Publications

To address the economic and reliability challenges of high-penetration renewable energy integration in electricity-heat-hydrogen integrated energy systems and support the dualcarbon strategy this paper proposes an optimal dispatch method integrating Information Gap Decision Theory (IGDT) and Fuzzy Chance-Constrained Programming (FCCP). An IES model coupling multiple energy components was constructed to exploit multi-energy complementarity. A stepped carbon trading mechanism was introduced to quantify emission costs. For interval uncertainties in renewable generation IGDT-based robust and opportunistic dispatch models were established; for fuzzy load uncertainties FCCP transformed them into deterministic equivalents forming a dual-layer “IGDT-FCCP” uncertainty handling framework. Simulation using CPLEX demonstrated that the proposed model dynamically adjusts uncertainty tolerance and confidence levels effectively balancing economy robustness and low-carbon performance under complex uncertainties: reducing total costs by 12.7% cutting carbon emissions by 28.1% and lowering renewable curtailment to 1.8%. This study provides an advanced decision-making paradigm for low-carbon resilient IES.

Aqueous phase reforming has been posed as a promising technology for renewable hydrogen production in the framework of the transition to a sustainable energy economy. Since the use of chemical compounds as process feedstock has proven to be one of the major constraints to its potential scalability several cost-free residual biomasses have been investigated as alternative substrates. This also allows for the recovery of residues offsetting the significant costs of waste management through conventional treatment. In recent years different wastes from the food processing industry such as brewery fish canning dairy industries fruit juice extraction and corn production wastewaters have taken the attention of scientific community due to their composition favorable to this process and its high-water content. However few and heterogeneous results can be found within the literature suggesting that the research into this application is now at a stage of development which will require further investigation. Therefore this work is focused on compiling and discussing the reported studies aiming to present a critical reflection on the potential of aqueous phase reforming as a means for the valorization of this kind of residue.

Reliable operation of proton exchange membrane fuel cells (PEMFCs) is crucial for their widespread commercialization and accurate fault diagnosis is the key to ensuring their long-term stable operation. However traditional fault diagnosis methods not only lack sufficient interpretability making it difficult for users to trust their diagnostic decisions but also one-dimensional (1D) feature extraction methods highly rely on manual experience to design and extract features which are easily affected by noise. This paper proposes a new interpretable fault diagnosis algorithm that integrates Gramian angular field (GAF) transform convolutional neural network (CNN) and gradient-weighted class activation mapping (Grad-CAM) for enhanced fault diagnosis and analysis of proton exchange membrane fuel cells. The algorithm is systematically validated using experimental data to classify three critical health states: normal operation membrane drying and hydrogen leakage. The method first converts the 1D sensor signal into a two-dimensional GAF image to capture the temporal dependency and converts the diagnostic problem into an image recognition task. Then the customized CNN architecture extracts hierarchical spatiotemporal features for fault classification while Grad-CAM provides visual explanations by highlighting the most influential regions in the input signal. The results show that the diagnostic accuracy of the proposed model reaches 99.8% which is 4.18% 9.43% and 2.46% higher than other baseline models (SVM LSTM and CNN) respectively. Furthermore the explainability analysis using Grad-CAM effectively mitigates the “black box” problem by generating visual heatmaps that pinpoint the key feature regions the model relies on to distinguish different health states. This validates the model’s decision-making rationality and significantly enhances the transparency and trustworthiness of the diagnostic process.

