Purpose: The paper introduces MHP (Mobile Hydrogen Powersupply), an off-grid fuel cell electric system to recharge (stranded) BEVs, and discusses MHP from the life cycle perspective. The LCA shows the effects of system architecture, charging efficiency, hydrogen supply routes, and the predicted electric vehicle recharging demand on global warming potential and energy consumption and further gives recommendations to optimize the assessed environmental impact.Methods: Demand scenarios of mobile recharging assistances due to BEVs, stranded with an uncharged battery, are predicted for Austria and the greater Vienna area. The introduction of MHP follows the discussion of system architecture, operation strategy, and energetic charging efficiency. The LCA follows the guidance of the ISO 14040 standard and applies the Circular Footprint Formula. The functional unit is 1 kWh of electrical energy, balanced at the charging interface. The system boundary includes raw material extraction, production, transport of resources and products, use, and end of life management. The hydrogen supply is modeled representatively for Austria. The selected impact categories are global warming potential and cumulated energy demand. The data originate, among others, from GEMIS Austria, GREET2, and ProBas.Results and discussion: Environmental impacts vary between 0.40 and 1.58 kg CO₂eq/kWh-el and 4.95 to 7.68 kWh/kWh-el in the life cycle. In production and end of life processes, the hydrogen storage system leads to the highest weight-specific GWP and CED of MHP sub-systems due to the large share of CFRP. The efficiency of the MHP system is directly reflected in the use phase’s environmental impacts. The impact of MHP cooling efficiency, charging efficiency, and operation strategy on GWP and CED is below 12%. The CED primarily originates from hydrogen production. If the hydrogen supply route is mostly renewable and generates minor GWP, the MHP efficiency has only a small impact on the life cycle’s GWP and the production and end of life processes gain importance.Conclusions: Optimized material selection and lightweight construction reduce the life cycle impact. Further, the paper demonstrates that hydrogen supply significantly affects MHP’s environmental impact. Therefore, besides optimizing the production and end of life processes, implementing a renewable hydrogen infrastructure and providing renewable energies and fuels must be strongly accelerated.

Reducing CO₂ emissions in general aviation is a critical challenge, where battery electric and fuel cell technologies face limitations in energy density, cost, and robustness. As a result, hydrogen (H₂) dual-fuel combustion is a promising alternative, but its practical implementation is constrained by abnormal combustion phenomena such as knocking and pre-ignition, which limit the achievable H₂ energy share. In response to these challenges, this paper focuses on strategies to mitigate these irregular combustion phenomena while effectively increasing the H₂ energy share. Experimental evaluations were conducted on an engine test bench using a one-cylinder dual-fuel H₂ kerosene (Jet A-1) engine, utilizing two strategies, including water injection (WI) and rising the air–fuel ratio (AFR) by increasing the boost pressure. Additionally, crucial combustion characteristics and emissions are examined and discussed in detail, contributing to a comprehensive understanding of the outcomes. The results indicate that these strategies notably increase the maximal possible hydrogen energy share, with potential benefits for emissions reduction and efficiency improvement. Finally, through the use of 0D/1D simulations, this paper offers critical thermodynamic and efficiency loss analyses of the strategies, enhancing the understanding of their overall impact.

Reducing CO₂ emissions is an increasingly important goal in general aviation. The dual-fuel hydrogen–kerosene combustion process has proven to be a suitable technology for use in small aircraft. This robust and reliable technology significantly reduces CO₂ emissions due to the carbon-free combustion of hydrogen during operation, while pure kerosene or sustainable aviation fuel (SAF) can be used in safety-critical situations or in the event of fuel supply issues. Previous studies have demonstrated the potential of this technology in terms of emissions, performance, and efficiency, while also highlighting challenges related to abnormal combustion phenomena, such as knocking and pre-ignition, which limit the maximum achievable hydrogen energy share. However, the causes of such phenomena—especially regarding the role of lubricating oils—have not yet been sufficiently investigated in hydrogen engines, making this a crucial area for further development. In this paper, investigations at the TU Wien, Institute of Powertrain and Automotive Technology, concerning the role of different engine oils in influencing pre-ignition tendencies in a hydrogen–kerosene dual-fuel engine are described. A specialized test procedure was developed to account for the unique combustion characteristics of the dual-fuel process, along with a detailed purge procedure to minimize oil carryover. Multiple engine oils with varying compositions were tested to evaluate their influence on pre-ignition tendencies, with a particular focus on additives containing calcium, magnesium, and molybdenum, known for their roles in detergent and anti-wear properties. Additionally, the study addressed the contribution of particles to pre-ignition occurrences. The results indicate that calcium and magnesium exhibit no notable impact on pre-ignition behavior; however, the addition of molybdenum results in a pronounced reduction in pre-ignition events, which could enable a higher hydrogen energy share and thus decrease CO₂ emissions in the context of hydrogen dual-fuel aviation applications.