Thermal desalination potential with parabolic trough collectors and geothermal energy in the Spanish southeast

Abstract

Desalination industry has become essential for the survival of the population in places with shortages of fresh water. Because is a costly process, the constant search for the best local renewable energy sources is a necessity. A theoretical Multi-effect distillation plant of 9000 m3/d located in the southeast Spanish (Almería) is intended to fed thermally with solar (parabolic trough collectors) and geothermal energy. Starting from the history of solar irradiation and temperatures of the province of Almería from 1994 to 2016 provided by Solargis database, a discrimination of the profile of temperatures is obtained at the exit of the solar panels. Putting in common the profile exit temperatures and the potentiality of the geothermal resource at the depth in the area under study, a series of possible configurations are obtained. The theoretical results of the study indicate that during 76% of the annual time is achieved with both resources (solar and geothermal) at that depth of the well in that specific climatological zone (490 m, t = 41.8 °C). Since the thermal gradient in the area is 8.87 °C per 100 m depth according to the studies carried out, only geothermal energy would be necessary at deep of 790 m to obtain working temperatures of the desalination plant at 70 °C. Applying the results to the existing desalination plants of the Spanish project named Actions for the Management and Utilization of Water is obtained 6 years of amortization and 510,387,920 kg/y CO2 avoided to the atmosphere for all of these plants.