Affordable “Green-ish" Production of Hydrogen from Methane

A rapid transition from a world powered primarily by low-cost fossil fuel combustion to more sustainable low emissions alternatives will only occur if those alternatives are widely available at comparable costs. In addition to electricity, hydrogen and other hydrogen containing fuels (e.g. NH₃) will likely be important in future sustainable energy economies provided their production costs are low. Hydrogen is produced today, for profit, from abundant low-cost methane by reforming and complete oxidation of the carbon from C(-4) to C(+4) producing ~ 7 tons CO₂/ton H₂. Partial oxidation of methane and other fossil resources in the absence of oxygen can produce solid carbon C(0) and potentially valuable hydrogen containing molecules without generating CO₂ at far lower cost than producing hydrogen from water by electrolysis. If society is willing to pay for CO₂ emissions reductions, methane pyrolysis can be the lowest cost option for producing hydrogen as a fuel. Methane pyrolysis is equilibrium limited and thermodynamics restrict high pressure industrial processes to high temperatures for acceptable conversion. Catalysis can enable the reaction rates and conditions to be practical at commercial scales. The evolution of several catalyst-based processes will be discussed, and their relative merits compared for producing hydrogen at large-scale without carbon dioxide emissions.