Mobile Lightweight Hydrogen Storage for large Quantities

Abstract

Future mobility is highly dependent on sustainable energy storage concepts especially with respect to water and air bound vehicles where an external energy supply (e.g. contact wires or charging points) is difficult to realise. Green hydrogen, either directly combusted or used in a fuel cell, is a promising option if the related technical demands can be met in a save and competitive way. With respect to hydrogen storage, high pressure, cryo or even combined high pressure-cryo storage devices can be considered but in any case, the physical boundary conditions (> 1000 bar burst pressure / 20K) are highly demanding. For airborne applications the structural weight and the required volume of the storage system are crucial aspects that need to be addressed in the coming years. Instead of kerosene tanks that can be easily integrated, a hydrogen storage system would have a massive impact on the overall airframe design. Further more the management of hydrogen boil-off and the insulation of the cryo systems must fulfill safety requirements that ensure aircraft operation on an accepted and proven safety level for several decades. Last not least the production of light weight, large cryo tanks is an open issue. Metal tanks do have a better level of maturity but composite tanks have a better weight reduction potential due to their structural adaptability. If highly automated manufacturing procedures like filament winding or automatic fibre placement can be applied there is a good chance that manufacturing cost will be competitive as well. On the other hand, there is a lack of experience with very large, cryogenic, composite hydrogen storage vessels and also with the long-term behavior of composites under cyclic loading. This needs to be further investigated. To provide the required operational safety level it is also very likely that these vessels will be equipped with a dedicated Structural Health Monitoring system that detects possible deviations in an early stage.