Publications
Green Hydrogen Generation by Water Photoelectrolysis: Economic and Environmental Analysis
Mar 2025
Publication
Water photoelectrolysis cells based on photoelectrochemical water splitting seem to be an interesting alternative to other traditional green hydrogen generation processes (e.g. water electrolysis). Unfortunately the practical application of this technology is currently hindered by several difficulties: low solar-to-hydrogen (STH) efficiency expensive electrode materials etc. A novel concept based on a tandem photoelectrolysis cell configuration with an anion-conducting membrane separating the photoanode from the photocathode has already been proposed in the literature. This approach allows the use of low-cost metal oxide electrodes and nickel-based co-catalysts. In this paper we conducted a study to evaluate the economic and environmental sustainability of this technology using the environmental life cycle cost. Preliminary results have revealed two main interesting aspects: the negligible percentage of externalities in the total cost.
Assessment of Carbon-abatement Pricing to Maximize the Value of Electrolytic Hydrogen in Emissions-intensive Power Sectors
Aug 2025
Publication
Electrolytic hydrogen can support the decarbonization of the power sector. Achieving cost-effective power-to-gas-to-power (PGP) integration through targeted emissions pricing can accelerate the adoption of electrolytic hydrogen in greenhouse gas-intensive power sectors. This study develops a framework for assessing the economic viability of electrolytic hydrogen-based PGP systems in fossil fuel-dependent grids while considering the competing objectives of the electricity system operator a risk-averse investor and the government. Here we show that given the risk-averse investor’s inherent pursuit of profit maximization a break-even carbon abatement cost of at least 57 Canadian Dollars per tonne of CO₂ by 2030 from the government with a shift in electricity market dispatch rules from sole system marginal pricereduction to system-wide emissions reduction is essential to stimulate price discovery for low-cost hydrogen production and contingency reserve provision by the PGP system. This work can help policymakers capture and incentivize the role of electrolytic hydrogen in low-carbon power sector planning.
Double-Layer Optimal Configuration of Wind–Solar-Storage for Multi-Microgrid with Electricity–Hydrogen Coupling
Oct 2025
Publication
To address the collaborative optimization challenge in multi-microgrid systems with significant renewable energy integration this study presents a dual-layer optimization model incorporating power-hydrogen coupling. Firstly a hydrogen energy system coupling framework including photovoltaics storage batteries and electrolysis hydrogen production/fuel cells was constructed at the architecture level to realize the flexible conversion of multiple energy forms. From a modeling perspective the upper-layer optimization aims to minimize lifecycle costs by determining the optimal sizing of distributed PV systems battery storage hydrogen tanks fuel cells and electrolyzers within the microgrid. At the lower level a distributed optimization framework facilitates energy sharing (both electrical and hydrogen-based) across microgrids. This operational layer maximizes yearly system revenue while considering all energy transactions—both inter-microgrid and grid-to-microgrid exchanges. The resulting operational boundaries feed into the upper-layer capacity optimization with the optimal equipment configuration emerging from the iterative convergence of both layers. Finally the actual microgrid in a certain area is taken as an example to verify the effectiveness of the proposed method.
Influence of Engine Oils on Pre-Ignition Tendency in a Hydrogen–Kerosene Dual-Fuel Engine
Mar 2025
Publication
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.
Retrofitted Production of Bio-hydrogen. Large-scale Biowaste Valorization via Solar-based Gasification
Aug 2025
Publication
Hydrogen production from gasification of biowaste generates large volumes of CO2 due to endothermic biowaste decomposition. Alternatively the Sun can provide that energy. To evaluate the yield and performance of solarbased gasifiers at country scale a multi-scale approach is required. First the operation of a solar gasifier is analyzed by developing a two-phase model validated and scaled to industrial level. Next the performance and yield of such technology as a function of the radiation received is studied taking Spain as a case study. The results were promising obtaining a syngas rich in H2. However tar and char were not reduced due to insufficient temperature. Scale-up studies revealed energy losses to the environment in the industrial-scale gasifier which suggested the use of segmented heating. In turn diameters no larger than 0.8 m and biomass feeding rates below 0.85 kg/s highlight the deployment of a modular design due to particle size limitations. Finally the large-scale waste valorization showed that the gasifier can only operate in Spain in the summer months. It can run over 180 h/month and more than 250 days/year only in C´ adiz and Santa Cruz de Tenerife which also showed the highest yearly production capacities.
Digital Twin Framework for Energy Transition in Gas Networks Based on Open-Source Tools: Methodology and Case Study in Southern Italy
Oct 2025
Publication
The ongoing digitalization of energy infrastructure is a crucial enabler for improving efficiency reliability and sustainability in gas distribution networks especially in the context of decarbonization and the integration of alternative energy carriers (e.g. renewable gases including biogas green hydrogen). This study presents the development and application of a Digital Twin framework for a real-world gas distribution network developed using open-source tools. The proposed methodology covers the entire digital lifecycle: from data acquisition through smart meters and GIS mapping to 3D modelling and simulation using tools such as QGIS FreeCAD and GasNetSim. Consumption data are collected processed and harmonized via Python-based workflows hourly simulations of network operation including pressure flow rate and gas quality indicators like the Wobbe Index. Results demonstrate the effectiveness of the Digital Twin in accurately replicating real network behavior and supporting scenario analyses for the introduction of greener energy vectors such as hydrogen or biomethane. The case study highlights the flexibility and transparency of the workflow as well as the critical importance of data quality and availability. The framework provides a robust basis for advanced network management optimization and planning offering practical tools to support the energy transition in the gas sector.
Wetting of the Microporous Layer at the Cathode of an Anion Exchange Membrane Water Electrolyzer
Aug 2025
Publication
Water management is crucial for the performance of anion exchange membrane water electrolyzers (AEM-WEs) to maintain membrane hydration and enable phase separation between hydrogen gas and liquid water. Therefore careful material selection for the anode and cathode is essential to enhance reactant/product transport and optimize water management under ‘dry cathode’ conditions. This study investigates the wetting characteristics of two commercially available porous transport layers (PTLs) used in AEM-WE: carbon paper and carbon paper with a microporous layer (MPL). Wettability was measured under static quasi-static and dynamic conditions to assess the effect of water and electrolytes (NaOH KOH K2CO3) across concentrations (up to 1 M) and operational temperatures (20 °C to 92 °C). Carbon paper exhibits mild hydrophobicity (advancing contact angles of ∼120° however with receding contact angle ∼0°) whereas carbon paper with MPL demonstrates superhydrophobicity (advancing and receding contact angles >145° and low contact angle hysteresis) maintaining a stable Cassie-Baxter wetting state. Dynamic wetting experiments confirmed the robustness of the superhydrophobicity in carbon paper with MPL facilitating phase separation between hydrogen gas and liquid water. The presence of supporting electrolytes did not significantly affect wettability and the materials retained hydrophobic properties across different temperatures. These findings highlight the importance of MPLs in optimizing water transport and gas rejection within AEM-WEs ensuring efficient and stable operation under “dry cathode” conditions. These PTLs (with and without the addition of the MPL) were integrated into AEM-WE and polarization curves were run. Preliminary data in a specific condition suggested the presence of the MPL within the PTL enhance AEM-WE performance.
Stimulating Efficiency for Proton Exchange Membrane Water Splitting Electrolyzers: From Material Design to Electrode Engineering
Jun 2025
Publication
Proton exchange membrane water electrolyzers (PEMWEs) are a promising technology for large-scale hydrogen production yet their industrial deployment is hindered by the harsh acidic conditions and sluggish oxygen evolution reaction (OER) kinetics. This review provides a comprehensive analysis of recent advances in iridium-based electrocatalysts (IBEs) emphasizing novel optimization strategies to enhance both catalytic activity and durability. Specifically we critically examine the mechanistic insights into OER under acidic conditions revealing key degradation pathways of Ir species. We further highlight innovative approaches for IBE design including (i) morphology and support engineering to improve stability (ii) structure and phase modulation to enhance catalytic efficiency and (iii) electronic structure tuning for optimizing interactions with reaction intermediates. Additionally we assess emerging electrode engineering strategies and explore the potential of non-precious metal-based alternatives. Finally we propose future research directions focusing on rational catalyst design mechanistic clarity and scalable fabrication for industrial applications. By integrating these insights this review provides a strategic framework for advancing PEMWE technology through highly efficient and durable OER catalysts.
