Applications & Pathways

In the automotive sector hydrogen is being increasingly explored as an alternative fuel to replace conventional carbon-based fuels. Its combustion characteristics make it well-suited for adaptation to internal combustion engines. The wide flammability range of hydrogen allows for higher dilution conditions resulting in enhanced combustion efficiency. When combined with lean combustion strategies hydrogen significantly reduces environmental impact virtually eliminating carbon dioxide and nitrogen oxide emissions while maintaining high thermal efficiency. This paper aims to assess the potential of using an outwardly opening poppet valve hydrogen direct injection (DI) system in a small engine for light-duty applications. To achieve this a comparison of performance emission levels and combustion parameters is conducted on a single-cylinder spark-ignition (SI) research engine fueled by hydrogen using both port fuel injection (PFI) and this new direct injection system. Two different engine loads are measured at multiple air dilution and injection timing conditions. The results demonstrate notable efficiency improvements ranging from 0.6% to 1.1% when transitioning from PFI to DI. Accurate control of injection timing is essential for achieving optimal performance and low emissions. Delaying the start of injection results in a 7.6% reduction in compression work at low load and a 3.9% reduction at high load. This results in a 3.1-3.2% improvement in ISFC in both load conditions considered.

Machine learning methods have been proven to be a useful tool for solving complex problems based on historical data in both scientific and engineering applications. Those properties make them a great candidate for providing a better insight into the operating characteristics of hydrogen electrochemical devices such as electrolyzers and fuel cells. Therefore this paper critically analyzes the current state of research on the application of machine learning methods for predicting operating parameters degradation detection with an emphasis on diagnostics and prognostics and fault detection in hydrogen electrochemical devices. The analysis includes a comparison of different methods discussion of existing challenges and exploration of future potential applications. Addition ally guidelines for future research along with recommendations and best practices for applying machine learning methods are provided.

On this episode of EAH Patrick Molloy Alicia Eastman and Chris Jackson are delighted to speak with Arsenio Dominguez the newly appointed Secretary General of the International Maritime Organization (IMO). Recorded before the highly successful MEPC81 Arsenio describes his vision for the IMO and his confidence in solutions that will reduce emissions from shipping without penalizing member states.

The podcast can be found on their website.

Air transportation contributes significantly to harmful and greenhouse gas emissions. To combat these issues there has been a recent emergence of aircraft electrification as a potential solution to mitigate environmental concerns and address fuel shortages. However current technologies related to batteries electric machinery and power systems are still in the developmental phase to meet the requirements for power and energy density weight safety and reliability. In the interim there is a focus on the more electric and hybrid electric propulsion systems for aircraft. Hydrogen with its high specific energy and carbon-free characteristics stands out as a promising alternative fuel for aviation. This paper is centred on the application of hydrogen in aircraft propulsion mainly fuel cell hybrid electric (FCHE) propulsion systems. Furthermore application of hydrogen as a fuel for the aircraft propulsion systems is considered. A comprehensive overview of the hydrogen propulsion systems in aviation is presented with an emphasis on the technical aspects crucial for creating a more sustainable and efficient air transportation sector. Additionally the paper acknowledges the technical and regulatory challenges that must be addressed to attain these goals.

Hydrogen fuel cell-based UAM (urban air mobility) systems are gaining significant attention due to their advantages of higher energy density and longer flight durations compared to conventional battery-based UAM systems. To further improve the flight times of current UAM systems various hydrogen storage methods such as liquid hydrogen and hydrogen metal hydrides are being utilized. Among these hydrogen metal hydrides offer the advantage of high safety as they do not require the additional technologies needed for high-pressure gaseous hydrogen storage or the maintenance of cryogenic temperatures for liquid hydrogen. Furthermore because of the relatively slower dynamic response of hydrogen fuel cell systems compared to batteries they are often integrated into hybrid configurations with batteries necessitating an efficient power management system. In this study a UAM system was developed by integrating a hydrogen fuel cell system with hydrogen metal hydrides and batteries in a hybrid configuration. Additionally a state machine control approach was applied to a distribution valve for the endothermic reaction required for hydrogen desorption from the hydrogen metal hydrides. This design utilized waste heat generated by the fuel cell stack to facilitate hydrogen release. Furthermore a fuzzy logic control-based power management system was implemented to ensure efficient power distribution during flight. The results show that approximately 43% of the waste heat generated by the stack was recovered through the tank system.

Aiming to solve the problems of insufficient dynamic responses the large loss of energy storage life of a single power cell and the large fluctuation in DC (direct current) bus voltage in fuel cell vessels this study takes a certain type of fuel cell ferry as the research object and proposes an improved equivalent minimum hydrogen consumption energy management strategy based on fuzzy logic control. First a hybrid power system including a fuel cell a lithium–iron–phosphate battery and a supercapacitor is proposed with the simulation of the power system of the modified mother ship. Second a power system simulation model and a double-closed-loop PI (proportion integration) control model are established in MATLAB/Simulink to design the equivalent hydrogen consumption model and fuzzy logic control strategy. The simulation results show that under the premise of meeting the load requirements the control strategy designed in this paper improves the Li-ion battery’s power the Li-ion battery’s SOC (state of charge) the bus voltage stability and the equivalent hydrogen consumption significantly compared with those before optimization which improves the stability and economy of the power system and has certain practical engineering value.

