Applications & Pathways

Recent advances in hydrogen internal combustion technologies highlight its potential for high efficiency and zero carbon emissions offering a promising alternative to fossil fuels. This paper investigates the effects of valve timings and overlaps on engine performance combustion characteristics and emissions in a boosted directinjection single-cylinder spark ignition engine using both gasoline and hydrogen. Optimized direct hydrogen injection effectively eliminates backfires and hydrogen slip during positive cam overlaps significantly reducing the pumping mean effective pressure. The study’s primary finding demonstrates the potential of hydrogen to operate as a direct substitute for a gasoline engine without necessitating changes to the cam profiles at the high load operation. Furthermore the study demonstrates that hydrogen leads to much higher thermal efficiencies across a wider range of engine loads when operated at a lean air-to-fuel ratio of 2.75. The engine operating with such a lean-burn hydrogen mixture keeps the engine-out NOx emission at ultra-low levels. Compared to gasoline hydrogen exhibits greater stability and a reduced reliance on camshaft timing during engine operation.

The EU Horizon2020 RISE project 778307 “Hydrogen fuelled utility and their support systems utilising metal hydrides” (HYDRIDE4MOBILITY) worked on the commercialization of hydrogen powered forklifts using metal hydride (MH) based hydrogen stores. The project consortium joined forces of 9 academic and industrial partners from 4 countries. The work program included a) Development of the materials for hydrogen storage and compression; b) Theoretical modelling and optimisation of the materials performance and system integration; c) Advanced fibre reinforced composite cylinder systems for H2 storage and compression; d) System validation. Materials development was focused on i) Zr/Ti-based Laves type high entropy alloys; ii) Mg-rich composite materials; iii) REMNiSn intermetallics; iv) Mg based materials for the hydrolysis process; v) Cost-efficient alloys. For the optimized AB2±x alloys the Zr/Ti content was optimized at A = Zr78-88Ti12–22 while B=Ni10Mn5.83VFe. These alloys provided a) Low hysteresis of hydrogen absorption-desorption; b) Excellent kinetics of charge and discharge; c) Tailored thermodynamics; d) Long cycle life. Zr0.85Ti0.15TM2 alloy provided a reversible H storage and electrochemical capacity of 1.6 wt% H and 450 mAh/g. The tanks development targeted: i) High efficiency of heat and hydrogen exchange; ii) Reduction of the weight and increasing the working H2 pressure; iii) Modelling testing and optimizing the H2 stores with fast performance. The system for power generation was validated at the Implats plant in a fuel cell powered forklift with on-board MH hydrogen storage and on-site H2 refuelling. The outcome on the HYDRIDE4MOBILITY project (2017–2024) (http://hydride4mobility.fesb.unist. hr) was presented in 58 publications.

The polymer electrolyte membrane (PEM) fuel cell system is considered to be an ideal alternative for the internal combustion engine especially when used on a city bus. Hybrid buses with fuel cell systems and energy storage systems are now undergoing transit service demonstrations worldwide. A hybrid PEM fuel cell city bus with a hierarchical control system is studied in this paper. Firstly the powertrain and hierarchical control structure is introduced. Secondly the vehicle control strategy including start-stop strategy energy management strategy and fuel cell control strategy including the hydrogen system and air system control strategies are described in detail. Finally the performance of the fuel cell was analyzed based on road test data. Results showed that the different subsystems were well-coordinated. Each component functioned in concert in order to ensure that both safety and speed requirements were satisfied. The output current of the fuel cell system changed slowly and the output voltage was limited to a certain range thereby enhancing durability of the fuel cell. Furthermore the economic performance was optimized by avoiding low load conditions.

