Development of an off-grid solar energy powered reverse osmosis desalination system for continuous production of freshwater with integrated photovoltaic thermal (PVT) cooling

Abstract

Increasing urbanisation and population growth have caused depletion of freshwater resources leading to exacerbation of water scarcity in remote communities. Whilst much attention has been paid to improving industrial-scale desalination plants over the past decade, the development of small-scale off-grid desalination units to facilitate freshwater supply for remote communities has been overlooked. This study presents a novel method for coupling solar photovoltaic thermal (PVT) cells to reverse osmosis (RO) desalination introducing seawater as the cooling medium to increase the thermal efficiency of solar energy generation and subsequently maximising the rate of freshwater production. The inclusion of a battery unit will enable a constant rate of freshwater supply leading to minimisation of membrane fouling which often occurs in renewable energy powered membrane desalination units. The integrative system has been simulated for the seawater properties and climatic conditions in Alexandria, Egypt. Furthermore, the modelling results indicate that using the proposed method will lead to a reduction of 0.12 kWh/m3 in the specific electricity consumption rate of RO desalination, as well as increasing the electricity generation capacity of the PVT cells leading to a 6% reduction in the required solar panel surface area.