Steam Methane Reforming

Steam methane reforming, also called steam reforming, is an industrial process that produces hydrogen by reacting methane, typically drawn from natural gas, with steam at high temperature over a catalyst, an endothermic reaction that yields carbon monoxide and hydrogen; a following water gas shift reaction then converts most of that carbon monoxide, along with more steam, into additional hydrogen and carbon dioxide. Industrial reformers run the primary reaction at 800 to 900 degrees Celsius and 20 to 30 bar of pressure, and the whole process achieves an efficiency of roughly 65 to 75 percent, making it, in capital cost terms, the least expensive method of producing hydrogen available today. Steam methane reforming supplies almost half of the hydrogen produced worldwide and underpins the ammonia industry, which produced 144 million tonnes of ammonia in 2018 using hydrogen made largely this way, while in the United States alone the process yields nine to ten million tons of hydrogen a year. Hydrogen made by steam reforming is classified as grey hydrogen when its carbon dioxide byproduct is released into the atmosphere, and as blue hydrogen when that carbon dioxide is instead captured and stored underground.