High-temperature proton exchange membrane fuel cells (HT-PEM FCs) represent a promising avenue for generating carbon dioxide-free electricity through the utilization of hydrogen fuel. These systems present numerous advantages and challenges for mobile applications positioning them as pivotal technologies for the realization of emission-free regional aircraft. Efficient thermal management of such fuel cell-powered systems is crucial for ensuring the safe and durable operation of the aircraft while concurrently optimizing system volume mass and minimizing parasitic energy consumption. This paper presents four distinct heat transfer principles tailored for the FC-system of a conceptual hydrogen-electric regional aircraft exemplified by DLR’s H2ELECTRA. The outlined approaches encompass conductive cooling air cooling liquid cooling phase change cooling and also included is the utilization of liquid hydrogen as a heat sink. Approaches are introduced with schematic cooling architectures followed by a comprehensive evaluation of their feasibility within the proposed drivetrain. Essential criteria pertinent to airborne applications are evaluated to ascertain the efficacy of each thermal management strategy. The following criteria are selected for evaluation: safety ease of integration reliability and life-cycle costs technology readiness and development as well as performance which is comprised of heat transfer weight volume and parasitic power consumption. Of the presented cooling methods two emerged to be functionally suitable for the application in MW-scale aircraft applications at their current state of the art: liquid cooling utilizing water under high pressure or other thermal carrier liquids and phase-change cooling. Air cooling and conductive cooling have a high potential due to their reduced system complexity and mass but additional studies investigating effects at architecture level in large-scale fuel cell stacks are needed to increase performance levels. These potentially suitable heat transfer technologies warrant further investigation to assess their potential for complexity and weight reduction in the aircraft drivetrain.

Ammonia due to its favorable physicochemical properties is considered an effective hydrogen carrier enabling the storage of surplus energy generated from renewable sources. Large-scale implementation of this concept requires the safe transport of ammonia over long distances commonly achieved through pipeline systems—a practice with global experience dating back to the 1960s. However operational history demonstrates that failures in such infrastructures remain inevitable often leading to severe environmental consequences. This article reviews both passive and active methods for preventing and mitigating incidents in ammonia pipeline systems. Passive measures include the assessment of material compatibility with ammonia and the designation of adequate buffer zones. Active methods focus on leak detection techniques such as balance-based systems acoustic monitoring and ammonia-specific sensors. Additionally the article highlights the potential environmental risks associated with ammonia release emphasizing its contribution to the greenhouse effect as well as its adverse impacts on soil surface and groundwater and human health. By integrating historical lessons with modern safety technologies the article contributes to the development of reliable ammonia transport infrastructure for the hydrogen economy.

The hybrid energy storage system (HESS) that combines battery with hydrogen storage exploits complementary power/energy characteristics but most studies optimize capacity and operation separately leading to suboptimal overall performance. To address this issue this paper proposes a bi-level co-optimization framework that integrates deep reinforcement learning (DRL) and mixed integer programming (MIP). The outer layer employs the TD3 algorithm for capacity configuration while the inner layer uses the Gurobi solver for optimal operation under constraints. On a standalone PV–wind–load-HESS system the method attains near-optimal quality at dramatically lower runtime. Relative to GA + Gurobi and PSO + Gurobi the cost is lower by 4.67% and 1.31% while requiring only 0.52% and 0.58% of their runtime; compared with a direct Gurobi solve the cost remains comparable while runtime decreases to 0.07%. Sensitivity analysis further validates the model’s robustness under various cost parameters and renewable energy penetration levels. These results indicate that the proposed DRL–MIP cooperation achieves near-optimal solutions with orders of magnitude speedups. This study provides a new DRL–MIP paradigm for efficiently solving strongly coupled bi-level optimization problems in energy systems.

The urgent global transition toward low-carbon energy systems has highlighted the need for systematic planning of hydrogen refueling stations (HRS) to facilitate clean energy adoption. This study develops an integrated framework for regional HRS layout optimization and carbon emission assessment considering population distribution land area and hydrogen demand. Using Hainan Province as a case study the model estimates regional hydrogen demand determines optimal HRS deployment evaluates spatial coverage and refueling distances and quantifies potential carbon emission reductions under various renewable energy scenarios. Model validation with Haikou demonstrates its reliability and applicability at the regional scale. Results indicate pronounced spatial disparities in hydrogen demand and infrastructure requirements emphasizing that prioritizing station deployment in densely populated urban areas can enhance accessibility and maximize emission reduction. The framework offers a practical data-efficient tool for policymakers and planners to guide early-stage hydrogen infrastructure development and supports strategies for regional decarbonization and sustainable energy transitions.

