Cryogenic, compressed, and liquid hydrogen fuel storage in vehicles

Abstract

Hydrogen is the viable energy carrier of future energy and transportation systems due to its clean emissions, light weight, and abundance. Its extremely low volumetric density, however, presents significant challenges to storage onboard vehicles. The study involves a survey of the current state of direct hydrogen storage technologies-cryogenic, compressed, and liquid storage-and an analysis of the problems associated with its storage. The significant storage problems that are reviewed and analyzed are issues with cool-down, boil-off, dormancy, materials, and space limitations. The goal of this study is to ultimately provide design insights on storage tanks, whether they be built for thermal performance (insulated), mechanical performance (pressure vessels), or both. The critical parameter that is analyzed is the inner shell wall thickness, or the layer that holds and encompasses the fuel. Graphs were provided to illustrate the reliance of the aforementioned problems on inner shell wall thickness. The results show that-given current materials-a nominal thickness of 10 cm is appropriate for liquid storage and a thickness of 4 cm is appropriate for flexibly fuelled storage and cryogenic compressed storage mechanisms.

(cont.) Additionally, the performance of these storage mechanisms was also projected for potential future materials. The conclusions were that more research needs to be dedicated into two broad areas: thermally-efficient insulation and stronger pressure vessel materials.