The energy of the CSP component in a SFP-facility can also directly power a traditional desalination plant offering a potential for increased freshwater production at the facility. The release of brine from the desalination plant would be channeled into the saltwater infrastructure in the SFP-facility for salt production, thus avoiding release of the brine back to the sea. Though many new desalination technologies are in development, three key types are most commonly used for large-scale seawater desalination. Multiple-effect distillation (MED) and multi-stage flash distillation (MSF) are both thermal methods that utilize high-grade waste heat to drive desalination, while reverse osmosis (RO) utilizes electricity.
Operating a thermal desalination plant requires taking ‘waste’ heat from the CSP steam cycle at a higher temperature than optimal, which reduces the efficiency of electricity generation but allows the large-scale production of freshwater. These processes work on the principle of distillation and require cooling to drive the condensation of freshwater, with cooling requirements similar to those of a stand-alone CSP system. This cooling will be provided by the saltwater-cooled greenhouse infrastructure. Alternatively, electricity produced by the CSP system may be used to power an RO desalination plant, which operates by generating pressure to ‘reverse’ osmosis through a membrane, pushing water molecules in seawater through the membrane while the salts, too large for the membrane’s holes, are held back in the brine solution. This method produces water of lesser purity than the thermal methods, but that is more than adequate for irrigation or drinking.