The hydrogen market is huge, currently about 10 million tons/year in the U.S. alone and a multi-billion dollar business. Industrial markets, such as refineries, ammonia production, chemical plants, etc, use most of the commercial quantities of hydrogen. Most of the hydrogen is either shipped to the end user via pipeline or trucked as compressed gas, at pressures of ~2,000 psi or greater. However, other applications for the hydrogen economy, especially vehicle refueling applications, require higher pressures, up to 12,000 psi. Successful development of efficient, high pressure water electrolysis systems is critically important in meeting these developing needs. It is anticipated that the worldwide combined industrial and emerging vehicle market for hydrogen will be >100 billion dollars.