With the conflict in Iran and the resulting closure of the Strait of Hormuz pushing oil and gas prices upwards, the prospect of a world that runs on 100% renewable energy seems even more attractive than usual. Before we can get there, though, experts in a range of fields say we’re going to need to solve a few physics problems – including one that goes straight back to Maxwell’s equations. Unlike energy that comes from processes such as burning fossil fuels, sending water downhill through turbines, or harnessing the heat from nuclear reactions, the supply of wind and solar energy varies in ways we cannot control. To complicate matters further, consumer demand also varies, and the two variations “do not necessarily match in time or in space,” observes Michael Jack, a physicist at the University of Otago in New Zealand.…