This paper presents a review of system design and analysis control strategy optimization and heat and mass integration of integrated solid oxide fuel cell (SOFC) and reciprocating internal combustion engine (ICE) system. Facing the future power-fuel-power path both SOFC and ICE can adapt to a variety of fuels which is one evidence that ICE is amenable to integration with SOFC while SOFC is more efficient cleaner and quieter than ICE. Different system topologies are classified whose dynamic performances are also analyzed. In addition the heat and mass integration of system is discussed. Moreover the combustion modes of ICE which can be applied to steady combustion high efficiency and low emissions are analyzed and compared. Meanwhile the potential and methods of system waste heat recovery are discussed. The exergy analysis energy density and techno-economy are discussed. Finally the results are discussed in the last section with the final conclusion that SOFC-ICE systems are very suitable for long-distance transportation such as maritime and aviation which can also solve problems of the carbon and pollutant emissions with the background of engine cannot be replaced in maritime while the system can adapt a variety of alternative fuels.

Hydrogen is considered one of the key pillars of an effective decarbonization strategy of the energy sector; however the potential of hydrogen as an electricity storage medium is debated. This paper investigates the role of hydrogen as an electricity storage medium in an electricity system with large hydropower resources focusing on the Swiss electricity sector. Several techno-economic and climate scenarios are considered. Findings suggest that hydrogen storage plays no major role under most conditions because of the large hydropower resources. More specifically no hydrogen storage is installed in Switzerland if today’s values of net-transfer capacities and low load-shedding costs are assumed. This applies even to hydrogen-favorable climate scenarios (dry years with low precipitation and dam inflows) and economic assumptions (high learning rates for hydrogen technologies). In contrast hydrogen storage is installed when net-transfer capacities between countries are reduced below 30% of current values and load-shedding costs are above 1000 EUR/MWh. When installed hydrogen is deployed in a few large-scale installations near the national borders.

To reach the decarbonisation goals a zero CO2 emissions large ship propulsion system is proposed in this work. The ship selected is a large ferry propelled by an internal combustion engine fuelled by an ammonia-hydrogen blend. The only fuel loaded in the vessel will be ammonia. The hydrogen required for the combustion in the engine will be produced onboard employing ammonia decomposition. The heat required for this decomposition section will be supplied by using the hot flue gases of the combustion engine. To address the issues regarding NOx emissions a selective catalytic reduction (SCR) reactor was designed. The main operating variables for all the equipment were computed for engine load values of 25% 50% 75% and 100%. Considering the lowest SCR removal rate (91% at an engine load of 100%) the NOx emissions of the vessel were less than 0.5 g/kWh lower than the IMO requirements. An energy analysis of the system proposed to transform ammonia into energy for shipping was conducted. The global energy and exergy efficiencies were 42.4% and 48.1%. In addition an economic analysis of the system was performed. The total capital cost (CAPEX) for the system can be estimated at 8.66 M€ (784 €/kW) while the operating cost (OPEX) ranges between 210 €/MWh (engine load 100%) and 243 €/MWh (engine load of 25%). Finally a sensitivity analysis for the price of ammonia was performed resulting in the feasibility of reducing the operating cost to below 150 €/MWh in the near horizon.

The present paper offers a thorough examination of the safety measures enforced at hydrogen filling stations emphasizing their crucial significance in the wider endeavor to advocate for hydrogen as a sustainable and reliable substitute for conventional fuels. The analysis reveals a wide range of crucial safety aspects in hydrogen refueling stations including regulated hydrogen dispensing leak detection accurate hydrogen flow measurement emergency shutdown systems fire-suppression mechanisms hydrogen distribution and pressure management and appropriate hydrogen storage and cooling for secure refueling operations. The paper therefore explores several aspects including the sophisticated architecture of hydrogen dispensers reliable leak-detection systems emergency shut-off mechanisms and the implementation of fire-suppression tactics. Furthermore it emphasizes that the safety and effectiveness of hydrogen filling stations are closely connected to the accuracy in the creation and upkeep of hydrogen dispensers. It highlights the need for materials and systems that can endure severe circumstances of elevated pressure and temperature while maintaining safety. The use of sophisticated leak-detection technology is crucial for rapidly detecting and reducing possible threats therefore improving the overall safety of these facilities. Moreover the research elucidates the complexities of emergency shut-off systems and fire-suppression tactics. These components are crucial not just for promptly managing hazards but also for maintaining the station’s structural soundness in unanticipated circumstances. In addition the study provides observations about recent technical progress in the industry. These advances effectively tackle current safety obstacles and provide the foundation for future breakthroughs in hydrogen fueling infrastructure. The integration of cutting-edge technology and materials together with the development of upgraded safety measures suggests a positive trajectory towards improved efficiency dependability and safety in hydrogen refueling stations.