Electrodialysis of brackish water powered by photovoltaic energy without batteries: direct connection behaviour

The shortage of drinking water is a major problem in the South East of Spain. In these areas, it is essential to make use of water from underground reservoirs, most of which are over exploited and suffer from saline contamination given their proximity to the sea. The desalination of brackish water by electrodialysis is a useful method for obtaining low cost drinking water. Photovoltaic energy can be used to power the electrodialysis system in remote areas in a reliable and autonomous way. Moreover, the photovoltaic array can be connected directly to the electrodialyzer, that is without batteries. Thus, the environmental threat of improper battery disposal is eliminated and increases the sustainability of the process. The aim of our paper is i) to demonstrate the feasibility of the desalination of brackish water by means of an electrodialysis system powered directly by photovoltaic solar panels, and ii) to explain theoretically the interaction between the photovoltaic generator and the electrodialysis system during the process. These systems are appropriate for small applications in isolated locations with lack of electric grid, where it is not necessary to produce water continuously and the volume of daily treated water required is small — about 1–10 m3.