The Total Costs of Energy Transitions With and Without Nuclear Energy
Oct 2025
Publication
Within energy system analysis there is discourse regarding the role and economic benefits of nuclear energy in terms of overall system costs. The reported findings range from considerable drawbacks to substantial benefits depending on the chosen models scenarios and underlying assumptions. This article addresses existing gaps by demonstrating how subtle variations in model assumptions significantly impact analysis outcomes. Historically uncertainties associated with nuclear energy costs have been well documented whereas renewable energy costs have steadily declined and have been relatively predictable. However as land availability increasingly constrains future renewable expansion development is shifting from onshore to offshore locations where cost uncertainties are greater and anticipated cost reductions are less reliable. This study emphasizes this fundamental shift highlighting how uncertainties in future renewable energy costs could strengthen the economic case of nuclear energy within fully integrated sector-coupled energy systems especially when the costs of all technologies and weather conditions are set in the moderate range. Focusing specifically on Denmark this article presents a thorough sensitivity analysis of renewable energy costs and weather conditions within anticipated future ranges providing a nuanced perspective on the role of nuclear energy. Ultimately the findings underscore that when examining total annual system costs the differences between scenarios with low and high nuclear energy shares are minimal and are within ±5 % for the baseline assumptions while updated adjustments reduce this variation to ±1 %.
Can Hydrogen Be Produced Cost-Effectively from Heavy Oil Reservoirs?
Oct 2025
Publication
The potential for hydrogen production from heavy oil reservoirs has gained significant attention as a dual-benefit process for both enhanced oil recovery and low-carbon energy generation. This study investigates the technical and economic feasibility of producing hydrogen from heavy oil reservoirs using two primary in situ combustion gasification strategies: cyclic steam/air and CO2 + O2 injection. Through a comprehensive analysis of technical barriers economic drivers and market conditions we assess the hydrogen production potential of each method. While both strategies show promise they face considerable challenges: the high energy demands associated with steam generation in the steam/air strategy and the complexities of CO2 procurement capture and storage in the CO2 + O2 method. The novelty of this work lies in combining CMG-STARS reservoir simulations with GoldSim techno-economic modeling to quantify hydrogen yields production costs and oil–hydrogen revenue trade-offs under realistic field conditions. The analysis reveals that under current technological and market conditions the cost of hydrogen production significantly exceeds the market price rendering the process economically uncompetitive. Furthermore the dominance of oil production as the primary revenue source in both methods limits the economic viability of hydrogen production. Unless substantial advancements are made in technology or a more cost-efficient production strategy is developed hydrogen production from heavy oil reservoirs is unlikely to become commercially viable in the near term. This study provides crucial insights into the challenges that must be addressed for hydrogen production from heavy oil reservoirs to be considered a competitive energy source.
Hydrogen Production Power Supply with Low Current Ripple Based on Virtual Impedance Technology Suitable for Offshore Wind–Solar–Storage System
Oct 2025
Publication
Hydrogen production from water electrolysis can not only reduce greenhouse gas emissions but also has abundant raw materials which is one of the ideal ways to produce hydrogen from new energy. The hydrogen production power supply is the core component of the new energy electrolytic water hydrogen production device and its characteristics have a significant impact on the efficiency and purity of hydrogen production and the service life of the electrolytic cell. In essence the DC/DC converter provides the large current required for hydrogen production. For the converter its input still needs the support of a DC power supply. Given the maturity and technical characteristics of new energy power generation integrating energy storage into offshore energy systems enables stable power supply. This configuration not only mitigates energy fluctuations from renewable sources but also further reduces electrolysis costs providing a feasible pathway for large-scale commercialization of green hydrogen production. First this paper performs a simulation analysis on the wind–solar hybrid energy storage power generation system to demonstrate that the wind–solar–storage system can provide stable power support. It places particular emphasis on the significance of hydrogen production power supply design—this focus stems primarily from the fact that electrolyzers impose specific requirements on high operating current levels and low current ripple which exert a direct impact on the electrolyzer’s service life hydrogen production efficiency and operational safety. To suppress the current ripple induced by high switching frequency and high output current traditional approaches typically involve increasing the output inductor. However this method substantially increases the volume and weight of the device reduces the rate of current change and ultimately results in a degradation of the system’s dynamic response performance. To this end this paper focuses on developing a virtual impedance control technology aiming to reduce the ripple amplitude while avoiding an increase in the filter inductor. Owing to constraints in current experimental conditions this research temporarily relies on simulation data. Specifically a programmable power supply is employed to simulate the voltage output of the wind–solar–storage hybrid system thereby bringing the simulation as close as possible to the actual operating conditions of the wind–solar–storage hydrogen production system. The experimental results demonstrate that the proposed method can effectively suppress the ripple amplitude maintain high operating efficiency and ultimately meet the expected research objectives. That makes it particularly suitable as a high-quality power supply for offshore hydrogen production systems that have strict requirements on volume and weight.
Techno-Economic Analysis of Marine Hybrid Clusters for Use in Chile and Mexico
Oct 2025
Publication
This study assesses the feasibility and profitability of marine hybrid clusters combining wave energy converters (WECs) and offshore wind turbines (OWTs) to power households and marine aquaculture. Researchers analyzed two coastal sites: La Serena Chile with high and consistent wave energy resources and Ensenada Mexico with moderate and more variable wave power. Two WEC technologies Wave Dragon (WD) and Pelamis (PEL) were evaluated alongside lithium-ion battery storage and green hydrogen production for surplus energy storage. Results show that La Serena’s high wave power (26.05 kW/m) requires less hybridization than Ensenada’s (13.88 kW/m). The WD device in La Serena achieved the highest energy production while PEL arrays in Ensenada were more effective. The PEL-OWT cluster proved the most cost-effective in Ensenada whereas the WD-OWT performed better in La Serena. Supplying electricity for seaweed aquaculture particularly in La Serena proves more profitable than for households. Ensenada’s clusters generate more surplus electricity suitable for the electricity market or hydrogen conversion. This study emphasizes the importance of tailoring emerging WEC systems to local conditions optimizing hybridization strategies and integrating consolidated industries such as aquaculture to enhance both economic and environmental benefits.
Early Transition to Near-zero Emissions Electricity and Carbon Dioxide Removal is Essential to Achieve Net-zero Emissions at a Low Cost in Australia
Aug 2025
Publication
Achieving net-zero emissions requires major changes across a nation’s economy energy and land systems particularly due to sectors where emissions are difficult to eliminate. Here we adapt two global scenarios from the International Energy Agency—the net-zero emissions by 2050 and the Stated Policies Scenario—using an integrated numerical economic-energy model tailored to Australia. We explore how emissions may evolve by sector and identify key technologies for decarbonisation. Our results show that a rapid shift to near-zero emissions electricity is central to reducing costs and enabling wider emissions reductions. From 2030 onwards carbon removal through land management and engineered solutions such as direct air capture and bioenergy with carbon capture and storage becomes critical. Australia is also well-positioned to become a global supplier of clean energy such as hydrogen made using renewable electricity helping reduce emissions beyond its borders.
A Decision-support Flowchart for Including Parameter Uncertainty in Prospective Life Cycle Inventory Modeling: An Application to a PEM Fuel Cell-based APU System for a Hydrogen-powered Aircraft
Oct 2025
Publication
Emerging energy technologies offer significant opportunities for climate change mitigation. However the assessment of their potential environmental impact through prospective life cycle assessment (pLCA) is challeng‑ ing owing to parameter uncertainties arising from data gaps temporal variability and evolving technological contexts when modeling their prospective life cycle inventories (pLCI). Existing methodologies lack standardized approaches for systematically integrating parameter uncertainty within pLCI frameworks often initially overlooking it. In order to fill this gap this study proposes a structured and transparent approach for incorporating parameter uncertainty directly into the pLCI modeling process. The goal is to enhance the robustness transparency and reproducibility of pLCI models. A decision–support flowchart based on an adapted six-step framework was developed to help life cycle assessment (LCA) practitioners address parameter uncertainty during the “goal and scope definition” and“life cycle inventory” phases of pLCA. The flowchart guides users through the process of defining of the assessment’s goal scope as well as its temporal and geographical boundaries and the technology’s maturity level (Step 1). Step 2 entails gathering data to depict the technology’s development. Steps 3 and 4 involve identifying parameters that are likely to change in the future such as manufacturing processes materials equipment and component dimensions as well as their respective uncertainties. Step 5 includes the learning effects required for industrial-scale production once the technology has reached maturity. Finally step 6 identifies external developments impacting the technology as well as contributing uncertainties. A case study of a fuel cell-based propulsion system for a hydrogen-powered aircraft in 2040 illustrates the applicability of the framework. This study introduces a structured flowchart to support decision making in cases when parameter uncertainty should be integrated into pLCI modeling. By supporting the selection of appropriate prospective meth‑ ods as well as uncertainty identification and characterization strategies the proposed flowchart enhances the trans‑ parency consistency and representativeness of the pLCA results facilitating their broader application in emerging technology assessment methods.
