High-density automotive hydrogen storage with cryogenic capable pressure vessels

LLNL is developing cryogenic capable pressure vessels with thermal endurance 5–10 times greater than conventional liquid hydrogen (LH2) tanks that can eliminate evaporative losses in routine usage of (L)H2 automobiles. In a joint effort BMW is working on a proof of concept for a first automotive cryo-compressed hydrogen storage system that can fulfill automotive requirements on system performance, life cycle, safety and cost. Cryogenic pressure vessels can be fueled with ambient temperature compressed gaseous hydrogen (CGH2), LH2 or cryogenic hydrogen at elevated supercritical pressure (cryo-compressed hydrogen, CcH2). When filled with LH2 or CcH2, these vessels contain 2–3 times more fuel than conventional ambient temperature compressed H2 vessels. LLNL has demonstrated fueling with LH2 onboard two vehicles. The generation 2 vessel, installed onboard an H2-powered Toyota Prius and fueled with LH2 demonstrated the longest unrefueled driving distance and the longest cryogenic H2 hold time without evaporative losses. A third generation vessel will be installed, reducing weight and volume by minimizing insulation thickness while still providing acceptable thermal endurance. Based on its long experience with cryogenic hydrogen storage, BMW has developed its cryo-compressed hydrogen storage concept, which is now undergoing a thorough system and component validation to prove compliance with automotive requirements before it can be demonstrated in a BMW test vehicle.