Heat Transfer Fluids for Future Parabolic Trough Solar Thermal Power Plants

Kurzfassung

Parabolic trough solar thermal power plants are at present the cheapest option for utility scale solar electricity production. At present several projects are under development in Spain, in the USA, Egypt, Morocco, Mexico, Algeria and Iran. The levelised cost of electricity (LCE) for solar thermal power plants is in the range of 13–21 €Cts/kWh. Accordingly, subsidies are necessary to bridge the gap between current LCE’s and market price. To achieve a sustainable competitiveness significant cost reduction is required. One possibility for cost reduction is increasing the efficiency. So far synthetic oil is used as a heat transfer fluid (HTF) in the absorber tubes of the collector field. This HTF limits the upper temperature of the power cycle to 370°C and thus the achievable efficiency to approx. 38%. Alternative HTF’s are under investigation. This paper compares the different HTF’s with respect to the operation temperature, overall operation aspects, storage concepts safety aspects and of course costs.