This device efficiently splits water into its component elements, hydrogen and oxygen, storing energy as H2. The key is a new catalyst based on abundant metals tungsten, iron and cobalt, that is three times more efficient than the current state-of-the-art. Credit: Marit Mitchell.One way to store intermittent sun and wind energy is to use it to split water into oxygen and hydrogen, and then use the hydrogen as fuel. Now scientists at SLAC and the University of Toronto have invented a new type of catalyst that makes this process three times more efficient. In this water-splitting device on the Toronto campus, hydrogen is bubbling up from the left electrode and oxygen is bubbling up from the right one. (Marit Mitchell/University of Toronto)