A quarter of humanity's carbon emissions come from industrial energy use – and a huge portion of that energy goes into creating heat for various processes. And right there lies a slam-dunk decarbonization opportunity that'll pay for itself incredibly quickly, reasons Oakland company Rondo Energy.

"We're at a spectacular moment in history," Rondo CEO John O'Donnell told the Wharton Current podcast. "Where on a per unit of energy cost basis, wind and solar power are cheaper than fuels. Not just cheaper than conventional electricity, but cheaper than fuel for heat in most of the world – headed for all of the world."

In other words, thanks to a huge crash in the price of renewable energy, there's no longer a "green premium" stopping most industrial heat consumers from decarbonizing and switching to clean solutions. The barrier, instead, is intermittency; you can buy renewable energy out of the grid at extremely low cost, right now – but only when the solar arrays are producing too much for the grid to use. You can't run your factory 24/7 that way unless you can store that energy up.