A hydrogen fueling system for generating hydrogen on demand is described. The system includes an electrolyzer configured to generate at least a predetermined quantity of hydrogen in a predetermined time when operated at no less than a predetermined current density and provided with at least a predetermined electrical energy over the predetermined time, where the predetermined quantity of hydrogen is at least 1 kg of hydrogen, the predetermined time is no more than 30 minutes, and the predetermined current density is at least 5 A/cm 2 . The system may further include an electrical energy storage system electrically connected to the electrolyzer and capable of supplying at least 20% of the predetermined electrical energy over the predetermined time. The electrolyzer may include an anode including a plurality of acicular particles dispersed in an ionomer binder, where the acicular particles include iridium.