Towards a Commercial Parabolic Trough CSP System Using Air as Heat Transfer Fluid

We report on major design innovations related to the trough concentrator, solar receiver, and thermal storage of a parabolic trough CSP system. A 9.7 m aperture parabolic trough mirror is formed by inflated, metallized, polymeric films mounted on a rigid and durable concrete support structure. The novel receiver design, which uses air as the heat transfer fluid at ambient pressure, is based on an array of absorber cavities coupled to secondary concentrating optics for operating temperatures exceeding 600 °C. The solar-heated air is directly fed to a thermal energy storage unit based on a packed bed of rocks to guarantee round-the-clock dispatchability of high-temperature heat to the power block. A commercial CSP plant with a projected peak thermal power output of 3.9 MWth is currently under construction in Ait Baha, Morocco.