With worries about a worldwide water crisis looming, the process of turning salty water into drinking water, long regarded as expensive, is looking up. A University of Virginia engineering professor is exploring ways to improve polymer membranes to make desalination simpler and less expensive. Geoffrey M. Geise, an assistant professor in the Department of Chemical Engineering, believes the membranes can also be used to help create and store clean energy. “Membranes purify water by blocking,…