There are several solar power plants in the Mojave Desert which supply power to the electricity grid. Solar Energy Generating Systems (SEGS) is the name given to nine solar power plants in the Mojave Desert which were built in the 1980s. These plants have a combined capacity of 354 megawatts (MW) making them the largest solar power installation in the world.[1] Nevada Solar One is a solar thermal plant with a 64 MW generating capacity, located near Boulder City, Nevada.[2] The Copper Mountain Solar Facility is a 48 MW photovoltaic power plant in Boulder City, Nevada.[3]
The Blythe Solar Power Project is a 968 MW solar thermal power station under construction in Riverside County, California. The Ivanpah Solar Power Facility is a 370 MW facility under construction which will consist of three separate solar thermal power plants. There are also plans to build other large solar plants in the Mojave Desert.[4]
Insolation (solar radiation) in the Mojave Desert is among the best available in the United States, and some significant population centers are located in the area. These plants can generally be built in a few years because solar plants are built almost entirely with modular, readily available materials.[5]
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The southwestern United States is one of the world's best areas for insolation, and the Mojave Desert receives up to twice the sunlight received in other regions of the country. This abundance of solar energy makes solar power plants a cleaner alternative to traditional power plants, which burn fossil fuels such as oil and coal.[6] Unlike traditional power plants, solar power stations provide an environmentally benign source of energy, produce virtually no emissions, and consume no fuel other than sunlight. Each facility, however, can range from 5 to ten square miles in size, making it difficult to accommodate projects on ecologically sensitive habitat. Because of this immense land requirement, some groups are encouraging more distributed generation, or rooftop solar. [6]
Currently, solar electricity is not cost competitive with bulk, baseload power. However, it provides electricity when and where power is most limited and most expensive, which is a strategic contribution. Solar electricity mitigates the risk of fuel-price volatility and improves grid reliability.[7]
While many of the costs of fossil fuels are well known, others (pollution related health problems, environmental degradation, the impact on national security from relying on foreign energy sources) are indirect and difficult to calculate. These are traditionally external to the pricing system, and are thus often referred to as externalities. A corrective pricing mechanism, such as a carbon tax, could lead to renewable energy, such as solar thermal power, becoming cheaper to the consumer than fossil fuel based energy.[5]
Solar thermal power plants can generally be built in a few years because solar plants are built almost entirely with modular, readily available materials. In contrast, many types of conventional power projects, especially coal and nuclear plants, require long lead times.[5]
Solar power towers use thousands of individual sun-tracking mirrors (called heliostats) to reflect solar energy onto a central receiver located on top of a tall tower. The receiver collects the sun's heat in a heat-transfer fluid that flows through the receiver. The U.S. Department of Energy, and a consortium of U.S. utilities and industry, built the first two large-scale, demonstration solar power towers in the desert near Barstow, California.[6]
Solar One operated successfully from 1982 to 1988, proving that power towers work efficiently to produce utility-scale power from sunlight. The Solar One plant used water/steam as the heat-transfer fluid in the receiver; this presented several problems in terms of storage and continuous turbine operation. To address these problems, Solar One was upgraded to Solar Two, which operated from 1996 to 1999. Both systems had the capacity to produce 10 MW of power.[6]
The unique feature of Solar Two was its use of molten salt to capture and store the sun's heat. The very hot salt was stored and used when needed to produce steam to drive a turbine/generator that produces electricity. The system operated smoothly through intermittent clouds and continued generating electricity long into the night.[8]
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.
