Travel ranges between 500 and 750 miles for hydrogen-powered cars and SUVs are enabled by a novel, valveless magnesium-hydride (MgH2) fueling system consisting of: a MgH2 fuel storage and reaction tank with separate compartments flanked by ~0.5 inch-thick, round (~12 inch diameter) resistance heaters; a lightweight, 2000 psi-rated water storage tank; a lightweight, 2000 psi-rated hydrogen storage tank; three small water pumps; a fluid manifold; flexible-steel hoses of various lengths and diameters for material transfer; and four, fuel-door-accessible ports through which hydrogen, water, water-slurried MgH2, and water-slurried "spent fuel"—Mg(OH)2—enter and exit the fueling system.

Safe and reliable operation of the system at a fueling station, and during road travel, is ensured by its mechanical simplicity, which arises from meticulous consideration and application of fundamental principles of physics, thermodynamics, chemical kinetics, and heat and mass transfer. A high material volumetric energy density is achieved by slurrying the MgH2 with cool water prior to fueling. Immediately thereafter, the entire fueling system is filled with ~1500 psi of gaseous hydrogen to allow the vehicle to travel 35-60 miles before any MgH2 is used to produce additional hydrogen.(1) After refueling, only water and hydrogen move through the system. The on-board, hydrogen-forming reaction, induced by heat from the fuel cell stack, and from the resistance heaters that flank individual compartments in the MgH2 fuel tank, is: MgH2 + 2H2O —> Mg(OH)2 + 2H2. This reaction produces hydrogen gas "on demand" in ~0.5-1.0 kilogram (kg) batches, Consequently, during vehicular operation, mass and pressure ranges for hydrogen gas in the fueling system are approximately 0.2-1.2 kg and 200-1500 psi, respectively.

At future fueling stations that dispense both 5,000 psi hydrogen and water-slurried MgH2, refueling procedures for MgH2-fueled vehicles will be only slightly more involved than those employed today for gasoline-powered vehicles. A single magnesium-hydride fuel dispenser will attach to four ports leading to the interior of the fueling system. Typically, refueling will be completed in ~3 minutes.

A thorough life-cycle cost analysis indicates that, when used to form hydrogen on board fuel cell-powered vehicles, the 2007-2010 cents-per-mile cost of MgH2 fuel will be only slightly higher than that of gasoline.

Due to its safety, simplicity, reliability, scalability, and high hydrogen storage capacity (approximately 1.6 times greater than comparable fueling systems that store 10,000 psi hydrogen), the new magnesium-hydride fueling system is ideally suited for extending the travel ranges of many fuel cell-powered hydrogen cars and SUVs currently under development.

(1)The ability to rapidly fill the fueling system with 1500 psi of "headspace" hydrogen gas through a fuel-door accessible, quick-connect access port gives the MgH2 fueling system plug-in battery functionality without the plug-in battery. The practical feasibility of home fueling a hydrogen-powered vehicle is thereby greatly enhanced, because only ~1 kg of hydrogen (stored at ~2000 psi) would need to be produced daily by a small electrolyzer in, or near, the garage or carport where the vehicle is normally parked.