It’s the most nettlesome problem in the quest to ditch fossil fuels: how can you get thousand-degree heat used in factory furnaces without pumping billions of tons of greenhouse gases into the atmosphere? Heat-intensive processes like steelmaking and oil refineries are the starting point for production of everything from cars to life-saving medicines. But fueling their ultra-high temperatures requires burning coal, oil and natural gas. That makes industry responsible for about 20% of the carbon dioxide produced by humans and heating processes, and a bigger emitter than all cars and aircraft combined.