Combined Effects of Copper Oxide Nanoparticles and Hydrogen Enrichment on the Performance and Emissions of Butanol Enriched Biodiesel in a Diesel Engine
Oct 2025
Publication
This study explores a multi-faceted approach to improving the combustion performance and emission characteristics of a single-cylinder four-stroke direct injection (DI) compression ignition engine through the combined effects of butanol enrichment green-synthesized copper oxide (CuO) nanoparticles and hydrogen supplementation. The baseline fuel was a B20 biodiesel blend further enriched with 10 % butanol to enhance oxygen availability and atomization. CuO nanoparticles were synthesized via an eco-friendly aloe vera extractmediated method and dispersed into the fuel to promote oxidation kinetics and stabilize combustion. Experimental results revealed that the B20+But10 %+CuO100 blend achieved the highest brake thermal efficiency (BTE) of 33.6 % at full load alongside notable reductions in carbon monoxide (CO) unburned hydrocarbons (HC) nitrogen oxides (NOx) and smoke opacity compared to neat B20. Reactivity controlled compression ignition (RCCI) trials further demonstrated that hydrogen enrichment at 5 LPM and 10 LPM improved flame propagation Brake thermal efficiency (33.89 % & 35.43 %) and reduced brake-specific fuel consumption of nearly 10 % (0.26 Kg/KWh) & 0.25 Kg/KWh). While excessive hydrogen supply (10 LPM) marginally increased HC emissions (110 PPM) at higher loads due to localized incomplete oxidation overall results confirm significant emission mitigation. The findings highlight that the synergistic integration of butanol oxygenation catalytically active CuO nanoparticles and optimized hydrogen enrichment offers a viable pathway toward cleaner combustion improved energy efficiency and reduced pollutant emissions in biodiesel-fueled CI engines.
Advancing Hydrogen Sustainability in Alberta: Life Cycle Sustainability Assessment of Hydrogen Production Pathways
Oct 2025
Publication
This study conducts a Life Cycle Sustainability Assessment (LCSA) of hydrogen production pathways in Alberta Canada evaluating environmental economic and social dimensions. Eight pathways are analyzed: steam methane reforming (SMR) with and without carbon capture and storage (CCS) autothermal reforming (ATR) with and without CCS and with and without grid electricity as well as alkaline electrolysis using grid and wind electricity. While alkaline electrolysis with wind electricity shows the best performance under the climate change and ozone depletion categories ATR + CCS (CO2 capture rate of 91 % no-grid electricity) demonstrates the strongest performance in seven of nine environmental impact categories being the worst performer in none and having the lowest social risks. Economically SMR and ATR without CCS exhibit the lowest levelized cost of hydrogen followed by ATR + CCS (CO2 capture rate of 91 % no-grid electricity). ATR + CCS (CO2 capture rate of 91 % no-grid electricity) emerges as a promising pathway offering an overall balance of sustainability under the current study’s assumptions. The results suggest that a blue hydrogen to electricity scenario where ATR + CCS with 100 % on-site hydrogen-fueled power generation replaces grid electricity may be the most suitable pathway for hydrogen production in Alberta. Key recommendations include optimizing environmental performance in climate change and ozone depletion impacts reducing costs and mitigating social risks in ATR pathways. This LCSA supports policies and investments to advance hydrogen’s role in Alberta’s decarbonization and energy transition.
Comprehensive Analysis of a Full-scale Solid Oxide Fuel Cell Stack Fueled by Ammonia
Oct 2025
Publication
Ammonia represents a promising alternative fuel and hydrogen carrier for power generation due to its advantages in storage and transportation compared to those of hydrogen. However challenges persist in the direct use of ammonia in solid oxide fuel cells (SOFCs) particularly with respect to performance degradation—an issue that necessitates comprehensive investigation at the full-stack scale. This study examines a ten-cell full-size SOFC stack under various operating conditions to evaluate the viability of ammonia as a direct fuel. Experiments were conducted using pure ammonia pure hydrogen fully reformed ammonia and 50 % pre-reformed ammonia at three operating temperatures (660◦C 710 ◦C and 760 ◦C). Performance was characterized through current–voltage curves electrochemical impedance spectroscopy and continuous monitoring of residual ammonia in the exhaust using Fourier-transform infrared spectroscopy. A 200-hour durability test was performed to assess long-term stability. The results demonstrated that at temperatures of ≥ 710 ◦C ammonia-fueled SOFCs performed comparably to hydrogen-fueled configurations within typical operating ranges (0.2–0.5 A/cm2 ). The stack achieved optimal performance at 55–80 % fuel utilization. The ammonia-fueled configurations exhibited different voltage behaviors at higher fuel utilizations compared with those of the hydrogen-fueled configurations. The residual ammonia concentration in the anode off-gas remained well below the safety thresholds. Long-term testing demonstrated an initial degradation that eventually stabilized at a more sustainable rate. These findings validate ammonia as a viable fuel for SOFC stacks when operated at appropriate temperatures (≥710 ◦C) and optimal fuel utilization offering a pathway toward sustainable carbon-free ammonia energy systems.
Scenario-based Modelling of Industrial Energy Demand and GHG Emissions: A 2050 Outlook for Slovenia
Oct 2025
Publication
Addressing GHG emissions in industrial sectors is crucial for developed nations’ energy and environmental policies. European countries use diverse strategies to mitigate industrial GHG impacts with energy models evaluating national objectives and supporting policy implementation. A new hybrid bottom-up technology-oriented simulation model has been developed for Slovenia’s industrial sector focusing on energy-intensive industries like paper metal chemical and cement production. This model linked with the macroeconomic GEM model assesses the impacts of GHG reduction measures on the national economy. This paper introduces the Reference Energy System model for the industrial sector REES SLO aiding Slovenia’s NECP update. It details input parameters model structure proposed measures peculiarities of energy-intensive industries and calculation results. The findings indicate that decarbonizing Slovenia’s industrial sector is feasible but demands immediate policy intervention substantial investments and a collaborative approach among stakeholders. Advanced technologies such as carbon capture utilization and storage (CCUS) hydrogen-based solutions and enhanced energy efficiency measures are essential components of this transition. The integration of renewable energy sources (RES) and circular economy principles further strengthens pathways toward sustainability. The REES IND model underscores the importance of aligning industrial decarbonization strategies with broader economic and environmental objectives. It provides a comprehensive framework for policymakers to evaluate the effectiveness of proposed measures and their long-term impacts. Achieving these goals requires a phased approach beginning with energy efficiency improvements and progressing to structural changes and advanced technologies. The model’s insights pave the way for sustainable industrial transformation aligning Slovenia’s industrial sector with national and European Union climate objectives.
Life Cycle Assessment of Future Electricity and Hydrogen Systems: Implications for Low-carbon Transport
Oct 2025
Publication
This study develops and applies a life cycle assessment (LCA) framework combined with predictive market models to evaluate the environmental impacts of electricity and hydrogen for transport in the EU27+UK from 2020 to 2050. By linking evolving power sector scenarios with hydrogen supply models we assess the wellto-wheels (WTW) performance of battery electric vehicles (BEVs) and fuel cell electric vehicles (FCEVs) under consistent energy assumptions. Results show that electricity decarbonization can reduce GWP by up to 80% by 2050 but increases land use and mineral/metal demand due to renewable infrastructure expansion. The environmental impacts of hydrogen production are strongly influenced by the electricity mix especially in high electrolysis scenarios. WTW analysis indicates that while BEVs consistently achieve lower WTW GWP than FCEVs across all scenarios both drivetrains exhibit notable trade-offs in other impact categories. Scenarios dominated by blue hydrogen although not optimal in terms of GWP present a more balanced environmental profile making them a viable transitional pathway in contexts that prioritize minimizing other environmental impacts.
