Solar Energy Generating Systems
Encyclopedia
Solar Energy Generating Systems (SEGS) is the largest solar energy generating facility in the world. It consists of nine solar power plants in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
's Mojave Desert
Mojave Desert
The Mojave Desert occupies a significant portion of southeastern California and smaller parts of central California, southern Nevada, southwestern Utah and northwestern Arizona, in the United States...
, where insolation
Insolation
Insolation is a measure of solar radiation energy received on a given surface area in a given time. It is commonly expressed as average irradiance in watts per square meter or kilowatt-hours per square meter per day...
is among the best available in the United States. SEGS I–II (44 MW) are located at Daggett
Daggett, California
Daggett is an unincorporated town located in San Bernardino County, California in the United States. The town is located on Interstate 40 ten miles East of Barstow. The town has a population of about 200. The ZIP code is 92327 and the community is inside area code 760.-History:The town was...
, SEGS III–VII (150 MW) are installed at Kramer Junction
Kramer Junction, California
Kramer Junction is a small community in the Mojave Desert at the intersection of U.S. Route 395 and State Route 58.Solar Energy Generating Systems sites SEGS III-VII are located less than a mile to the northwest....
, and SEGS VIII–IX (160 MW) are placed at Harper Lake
Harper Lake
Harper Lake is a dry lake located in the Mojave Desert near the small community of Lockhart in northwestern San Bernardino County of Southern California...
. NextEra Energy Resources
NextEra Energy Resources
NextEra Energy Resources is an wholesale electricity supplier based in Juno Beach, Florida. It is a subsidiary of NextEra Energy, Inc. , a Fortune 200 company. Prior to 2009, NextEra Energy Resources was known as FPL Energy....
operates and partially owns the plants located at Kramer Junction and Harper Lake.
Plants' scale and operations
MWE
MWE may refer to:*Manufacturer's Weight Empty*McDermott Will & Emery*Midwest Express, an airline*Merowe Airport - IATA code*Multiword expressionMWe may refer to:*Megawatt electrical...
— a capacity factor
Capacity factor
The net capacity factor or load factor of a power plant is the ratio of the actual output of a power plant over a period of time and its potential output if it had operated at full nameplate capacity the entire time...
of 21%. In addition, the turbines can be utilized at night by burning natural gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...
.
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.
The facilities have a total of 936,384 mirrors and cover more than 1600 acres (6.5 km²). Lined up, the parabolic mirrors would extend over 229 miles (368.5 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).
Principle of operation
Parabolic trough
A parabolic trough is a type of solar thermal energy collector. It is constructed as a long parabolic mirror with a Dewar tube running its length at the focal point. Sunlight is reflected by the mirror and concentrated on the Dewar tube...
solar thermal technology along with natural gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...
to generate electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
. 90% of the electricity is produced by the sunlight
Sunlight
Sunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...
. 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.
Mirrors
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.Heat transfer
The sunlight bounces off the mirrors and is directed to a central tube filled with synthetic oilSynthetic oil
Synthetic oil is a lubricant consisting of chemical compounds that are artificially made . Synthetic lubricants can be manufactured using chemically modified petroleum components rather than whole crude oil, but can also be synthesized from other raw materials...
, which heats to over 400 °C (752 °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
Rankine cycle
The Rankine cycle is a cycle that converts heat into work. The heat is supplied externally to a closed loop, which usually uses water. This cycle generates about 90% of all electric power used throughout the world, including virtually all solar thermal, biomass, coal and nuclear power plants. It is...
steam turbine, thereby generating electricity. Synthetic oil is used to carry the heat (instead of water) to keep the pressure within manageable parameters.
Individual locations
The SEGS power plants were built by Luz IndustriesBrightSource Energy
BrightSource Energy is an Oakland, California, corporation that designs, builds, finances and operates utility-scale solar power plants that deliver clean, low-cost solar energy to utility and industrial customers worldwide at prices that compete with fossil fuels.Greentech Media ranked...
, and commissioned between 1984 and 1991. After Luz Industries bankruptcy
Bankruptcy
Bankruptcy is a legal status of an insolvent person or an organisation, that is, one that cannot repay the debts owed to creditors. In most jurisdictions bankruptcy is imposed by a court order, often initiated by the debtor....
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, KJC Operating Company, IEEE, NREL | |||||||
Harper Lake
SEGS VIII and SEGS IX, located at 35.0316°N 117.348 °W, are the largest solar power plants individually and collectively in the world. 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.Kramer Junction
This location (35.0142°N 117.559 °W) receives an average of 340 days of sunshine per year, which makes it an ideal place for solar power generation. The average direct normal radiationDirect insolation
Direct insolation is the solar irradiance measured at a given location on Earth with a surface element perpendicular to the Sun's rays, excluding diffuse insolation . Direct insolation is equal to the solar constant minus the atmospheric losses due to absorption and scattering...
(DNR) is 7.44 kWh/m²/day (310 W/m²), one of the best in the nation.
Daggett
SEGS I and II are located at 34.8631°N 116.827 °W.Accidents and incidents
In February 1999, a 900000 gallons (3,406.9 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 acidSulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
and sodium hydroxide. The immediate area of 0.5 square miles (1.3 km²) was evacuated.
See also
- List of concentrating solar thermal power companies
- List of photovoltaic power stations
- List of solar thermal power stations
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