“Eventually, this method could produce zero emission cement, if the EAF was powered by renewable energy.”
Cement is almost 90 percent of concrete’s emissions, and concrete is about 7.5 percent of all human CO2. Cambridge swaps the lime flux in steel recycling furnaces for crushed old cement and gets reactivated cement out the other end at no added cost. The target is one billion tonnes a year by 2050, a quarter of today’s demand. The “zero emission” part still depends on a grid that doesn’t exist yet.