A Priori and a Posteriori Analyses of Differential and Preferential Diffusion in Large Eddy Simulations of Partially Premixed Hydrogen-air Flames
Oct 2025
Publication
Differential diffusion (DD) and non-unity Lewis number (Le) effects in the filtered equations of the mixture fraction progress variable their respective sub-grid scale (SGS) variances and enthalpy are investigated using a priori and a posteriori analyses of a lifted turbulent hydrogen jet flame. The a priori analyses show that the absolute magnitudes of the DD terms in the filtered mixture fraction equation and its SGS variance are significant individually but their net contribution is small. The DD effects are found to be small for the progress variable and its SGS variance. One non-unity Le term is of similar magnitude to the turbulent flux for the filtered enthalpy and is independent of turbulent transport. Therefore a simple model for this effect is constructed using flamelets. A priori validation of this model is performed using direct numerical simulation data of a lifted hydrogen flame and its a posteriori verification is undertaken through two large eddy simulations. This effect influences the enthalpy field and hence the temperature is affected because of the relative increase (decrease) in thermal diffusivity for lean (rich) mixtures. Hence higher peak temperatures are observed in the rich mixture when the non-unity Le effects are included. However its overall effects on the flame lift-off height and flame-brush structure are observed to be small when compared with measurements. Hence the DD and non-unity Le effects are negligible for LES of partially premixed combustion of hydrogen–air mixtures in high Reynolds number flows. Novelty and significance The relative importance of differential and preferential diffusion effects for large eddy simulations using the tabulated chemistry approach is systematically assessed. The consistency among the complete set of equations and their closure models of the controlling variables (filtered mixture fraction progress variable their subgrid scale variances and enthalpy) for partially premixed combustion is maintained on the physical and mathematical grounds for the first time. The novelty of this work lies in the development validation and verification of a computationally simple yet accurate and robust model for these diffusion effects and its a priori and a posteriori analyses. It is demonstrated that the influence of non-equidiffusion is small for turbulent partially premixed hydrogen–air flames and hence the standard unity Lewis number approach is shown to be sufficient for turbulent partially premixed flames with high turbulence levels which are typical in practical applications.
Fuel Cell Air Compressor Concepts to Enhance the Efficiency of FCEV
Oct 2025
Publication
The thermal management system and the balance-of-plant (BoP) in fuel cell electric vehicles (FCEV) are characterized by a particularly high level of complexity and a number of interfaces. Optimizing the efficiency of the overall vehicle is of special importance to maximize the range and increase the attractiveness of this technology to customers. This paper focuses on the optimization potential of the air supply system in the BoP whereby the charging concepts of the electric supercharger (ESC) and the electrically assisted turbocharger (EAT) as well as the integration of water spray injection (WSI) at the compressor inlet are investigated in the framework of an FCEV complete vehicle co-simulation. As a benchmark for the integration of these optimization measures the complete vehicle co-simulation is designed for a fuel cell electric passenger car of the current generation. Here thermo-hydraulic fluid circuits in the thermal management software KULI are coupled with mathematical-physical models in MATLAB/Simulink. Applying advanced simulation methodologies for the components of fuel cell powertrain and vehicle cabin enables the mapping of the effects of realistic operating conditions on the FCEV characteristics. The EAT offers the advantage over the ESC that due to the arrangement of an exhaust gas turbine a part of the exhaust gas enthalpy flow downstream of the fuel cell stack can be recovered which reduces the electrical compressor drive power. Moreover an additional reduction of this power consumption can be achieved by WSI as the effect of evaporative cooling lowers the initial compression temperature. For analysis and comparison these concepts are again modeled with high degree of detail and integrated into the benchmark overall vehicle simulation. The results indicate considerable reductions in the electric compressor drive power of the EAT compared to the ESC with noteworthy potential for reducing the vehicle’s hydrogen consumption. At an operating point in Worldwide harmonized Light Duty Test Cycle (WLTC) under 35 ◦ C ambient temperature and 25 % relative humidity the electrical compressor drive power shows a reduction potential of −40 % which corresponds to a vehicle-level hydrogen consumption reduction of up to −3 %. In addition the results also highlight the effect of the WSI in both charging concepts whereby its potential to reduce the hydrogen consumption on the overall vehicle level is relatively small. In WLTC at 35 ◦C ambient temperature and 25 % relative humidity the compressor drive power reduction potential for ESC and EAT averages −5 % while the effect on hydrogen consumption is only around −0.25 %.
Influence of Optimized Decarburization on Hydrogen Uptake and Aqueous Corrosion Behaviors of Ultrasong Martensitic Steel
Oct 2025
Publication
This study examined the effects of microstructural alterations by controlling the surface carbon gradient via a thermal decarburizing process on hydrogen evolution adsorption and permeation along with neutral aqueous corrosion behavior of an ultra-high-strength steel with a tensile strength of 2.4 GPa. Microstructural analyses showed that an optimized decarburizing process at 1100 ◦C led to partial transformation to ferrite without precipitating Fe3C in a marked fraction. Electrochemical impedance spectroscopy along with the permeation results revealed that there was a notable decrease in hydrogen evolution and subsurface hydrogen concentration. Moreover immersion test in a neutral aqueous condition showed slower corrosion kinetics with a comparatively uniform corroded surface indicating improved corrosion resistance. However the extent of improvement is significantly limited under non-optimized decarburizing conditions specifically when the temperature is below or above 1100 ◦C due to insufficient decarburization or the formation of coarse-spheroidized Fe3C particles accompanied by a porous subsurface layer. In particular a far greater adsorption tendency at bridge sites on Fe3C (001) in a pre-charged surface is highlighted. This study provides insight that the adjustment of the carbon gradient through an optimized annealing process can be an effective technical strategy to overcome the critical drawbacks of ultrastrong martensitic steels under hydrogen-rich or corrosive conditions.
Highly Selective Production of ‘‘Jadeite Hydrogen” from the Catalytic Decomposition of Diesel
Mar 2025
Publication
Clean hydrogen (H2) is highly desirable for the sustainable development of society in the era of carbon neutrality. However the current capability of water electrolysis and steam methane (CH4) reforming to produce green and blue H2 is very limited mainly due to the high production cost difficult scale-up technology or operational risk. Here we propose the direct catalytic decomposition of diesel using a nano-Fe-based catalyst to produce the so-called ‘‘jadeite H2” while simultaneously fixing the carbon from the diesel in the form of carbon nanotubes (CNTs). Efforts are made to understand the suppression mechanism of the CH4 byproduct such as by tuning the catalyst type space velocity and reaction time. The optimal green index (GI)—that is the molar ratio of H2/carbon in a gaseous state—of the proposed technology exceeds 42 which is far higher than those of any previously reported chemical vapor deposition (CVD) method. Moreover the carbon footprint (CFP) of the proposed technology is far lower than those of grey H2 blue H2 and other dehydrogenation technologies. Compared with most of the technologies mentioned above the energy consumption (per mole of H2) and reactor amplification of the proposed technology validate its high efficiency and great practical feasibility.
Recent Advances in MXene-based Nanocomposites for Photocatalytic Wastewater Treatment, Carbon Dioxide Reduction, and Hydrogen Production: A Comprehensive Review
Oct 2025
Publication
This review critically examines recent advancements in MXene-based nanocomposites and their roles in photocatalytic applications for environmental remediation and renewable energy. MXenes two-dimensional transition metal carbides nitrides and carbonitrides (Mn+1XnTx where M = transition metal X = C/N Tx = surface terminations such as –O –OH –F) exhibit high electrical conductivity tunable band structures hydrophilic surfaces and large specific surface areas. These properties make them highly effective in enhancing photocatalytic activity when incorporated into composite systems. The review summarizes synthesis methods structural modifications and the mechanisms underlying photocatalytic performance highlighting their efficiency in degrading organic inorganic and microbial pollutants converting CO₂ into value-added chemicals and generating H₂ via water splitting. Key challenges including stability oxidation and scalability are analyzed along with strategies such as surface passivation heterojunction formation and hybridization with antioxidant materials to improve performance. Future research should focus on developing green synthesis methods improving long-term stability and exploring scalable production to facilitate practical deployment. These insights provide a comprehensive understanding of MXene nanocomposites supporting their advancement as multifunctional photocatalysts for a clean and sustainable energy future.
Pathways to Environmental Sustainability through Energy Efficiency: A Strategic Next Energy Vision for Sustainable Development by 2050
Oct 2025
Publication
As the global push for carbon neutrality accelerates energy efficiency has become essential for sustainable development especially for nations like Nigeria that face rising energy demands and significant environmental challenges. This study explores how integrating energy efficiency with carbon neutrality can support Nigeria’s strategic energy goals while offering global lessons for other countries facing similar challenges focusing on key sectors including industry transport and power generation. The study systematically examines the impacts of renewable energy (RE) technologies like solar wind and hydropower—alongside policy reforms technological innovations and demand-side management strategies to advance energy efficiency in Nigeria. Key findings include the identification of strategic policy frameworks technological solutions and the transformative role of green hydrogen in decarbonizing hard-to-electrify sectors. The study also emphasizes the importance of international climate finance decentralized RE systems like solar mini-grids for improving energy access and economic opportunities for job creation in the RE sector. Furthermore it highlights the need for behavioral changes community engagement and consistent policy implementation to address infrastructure gaps and drive energy efficiency goals. The novelty of this research lies in its scenario-based analysis of Nigeria’s low-carbon transition detailing both the opportunities and challenges such as policy inconsistencies infrastructure deficits and financial constraints. The findings stress the importance of international collaboration technological advancements and targeted investments to overcome these challenges. By offering actionable insights and strategic recommendations this study provides a roadmap for policymakers industry stakeholders and researchers to drive Nigeria towards a sustainable carbon-neutral future by 2050.
