ly powered a steam engine with sunlight in 1866 - the first known example of a concentrating solar-powered mechanical device.
Concentrating Solar Power (CSP) systems use lenses or mirrors combined with tracking systems to focus sunlight which is then used to generate electricity. The primary mechanisms for concentrating sunlight are the parabolic trough, the solar power tower (not to be confused with solar updraft towers) and the parabolic dish. The high temperatures produced by CSP systems can also be used to provide heat and steam for a variety of applications (cogeneration). CSP technologies require direct sunlight (insolation) to function and are of limited use in locations with significant cloud cover.
Solar thermal power plants have been in commercial use in southern California since 1985. An area of desert around 250 km by 250 km covered with CSP power generation could supply all the world's current electricity demand.
Solar thermal plants can be built in their entirety within a few years - much faster than many conventional power projects. Solar thermal plants are built almost entirely with modular, commodity materials (and thus have short development and construction times) and do not encounter the sort of opposition on environmental grounds that traditional forms of power generation like coal and nuclear face.
Operational plants include :
* US (California) - 354 MW FPL's Solar Energy Generating Systems (SEGS) plant, using parabolic troughs
* US (Arizona) - 1 MW Acciona Energy's Saguaro Solar Generating Station using parabolic troughs
* Spain (Seville) - 11 MW Abengoa's PS10 solar tower
* Australia (NSW) - 35 MW Liddell Power Station using fresnel reflectors
* US (Nevada) - 64 MW Acciona Energy's Nevada Solar One plant (not to be confused with the Solar One / Solar Two experimental plants) using parabolic troughs
Plants currently under construction :
* Spain (Seville) - 20 MW Abengoa's PS20 solar tower
* Spain (Seville) - 20 MW (each) Abengoa's PS20 and AZ20 solar towers
* Spain (Seville) - 50 MW (each) Abengoa's Solnova 1 and 3 using parabolic troughs (5 plants planned in all)
* Spain (Andalusia) - 17 MW Sener's Solar Tres solar tower (molten salt energy storage)
* Spain (Andalusia) - 50 MW (each) Sener's Andasol I, II and III plants (molten salt energy storage)
Solar Thermal Heating Up
There has been a spate of new announcements regarding solar thermal power over the past year - there are over 5,800 MW of solar thermal plants in the planning stages worldwide.
The company receiving the most attention seems to be Ausra, a company set up by Dr David Mills (who pioneered the CSP plant at the Liddell power plant in New South Wales using compact linear Fresnel-reflector technology) with backing from Vinod Khosla and Kleiner, Perkins, Caulfield & Byers (see here for a brief demo of how their technology works). Mills estimates that solar thermal plants could provide more than 90 percent of current U.S. power demand at prices competitive with coal and natural gas. "There's almost no limit to how much you can put into the grid," he says.
Mills presented a paper (pdf) at the IEA SolarPACES conference in Las Vegas recently which revealed some interesting statistics about the construction cost of solar-thermal technologies: US$3,000 per kW of capacity, estimating this will drop to US$1,500 per kW over the next "several" years. The New York Times last year quoted GE Energy executives estimating coal plant construction between US$2,000 and US$3,000 per kW. Ausra says it can generate electricity for 10 cents per kWh (close to the current cost using natural gas), and it expects the price to drop even further.
According to Technology Review:
What distinguishes Ausra's design is its relative simplicity. In conventional solar-thermal plants such as Solel's, a long trough of parabolic mirrors focuses sunlight on a tube filled with a heat-transfer fluid, often some sort of oil or brine. The fluid, in turn, produces steam to drive a turbine and produce electricity. Ausra's solar collectors employ mass-produced and thus cheaper flat 