Titanium dioxide (TiO2) is widely used in solar cells and photocatalysts given its excellent photoactivity low cost and high structural electronic and optical stability. Here a novel TiO2 composite was prepared by coating TiO2 inverse opal (IO) with TiO2 nanorods (NRs). With a porous three-dimensional network structure the composite exhibited higher light absorption; enhanced the separation of the electron–hole pairs; deepened the infiltration of the electrolyte; better transported and collected charge carriers; and greatly improved the power conversion efficiency (PCE) of the quantum-dot sensitized solar cells (QDSSCs) based on it while also boosting its own photocatalytic hydrogen generation efficiency. A very high PCE of 12.24% was achieved by QDSSCs utilizing CdS/CdSe sensitizer. Furthermore the TiO2 composite exhibited high photocatalytic activity with a H2 release rate of 1080.2 µ mol h−1 g −1 several times that of bare TiO2 IO or TiO2 NRs.

Hydrogen is widely regarded as a promising carbon-free alternative fuel. However the development of low-emission marine gas turbine combustion systems has been hindered by the associated risks of combustion instability also termed as thermoacoustic oscillations. Although there is sufficient literature on hydrogen fuel and combustion instability systematic reviews addressing the manifestations and mechanisms of these instabilities remain limited. The present study aims to provide a comprehensive review of combustion instabilities in hydrogen-enriched marine gas turbines with a particular focus on elucidating the characteristics and underlying mechanisms. The review begins with a concise overview of recent progress in understanding the fundamental combustion properties of hydrogen and then details various instability phenomena in hydrogen-enriched methane flames. The mechanisms by which hydrogen enrichment affects combustion instabilities are extensively discussed particularly in relation to the feedback loop in thermoacoustic combustion systems. The paper concludes with a summary of the key combustion instability challenges associated with hydrogen addition to methane flames and offers prospects for future research. In summary the review highlights the interaction between hydrogenenriched methane flames and thermoacoustic phenomena providing a foundation for the development of stable low-emission combustion systems in industrial marine applications incorporating hydrogen enrichment.

While community energy initiatives and pilot projects have demonstrated technical feasibility and economic benefits their site-specific nature limits transferability to systematic scalable investment models. This study addresses this gap by proposing a modular framework for Renewable Energy Valleys (REVs) developed from real-world Community Energy Lab (CEL) demonstrations in Crete Greece which is an island with pronounced seasonal demand fluctuation strong renewable potential and ongoing hydrogen valley initiatives. Four modular business schemes are defined each representing different sectoral contexts by combining a baseline of 50 residential units with one representative large consumer (hotel rural households with thermal loads municipal swimming pool or hydrogen bus). For each scheme a mixed-integer linear programming model is applied to optimally size and operate integrated solar PV wind battery (BAT) energy storage and hydrogen systems across three renewable energy penetration (REP) targets: 90% 95% and 99.9%. The framework incorporates stochastic demand modeling sector coupling and hierarchical dispatch schemes. Results highlight optimal technology configurations that minimize dependency on external sources and curtailment while enhancing reliability and sustainability under Mediterranean conditions. Results demonstrate significant variation in optimal configurations across sectors and targets with PV capacity ranging from 217 kW to 2840 kW battery storage from 624 kWh to 2822 kWh and hydrogen systems scaling from 65.2 kg to 192 kg storage capacity. The modular design of the framework enables replication beyond the specific context of Crete supporting the scalable development of Renewable Energy Valleys that can adapt to diverse sectoral mixes and regional conditions.