Catalytic Pathways Towards Sustainable Aviation Fuel Production from Waste Biomass: A Systematic Review
Oct 2025
Publication
Sustainable aviation fuel (SAF) derived from renewable resources presents a practical alternative to Jet-A fuel by mitigating the ecological impact of aviation’s reliance on fossil fuel. Among the available feedstocks waste biomass and waste oils present key advantages due to their abundance sustainability potential and waste valorization benefits. Despite continuous progress in SAF technologies comprehensive assessments of catalytic routes and their efficiency in transforming waste-based feedstocks into aviation-grade fuels remain limited. This review addresses this gap by systematically evaluating recent studies (2019–2024) that investigate catalytic conversion and upgrading of waste-derived biomass toward SAF production. Selection of thermochemical processes including pyrolysis gasification and hydrothermal liquefaction or biological pathways is driven by the physicochemical characteristics of the waste. These processes yield intermediates such as biocrude and bio-oils undergo catalytic upgrading to meet aviation fuel standards. Zeolitic acids sulfided NiMo or CoMo catalysts noble-metal/oxide systems and bifunctional or carbon-based catalysts drive hydroprocessing deoxygenation cracking and isomerisation reactions delivering high selectivity toward C8-C16fractions. Performance mechanisms and selectivity of these catalysts are critically assessed in relation to feedstock characteristics and operating conditions. Key factors such as metal-acid balance hierarchical porosity and tolerance to heteroatoms enhance catalytic efficiency. Persistent challenges including deactivation coking sintering and feedstock impurities continue to limit long-term performance and scalability in waste-to-SAF applications. Mitigation strategies including oxidative and resulfidation regeneration and support modification have demonstrated improved stability. Moreover waste-derived catalysts and circularity enhance process sustainability. Future work should align catalyst design with feedstock pretreatment and techno-economic assessments to scale sustainable and cost-effective waste-to-SAF pathways.
QDQN-ThermoNet: A Quantum-driven Dual Depp Q-network Framework for Intelligent Thermal Regulation in Solid-state and Hydrogen Fuel Cell Systems of Future Electric Vehicles
Oct 2025
Publication
This paper presents QDQN-ThermoNet a novel Quantum-Driven Dual Deep Q-Network framework for intelligent thermal regulation in next-generation electric vehicles with hybrid energy systems. Our approach introduces a dual-agent architecture where a classical DQN governs solid-state battery thermal management while a quantumenhanced DQN regulates proton exchange membrane fuel cell dynamics both sharing a unified quantumenhanced experience replay buffer to facilitate cross-system information transfer. Hardware-in-the-Loop validation across diverse operational scenarios demonstrates significant performance improvements compared to classical methods including enhanced thermal stability (95.1 % vs. 82.3 %) faster thermal response (2.1 s vs. 4.7 s) reduced overheating events (0.3 vs. 3.2) and superior energy efficiency (22.4 % energy savings). The quantum-enhanced components deliver 38.7 % greater sample efficiency and maintain robust performance under sparse data conditions (33.9 % improvement) while material-adaptive control strategies leveraging MXeneenhanced phase change materials achieve a 50.3 % reduction in peak temperature rise during transients. Component lifetime analysis reveals a 33.2 % extension in battery service life through optimized thermal management. These results establish QDQN-ThermoNet as a significant advancement in AI-driven thermal management for future electric vehicle platforms effectively addressing the complex challenges of coordinating thermal regulation across divergent energy sources with different optimal operating temperatures.
Fuel Cell and Electric Vehicles: Resource Use and Associated Environmental Impacts
Oct 2025
Publication
Achieving transport decarbonization depends on electric vehicle (EV) and fuel cell vehicle (FCV) deployment yet their material demands and impacts vary by vehicle type. This study explores how powertrain preferences in light-duty vehicles (LDVs) and heavy-duty vehicles (HDVs) shape future resource use and material-related environmental outcomes. Using dynamic material flow analysis and prospective life cycle assessment we assess three scenarios. In the S3 EV-dominant scenario 2050 lithium and cobalt demand rises by up to 11.9-fold and 1.8-fold relative to 2020 with higher global warming and human toxicity impacts. The S2 FCV-dominant scenario leads to a 21.7-fold increase in platinum-group metal demand driving up freshwater ecotoxicity and particulate emissions. A balanced S1 scenario EVs in LDVs and FCVs in HDVs yields moderate material demand and environmental burdens. These findings demonstrate that no single pathway can fully resolve material-related impacts while combining EVs and FCVs across LDVs and HDVs enables a more balanced and sustainable transition.
A Review and Inventory of U.S. Hydrogen Emissions for Production, Distribution and Storage
Nov 2025
Publication
In response to the growing global interest in hydrogen as an energy carrier this study provides the first attempt to develop a baseline inventory of U.S. hydrogen emissions from production distribution and storage. The scope of this study was limited to pure hydrogen emissions and excludes emissions from low purity hydrogen streams and carriers. A detailed literature search was conducted utilizing various greenhouse gas emissions inventory protocol principles and guidelines to consolidate a list of activity data and emission factors. The best available activity data and emission factors were then selected via a Multi-Criteria-Based Decision Making Method named Technique for Order Preference by Similarity to Ideal Solution or modelled using best-engineering estimates. The study estimated total U.S. hydrogen emissions of 0.063 MMTA with emission bounds ranging from 0.02 to 0.11 MMTA. Given the total estimated H2 production capacity of 7.97 MMTA the study estimates a total U.S. hydrogen emission rate for production distribution and storage of 0.79% (0.26%–1.32%). To reduce the uncertainty in the estimated total hydrogen emissions future work should be conducted to measure facility-level hydrogen emission factors across multiple sectors. The inventory framework developed in this study can serve as a living document that can be updated and enhanced as more empirical data is obtained. This study also provides detailed insights regarding key emission or leakage sources and causes from each supply chain stage. The insights and conclusions from this study can provide direction for hydrogen production companies and safety professionals as they develop hydrogen emission mitigation measures and controls.
From Investment to Impact: Exploring Socio-economic Prospect of Hydrogen Investment in Tees Valley, UK
Oct 2025
Publication
Financial viability is fundamental for investment success however long run sustainable investment relies on delivering tangible socio-economic benefits that foster societal acceptance enhancing community welfare and well-being. This study developed a quantitative model to evaluate the socio-economic impact of a proposed 1 GW green and 2 GW blue hydrogen investment in Tees Valley UK from 2027 to 2035. We introduced the socioeconomic impact (SEI) ratio defined as the ratio of socio-economic impact to the Levelized Cost of Hydrogen (LCOH) to illustrate the significance of socio-economic impact beyond financial returns. Findings indicate that the cumulative environmental and economic impact of green hydrogen amounted to £1.5 ± 0.5 bn and £1.35 ± 0.27 bn respectively with an employment impact of £269 ± 28 mn. In contrast the proposed blue hydrogen investment is expected to deliver £2.9 ± 0.9 bn environmental impact £1.84 ± 0.37 bn economic impact and £212 ± 26 mn employment social impact. The SEI ratio of green hydrogen was found to range between 48 % and 62 % and 60 %–79 % for blue hydrogen suggesting overall SEI ratio of approximately 60 % for combined green and blue investment. Sensitivity analysis using Monte Carlo simulation revealed that the results are particularly sensitive to the Gross Value Added (GVA) emission and employment factors. These findings highlight the importance of integrating socio-economic considerations into hydrogen planning investment strategies and decision-making to optimise environmental societal and economic outcomes.
Numerical Investigation of Combustion, Performance, and Emission Attributes of Premixed Ammonia-hydrogen/air Flames within a Swirl Burners of a Gas Turbine
Oct 2025
Publication
This study investigates numerically combustion attributes and NOx formation of premixed ammonia-hydrogen/air flames within a swirl burner of a gas turbine considering various conditions of hydrogen fraction (HF: 0 % 5 % 30 % 40 % and 50 %) equivalence ratio (φ: 0.85 1.0 and 1.2) and mixture inlet temperature (Tin: 400–600 K). The results illustrate that flame temperature increases with hydrogen addition from 1958 K for pure ammonia to 2253 K at 50 % HF. Raising the inlet temperature from 400 K to 600 K markedly enhances combustion intensity resulting in an increase of the Damköhler number (Da) from 117 to 287. NOx levels rise from ∼1800 ppm (0 % HF) to ∼7500 ppm (50 % HF) and peak at 8243 ppm under lean conditions (φ = 0.85). Individual NO N2O and NO2 emissions also reach maxima at φ = 0.85 with values of 5870 ppm 2364 ppm and 10 ppm respectively decreasing significantly under richer conditions (2547 ppm 1245 ppm and 5 ppm at φ = 1.2). These results contribute to advancing low-carbon fuel technologies and highlight the viability of ammonia-hydrogen co-firing as a pathway toward sustainable gas turbine operation.
