PT is the most mature CSP technology, accounting for more than 90% of the currently installed CSP capacity., It is based on parabolic mirrors that concentrate the sun’s rays on heat receivers (i.e. steel tubes) placed on the focal line. Receivers have a special coating to maximize energy absorption and minimize infrared re-irradiation and work in an evacuated glass envelope to avoid convection heat losses .
The solar heat is removed by a heat transfer fluid (e.g. synthetic oil, molten salt) flowing in the receiver tube and transferred to a steam generator to produce the super-heated steam that runs the turbine. Mirrors and receivers track the sun’s path along a single axis (usually East to West). An array of
mirrors can be up to 100 meters long with a curved aperture of 5-6 meters.
Most PT plants currently in operation have capacities between 14-80 MWe, efficiencies of around 14-16% (i.e. the ratio of solar irradiance power to net electric output) and maximum operating temperatures of 390°C, which is limited by the degradation of synthetic oil used for heat transfer. The use of molten salt at
550°C for either heat transfer or storage purposes is under demonstration. High temperature molten salt may increase both plant efficiency (e.g. 15%-17%) and thermal storage capacity. In addition to the SEGS project (i.e. nine units with a total capacity of 354 MW in operation since the 1980s--, major and more recent PT projects in operation include two 70-MW units in the United States (i.e. Nevada Solar One and MNGSECFlorida), about thirty 50-MW units in Spain and smaller units in a number of other countries .
The three 50-MW Andasol units by ACS/Cobra Group and Marquesado Solar SL and the two 50-MW (Valle I and II) plants by Torresol Energy in Spain are particularly interesting, as they use synthetic oil as the heat transfer fluid and molten salt as the thermal storage fluid. They have a thermal storage capacity of
around 7.5 hours, which can raise the capacity factor up to 40%. In Italy, a 5-MW demonstration plant (ENEL, ENEA) with eight hours of thermal storage started operation in June 2010 to test the use of molten salt as either heat transfer or storage fluid, which can significantly improve the storage performance and the
capacity factor (by up to 50%) because the higher operation temperature and thermal capacity of molten salt enable more storage capacity with reduced storage volume and costs .
Large PT plants under construction include the Mojave project (a 250 MW plant in California due to start operation in 2013), the 280 MW Solana project in Arizona due in 2013, the Shams 1 100MW project in the United Arab Emirates due in 2012/2013), the Godawari project (India, 50 MW, 2013) and a further fifteen 50-MW plants in Spain.
The solar heat is removed by a heat transfer fluid (e.g. synthetic oil, molten salt) flowing in the receiver tube and transferred to a steam generator to produce the super-heated steam that runs the turbine. Mirrors and receivers track the sun’s path along a single axis (usually East to West). An array of
mirrors can be up to 100 meters long with a curved aperture of 5-6 meters.
Most PT plants currently in operation have capacities between 14-80 MWe, efficiencies of around 14-16% (i.e. the ratio of solar irradiance power to net electric output) and maximum operating temperatures of 390°C, which is limited by the degradation of synthetic oil used for heat transfer. The use of molten salt at
550°C for either heat transfer or storage purposes is under demonstration. High temperature molten salt may increase both plant efficiency (e.g. 15%-17%) and thermal storage capacity. In addition to the SEGS project (i.e. nine units with a total capacity of 354 MW in operation since the 1980s--, major and more recent PT projects in operation include two 70-MW units in the United States (i.e. Nevada Solar One and MNGSECFlorida), about thirty 50-MW units in Spain and smaller units in a number of other countries .
The three 50-MW Andasol units by ACS/Cobra Group and Marquesado Solar SL and the two 50-MW (Valle I and II) plants by Torresol Energy in Spain are particularly interesting, as they use synthetic oil as the heat transfer fluid and molten salt as the thermal storage fluid. They have a thermal storage capacity of
around 7.5 hours, which can raise the capacity factor up to 40%. In Italy, a 5-MW demonstration plant (ENEL, ENEA) with eight hours of thermal storage started operation in June 2010 to test the use of molten salt as either heat transfer or storage fluid, which can significantly improve the storage performance and the
capacity factor (by up to 50%) because the higher operation temperature and thermal capacity of molten salt enable more storage capacity with reduced storage volume and costs .
Large PT plants under construction include the Mojave project (a 250 MW plant in California due to start operation in 2013), the 280 MW Solana project in Arizona due in 2013, the Shams 1 100MW project in the United Arab Emirates due in 2012/2013), the Godawari project (India, 50 MW, 2013) and a further fifteen 50-MW plants in Spain.
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