Modular hydrogen generation system

A modular hydrogen generation system (“system”) comprising:

• a high-pressure containment vessel (“vessel”) having a sidewall and a floor, the vessel defining an opening opposite the floor and a hydrogen plenum therebetween;
• a hydrogen generation insert (“insert”) having a first end and a second end and shaped to be inserted through the opening and into the hydrogen plenum, the insert including:
• a cover at the first end of the insert defining an upper and a lower surface and having a plurality of high-pressure fittings thereon;
• one or more proton-exchange membrane (“PEM”) cells;
• an oxygen-water separator;
• and
• a passive dual regulator with relative differential venting (“regulator”) wherein when the insert is received in the hydrogen plenum, the regulator receives oxygen from the oxygen-water separator and hydrogen from the hydrogen plenum and regulates pressure imbalances between an oxygen-side of the system, vents oxygen to an exterior of the high-pressure containment vessel, and vents hydrogen to an exterior of the vessel to allow collection of hydrogen and oxygen and avoid rupture of the one or more PEM cells during operation,
• wherein when the insert is inserted into the hydrogen plenum, hydrogen and oxygen can be produced at an interior pressure of from 200 to 6,000 psi.