Effectiveness of desalination powered by a tracking solar array to treat saline bore water Original Research Article

A solar powered desalination unit was tested between October 2008 and February 2010 in the Brisbane Botanic Gardens, Mt. Coot-tha, Queensland, Australia to provide garden irrigation during drought conditions. Water was extracted from a saline bore, and the salt was removed with a 30 kL/d brackish bore water desalination unit. The driving force was provided by a bore pump driven by a 1.44 kW tracking solar array. This study demonstrated that solar powered desalination of saline bore water delivered fresh water to the rated flow rate of the RO membrane rack during periods of sunshine. During periods of overcast or rainy weather, the performance of desalination decreased. Consumption of permeate for flushing further reduced overall recovery rate during rainy weather. Solar desalination performance was inversely related to the El Niño Southern Oscillation Index (polynomial fitting R² > 0.4). Analysis of performance in relation to satellite-derived daily horizontal solar radiation shows stronger correlation with permeate production. Wet seasons tended to hinder performance. Performance in terms of specific energy consumption is related to salinity. Other factors that contributed to the present finding of low specific energy consumption included tracking solar arrays, avoidance of batteries, and utilization of bore pump pressure to drive RO.