ANALYSIS OF HYBRID PHOTOVOLTAIC/THERMAL (PV/T) SOLAR SYSTEMS FOR SMALL SCALE REVERSE OSMOSIS DESALINATION PLANTS

摘要

Facing global fresh water shortages, reverse osmosis (RO) seawater desalination is one of the most promising technical solutions. This paper will concentrate on small-scale, stand-alone RO plants driven by photovoltaic (PV) systems. A novel possibility to make a solar driven RO plant not only technically, but also economically viable will be described: using hybrid photovoltaic/thermal (PV/T) solar systems. This has two main advantages: preheated feed water leads to significantly higher fresh water output as RO membrane recovery ratio highly depends on the feed water temperature. Meanwhile, the PV module is cooled resulting in higher electrical efficiency and consequently a higher water output. A simulation for estimating the potential of this combination was performed. It will be shown that PV/T driven plants produce about 30% to 40% more potable water than PV driven plants. Compared to a pure RO-PV system, 20% to 30% of collector area could be saved. However, only a small cooling effect of the fluid can be observed. Furthermore, it will turn out that PV/T systems can also be an economic alternative to pressure recovery systems, which, up to now, are only feasible in large-scale desalination plants.