The world’s biggest miner is trying to figure out if tiny rock-eating microbes can help it solve a notoriously difficult climate puzzle — how to cut emissions from steelmaking. Most steel today is made in blast furnaces powered by coal, the dirtiest fossil fuel, but there’s a way to refine the metal using less polluting natural gas or hydrogen in a process called the “direct reduced iron” (DRI) method, that reduces iron ore to iron without melting it.
