Researchers at the University of Texas at Austin and the University of Marburg in Germany have developed a desalinization technique that uses an electrochemical process instead of physical membranes, making it possible to remove the salt from water with the power of a single store-bought battery. Eventually the science could be incorporated into small microgrids, thus addressing two major issues that face many impoverished communities around the world: lack of electrical power and poor quality water for drinking and farming. The desalinization works at a microscale level. The researchers apply a small voltage (3.0 volts) to a plastic chip filled with seawater. The chip contains a microchannel with two branches. At the junction of the channel an embedded electrode neutralizes some of the chloride ions in seawater to create an “ion depletion zone” that increases the local electric field compared with the rest of the channel. This change in the electric field is sufficient to redirect salts into one branch, allowing desalinated water to pass through the other branch.
The process is called electrochemically mediated seawater desalination. It’s patent-pending and is in commercial development by startup company Okeanos Technologies.
Although the technique is only 25 percent effective so far, the researchers are confident they can improve it to the 99 percent required for potable water.
If so, the minimal power requirement for the process could be added to the types of microgrids, such as Nextek’s STAR portable solar generator, that have been developed to bring electrical power to isolated, economically-disadvantaged communities around the world.
According to estimates, about a third of the planet’s population lives in water-stressed areas that have access to abundant seawater, but not to the energy infrastructure or money necessary to desalt water using conventional technology. As a result, millions of deaths per year in these regions are attributed to water-related causes.