Green Hydrogen Production Using Proton-Exchange-Membrane Water Electrolysis

Green hydrogen produced by water electrolysis powered by renewable electricity is widely regarded as an indispensable energy carrier for decarbonizing sectors that resist direct electrification, including steel, ammonia, refining, and heavy transport. Among the electrolysis technologies, proton-exchange-membrane (PEM) water electrolysis is especially well suited to coupling with intermittent renewables owing to its high current density, compact footprint, rapid dynamic response, and ability to operate at high differential pressure. This paper reviews the operating principles of PEM electrolysis and develops an electrochemical model that resolves the cell voltage into its reversible, activation, ohmic, and concentration components to quantify the trade-off between energy efficiency and hydrogen-production rate. The model is used to compare PEM with alkaline and solid-oxide electrolysis and to estimate the levelized cost of hydrogen (LCOH) as a function of electricity price and capacity factor. At a current density of 2 A/cm-squared the modeled PEM cell operates at a voltage efficiency of about 74 percent, and the LCOH analysis shows that hydrogen approaches the cost-competitiveness target of roughly two US dollars per kilogram only when low-cost electricity is available at a high capacity factor. The study identifies efficiency, durability, and electricity cost as the principal levers for scaling green hydrogen.