Global applicability of solar desalination

Over-exploited fresh water resources, fossil-fuel depletion and climate change all highlight need for desalination powered by renewable energy. This study briefly reviews literature on solar desalination technologies and examines economic and environmental feasibility. The maturest technology appears to be reverse osmosis driven by photovoltaics. Many studies refer to apparent spatial coincidences of water scarcity, solar energy abundance and saline water availability, but none examine the phenomenon objectively from a global perspective. This study proposes a method for correlating international data on water scarcity and stress, saline water resources, and insolation levels, to calculate rank scores (0 ≤ R ≤ 1) which identify where solar desalination is most applicable. Low scores (R < 0.125) occur in landlocked nations with limited saline groundwater resources (Nepal, Bolivia, South Sudan) and near polar regions where fresh water is abundant and solar insolation levels are low (Canada, Russia and Scandinavia). High scores (R > 0.422) occur in 30 nations, including Middle Eastern and North African countries where fossil fuelled desalination is commonplace, and solar desalination has obvious applicability. The analysis identifies 28 further countries (including parts of USA, China, India, Indonesia, Australia, and countries throughout Africa, Asia, South America and Europe) where 0.273 < R < 0.422 scores indicate that other, less obvious, solar desalination opportunities exist.