Open Access

As the world moves toward decarbonization and a green energy transition, hydrogen is increasingly recognized as a key energy carrier. However, its characteristics include a low volumetric energy density, necessitating storage in a high-density form to enable efficient energy transfer. Liquefied hydrogen (LH₂) offers a solution by providing high gravimetric energy storage within a confined volume. However, cryogenic hydrogen presents significant technical and safety challenges that must be addressed. This presentation explores the safety aspects that impact the integrity of storage systems and provides practical data analysis alongside experimental results, contributing to a broader understanding of liquid hydrogen storage and transportation.

To expand the hydrogen supply value chain, the transportation of this highly energy-dense material in its liquid phase presents significant challenges. However, developing an efficient and cost-effective insulation solution can substantially improve the economic feasibility of large-scale hydrogen transport. Such improvements not only enhance the profitability of storing and delivering high energy content within a limited volume, but also strengthen the overall value of the supply chain. Ultimately, this will support more efficient integration of hydrogen into the energy system and improve its economic viability.

With advances in technological development, stationary and mobile storage units for compressed hydrogen are becoming larger and larger. Their number is also increasing. At the same time, their design has evolved from steel and aluminium to pressure vessels made of composite materials. For safety reasons the design approval of those composite cylinders requires fire engulfment tests, which are mainly organised as open-air tests always needs dedicated protection measures. Under some conditions those protections measures even reduce the effort for organisational safety measures if e.g. the emission of splinters can get totally prevented. Another aspect is the improved reproducibility of fire tests by reducing the influence of wind, especially wind turbulence. Between 2017 and 2019, BAM developed a stackable protective frame made of steel to safely capture splinters for the safe execution of high-energy impact tests. However, this frame was not flexible enough for the follow up project, which led to a completely new protection concept for (potentially) destructive tests on gas-filled pressure vessels. This concept is based on very robust building blocks with knobs and holes of a dimension of 1m x 0.5m x 0.5m made from welded steel. Despite their considerable weight of around 500 kg, they can be combined and stacked very easily like ‘Lego bricks’. The presentation will show the flexibility of the concept, some results of tests on the robustness against pressure waves and the effectiveness in wind attenuation. Finally, the interaction with a new, also modular burner concept for localised fires and full engulfment fires will be presented.

The transition from fossil fuels to low-emission alternatives is essential to mitigate carbon emissions in energy-intensive sectors. Liquid hydrogen (LH2) is a promising energy carrier due to its high gravimetric energy density, but its storage requires advanced insulation to minimize heat ingress and prevent excessive boil-off losses. Multilayer insulation (MLI), perlite, and microspheres are commonly used under vacuum conditions, yet their performance under fire exposure remains a critical concern. This study investigates the thermal degradation of insulation materials and its impact on heat transfer in an event with extreme thermal load conditions using the Cryogenic High-Temperature Thermal Vacuum Chamber (CHTTVC). The heat flow dynamics are analyzed, and an equivalent heat transfer coefficient is proposed to quantify the impact of insulation deterioration as the outer wall temperature increases. Additionally, a novel liquid-vapor interface monitoring method is introduced to improve real-time detection of phase changes within the tank. The results highlight that insulation failure substantially increases the heat flow, which, if not mitigated, can lead to boiling liquid expanding vapor explosions (BLEVE), jet fires, or catastrophic tank failure. The findings provide valuable insights into optimizing LH2 storage safety and improving emergency response strategies for cryogenic tanks exposed to extreme thermal conditions.

To reduce carbon dioxide emissions, energy carries such as hydrogen consider to be a solution. Consumption of hydrogen as a fuel meets several restrictions such as its low volumetric energy density in gas phase. To tackle this problem, storage as well as transportation in liquid phase is recommended. To be able to handle this component in liquid phase, an efficient thermal insulation e.g., MLI insulation is required. Some studies have been revealed vulnerability of this type of insulation against high heat flux, for instance a fire accident. Some investigations have been depicted the importance of consideration of the MLI thermal degradation in terms of its reflective layer. However, limited number of studies have been focused on the thermal degradation of spacer material and its effect on the overall heat flux. In this study, through systematic experimental measurements, the effect of thermal loads on glass fleece, glass paper as well as polyester spacers are investigated. The results are reported in various temperature and heat flux profiles. Interpreting the temperature profiles revealed as the number of spacers in the medium increases, the peak temperature detectable by the temperature sensor on the measurement plate decreases. Moreover, the contribution of each individual spacer in all cases regarding the experimental temperature range is assessed to be around 8%. This value may increase to around 50% for glass paper and polyester spacers, and to around 25% for glass fleece spacers as the number of spacer layers increases up to six layers. To utilize the outcomes of the experiment later and integrate the results into numerical and CFD simulations, a model is proposed for the mentioned experimental temperature range up to 300°C to predict a heat flux attenuation factor. The model proposes a fitting factor that can reproduce the least square fitted line to the experimental data.