Technological aspects of advancement in low-capacity solar thermal desalination units

Drinking water of acceptable quality has become a scarce commodity. The standard high-capacity desalination methods such as multi-stage flash evaporation and multi-effect evaporation, vapour compression and reverse osmosis are reliable in the range of about 100–500,000 m3/day fresh-water productions. However, the wide-scale implementations of these methods face numerous technological, economic and political barriers and these methods are not used in decentralised regions with a poor infrastructure due to their permanent need of qualified maintenance and electricity supply. In this paper, various low-capacity solar thermal desalination systems, with fresh-water output production in the range of 10–150 l/day for the use in rural areas, are reviewed and classified based on five technological aspects such as the development of the technology of the systems, the applicability of high-capacity thermal desalination technologies, the enhancement of solar heat collectors, the hybridisation of thermal desalination technologies and heat recovery processes. Most of the reviewed systems are in the research stage and have not cleared economic feasibility such as the price per cubic metre of water that may stimulate the decision-maker to direct these studies into the actual commercial applications to find a solution to the water scarcity problem in isolated and remote areas. Although many of the developed systems have several novel and valuable features, more efforts are required for further investigating more efficient, economic and applicable solar energy-driven low-capacity desalination systems.