Page - 110 - in Water, Energy, and Environment - A Primer

needed toaddress the instabilityofSolarOnewhensunlightwas disruptedbypassingclouds.SolarTwowassuccessfully testedat a10MWelectrical output, but operationwasdiscontinued in the mid-1990swhentheCSTPindustrywasunwillingtosharefurther development costs with DOE. The Solar Two tower was eventually demolished in 2009 and its heliostats are now being used for astronomy research. 8.2.2.2 Linear concentrator The most common type of linear concentrator system captures the Sun’s energy with long rectangular curved mirrors (parabolic troughs) that track the Sun and focus sunlight on glass tubes that run along the troughs’ focal lines. The tubes are filled with a dark, heat-absorbing fluid that transfers its heat to water to generate steam (seeFigure 8.7). Figure 8.7 Parabolic trough CSTP system (Source: U.S. National RenewableEnergyLaboratory). Water,Energy, andEnvironment–APrimer110