Assessment of different configurations for combined parabolic-trough (PT) solar power and desalination plants in arid regions

The combination of desalination technology into concentrating solar power (CSP) plants needs to be considered for the planned installation of CSP plants in arid regions. There are interesting synergies between the two technologies, like the possibility of substituting the condenser of the power cycle for a thermal desalination unit. This paper presents a thermodynamic evaluation of different configurations for coupling parabolic-trough (PT) solar power plants and desalination facilities in a dry location representing the Middle East and North Africa (MENA) region. The integration of a low-temperature multi-effect distillation (LT-MED) plant fed by the steam at the outlet of the turbine replacing the condenser of the power cycle has been simulated and compared with the combination of CSP with a reverse osmosis (RO) plant. Furthermore, an additional novel concept of concentrating solar power and desalination (CSP+D) has been evaluated: a LT-MED powered by the steam obtained from a thermal vapour compressor (TVC) using the exhaust steam of the CSP plant as entrained vapour and steam extracted from the turbine as the motive vapour of the ejector. This new concept (LT-MED-TVC) has been analyzed and compared with the others, evaluating its optimization for the integration into a CSP plant by considering different extractions of the turbine.

► Combined solar power and desalination evaluated thermodynamically in arid regions.
► Low-temperature multi-effect distillation (LT-MED) replacing the condenser is more efficient than coupling with reverse osmosis (RO).
► LT-MED-TVC has smaller efficiency, although cooling requirements are lower.
► With steam extractions from low-P turbine at 2 bar, CSP+LT-MED-TVC is competitive.