This notebook delineates the most established and oldest of solar thermal electrical generation systems: Parabolic Trough.
Parabolic trough systems use a linear array of parabolic mirrors to focus solar radiation onto an evacuated collector tube filled with a heat transfer fluid, usually an organic compound such as Therminol or a mineral oil. This heated fluid is then pumped into a conventional thermal power block, where it is used to flash steam in a boiler and operate a steam turbine to generate electricity.
Parabolic trough technology was first employed in the Egyptian village of Ma'adi in 1913, a 55 horsepower system that was used to pump water.
The first commercial applications of parabolic troughs were in the portfolio of 8 solar thermal plants build in the 1980s and early 1990s in southern California, by the Israeli technology pioneer Luz. Though Luz was forced into bankruptcy in 1991, the plants continue to operate, and at 354MW of combined nameplate capacity, still comprise the largest portfolio of solar thermal plants in the world.
With the resurgence in interest in solar thermal power, parabolic trough remains the industry standard. Following the commissioning of the 64MW Nevada Solar One in 2007, several hundred MW of Spanish parabolic trough projects will come online in the next year. A number of US utilities, in particular PNM (New Mexico) have specified parabolic trough as the 'technology of choice' in their recent requests for proposals for solar thermal power.
Leading companies are Solel, founded by veterans of Luz (Israel), Solar Millennium (Germany), Acciona (Spain), Abengoa (Spain) and SkyFuel (US).
