Multi-fuel reformers for fuel cells used in transportation: Assessment of hydrogen storage technologies. Phase 2: Final report

During Phase 1 of this program, the authors evaluated all known hydrogen storage technologies (including those that are now practiced and those that are development) in the context of fuel cell vehicles. They determined that among the development technologies, carbon sorbents could most benefit from closer scrutiny. During Phase 2 of this program, they tested ten different carbon sorbents at various practical temperatures and pressures, and developed the concept of the usable Capacity Ratio, which is the ratio of the mass of hydrogen that can be released from a carbon-filled tank to the mass of hydrogen that can be released from an empty tank. The authors also commissioned the design, fabrication, and NGV2 (Natural Gas Vehicle) testing of an aluminum-lined, carbon-composite, full-wrapped pressure vessel to store hydrogen at 78 K and 3,000 psi. They constructed a facility to pressure cycle the tank at 78 K and to temperature cycle the tank at 3,000 psi, tested one such tank, and submitted it for a burst test. Finally, they devised a means by which cryogenic compressed hydrogen gas tanks can be filled and discharged using standard hardware--that is, without using filters, valves, or pressure regulators that must operate at both low temperature and high pressure. This report describes test methods and test results of carbon sorbents and the design of tanks for cold storage. 7 refs., 91 figs., 10 tabs