Most steel produced today is done by burning coal, the most carbon-intense of the fossil fuels. To help limit global warming, the steel industry will need to shrink its carbon footprint significantly. Sustainable steel is a growing research topic for Stanford. One large project seeks to use green hydrogen and light-sensitive photocatalyst to reduce CO2 emissions from steel production. Another project explores the potential for replacing steel and concrete with construction materials made completely from carbon produced by heating – not combusting – natural gas.