Small-scale desalination plant driven by solar energy for isolated communities

Abstract

In the last years, an increasing number of countries has been affected by water shortage. Seawater desalination driven by solar energy, which is usually available in arid regions, might be a solution to satisfy the freshwater demand. In this study, the feasibility of a stand-alone multi-effect desalination (MED) plant driven by solar energy for an isolated community was studied. The system was made up of a solar field, a MED unit, and a thermal storage that mitigated solar energy fluctuations. Simulations with different top brine temperature and inclination and number of the solar panels were carried out in Matlab and Aspen Plus on an hourly basis by considering one typical meteorological year for ambient temperature and solar radiation. Two different sources of electrical energy were considered: A photovoltaic (PV) field and a diesel generator. The results were compared from an energetic and economic point of view, by considering the adoption of plastic as a material for MED heat exchangers. The maximum water production was obtained with December as the design month. Polytetrafluoroethylene heat exchangers allowed the cost of water to be reduced up to 9.5% compared to conventional exchangers. The lowest cost of water (7.09 $/m3) was obtained with September as the design month and a tilt angle of 45◦ with the PV field as the electrical power source.