Parabolic Trough Technology is the most proven solar thermal electric technology. Trough solar systems use parabolic shaped, trough shaped reflectors. These reflector focus the sun’s energy onto a receiver pipe running at the focus of the reflector. The receiver is a tube positioned directly above the middle of the parabolic mirror and is filled with a working fluid. The reflector follows the Sun during the daylight hours by tracking along a single axis. The concentrated energy heats the fluid at 150-3500C. The fluid is then used to generate steam which powers a turbine that drives an electrical generator.
Solar energy Generating Systems (SEGS) is the largest solar energy generating facility in the world, with 354MW of installed capacity in 9 plants. These 9 plants are located in California’s Mojave Desert. The average gross solar output for all nine plants at SEGS is around 75 MWe - a capacity factor of 21%. 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.
Nevada Solar One is another parabolic trough plant with a nominal capacity of 64MW and maximum capacity of 75MW. The plant employs 760 parabolic concentrators with more than 182,000 mirrors that concentrate the sun’s rays onto more than 18,240 receiver tubes. Fluid that heats up to 735°F flows through these tubes. This heat is used to produce steam that drives a conventional turbine, which is connected to a generator that produces electricity.
Adansol Solar Power Station is Europe’s first commercial parabolic Trough solar thermal plant, located near Guadix in Andalusia, Spain. The AndaSol-1 solar thermal plant consists of a solar field of 510,120 m² of SKAL-ET type parabolic trough collectors, a 6-hour molten-salt thermal storage system, and a Rankine cycle with a 49.9 MWe net capacity. In direct operation mode, the heat transfer fluid is circulated through the solar field to the steam generation system, where steam is produced at a temperature of 377°C and a pressure of 100 bars. The steam generation system consists of two parallel heat exchanger trains and two, again connected in parallel, reheaters. The HTF fluid acts as the heat transfer medium between the solar field and the power block is heated up in the solar collectors and cooled down while producing steam in the steam generator. This steam is sent to the power block, where it is expanded in a steam turbine that drives the electricity generator.
Linear Fresnel reflectors:
The linear Fresnel reflector power plant uses a series of long, narrow, shallow curvature mirrors (or even flat mirrors). The sunlight is concentrated through these mirrors onto tubes through which the working fluid is pumped. Fresnel reflectors are much cheaper than parabolic reflectors.
Kimberlina solar thermal power plant is the first Compact Linear Fresnel Reflector project in North America. This plant is located in Bakersfield, California, United States. Ausra began construction of the power plant in March 2008. Kimberlina will generate upto 5 megawatts of electricity.
Fact sheet: http://www.ausra.com/pdfs/KimberlinaOverview.pdf
Puerto Errado 1 Thermosolar Power Plant is operated by Novatec Solar España. This plant is located in Calasparra, Spain. This plant will generate electricity upto 2,800 MWh/yr.
Solar Dish Stirling:
Solar Dish Stirling system consists of a highly reflective silvered mirror dish concentrator that reflects solar radiation onto a receiver mounted at the focal point. The concentrated sunlight heats a working fluid in contact with the receiver to a temperature of approximately 7500C. This thermal energy is used by a Stirling engine, which spins the alternator to generate electricity.
The Big Dish is a parabolic dish concentrator developed by the Solar Thermal Group, Australian National University. The initial prototype, SG3, was constructed on the Canberra campus of the Australian National University. In 2006, a joint project led by the Solar Thermal Group with commercial partner Wizard Power, and funding from Australian’s Government’s Renewable Energy Development Initiative, began the design and construction of SG4. SG4 is located next to the SG3 dish, and was completed in 2009.
Solar Power Tower:
Solar power towers generate electric power from sunlight by focusing concentrated solar radiation on a tower-mounted heat exchanger (receiver). The system uses hundreds to thousands of sun-tracking mirrors called heliostats to focus sun’s rays on a receiver at the top of a tower. A heat transfer fluid heated in the receiver is used to generate steam. The steam is then used in turbine generator to generate electricity.
Solar One was a pilot solar-thermal project built in the Mojave Desert just east of Barstow, CA, USA. It was the first test of a large-scale thermal solar power tower plant. Solar One pilot project came online in 1982 and was used to produce electricity until 1988. The project produced 10 MW of electricity using 1,818 mirrors, each 40 m² (430 ft²) with a total area of 72,650 m² (782,000 ft²).
In 1995 Solar One was converted into Solar Two, by adding a second ring of 108 larger 95 m² (1,000 ft²) heliostats around the existing Solar One, totaling 1926 heliostats with a total area of 82,750 m² (891,000 ft²). This gave Solar Two the ability to produce 10 megawatts. Instead of using the sunlight to heat water, it was used to heat a molten salt solution. Once the molten salt is heated, it is stored in large tanks at the base of the tower for later use. This allows the operators of the plant to tap into its stored heat when they need it, not just when the sun is shining.
Due to the success of Solar Two, a commercial power plant, called Solar Tres Power Tower, is being built in Spain by Torresol Energy using Solar One and Solar Two’s technology for commercial electrical production of 15 MW. Solar Tres will be three times larger than Solar Two with 2,493 heliostats, each with a reflective surface of 96 m². The total reflective area will be 240,000 m². They will be made of a highly reflective glass with metal back to cut costs by about 45%. A larger molten nitrate salt storage tank will be used giving the plant the ability to store 600 MWh, allowing the plant to run 24x7 during the summer.
About Concentrated solar power
Concentrating Solar Power is a technology to convert solar radiation into electricity. CSP technologies use mirrors or lenses to concentrate light energy from the sun. This light energy is converted to heat to create steam to drive a turbine that generates electrical power. - view more