Low-grade heat from solar ponds: trends, perspectives, and prospects

Technology developments have increased the more efficient use of solar energy, which has led to the emergence of novel technologies to absorb, convert and store solar irradiations. Solar ponds are one of the large-scale systems that have the proper potentials to achieve these objectives. The obtained thermal energy from the solar ponds is classified as low-grade heat. This paper brings together the benefits of the progress of solar ponds. Initially, the new types of construction, salts, and additives for achieving enhancements in the thermal performance of the solar ponds are presented. Then, advanced models for reducing the heat losses from side walls, upper and lower zones are assessed. Finally, different tools for evaluating the solar ponds are reviewed. In this review, the accomplishments in all processes for the absorption of solar irradiation, storing and extracting thermal energy, and the application of salinity gradient solar ponds are reviewed in detail.