Desalination by solar powered membrane distillation systems

Membrane distillation (MD) is a hybrid membrane-evaporative process which has been of interest for desalination. MD requires two types of energy, namely, low temperature heat and electricity. Solar collectors and PV panels are mature technologies which could be coupled to MD process. The interest of using solar powered membrane distillation (SPMD) systems for desalination is growing worldwide due to the MD attractive features. Small scale SPMD units suitable to provide water for human needs in remote areas where water and electricity infrastructures are currently lacking have been developed and tested by a number of researchers. The combination of solar energy with MD has proven technically feasible; however, the cost of produced water is relatively high compared with that produced from the commercial PV-RO process. The production of commercial, reliable, low cost and long lasting MD modules will put this process on the front edge of desalination technologies. The aim of this article is to present the main features of MD along with its basic principles. Efforts of researchers in coupling MD with solar energy and their cost estimates are reviewed as well.