Algeria’s transition toward sustainable energy requires the exploitation of its abundant solar and wind resources for green hydrogen production. This study assesses the technoeconomic feasibility of an off-grid PV/wind hybrid system integrated with a hydrogen subsystem (electrolyzer fuel cell and hydrogen storage) to supply both electricity and hydrogen to decentralized sites in Algeria. Using HOMER Pro five representative Algerian regions were analyzed accounting for variations in solar irradiation wind speed and groundwater availability. A deferrable water-extraction and treatment load was incorporated to model the water requirements of the electrolyzer. In addition a comprehensive sensitivity analysis was conducted on solar irradiation wind speed and the capital costs of PV panels and wind turbines to capture the effects of renewable resource and investment cost fluctuations. The results indicate significant regional variation with the levelized cost of energy (LCOE) ranging from 0.514 to 0.868 $/kWh the levelized cost of hydrogen (LCOH) between 8.31 and 12.4 $/kg and the net present cost (NPC) between 10.28 M$ and 17.7 M$ demonstrating that all cost metrics are highly sensitive to these variations.

The article presents a comparison between the pressure conditions of a real low-pressure gas network and the results of hydraulic calculations obtained using various simulation programs and empirical equations. The calculations were performed using specialized gas network analysis software: STANET (ver 10.0.26) SimNet SSGas 7 and SONET. Additionally the simulation results were compared with calculations based on the empirical Darcy–Weisbach and Renouard equations. In the first part of the analysis two calculation models were compared. In one model the geodetic elevation of individual network nodes was included (elevation-aware model) while in the second calculations were performed without considering node elevation (flat model). For low-pressure gas networks accounting for elevation is critical due to the presence of the pressure recovery phenomenon which does not occur in medium- and high-pressure networks. Furthermore considering the growing need to increase the share of renewable energy the study also examined the network’s operating conditions when using natural gas–hydrogen mixtures. The following hydrogen concentrations were considered: 2.5% 5.0% 10.0% 20.0% and 50.0%. The results confirm the importance of incorporating elevation data in the modeling of low-pressure gas networks. This is supported by the small differences between calculated results and actual pressure measurements taken from the operating network. Moreover increasing the hydrogen content in the mixture intensifies the pressure recovery effect. The hydraulic results obtained using different computational tools were consistent and showed only minor discrepancies.

The cooling effect from the para-ortho hydrogen conversion (POC) combined with a vaporcooled shield (VCS) and multi-layer insulation (MLI) can effectively extend the storage duration of liquid hydrogen in cryogenic tanks. However there is currently no effective and straightforward empirical correlation available for predicting the catalytic POC efficiency in VCS pipelines. This study focuses on the development of correlations for the catalytic conversion of para-hydrogen to ortho-hydrogen in pipelines particularly in the context of cryogenic hydrogen storage systems. A model that incorporates the Langmuir adsorption characteristics of catalysts and introduces the concept of conversion efficiency to quantify the catalytic process’s performance is introduced. Experimental data were obtained in the temperature range of 141.9~229.9 K from a cryogenic hydrogen catalytic conversion facility where the effects of temperature pressure and flow rate on the catalytic conversion efficiency were analyzed. Based on a validation against the experimental data the proposed model offers a reliable method for predicting the cooling effects and optimizing the catalytic conversion process in VCS pipelines which may contribute to the improvement of liquid hydrogen storage systems enhancing both the efficiency and duration of storage.

During the critical period of energy transition the collaborative optimization of the electricity-hydrogentransportation coupling system is of vital importance for achieving efficient energy utilization and sustainable development.This paper proposes a collaborative operation mechanism of Distributed Robust Optimization (DRO) considering carbon emissions. Firstly a Stackelberg game dynamic pricing strategy is constructed for the integrated energy station (IES) and the electricity-hydrogen hybrid charging station (HRS) where the upper-level IES optimizes the electricity price setting strategy and the lower-level HRS dynamically adjusts the electricity purchase-hydrogen production plan. Secondly the Wasserstein distance is used to describe the uncertainties of hydrogen vehicle loads and wind-solar power generation and a bisection algorithm-column constraint generation (BA-C&CG) hybrid algorithm is designed to solve the model. Finally the numerical example verification shows that the daily operation cost of HRS under the proposed mechanism is as low as 1108.53 EUR which is 10.58 % and 7.38 % lower than that of the commonly used stochastic optimization (SO) and robust optimization (RO) respectively. The variance analysis (F = 536.05P < 0.001) confirms that the cost advantage is statistically significant. In terms of carbon emission reduction effect the DRO-Stackelberg game model has the lowest daily carbon cost (6.98EUR). This mechanism effectively balances the economic and robustness of the system and the single dispatch calculation time is only 112.09 s meeting the real-time operation requirements of engineering. It provides technical support for the low-carbon collaborative operation of the electricity-hydrogen-transportation coupling system.

