“Efficiency improvements in the logistic chain of alternative fuels for marine applications: Analysis and development of new containment systems for liquid and gaseous hydrogen”

After a thorough review of research on liquid hydrogen (LH2) storage and transportation, technical and safety challenges have been identified. For instance, the study of the fluid sloshing phenomenon during the transportation process of LH2 is considered a crucial issue, particularly in maritime applications where cryogenic liquids are transported by ships. The dynamic motion of ships generates continuous liquid oscillations inside cryogenic tanks, which significantly influence the performance of the thermal and pressure behaviours. The other main challenge is the transient non-uniform cool down and the large thermal stresses that are exposed to the storage tank walls during the precooling and loading processes of LH2. The present study investigates the previous two issues of LH2 during the transportation and filling procedures on a large-scale cryogenic storage tank with a gross volume of 5000 m³, a representative of an industrial scale from the marine transport field. A two-dimensional (2D) model of the tank is built on ANSYS CFX to simulate the sloshing phenomenon effect on the thermal and hydrodynamic behaviours of liquid and gaseous hydrogen in a cryogenic tank with and without baffles. On the other hand, a model of transient energy equations is built on MATLAB to be solved for each discretized wall segment to calculate the tank cool down characteristics. For the sloshing model, the results reveal that the gaseous temperature and pressure behaviours oscillate almost around the initial values in the case without baffles, while they are decreased consistently in the case with baffles. Moreover, the maximum total pressure on the tank knuckle is mitigated by baffles with a gradual reduction. The other model of the tank cool down during LH2 filling provides a detailed estimation of the wall-temperature evolution, precooling time, LH2 filling time, and the masses consumed and the boil-off gas for both liquid nitrogen and LH2. Further study is performed on the hybrid renewable energy systems, which are considered a practical and sustainable solution for supplying electricity in remote and off-grid regions. The study aims to design a reliable standalone hybrid energy system using HOMER Pro software to meet the electricity demand of a household in Siwa Oasis. The simulations show an optimal configuration that includes a 3 kW PV array, 3.5 kW solar converter, four 1.8 kWh batteries, a 2 kW electrolyzer, a hydrogen storage tank (0.189 kg at 232 bar), and a 0.5 kW proton exchange membrane (PEM) fuel cell. The cost results provide a Net Present Cost (NPC) of $25,388 and a Levelized Cost of Energy (LCOE) of $1.38/kWh. The overall system performance confirms its technical and economic feasibility for clean, off-grid electrification in remote desert regions.