Solar-powered Hydrogen Production: Modelling PEM Electrolyser Systems for Optimal Integration with Solar Energy
Oct 2025
Publication
This study presents an experimental approach to modelling PEM electrolysers for green hydrogen production using solar energy. The objective is to implement a temperature steady-state electrolyser model to assess the optimal coupling configuration with a photovoltaic plant and estimate the yearly hydrogen production capacity. The research focuses on the energy consumption of ancillary systems under different load conditions developing a steady-state operational model that improves hydrogen production predictions by accounting for these consumptions. The model based on polynomial equations captures the non-linear variation in energy costs under partial load conditions. PEM electrolysers produce hydrogen above 3.0 quality (99.9% purity) and it is feasible to integrate purification processes to reach 5.0 quality (99.999% purity). While small-scale systems include purification large-scale facilities separate it enabling process optimisation. Two models are introduced to estimate hydrogen mass flow depending on purity: a base-purity model and a high-purity model that includes drying and pressure swing adsorption. Both are based on experimental data from a five-year-old small-scale electrolyser and are applicable to large-scale systems at partial load. Due to test conditions the model applied to large-scale facilities underestimates hydrogen production affected by energy losses from a non-optimised purification process and electrolyser degradation. Model validation with large-scale operational data from the literature shows the model captures plant behaviour well despite the consistent underestimation described above. The model is applied to several European locations to identify optimal photovoltaic-to-electrolyser ratios. Oversizing factors between 1.4 and 2 are needed to cover ancillary consumption. The levelised cost remains comparable for both purity levels despite higher energy demands for high-purity hydrogen due to the greater cost of the electrolyser over the photovoltaic plant.
Large-Scale Hydrogen Storage in Deep Saline Aquifers: Multiphase Flow, Geochemical–Microbial Interactions, and Economic Feasibility
Nov 2025
Publication
The development of large-scale flexible and safe hydrogen storage is critical for enabling a low-carbon energy system. Deep saline aquifers (DSAs) offer substantial theoretical capacity and broad geographic distribution making them attractive options for underground hydrogen storage. However hydrogen storage in DSAs presents complex technical geochemical microbial geomechanical and economic challenges that must be addressed to ensure efficiency safety and recoverability. This study synthesizes current knowledge on hydrogen behavior in DSAs focusing on multiphase flow dynamics capillary trapping fingering phenomena geochemical reactions microbial consumption cushion gas requirements and operational constraints. Advanced numerical simulations and experimental observations highlight the role of reservoir heterogeneity relative permeability hysteresis buoyancy-driven migration and redox-driven hydrogen loss in shaping storage performance. Economic analysis emphasizes the significant influence of cushion gas volumes and hydrogen recovery efficiency on the levelized cost of storage while pilot studies reveal strategies for mitigating operational and geochemical risks. The findings underscore the importance of integrated coupled-process modeling and comprehensive site characterization to optimize hydrogen storage design and operation. This work provides a roadmap for developing scalable safe and economically viable hydrogen storage in DSAs bridging the gap between laboratory research pilot demonstration and commercial deployment.
Verification of the reactingFoam Solver Through Simulating Hydrogen–Methane Turbulent Diffusion Flame, and an Overview of Flame Types and Flame Stabilization Techniques
Nov 2025
Publication
This study aims to qualitatively and quantitatively assess the ability of the flow solver “reactingFoam” of the open-source OpenFOAM software v.2506 for a control-volume-based computational fluid dynamics (CFD) solver in treating the reacting flow problem of a popular benchmarking bluff-body-stabilized turbulent diffusion (non-premixed) flame that is the HM1 flame. The HM1 flame has a fuel stream composed of 50% hydrogen (H2) and 50% methane (CH4) by mole. Thus the acronym “HM1” stands for “hydrogen– methane with level 1 of jet speed”. This fuel stream is surrounded by a coflow of oxidizing air jet. This flame was studied experimentally at the University of Sydney. A measurement dataset of flow and chemical fields was compiled and made available freely for validating relevant computational models. We simulate the HM1 flame using the reactingFoam solver and report here various comparisons between the simulation results and the experimental results to aid in judging the feasibility of this open-source CFD solver. The computational modeling was conducted using the specialized wedge geometry suitable for axisymmetric problems. The turbulence–chemistry interaction (TCI) was based on the Chalmers’ partially stirred reactor (CPaSR) model. The two-equation k-epsilon framework is used in modeling the small eddy scales. The four-step Jones-Lindstedt (JL) reaction mechanism is used to describe the chemical kinetics. Two meshes (coarse and fine) were attempted and a converged (mesh-independent) solution was nearly attained. Overall we notice good agreement with the experimental data in terms of resolved profiles of the axial velocity mass fractions and temperature. For either mesh resolution the overall deviation between the computational results and the experimental results is approximately 8% (mean absolute deviation) and 10% (root mean square deviation). These are favorably low. The current study and the presented details about the reactingFoam solver and its implementation can be viewed as a good case study in CFD modeling of reacting flows. In addition the information we provide about the measurement dataset the emphasized recirculation zone the entrainment phenomena and the irregularity in the radial velocity can help other researchers who may use the same HM1 data.
Assessing the Viability of Hydrogen-Based Wind Energy Conversion and Transmission Systems Versus the Existing Electrical-Based System—A Comprehensive Review
Nov 2025
Publication
This study presents a comprehensive review of the viability of hydrogen as an energy carrier for offshore wind energy compared to existing electricity carrier systems. To enable a state-of-the-art system comparison a review of wind-to-hydrogen energy conversion and transmission systems is conducted alongside wind-to-electricity systems. The review reveals that the wind-to-hydrogen energy conversion and transmission system becomes more cost-effective than the wind-to-electricity conversion and transmission system for offshore wind farms located far from the shore. Electrical transmission systems face increasing technical and economic challenges relative to the hydrogen transmission system when the systems move farther offshore. This study also explores the feasibility of using seawater for hydrogen production to conserve freshwater resources. It was found that while this approach conserves freshwater and can reduce transportation costs it increases overall system costs due to challenges such as membrane fouling in desalination units. Findings indicated that for this approach to be sustainable proper management of these challenges and responsible handling of saline waste are essential. For hydrogen energy transmission this paper further explores the potential of repurposing existing oil and gas pipeline infrastructure instead of constructing new pipelines. Findings indicated that with proper retrofitting the existing natural gas pipelines could provide a cost-effective and environmentally sustainable solution for hydrogen transport in the near future.
Outlook on the Decarbonization of Non-Electrified Passenger Railway Connections in Poland
Nov 2025
Publication
The decarbonization of regional passenger rail transport is one of the key challenges for the sustainable transformation of the transport sector in Poland. While railway transportation remains one of the least carbon-intensive modes of transport significant emission disparities persist between electrified and non-electrified lines where diesel traction is still prevalent. This article presents a comparative analysis of various propulsion technologies—diesel hybrid battery-electric and hydrogen fuel-cell—taking into account both local (TTW) and total (WTW) greenhouse gas emissions. The study incorporates Poland’s current energy mix and proposes a methodological framework to assess emissions at the line level. It highlights the risks of focusing exclusively on in situ zero-emission technologies and calls for a more flexible efficiency-based approach to fleet modernization. The analysis demonstrates that hybrid and optimized combustion-based systems can provide substantial emission reductions in the short term especially in rural and transitional regions. The paper also critically discusses transport funding policies pointing to discrepancies between incentives for private electric mobility and the lack of support for public transport solutions that could effectively counter mobility exclusion. The presented methodology and conclusions provide a basis for further research on transport decarbonization strategies tailored to national and regional contexts.
How Heat-Powered Heat Pumps Could Reduce the Need for Grid-Scale Energy Storage
Nov 2025
Publication
This paper explores how the deployment of “High-Performance Heat-Powered Heat Pumps” (HP3 s)—a novel heating technology—could help meet the domestic heating demand in the UK and reduce how much grid-scale energy storage is needed in comparison to a scenario where electrical heat pumps fully supply the heating demand. HP3 systems can produce electricity which can partially alleviate the stress caused by electrical heat pumps. A parametric analysis focusing on two variables the penetration of HP3 systems (H) and the amount of electricity exported (Ɛ) is presented. For every combination of H and Ɛ the electricity system is optimized to minimize the cost of electricity. Three parameters define the electricity system: the generation mix the energy storage mix and the amount of over-generation. The cost of electricity is at its highest when electrical heat pumps supply all demand. This reduces as the penetration of HP3 systems increases due to a reduction in the need for energy storage. When HP3 systems supply 100% of the heating demand the total cost of electricity and the storage capacity needed are 6% and 50% lower respectively compared to a scenario where electrical heat pumps are in 100% of residences.
