Resource requirements for the implementation of a global H2-powered aviation

In this paper, the resource requirements for the implementation of global H2-powered aviation are investigated to answer one of the main questions asked by many stakeholders in the aviation industry: Are there any resource limitations for the implementation of H2-powered aviation on a global scale? For this, the raw material, renewable energy and water demands for the deployment and operational phase are investigated on a global and regional perspective. It is found that the iridium demand for a global hydrogen economy could be critical as it would exceed not only the current annual production by a factor of 11 but also the current reserves about 1.7 times. The H2-powered aviation alone is not the main driver of iridium demand but could increase the limitations. With reduced specific raw material demands of further optimized electrolysis technologies and increased annual raw material production, the limitations especially for the iridium demand could be overcome. Renewable energy capacities and water availability are sufficient for demands from H2-powered aircraft on a global perspective. Nevertheless, the limited availability of renewable energy sources in some regions and regional water constraints may necessitate hydrogen import for certain airports. While water desalination is likely to overcome water constraints in regions close to the sea, for airports located in regions with detrimental availability of renewable energy sources the import of hydrogen is the only way to ensure a hydrogen supply for H2-powered aviation

H2-powered aviation at airports – Design and economics of LH2 refueling systems

In this paper, the broader perspective of green hydrogen (H2) supply and refueling systems for aircraft is provided as an enabling technology brick for more climate friendly, H2-powered aviation. For this, two H2 demand scenarios at exemplary airports are determined for 2050. Then, general requirements for liquid hydrogen (LH2) refueling setups in an airport environment are derived and techno-economic models for LH2 storage, liquefaction and transportation to the aircraft are designed. Finally, a cost trade-off study is undertaken for the design of the LH2 setup including LH2 refueling trucks and a LH2 pipeline and hydrant system. It is found that for airports with less than 125 ktLH2 annual demand a LH2 refueling truck setup is the more economic choice. At airports with higher annual LH2 demands a LH2 pipeline & hydrant system can lead to slight cost reductions and enable safer and faster refueling. However, in all demand scenarios the refueling system costs only mark 3 to 4% of the total supply costs of LH2. The latter are dominated by the costs for green H2 produced offsite followed by the costs for liquefaction of H2 at an airport. While cost reducing scaling effects are likely to be achieved for H2 liquefaction plants, other component capacities would already be designed at maximum capacities for medium-sized airports. Furthermore, with annual LH2 demands of 100 ktLH2 and more, medium and larger airports could take a special H2 hub role by 2050 dominating regional H2 consumption. Finally, technology demonstrators are required to reduce uncertainty around major techno-economic parameters such as the investment costs for LH2 pipeline & hydrant systems. © 2022 The Author

H2-powered aviation – Design and economics of green LH2 supply for airports

The economic competitiveness of hydrogen-powered aviation highly depends on the supply costs of green liquid hydrogen to enable true-zero CO2 flying. This study uses non-linear energy system optimization to analyze three main liquid hydrogen (LH2) supply pathways for five locations. Final liquid hydrogen costs at the dispenser supply costs could reach 2.04 USD/kgLH2 in a 2050 base case scenario for locations with strong renewable energy source conditions. This could lead to cost-competitive flying with hydrogen. Reflecting techno-economic uncertainties in two additional scenarios, the liquid hydrogen cost span at all five airport locations ranges between 1.37–3.48 USD/kgLH2, if hydrogen import options from larger hydrogen markets are also available. Import setups are of special importance for airports with a weaker renewable energy source situation, e.g., selected Central European airports. There, on-site supply might not only be too expensive, but space requirements for renewable energy sources could be too large for feasible implementation in densely populated regions. Furthermore, main costs for liquid hydrogen are caused by renewable energy sources, electrolysis systems, and liquefaction plants. Seven detailed design rules are derived for optimized energy systems for these and the storage components. This and the cost results should help infrastructure planners and general industry and policy players prioritize research and development needs

Design Considerations for the Electrical Power Supply of Future Civil Aircraft with Active High-Lift Systems

Active high-lift systems of future civil aircraft allow noise reduction and the use of shorter runways. Powering high-lift systems electrically have a strong impact on the design requirements for the electrical power supply of the aircraft. The active high-lift system of the reference aircraft design considered in this paper consists of a flexible leading-edge device together with a combination of boundary-layer suction and Coanda-jet blowing. Electrically driven compressors distributed along the aircraft wings provide the required mass flow of pressurized air. Their additional loads significantly increase the electric power demand during take-off and landing, which is commonly provided by electric generators attached to the aircraft engines. The focus of the present study is a feasibility assessment of alternative electric power supply concepts to unburden or eliminate the generator coupled to the aircraft engine. For this purpose, two different concepts using either fuel cells or batteries are outlined and evaluated in terms of weight, efficiency, and technology availability. The most promising, but least developed alternative to the engine-powered electric generator is the usage of fuel cells. The advantages are high power density and short refueling time, compared to the battery storage concept

Characterization of granular mixing in a helical ribbon blade blender

Experiments of bulk solid mixing in a twin ribbon blade blender have been performed in this work in order to characterize mixing behavior in such a mixer for binary mixtures with different cohesionless materials. The effects of fill height and blade rotation speed on mixing homogeneity have been studied. Mixing homogeneity was determined by sampling. It has been observed that mixing is relatively fast towards a final mixing state within approximately 100 blade rotations for different combinations of material, fill height and blade rotational speed. Moreover, these final mixing states seemed stable within a range of fluctuations, which may prove useful in determining an optimal mixing time for binary, cohesionless particle mixtures and potentially lead to a reduction in the required number of blade rotations in mixers of this type in industry. Mixing homogeneity results indicated an increased final mixing homogeneity for increasing fill height, most clearly in the range of 30–70 vol.% in the studied twin ribbon blade mixer. The torque on one of the shafts was determined. The latter results showed that no significant influence of rotational speed on the required torque for the tested mixtures at rotational velocities in the range of Fr 0.17–1.1 could be determined for most combinations of the tested materials and fill heights in this work. The quantitative characterization of mixing behavior with the two key parameters mixing homogeneity and torque on the shaft may be used for mixer validation of DEM simulations