This manuscript presents a comprehensive technical review of low-temperature proton exchange membrane fuel cells (LT-PEMFCs) focusing on their performance applications and current challenges within commercial contexts. LT-PEMFCs have reached commercial deployment in light-duty vehicles buses trains heavy-duty trucks stationary combined heat and power units and early maritime platforms. This review consolidates datasheetbased specifications and reconstructed performance parameters from leading manufacturers complemented by qualitative evidence from large-scale deployments in Japan and China to provide the first cross-sectoral benchmarking of LT-PEMFC systems. The analysis is structured around the key performance indicators (KPIs) of the Clean Hydrogen Joint Undertaking and the U.S. Department of Energy which define quantitative targets for 2024 and 2030. Results show that while several light-duty and bus platforms already meet or approach KPI compliance for hydrogen consumption and efficiency other sectors such as heavy-duty stationary and maritime remain below target ranges due to integration constraints and limited transparency in datasheet reporting. The study further highlights divergences between laboratory-reported stack metrics and commercial module specifications demonstrating the need for harmonized definitions of volumetric power density efficiency at rated power and durability. By situating catalogue-only and prototype systems within the technological pipeline the review clarifies how near-term developments may close performance gaps and reduce platinum dependency while also acknowledging the economic and infrastructural dimensions that condition future adoption. This includes recent advances in PGM-free catalysts alloyed and core–shell architectures and ionomer-free electrodes which complement low-PGM approaches in reducing material cost and supply risk. The contribution lies in delivering a transparent and replicable framework that not only maps the current state of LT-PEMFC commercialization but also provides directionality for research policy and industrial innovation on the pathway to 2030 deployment objectives. This represents the first systematic cross-sectoral benchmarking of LTPEMFCs that integrates datasheet-derived and reconstructed specifications with DOE and CHJU KPI frameworks providing both quantitative visualizations and a replicable methodology that clarifies current achievements while indicating where targeted innovation is needed to reach 2030 objectives.

Due to the high cost of hydrogen utilization and the uncertainties in renewable energy generation and load demand significant challenges are posed for the operation optimization of hydrogen-containing integrated energy systems (IESs). In this study a robust operational model for an electric–heat–gas IES (EHG-IES) is proposed considering the hydrogen energy system heat recovery (HESHR) and multiple uncertainties. Firstly a heat recovery model for the hydrogen system is established based on thermodynamic equations and reaction principles; secondly through the constructed adjustable robust optimization (ARO) model the optimal solution of the system under the worst-case scenario is obtained; lastly the original problem is decomposed based on the column and constraint generation method and strong duality theory resulting in the formulation of a master problem and subproblem with mixed-integer linear characteristics. These problems are solved through alternating iterations ultimately obtaining the corresponding optimal scheduling scheme. The simulation results demonstrate that our model and method can effectively reduce the operation and maintenance costs of HESHR-EHG-IES while being resilient to uncertainties on both the supply and demand sides. In summary this study provides a novel approach for the diversified utilization and flexible operation of energy in HESHR-EHG-IES contributing to the safe controllable and economically efficient development of the energy market. It holds significant value for engineering practice.

Renewable Energy Sources (RESs) are characterized by high unevenness cyclicality and seasonality of energy production. Due to the trends in the production of electricity itself and the utilization of hydrogen distributed generation systems are preferred. They can be connected to the energy distribution network or operate without its participation (off-grid). However in both cases such distributed energy sources should be balanced in terms of power generation. According to the authors it is worth combining different RESs to ensure the stability of energy production from such a mix. Within the mix the sources can complement and replace each other. According to the authors an effective system for generating energy from RESs should contain at least two different sources and energy storage. The purpose of the analyses and calculations performed is to determine the characteristics of energy generation from a photovoltaic system and a wind turbine with a specific power and geographical location in the Lublin region in Poland. Another important goal is to determine the substitutability of the sources studied. Probabilistic analysis will be used to determine the share of given energy sources in the energy mix and will allow us to estimate the size of the stationary energy storage. The objective of these procedures is to strive for the highest possible share of renewable energy in the total energy required to charge electric vehicle fleets and to produce low-emission hydrogen for transportation. The article proves that the appropriately selected components of the photovoltaic and wind energy mix located in the right place lead to the self-balancing of the local energy network using a small energy storage. The conclusions drawn from the conducted research can be used by RES developers who intend to invest in new sources of power generation to produce low-emission hydrogen. This is in line with the current policy of the European Union aimed at climate and energy transformation of many companies using green hydrogen.

