The steam-methane reformer is one of the chemical industry’s most brutal juggernauts. Surrounded by a 900 °C inferno of natural gas, the reactor heats methane and water it holds inside, causing the molecules to slam together to form syngas, a valuable mixture of carbon monoxide and hydrogen. But these aren’t the only emissions from the reformer. Combustion of the natural gas and further reaction of the CO with steam both release carbon dioxide. All told, the process accounts for about 3% of our global CO2 emissions.