A new protocol is presented to directly characterise the toughness of microstructural regions present within the weld heat-affected zone (HAZ) the most vulnerable location governing the structural integrity of hydrogen transport pipelines. Heat treatments are tailored to obtain bulk specimens that replicate predominantly ferriticbainitic bainitic and martensitic microstructures present in the HAZ. These are applied to a range of pipeline steels to investigate the role of manufacturing era (vintage versus modern) chemical composition and grade. The heat treatments successfully reproduce the hardness levels and microstructures observed in the HAZ of existing natural gas pipelines. Subsequently fracture experiments are conducted in air and pure H2 at 100 bar revealing a reduced fracture resistance and higher hydrogen embrittlement susceptibility of the HAZ microstructures with initiation toughness values as low as 32 MPa√ m. The findings emphasise the need to adequately consider the influence of microstructure and hard brittle zones within the HAZ.

This article describes hydrogen production via water splitting because of high green energy demand globally. The amounts of hydrogen produced with zirconium in thermal processes at 473 K and radiation-thermal processes at 473 K and 773K were 1.55 x 1018 2.2 x 1018 and 4.1 x 1018 molecules/g. These amounts on aluminum and stainless steel were 1.05 x 1018 1.95 x 1018 and 3.0 x 1018 molecules/g; and 0.30 x 1018 1.27 x 1018 and 2.6 x 1018 molecules/g. A comparison was carried out and the order of hydrogen production was zirconium > aluminum > stainless steel. The activation energy in radiation-thermal and thermal processes were 14.2 and 65.0 kJ/mol (Zr) 12.05 and 63.1 kJ/mol (Al) and 11.16 and 61.52 kJ/mol (SS). The mechanisms of water splitting were developed and described for future use. The described methods are scalable and can be transferred to a pilot scale.

High-temperature (HT) proton exchange membrane (PEM) fuel cells (FC) offer key advantages for sustainable transportation especially in heavy-duty applications due to their improved thermal efficiency and water management. This study introduces an inverse design framework to develop flow field plates integrated with a gas diffusion layer (GDL) enabling scalable electrochemical performance from the unit cell to the plate level. A reduced-order homogenization-based multiphysics model is developed to evaluate designs with approximately 1000× faster computation. Flow channel orientation is optimized using a tensor field method and dehomogenized into manufacturable geometries. Optimized designs validated through high-fidelity 3D simulations show up to 12% higher average current density and 88% lower pressure drop compared to conventional parallel and mesh configurations. To address fabrication challenges solid-to-porous metal additive manufacturing is employed producing monolithic structures that integrate flow channels with a porous metal GDL. Both numerical and physical tests confirm high permeability and improved power output compared to carbon-based GDLs. These findings highlight the effectiveness of combining advanced computational modeling with metal 3D printing to enhance the performance and manufacturability of high-temperature PEMFC supporting their broader adoption in sustainable energy applications.

