Polymer membranes make everything from rain jackets to medical devices. But they’re also integral parts of hydrogen fuel cells, powering cars that give off nothing but water vapor. How do fuel cells work, and why aren’t you driving one yet? Solutions is made with funding and featuring scientists from 3M, Ascend Performance Materials, Baker Hughes, BASF, Dow, DuPont, Procter & Gamble, PPG, Royal DSM, SABIC, Solvay, and W. L. Gore & Associates, none of whom influenced any editorial decisions.