World-wide water scarcity, especially in the developing world, indicates a pressing need to develop inexpensive, decentralized small-scale desalination technologies which use renewable resources of energy. Major desalination processes consume a large amount of energy derived from oil and natural gas as heat and electricity, while emitting harmful CO2. Solar desalination has emerged as a promising renewable energy-powered technology for producing fresh water. One of the innovative methods for decentralized low-scale puriﬁcation of water is the humidiﬁcation dehumidiﬁcation (HDH) desalination technology. Combining the principle of humidification-dehumidification with solar desalination results in an increase in the overall efficiency of the desalination plant. Solar still is an ideal source of fresh water for both domestic and agricultural aspects. It is one of the most important viable applications of solar energy.
In this review the operated desalination of solar stills and HDH units; their operating principle; advantage and disadvantage has been extensively reviewed.