Hybrid Wind–Solar–Fuel Cell–Battery Power System with PI Control for Low-Emission Marine Vessels in Saudi Arabia
Nov 2025
Publication
The maritime industry is under increasing pressure to reduce greenhouse gas emissions especially in countries such as Saudi Arabia that are actively working to transition to cleaner energy. In this paper a new hybrid shipboard power system which incorporates wind turbines solar photovoltaic (PV) panels proton-exchange membrane fuel cells (PEMFCs) and a battery energy storage system (BESS) together for propulsion and hotel load services is proposed. A multi-loop Energy Management System (EMS) based on proportional–integral control (PI) is developed to coordinate the interconnections of the power sources in real time. In contrast to the widely reported model predictive or artificial intelligence optimization schemes the PI-derived EMS achieves similar power stability and hydrogen utilization efficiency with significantly reduced computational overhead and full marine suitability. By taking advantage of the high solar irradiance and coastal wind resources in Saudi Arabia the proposed configuration provides continuous near-zeroemission operation. Simulation results show that the PEMFC accounts for about 90% of the total energy demand the BESS (±0.4 MW 2 MWh) accounts for about 3% and the stationary renewables account for about 7% which reduces the demand for hydro-gas to about 160 kg. The DC-bus voltage is kept within ±5% of its nominal value of 750 V and the battery state of charge (SOC) is kept within 20% to 80%. Sensitivity analyses show that by varying renewable input by ±20% diesel consumption is ±5%. These results demonstrate the system’s ability to meet International Maritime Organization (IMO) emission targets by delivering stable near-zero-emission operation while achieving high hydrogen efficiency and grid stability with minimal computational cost. Consequently the proposed system presents a realistic certifiable and regionally optimized roadmap for next-generation hybrid PEMFC–battery–renewable marine power systems in Saudi Arabian coastal operations.
Green Hydrogen in Europe: Where Are We Now?
Nov 2025
Publication
As global efforts to decarbonize intensify hydrogen produced via renewable electricity has emerged as a pivotal energy vector for a sustainable industrial future. This commentary provides a critical analysis of the current state of the hydrogen economy in Europe detailing the core principles operational mechanisms and industrial status of four primary water electrolysis technologies: alkaline (ALK) proton exchange membrane (PEM) solid oxide (SOEC) and anion exchange membrane (AEM). Furthermore it explores the significant socio-political challenges inherent in producing green hydrogen in non-EU nations for subsequent import into the European market.
A Deep Neural Network-Based Approach for Optimizing Ammonia–Hydrogen Combustion Mechanism
Nov 2025
Publication
Ammonia is a highly promising zero-carbon fuel for engines. However it exhibits high ignition energy slow flame propagation and severe pollutant emissions so it is usually burned in combination with highly reactive fuels such as hydrogen. An accurate understanding and modeling of ammonia–hydrogen combustion is of fundamental and practical significance to its application. Deep Neural Networks (DNNs) demonstrate significant potential in autonomously learning the interactions between high-dimensional inputs. This study proposed a deep neural network-based method for optimizing chemical reaction mechanism parameters producing an optimized mechanism file as the final output. The novelty lies in two aspects: first it systematically compares three DNN structures (Multilayer perceptron (MLP) Convolutional Neural Network and Residual Regression Neural Network (ResNet)) with other machine learning models (generalized linear regression (GLR) support vector machine (SVM) random forest (RF)) to identify the most effective structure for mapping combustion-related variables; second it develops a ResNet-based surrogate model for ammonia–hydrogen mechanism optimization. For the test set (20% of the total dataset) the ResNet outperformed all other ML models and empirical correlations achieving a coefficient of determination (R2 ) of 0.9923 and root mean square error (RMSE) of 135. The surrogate model uses the trained ResNet to optimize mechanism parameters based on a Stagni mechanism by mapping the initial conditions to experimental IDT. The results show that the optimized mechanism improves the prediction accuracy on laminar flame speed (LFS) by approximately 36.6% compared to the original mechanism. This method while initially applied to the optimization of an ammonia–hydrogen combustion mechanism can potentially be adapted to optimize mechanisms for other fuels.
Analysis of Exergy Flow and CCUS Carbon Reduction Potential in Coal Gasification Hydrogen Production Technology in China
Nov 2025
Publication
Coal constitutes China’s most significant resource endowment at present. Utilizing coal resources for hydrogen production represents an early-stage pathway for China’s hydrogen production industry. The analysis of energy quality and carbon emissions in coal gasification-based hydrogen production holds practical significance. This paper integrates the exergy analysis methodology into the traditional LCA framework to evaluate the exergy and carbon emission scales of coal gasification-based hydrogen production in China considering the technical conditions of CCUS. This paper found that the life cycle exergic efficiency of the whole chain of gasification-based hydrogen production in China is accounted to be 38.8%. By analyzing the causes of exergic loss and energy varieties it was found that the temperature difference between the reaction of coal gasification and CO conversion unit and the pressure difference due to the compressor driven by the electricity consumption of the compression process in the variable pressure adsorption unit are the main causes of exergic loss. Corresponding countermeasures were suggested. Regarding decarbonization strategies the CCUS process can reduce CO2 emissions across the life cycle of coal gasification-based hydrogen production by 48%. This study provides an academic basis for medium-to-long-term forecasting and roadmap design of China’s hydrogen production structure.
Advancing the Energy Transition in the Steel Industry: A Game-theoretic Bilevel Approach for Green Hydrogen Supply Chains
Sep 2025
Publication
Green hydrogen is essential for advancing the energy transition as it is regarded as a CO2-neutral flexible and storable energy carrier. Particularly in steel production which is known for its high energy intensity hydrogen has great potential to replace conventional energy sources. In a game-theoretic bi-level optimization model involving a power plant operator and a steel company we investigate in which situations the production and use of green hydrogen is advantageous from an economic and ecological point of view. Through an extensive case study based on a realworld scenario we can observe that hydrogen production can serve as a profitable and flexible secondary income opportunity for the power plant operator and help avoid curtailment and spot market losses. On the other hand the steel manufacturer can reduce CO2 emissions and associated costs while also meeting the growing customer demand for low-carbon products. However our findings also highlight important trade-offs and uncertainties. While lower electricity generation costs or improved electrolyzer efficiency enhance hydrogen’s competitiveness increases in coal and CO2 emission prices do not always result in greater hydrogen adoption. This is due to the persistent reliance on a non-replaceable share of coal in steel production which raises the overall cost of both low-carbon and carbon-intensive steel. The model further shows that consumer demand elasticity plays a critical role in determining hydrogen uptake. These insights underscore the importance of not only reducing hydrogen costs but also designing supportive policies that address market acceptance and the full cost structure of green industrial products.
Process Analysis and Techno-economic Comparison of Aviation Biofuel Production via Microbial Oil and Ethanol Upgrading
Oct 2025
Publication
The transport sector is the largest source of greenhouse gases in the EU after the energy supply one contributing approximately 27% of total emissions. Although decarbonization pathways for light-duty transport are relatively well established heavy-duty transport shipping and aviation emissions are difficult to eliminate through electrification. In particular the aviation sector is strongly dependent on liquid hydrocarbons making the development of sustainable aviation fuels (SAFs) a critical priority for achieving long-term climate targets. This study evaluates four biomass-to-liquid pathways for producing jet-like SAF from lignocellulosic biomass: (1) triacylglycerides (TAGs) production from syngas fermentation (2) TAGs production from sugar fermentation (3) ethanol production from syngas fermentation and (4) ethanol production from sugar fermentation. These pathways are simulated using Aspen Plus™ and the mass and heat balances obtained are used to assess their technical performance (e.g. carbon utilization energetic fuel efficiency) and techno-economic viability (e.g. production cost capital investment). Pathway (4) demonstrated the highest jet fuel selectivity (63%) and total carbon utilization (32.5%) but at higher power demands. Pathway (1) was self-sufficient in energy due to internal syngas utilization but exhibited lower carbon efficiencies. Cost analysis revealed that microbial oil-based pathways were restrained by higher hydrogen demands and lower product selectivity compared to ethanol-based routes. However with advancements in microbial oil production efficiency and reduced water usage these pathways could become competitive.
