Thermoeconomic comparison of integrating seawater desalination processes in a concentrating solar power plant of 5 MWe

• A thermoeconomic comparison between MED and RO desalination technologies is performed.
• It is analyzed the coupling between MED and RO units and PT-STPP plants.
• SWRO produces the lower LWC, both with direct or indirect integration.
• Decoupling the SWRO from the STPP is the best option (lowest LWC).

In this work a thermoeconomic analysis of the joint production of electricity and water for a simulated 5 MWe Solar Thermal Power Plant (STPP) based on parabolic trough mirrors and Direct Steam Generation (DSG) is carried out. The location considered for this plant is Almería, in southeast of Spain. Two different seawater technologies have been selected to be coupled with the STPP: Multi-Effect Distillation (MED) and Reverse Osmosis (RO). The Power Block (PB) has been designed to maximize the thermal efficiency, including regeneration and reheating. Four coupling arrangements have been investigated: the MED replacing the condenser of the PB, the MED being fed by one steam extraction of the PB, the RO directly using the electricity generated in the PB and the RO connected to the local grid. Results show that the best coupling option is with the RO unit being connected to the local grid, which produces the lower Levelized Water Cost (LWC).