Applications & Pathways

The road transport sector is one of the major contributors to greenhouse gas emissions as it still largely relies on traditional powertrain solutions. While some progress has been made in the passenger car sector with the diffusion of battery electric vehicles heavy-duty transport remains predominantly dependent on diesel internal combustion engines. This research aims to evaluate and compare three potential solutions for the decarbonisation of heavy-duty freight transport from an economic perspective: Battery Electric Trucks (BETs) Fuel Cell Electric Trucks (FCETs) and Hydrogen-fuelled Internal Combustion Engine Trucks (H2ICETs). The study focuses on the Finnish market and road network where affordable and low-carbon electricity creates an ideal environment for the development of alternative powertrain vehicles. The analysis employs the Total Cost of Ownership (TCO) method which allows for a comprehensive assessment of all cost components associated with the vehicles throughout their entire lifecycle encompassing both initial expenses and operational costs. Among the several factors affecting the results the impact of the three powertrain technologies on the admissible payloads has been taken into account. The study specifically focuses on the costs directly incurred by the truck owner. Additionally to evaluate the cost effectiveness of the proposed powertrain technologies under different scenarios a sensitivity analysis on electricity and hydrogen prices is conducted. The outcomes of this study reveal that no single powertrain solution emerges as universally optimal as the most cost-effective choice depends strongly on the truck type and its use (i.e. daily mileage). For relatively small trucks (18 t) covering short driving distances (approximately 100 to 200 km/day) BETs prove to be the best solution due to their higher efficiency and lower vehicle costs compared to FCETs. Conversely for larger trucks (42 and 76 t) engaged in longer hauls (>300 km/day) H2ICETs exhibit larger cost benefits due to their lower vehicle costs among the three options under investigation. Finally for small trucks (18 t) travelling long distances (200 km/day or more) FCETs represent a competitive choice due to their high efficiency and costeffective energy storage system. Considering future advancements in FCETs and BETs in terms of improved performance and reduced investment cost the fuel cell-based solution is expected to emerge as the best option across various combinations of truck sizes and daily mileages.

The ambitious targets set by the International Maritime Organization for reducing greenhouse gas emissions from shipping require radical actions by all relevant stakeholders. In this context the interest in high efficiency and low emissions (even zero in the case of hydrogen) fuel cell technology for maritime applications has been rising during the last decade pushing the research developed by academia and industries. This paper aims to present a comparative review of the fuel cell systems suitable for the maritime field focusing on PEMFC and SOFC technologies. This choice is due to the spread of these fuel cell types concerning the other ones in the maritime field. The following issues are analyzed in detail: (i) the main characteristics of fuel cell systems; (ii) the available technology suppliers; (iii) international policies for fuel cells onboard ships; (iv) past and ongoing projects at the international level that aim to assess fuel cell applications in the maritime industry; (v) the possibility to apply fuel cell systems on different ship types. This review aims to be a reference and a guide to state both the limitations and the developing potential of fuel cell systems for different maritime applications.

The hydrogen internal combustion engine (H2-ICE) is proposed as a robust and viable solution to decarbonise the heavy-duty on- and off-road as well as the light-duty automotive sectors of the transportation markets and is therefore the subject of rapidly growing research interest. With the potential for engine performance improvement by controlling the internal mixture formation and avoiding combustion anomalies hydrogen direct injection (H2DI) is a promising combustion mode. Furthermore the H2-ICE poses an attractive proposition for original equipment manufacturers (OEMs) and their suppliers since the fundamental base engine design components and manufacturing processes are largely unchanged. Nevertheless to deliver the highest thermal efficiency and zero-harm levels of tailpipe emissions moderate adaptations are needed to the engine control air path fuel injection and ignition systems. Therefore in this article critical design features fuel-air mixing combustion regimes and exhaust after-treatment systems (EATS) for H2DI engines are carefully assessed.

This study introduces a novel hybrid solar–biomass cogeneration power plant that efficiently produces heat electricity carbon dioxide and hydrogen using concentrated solar power and syngas from cotton stalk biomass. Detailed exergy-based thermodynamic economic and environmental analyses demonstrate that the optimized system achieves an exergy efficiency of 48.67% and an exergoeconomic factor of 80.65% and produces 51.5 MW of electricity 23.3 MW of heat and 8334.4 kg/h of hydrogen from 87156.4 kg/h of biomass. The study explores four scenarios for green hydrogen production pathways including chemical looping reforming and supercritical water gasification highlighting significant improvements in levelized costs and the environmental impact compared with other solar-based hybrid systems. Systems 2 and 3 exhibit superior performance with levelized costs of electricity (LCOE) of 49.2 USD/MWh and 55.4 USD/MWh and levelized costs of hydrogen (LCOH) of between 10.7 and 19.5 USD/MWh. The exergoenvironmental impact factor ranges from 66.2% to 73.9% with an environmental impact rate of 5.4–7.1 Pts/MWh. Despite high irreversibility challenges the integration of solar energy significantly enhances the system’s exergoeconomic and exergoenvironmental performance making it a promising alternative as fossil fuel reserves decline. To improve competitiveness addressing process efficiency and cost reduction in solar concentrators and receivers is crucial.

In response to environmental concerns related to carbon and nitrogen emissions hydrogen-powered aircraft (HPA) are poised for significant development over the coming decades driven by advances in power electronics technology. However HPA systems present complex multi-domain challenges encompassing electrical hydraulic mechanical and chemical disciplines necessitating efficient modeling and robust validation platforms. This paper introduces a physics-informed machine learning (PIML) approach for multi-domain HPA system modeling enhanced by hardware accelerated parallel hardware emulation to construct a real-time digital twin. It delves into the physical analysis of various HPA subsystems whose equations form the basis for both traditional numerical solution methods like Euler’s and Runge-Kutta methods (RKM) as well as the physics-informed neural networks (PINN) components developed herein. By comparing physics-feature neural networks (PFNN) and PINN with conventional neural network strategies this paper elucidates their advantages and limitations in practical applications. The final implementation on the Xilinx® UltraScale+™ VCU128 FPGA platform showcases the PIML method’s high efficiency accuracy data independence and adherence to established physical laws demonstrating its potential for advancing real-time multi-domain HPA emulation.