The marine industry must reduce emissions to comply with recent and future regulations. Solid oxide fuel cells (SOFCs) are seenas a promising option for efficient power generation on ships with reduced emissions. However it is unclear how the devices canbe integrated and how this affects the operation of the ship economically and environmentally. This paper reviews studies thatconsider SOFC for marine applications. First this article discusses noteworthy developments in SOFC systems includingpower plant options and fuel possibilities. Next it presents the design drivers for a marine power plant and explores how anSOFC system performs. Hereafter the possibilities for integrating the SOFC system with the ship are examined alsoconsidering economic and environmental impact. The review shows unexplored potential to successfully integrate SOFC withthermal and electrical systems in marine vessels. Additionally it is identified that there are still possibilities to improve marineSOFC systems for which a holistic approach is needed for design at cell stack module and system level. Nevertheless it isexpected that hybridisation is needed for a technically and economically feasible ship. Despite its high cost SOFC systemscould significantly reduce GHG NO X SO X PM and noise emissions in shipping

In the coming years as a result of changing climate policies and finite fossil fuel resources energy producers will be compelled to introduce new fuels with lower carbon footprints. One of the solutions is hydrogen which can be burned or co-fired with methane in energy generation systems. Therefore this study presents a thermodynamic and emission analysis of a gas turbine fueled by a mixture of CH4 and H2 as well as pure hydrogen. Numerical studies were conducted for the actual operating parameters of the LM6000 gas turbine in both simple and combined cycles. Aspen Hysys and Chemkin-Pro 2023R1 commercial software were used for the calculations. It was demonstrated that with a constant turbine inlet temperature set at 1723 K the thermal efficiency increased from 39.4% to 40.2% for the gas turbine cycle and from 49% to 49.4% for the combined cycle gas turbine. Nitrogen oxides emissions were calculated using the reactor network revealing that an increase in H2 content above 20%vol. in the fuel leads to a significant rise in nitric oxides emissions. In the case of pure H2 emissions are more than three times higher than for CH4 . The main reason for this increase in emissions was identified as the greater presence of H O and OH radicals in the reaction zone causing an acceleration in the formation of nitric oxides.

Enhancing system durability and fuel economy stands as a crucial factor in the energy management of fuel cell hybrid vehicles. This paper proposes an Equivalent Consumption Minimization Strategy (ECMS) based on the Genetic Algorithm (GA) aiming to minimize the overall operating cost of the system. First this study establishes a dynamic model of the hydrogen–electric hybrid vehicle a static input–output model of the hybrid power system and an aging model. Next a speed prediction method based on an Autoregressive Integrated Moving Average (ARIMA) model is designed. This method fits a predictive model by collecting historical speed data in real time ensuring the robustness of speed prediction. Finally based on the speed prediction results an adaptive Equivalence Factor (EF) method using a GA is proposed. This method comprehensively considers fuel consumption and the economic costs associated with the aging of the hydrogen–electric hybrid system forming a total operating cost function. The GA is then employed to dynamically search for the optimal EF within the cost function optimizing the system’s economic performance while ensuring real-time feasibility. Simulation outcomes demonstrate that the proposed energy management strategy significantly enhances both the durability and fuel economy of the fuel cell hybrid vehicle.

During the development of hydrogen fuel cell systems with the augmentation of power conventional air-cooling systems which are frequently employed in portable scenarios encounter difficulties in maintaining the balance between radiator heat dissipation and power consumption. In contrast liquid-cooling systems are widely adopted in high-power applications. In this regard aiming to address the heat dissipation problem and make use of the wastewater from the stack tailpipe a novel spray cooling system integrated with the traditional air-cooling for the radiator of hydrogen fuel cell systems is put forward. Through experimental investigations based on heat transfer theory and the design principles of fuel cell systems it is discovered that under specific nozzle apertures and spray water pressures the heat dissipation rate can be enhanced by 40 % and 30 % respectively. With particular radiator internal water flow rates and fan speeds the heat dissipation rate can be increased by 30 % and 108 % respectively. And the spray angle of 60 ◦ is the best angle. In contrast to the conventional air-cooling system the spray-air cooling system exhibits a heat dissipation rate that is approximately 50 % higher. Exper imental analyses demonstrate that the new system effectively harnesses water resources and enhances the heat dissipation performance of the radiator thereby providing a technical reference for the application of spray cooling in the radiators of hydrogen fuel cell systems.