Trough systems predominate among today's commercial solar power plants. Nine separate trough power plants, called Solar Energy Generating Systems (SEGS), were built in the 1980s in the Mojave Desert near Barstow by the Israeli company Luz Industries. These plants have a combined capacity of 354 MW. Today they generate enough electricity to meet the power needs of approximately 500,000 people.[1]
Trough systems convert the heat from the sun into electricity. Because of their parabolic shape, trough collectors can focus the sun at 30-60 times its normal intensity on a receiver pipe located along the focal line of the trough. Synthetic oil circulates through the pipe and captures this heat, reaching temperatures of 390 °C (735 °F). The hot oil is pumped to a generating station and routed through a heat exchanger to produce steam. Finally, electricity is produced in a conventional steam turbine.[1] The SEGS plants are configured as hybrids to operate on natural gas on cloudy days or after dark, and natural gas provides 25% of the total output.[1]
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, National Renewable Energy Laboratory, and Acciona Solar.[2]
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, and 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.[2]
Solar thermal power plants designed for solar-only generation are well 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 baseload needs.[9]
The cost of Nevada Solar One is in the range of $220–250 million. The power produced is slightly more expensive than wind power, but less than photovoltaic (PV) power.[10]
The Copper Mountain Solar Facility is a 48 megawatt (MW) solar photovoltaic power plant in Boulder City, Nevada.[3] Sempra Generation began construction of the plant in January 2010 and on December 1, 2010, the company announced that it had finished the project and the facility was generating electricity. At its construction peak more than 350 workers were installing the 775,000 First Solar panels on the 380 acre site.[3]
The power from Copper Mountain Solar Facility (and the adjacent 10 MW El Dorado Solar Power Plant) has been sold to Pacific Gas & Electric under separate 20-year contracts. Californian utilities are required to obtain 20 percent of their energy supply from renewable energy sources by the end of 2010, increasing to 33 percent by 2020.[3]
In December 2007, the U.S. Air Force announced the completion of the Nellis Solar Power Plant, a solar photovoltaic (PV) system, at Nellis Air Force Base in Clark County, Nevada. Occupying 140 acres (57 ha) of land leased from the Air Force at the western edge of the base, this ground-mounted photovoltaic system employs an advanced sun tracking system, designed and deployed by PowerLight subsidiary of SunPower. Tilted toward the south, each set of solar panels rotates around a central bar to track the sun from east to west.[11] The 14-megawatt (MW, million watt) system will generate more than 30 million kilowatt-hours of electricity each year (about 82 thousand kilowatt-hours per day) and supply approximately 25 percent of the total power used at the base. The Nellis Solar Power Plant is one of the largest solar photovoltaic systems in North America.[12][13]
The Sierra SunTower is a 5 MW commercial concentrating solar power (CSP) plant built and operated by eSolar. The plant is located in Lancaster, California and is the only CSP tower facility operating in North America. The project site occupies approximately 8 hectares (20 acres) in an arid valley in the western corner of the Mojave Desert at 35° north latitude.
The Blythe Solar Power Project is a 968 MW solar photovoltaic facility proposed for Riverside County, California. The companies involved are Solar Millennium and Chevron. The initial plan was to use a solar thermal parabolic trough design, although the companies switched to solar photovoltaic panels-the same technology used in rooftop installation-because of the lower costs. Still, Solar Millennium lacked the financing to begin construction of the projects, and sold the proposal to German-firm Solarhybrid, which is in discussions with First Solar to enter into a joint venture to build the Blythe project. [14] [15][16]
The 392MW Ivanpah Solar Power Facility, located 40 miles (64 km) southwest of Las Vegas, is the world’s largest solar-thermal power plant project currently under construction.[17] BrightSource Energy received a $1.6 billion loan guarantee from the United States Department of Energy to build the project, which will deploy 347,000 heliostat mirrors focusing solar energy on boilers located on centralized solar power towers. The project is controversial for its environmental impacts, included the elimination of desert tortoise habitat. As of September 2011, at least 127 desert tortoises were displaced by the 5.6 square mile project.[18] [17][19]
The Mojave Solar Park is a solar thermal power facility under construction in the Mojave Desert in California, which is located 100 miles northeast of Los Angeles near Barstow. The 280 MW concentrating solar power (CSP) plant will cost an estimated $1.6 billion in total and should be completed in 2014. Abengoa has successfully secured a $1.2 billion loan guarantee from the US government for the project.[20]
The 230 MW Antelope Valley Solar Ranch is a First Solar photovoltaic project which is under construction in the Antelope Valley area of the Western Mojave Desert, and due to be completed in 2013. The project has received a $680 million government loan guarantee and will involve 350 construction workers. It features an innovative utility-scale deployment of inverters with voltage regulation and monitoring technologies, which will "enable the project to provide more stable and continuous power". Electricity from the Antelope Valley Solar Ranch project will be sold to Pacific Gas & Electric Company.[21][22]
Solar thermal power plants require large amounts of land. According to the Bureau of Land Management, there were proposals to cover nearly 40 square miles of public land in California. If all of the proposed projects were built, they would generate approximately 3500 megawatts.[23] The requirement for so much land has spurred efforts to encourage solar facilities to be built on already-disturbed lands, and the Department of Interior identified Solar Energy Zones that it judges to contain lower value habitat where solar development would have less of an impact on ecosystems.[24] Sensitive wildlife impacted by large solar facility plans include the desert tortoise, Mohave Ground Squirrel, Mojave fringe-toed lizard, and Desert Bighorn sheep.
Some of the land in the eastern portion of the Mojave Desert is to be preserved, but the solar industry has expressed interest in areas of the western desert, "where the sun burns hotter and there is easier access to transmission lines", says Kenn J. Arnecke of "FPL Energy". A sentiment shared by many executives in the industry.[25]
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