (1.3 km2) was evacuated.[12]
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