Hydrogen-fueled internal combustion engines are a promising CO2-free and zero-impact emission alternative to battery or fuel cell electric powertrains. Advantages include long service life robustness against fuel impurities and a strong infrastructural base with existing production lines and workshop stations. In order to make hydrogen engines harmless in terms of pollutant emissions as well NOX emissions at the tailpipe must be reduced as low as the zero-impact emission level. Here the application of selective catalytic reduction (SCR) catalysts is a promising solution that can be rapidly adopted from conventional diesel engines. This paper therefore investigates the influences of the hydrogen concentration in the raw exhaust gas of the NO2/NOX ratio and of the space velocity on the performance of two different SCR technologies. The results show that both types of SCR copper-zeolite and vanadium-based have their advantages and drawbacks. Copper-based SCR catalysts have an early light-off temperature and reach maximum efficiencies of up to >99%. On the other hand vanadium systems promise almost no secondary N2O emissions. As a result we combined both approaches to create a superior solution with high efficiency and lowest secondary emissions.

Hydrogen energy represents an ideal medium for energy storage. By integrating hydrogen power conversion utilization and storage technologies with distributed wind and photovoltaic power generation techniques it is possible to achieve complementary utilization and synergistic operation of multiple energy sources in the form of microgrids. However the diverse operational mechanisms varying capacities and distinct forms of distributed energy sources within hydrogen-coupled microgrids complicate their operational conditions making fine-tuned scheduling management and economic operation challenging. In response this paper proposes an energy management method for hydrogen-coupled microgrids based on the deep deterministic policy gradient (DDPG). This method leverages predictive information on photovoltaic power generation load power and other factors to simulate energy management strategies for hydrogen-coupled microgrids using deep neural networks and obtains the optimal strategy through reinforcement learning ultimately achieving optimized operation of hydrogen-coupled microgrids under complex conditions and uncertainties. The paper includes analysis using typical case studies and compares the optimization effects of the deep deterministic policy gradient and deep Q networks validating the effectiveness and robustness of the proposed method.

The surge in interest surrounding renewable energy stems from concerns regarding pollution and the finite supply ofnonrenewable resources. Solar PV and wind hybrid renewable energy systems (HRES) are increasingly recognized as practicaland cost-effective solutions particularly in remote areas. However the intermittent nature of solar and wind power presents achallenge. To address this incorporating a hydrogen source into the system has been proposed. This study focuses onmodelling and sizing a hybrid energy system tailored for remote areas accommodating both home and electric vehicle loads.The simulation is conducted for Siliguri West Bengal India with the goal of optimizing productivity minimizing expensesand considering economic factors using HOMER Pro software. The integration of green hydrogen-based power generationwith photovoltaic and wind HRES emerges as an effective solution. Solar power in particular showcases promisingopportunities for the electrolysis process and HRES systems. The presented work facilitates the modelling of a green hydrogen-based green energy system taking into account capacity cost and emission constraints. Various case studies are conducted toenhance system efficiency and reduce the costs of energy (COE). In this paper three cases of grid-connected and three cases ofoff-grid or grid-disconnected systems are considered for highlighting the benefits of hydrogen energy incorporation in bothtypes of systems. This research contributes to sustainable energy solutions advancing a greener and more efficient energylandscape especially in addressing the recent development in load combinations of home and electric vehicle loads in bothgrid-connected as well as grid-disconnected system.

The use of compression ignition engines (CIEs) is associated with increased greenhouse gas emissions. It is therefore necessary to research sustainable solutions and reduce the negative environmental impact of these engines. A widely studied alternative is the use of H2 in dual-fuel mode. This review has been developed to include the most recent studies on the subject to collect and compare their main conclusions on performance and emissions. Moreover this study includes most relevant emission control strategies that have not been extensively analyzed in other reviews on the subject. The main conclusion drawn from the literature is the negative effect of the addition of H2 on NOx. This is due to the increase in temperature during combustion which increases NOx formation as the thermal mechanism predominates. Therefore to reduce these emissions three strategies have been studied namely exhaust gas recirculation (EGR) water injection (WI) and compression ratio (CR) reduction. The effect of these techniques on NOx reduction together with their effect on other analyzed performance parameters have been deeply analyzed. The studies reviewed in this work indicate that hydrogen is an alternative fuel for CIEs when used in conjunction with techniques that have proven to be effective in reducing NOx.

The introduction of several alternative marine fuels is considered an important strategy for maritime decarbonization. These alternative marine fuels include liquefied natural gas (LNG) liquefied biogas (LBG) hydrogen ammonia methanol ethanol hydrotreated vegetable oil (HVO) etc. In some studies nuclear power and electricity are also included in the scope of alternative fuels for merchant ships. However the operation of alternative-fuel-powered ships has some special risks such as fuel spills vapor dispersion and fuel pool fires. The existing international legal framework does not address these risks sufficiently. This research adopts the method of legal analysis to examine the existing international legal regime for regulating the development of alternative-fuel-powered ships. From a critical perspective it evaluates and predicts the consequences of these policies together with their shortcomings. Also this research explores the potential solutions and countermeasures that might be feasible to deal with the special marine environmental risks posed by alternative-fuel-powered ships in the future.