Making steel, an alloy of iron and carbon, is notoriously polluting. But Electra, a Boulder-based company looking to change that, opened its first pilot plant in 2024 and has already partnered with the largest U.S. steelmaker, Nucor. Electra zeroed in on the iron-refinement step of the process, where 90% of steelmaking’s CO2 emissions occur. “We needed to shift the operating temperature of ironmaking from 1,600°C to a lower temperature so that the process could start and stop quickly and seamlessly integrate with intermittent resources, like wind and solar energy,” says CEO and co-founder Sandeep Nijhawan. Electra’s renewable-energy-powered process uses an electrochemical hydrometallurgical method at temperatures that are only around 60°C. It’s also found ways to clear major technical hurdles that other attempts at this kind of iron refinement have failed to surmount. Notably it can use ores with low iron content, which avoids global supply-chain strains that have arisen due to an ongoing shortage of higher-purity iron ores.