An Empirical Study of Kingdom of Saudi Arabia Citizens' Intentions about the Adoption of Hydrogen Fuel Cell Vehicles
Oct 2025
Publication
A comprehensive understanding of consumer preferences and demand factors is essential for successfully implementing demand-side strategies for alternative energy solutions such as hydrogen. This study aims to identify the key determinants influencing the adoption propensity for Hydrogen fuel cell vehicles (HFCVs) in the Kingdom of Saudi Arabia (KSA). Developing a conceptual framework to organise the key factors influencing consumers’ decisions to adopt or reject this technology. Using data from an online survey of 384 prospective customers we employed structural equation modelling (SEM) via Smart-PLS 4.1 to analyze consumer intent. The findings reveal that perceived benefits barriers opinions and governmental initiatives have a significant impact on the likelihood of HFCV adoption. The study emphasises the significance of collaborative efforts among key stakeholders including manufacturers hydrogen producers research institutions and financial entities in addressing challenges and advancing the development of the hydrogen transportation ecosystem in KSA. Financial incentives and subsidies such as purchasing subsidies awareness and reduced registration costs for HFCVs may be instituted.
Towards Green and Smart Ports: A Review of Digital Twin and Hydrogen Applications in Maritime Management
Oct 2025
Publication
Modern ports are pivotal to global trade facing increasing pressures from operational demands resource optimization complexities and urgent decarbonization needs. This study highlights the critical importance of digital model adoption within the maritime industry particularly in the port sector while integrating sustainability principles. Despite a growing body of research on digital models industrial simulation and green transition a specific gap persists regarding the intersection of port management hydrogen energy integration and Digital Twin (DT) applications. Specifically a bibliometric analysis provides an overview of the current research landscape through a study of the most used keywords while the document analysis highlights three primary areas of advancement: optimization of hydrogen storage and integrated energy systems hydrogen use in propulsion and auxiliary engines and DT for management and validation in maritime operations. The main outcome of this research work is that while significant individual advancements have been made across critical domains such as optimizing hydrogen systems enhancing engine performance and developing robust DT applications for smart ports a major challenge persists due to the limited simultaneous and integrated exploration of them. This gap notably limits the realization of their full combined benefits for green ports. By mapping current research and proposing interdisciplinary directions this work contributes to the scientific debate on future port development underscoring the need for integrated approaches that simultaneously address technological environmental and operational dimensions.
Nodal Marginal Price Decomposition Mechanism for the Hydrogen Energy Market Considering Hydrogen Transportation Characteristics
Oct 2025
Publication
With the growing significance of hydrogen in the global energy transition research on its pricing mechanisms has become increasingly crucial. Focusing on hydrogen markets predominantly supplied by electrolytic production this study proposes a nodal marginal hydrogen price decomposition algorithm that explicitly incorporates the time-delay dynamics inherent in hydrogen transmission. A four-dimensional price formation framework is established comprising the energy component network loss component congestion component and time-delay component. To address the nonconvex optimization challenges arising in the market-clearing model an improved second-order cone programming method is introduced. This method effectively reduces computational complexity through the reconstruction of time-coupled constraints and reformulation of the Weymouth equation. On this basis the analytical expression of the nodal marginal hydrogen price is rigorously derived elucidating how transmission dynamics influence each price component. Empirical studies using a modified Belgian 20-node system demonstrate that the proposed pricing mechanism dynamically adapts to load variations with hydrogen prices exhibiting a strong correlation with electricity cost fluctuations. The results validate the efficacy and superiority of the proposed approach in hydrogen energy market applications. This study provides a theoretical foundation for designing efficient and transparent pricing mechanisms in emerging hydrogen markets.
Optimization of Novel Variable-Channel-Width Solid Oxide Electrolysis Cell (SOEC) Design for Enhanced Hydrogen Production
Oct 2025
Publication
This study presents a novel solid oxide electrolysis cell (SOEC) design with variable channel widths to optimize thermal management and electrochemical performance for enhanced hydrogen production. Using high-fidelity computational modeling in COMSOL Multiphysics 6.1 five distinct channel width configurations were analyzed with a baseline model validated against experimental data. The simulations showed that modifying the channel geometry particularly in Scenario 2 significantly improved hydrogen production rates by 6.8% to 29% compared to a uniform channel design with the effect becoming more pronounced at higher voltages. The performance enhancement was found to be primarily due to improved fluid velocity regulation which increased reactant residence time and enhanced mass transport rather than a significant thermal effect as temperature distribution remained largely uniform across the cell. Additionally the inclusion of a dedicated heat transfer channel was shown to improve current density and overall efficiency particularly at lower voltages. While a small increase in voltage raised internal cell pressure the variable-width designs especially those with widening channels led to greater hydrogen output albeit with a corresponding increase in system energy consumption due to higher pressure. Overall the findings demonstrate that strategically designed variable-width channels offer a promising approach to optimizing SOEC performance for industrial-scale hydrogen production.
Effects of Operating Parameters on Combustion Characteristics of Hydrogen-Doped Natural Gas
Oct 2025
Publication
The operational optimization of industrial boilers utilizing hydrogen-enriched natural gas is constrained by two critical gaps: insufficient understanding of the coupled effects of hydrogen blending ratio equivalence ratio and boiler load on combustion performance— compounded by unresolved challenges of combustion instability flashback and elevated NOx emissions—and a lack of systematic investigations combining these parameters in industrial-scale systems (prior studies often focus on single variables like hydrogen fraction). To address this a comprehensive computational fluid dynamics (CFD) analysis was conducted on a 2.1 MW industrial boiler employing the Steady Laminar Flamelet Model (SLFM) with a modified k-ε turbulence model and the GRI-Mech 3.0 mechanism. Simulations covered hydrogen fractions (f(H2) = 0–25%) equivalence ratios (Φ = 0.8–1.2) and load conditions (15–100%). All NOx emissions reported herein are normalized to 3.5% O2 (mg/Nm3 ) for regulatory comparison. Results show that increasing the hydrogen content raises the flame temperature and NOx emissions while reducing CO and unburned hydrocarbons; a higher equivalence ratio elevates temperature and NOx with Φ = 0.8 balancing efficiency and emission control; and reducing load significantly lowers furnace temperature and NO emissions. Notably the boiler’s unique staged-combustion configuration (81% fuel supply to the central rich-combustion nozzle 19% to the concentric lean-combustion nozzle) was found to mitigate NOx formation by 15–20% compared to single-inlet burner designs and its integrated cyclone blades (generating maximum swirling velocity of 14.2 m/s at full load) enhanced fuel–air mixing which became particularly critical for maintaining combustion stability at low loads (≤20%) and high hydrogen blending ratios (≥20%). This study provides quantitative trade-off insights between combustion efficiency and pollutant formation offering actionable guidance for the safe efficient operation of hydrogen-enriched natural gas in industrial boilers.
Simulation of the Hydrogen Railway Engine Performance Under Different Load Conditions and Control Parameters
Oct 2025
Publication
The article examines the use of hydrogen fuel as an alternative to traditional diesel fuel for internal combustion engines (ICE) in railway applications. The main objective of the study is to analyze the operational consumption of hydrogen fuel based on the mathematical modeling of the working cycle of the EMD 12-645E3C engine installed on CIE 071 locomotives used in freight and passenger service. The article provides information on the design features of the EMD 12-645E3C engine its technical parameters and the results of bench tests. The indicator parameters of the engine at various controller positions are determined and analyzed and the results of mathematical modeling of its operation on hydrogen fuel are presented. Particular attention is paid to changes in indicator parameters including the maximum combustion pressure and the peak gas temperature in the cylinder as well as comparing the mass consumption of diesel and hydrogen fuel. The study results demonstrate that the use of hydrogen allows the engine to maintain effective power across all operational modes while simultaneously reducing energy costs up to 8%. In this case the pressure and temperature of the gases in the cylinder increased by 3–6% and 5–8%. Recommendations are also provided regarding technical challenges associated with transitioning to hydrogen fuel including the modernization of the combustion chamber fuel system and safety system.
Assessment of the Use of a Passive Pre-Chamber in a Marine Engine Fueled with Ammonia–Hydrogen Mixtures
Oct 2025
Publication
This study investigates the combustion process in a marine spark-ignition engine fueled with an ammonia–hydrogen blend (15% hydrogen by volume) using a passive pre-chamber. A 3D-CFD model supported by a 1D engine model was employed to analyze equivalence ratios between 0.7 and 0.9 and pre-chamber nozzle diameters from 7 to 3 mm. Results indicate that combustion is consistently initiated by turbulent jets but at an equivalence ratio of 0.7 the charge combustion is incomplete. For lean mixtures reducing nozzle size improves flame propagation although not sufficiently to ensure stable operation. At an equivalence ratio of 0.8 reducing the nozzle diameter from 7 to 5 mm advances CA50 by about 6 CAD while further reduction causes minor variations. At richer conditions nozzle diameter plays a negligible role. Optimal performance was achieved with a 7 mm nozzle at equivalence ratio 0.8 delivering about 43% efficiency and 1.17 MW per cylinder.
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