利用者:Elden~jawiki/Solar Energy Generating Systems

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.

Contents [hide] 1 Plants' scale and operations 2 Principle of operation 2.1 Mirrors 2.2 Heat transfer 3 Individual locations 3.1 Harper Lake 3.2 Kramer Junction 3.3 Daggett 4 Accidents and incidents 5 See also 6 References 7 External links

[edit] Plants' scale and operations Close-up aerial view. Note that several of the mirrors have been brokenThe 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).

[edit] Principle of operation Sketch of a Parabolic Trough CollectorThe 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.

[edit] Mirrors Mr. Twister mirror washing machineThe 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.

[edit] Heat transferThe 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,[3] thereby generating electricity. Synthetic oil is used to carry the heat (instead of water) to keep the pressure within manageable parameters.

[edit] Individual locationsThe SEGS power plants were built by Luz Industries,[3][4] and commissioned between 1984 and 1991. Kramer Junction employs about 95 people and 45 people work at Harper Lake.

SEGS plant history and operational data 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,[5] KJC Operating Company,[6] IEEE,[7] NREL[8]

[edit] Harper Lake Close-up of the Kramer Junction mirrors.SEGS VIII and SEGS IX, located at 35°01′54″N 117°20′53″W / 35.0316°N 117.348°W / 35.0316; -117.348 (SEGS VIII and IX), are the largest solar power plants individually and collectively in the world.[9] 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. SEGS VIII and IX have operated continuously and have been commercially successful since the very beginning.[3]

[edit] Kramer JunctionThis location (35°00′51″N 117°33′32″W / 35.0142°N 117.559°W / 35.0142; -117.559 (SEGS III–VII)) 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),[6] one of the best in the nation.

[edit] DaggettSEGS I and II are located at 34°51′47″N 116°49′37″W / 34.8631°N 116.827°W / 34.8631; -116.827 (SEGS I and II).

[edit] Accidents and incidentsIn 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.[10]

[edit] See alsoList of solar thermal power stations Parabolic trough Solar power Solar power plants in the Mojave Desert Solar thermal energy