A review of natural materials for solar evaporation

One way to harvest solar energy is to produce steam from liquid water. Steam can be used to provide freshwater even in a harsh environment, with extreme temperature and low groundwater supplies. It can also be extracted from polluted soil or water, purifying the water in the process at the same time. Water evaporation systems are energy effective, with efficiencies ranging from 60% to over 90%. Furthermore, they can be cost-effective and have a low environmental impact, using the right materials. In this article, we will review natural materials, mainly of biological origin, proposed for solar evaporation, from wood and plants to algae and other atypical biomass such as fungi or wastes such as pomelo peels, through gels and foams, raw or charred. Their evaporation effectiveness will be presented and discussed, as well as their energy efficiency. This timely review suggests the suitability of natural materials for this application and reports on the progress that has already been achieved, as well as on the advances that remain to be made to improve the performance of these low cost, low environmental impact but high performance systems.