Combined Fresh Water Production and Power Generation from Geothermal Reservoirs

Abstract

Using a novel thermodynamic system, utilizing the renewable energy source, electrical power generation and water desalination can be achieved simultaneously, which properly addresses the twin challenges of energy and fresh water shortage. This novel system features a reaction turbine with a pair of convergent -divergent nozzles, which converts the salt water, heated by solar energy, into a mixture of vapour and brine by taking advantage of the trilateral flash cycle. The flashing process occurs in a vacuum chamber which is maintained at a low temperature by an internal coil condenser cooled by water. The reactive force due to the flow exiting the nozzles creates a torque on the rotor arms, which in turn rotates an electric generator and thus generates electrical power. A series of test results such as power generation, fresh water production and system efficiency are presented, which are analysed and also compared with those obtained from the previous experiments. Moreover, a prototype of an improved system is described, which involves a novel disk-shape reaction turbine with a curved flow path for the nozzle, and a new external condensing system that contains four plate heat exchangers. This new system is expected to produce more power, up to 2 kW, in comparison to the current system’s maximum power generation of 450 W. In the final part of this paper, the performance of a salinity gradient solar pond and evacuated tube solar water heater as possible renewable energy sources for this kind of system are discussed.