The transition to carbon-neutral energy has renewed interest in hydrogen as a gas turbine fuel in the form of fuel blends with hydrocarbons. However the distinct fluid properties and chemical kinetics of hydrogen and hydrocarbon blends necessitate redeveloped combustor designs. While conventional combustor design and emissions estimation through computational fluid dynamics (CFD) is preferred it is computationally intensive and impractical for system-level simulations. To alleviate this a thermofluid network model was developed to predict the performance of a MGT combustor operating on pure and fuel blends of propane and hydrogen. It incorporates sub-component pressure losses and heat transfer and presents the first implementation of well-stirred and plug-flow reactors into Flownex SE. A 3-D CFD study of the combustor revealed that hydrogen addition improved combustion efficiency and reduced wall temperatures. However although it produces less CO2 it leads to 70 % more CO and 80 % more NO than for propane-only operation. Validated against the 3-D CFD data the network model predicted the combustor outlet total temperature and pressure within 0.55 % and 0.26 % respectively. The change in total pressure across subcomponents (<6 %) and the mass flow distribution showed similarly strong agreement. Major species mass fractions CO₂ and H₂O were predicted accurately. However by assuming that the temperature and composition are uniform within combustion zones zone and wall temperatures and pollutant predictions deviated considerably. NO was overpredicted by a factor of 8.2–10.7 and CO was overpredicted for propane-only but underpredicted for blended cases. The network model achieved this performance 420 times faster than CFD making it suitable for rapid design exploration.

Ammonia is a cornerstone of modern agriculture supplying the nitrogen essential for crops that nourish nearly half the global population. Yet its production is responsible for ~2 % of global greenhouse gas emissions. To meet climate and food security goals sustainable low-carbon and resilient ammonia production systems are needed. Here we develop a spatially explicit techno-economic model to compare centralized and decentralized ammonia production pathways across the U.S. a major global ammonia producer and consumer spanning the full supply chain from hydrogen production to fertilizer delivery. We integrate high-resolution supply and demand data and apply linear optimization to estimate delivered ammonia costs accounting for geographic mismatches and transportation. Our results show that decentralized ammonia production whether powered by grid electricity or solar energy is substantially more expensive than centralized production from natural gas or coal. Centralized natural gas-based ammonia has a median production cost of 326 USD/tonne NH3 compared to 499 USD/tonne for coal. Decentralized grid-powered systems range from 659 to 1634 USD/tonne and solar-powered systems from 1077 to 2266 USD/tonne. Transportation costs for centralized production range from 7 to 85 USD/tonne with a median of 40 USD/tonne resulting in a delivered cost of 343 USD/tonne. Median delivered costs for decentralized grid- and solar-powered systems are 1069 and 1494 USD/tonne respectively. Decentralized systems require electricity prices below 19 USD/MWh (grid) and 17 USD/MWh (solar) to achieve cost parity well below 2024 U S. averages of 117 USD/MWh. These results highlight the economic challenges facing decentralized ammonia production and the importance of electricity cost reductions tax credits carbon pricing or further technological breakthroughs for broader viability.

Solid oxide fuel cell (SOFC) systems offer high-efficiency conversion of the chemical energy of fuel gases into electrical energy. To meet market and policy targets such systems must be able of operating on an industrial scale and be compatible with environmentally friendly fuels. This study models the scale-up of a 750 W naturalgas-fueled SOFC to a 240 kW system with various gas-path configurations evaluating the impact of blending up to 30 vol% of hydrogen (H2) into the methane feed. Aspen Plus simulations coupled with pressure-loss and carbon-deposition models were used to optimize recirculation ratio and reactant utilization for maximum efficiency. The parallel configuration achieved the highest electrical efficiency of 64.0 % while series-connected and intermediate systems suffered from increased pressure losses. H2 admixture simulations confirm that operation is feasible without loss of efficiency in the small- and large-scale systems due to reduced carbondeposition potential. A techno-economic analysis indicates a 91.7 % cost reduction through scale-up and a 1.6 % cost increase for adjusting the system to H2 admixtures. The economic viability of the large-scale system was evaluated for all tested fuel compositions (0.201–0.204 €/kWh) with payback times under 20 years at market-relevant electricity prices. These results demonstrate the technical and economic feasibility of large-scale H2-adapted SOFC systems for industrial decarbonization.

In this work a plasma fluidized bed reactor has been studied as an electrified methane decomposition reactor for sustainable hydrogen production. A combined 3D rotating gliding arc/fluidized bed reactor assembly demonstrates a stable operation with a CH4/Ar mixture containing up to 8 vol% of CH4. The reactor provides a 97.2 % H2 selectivity at a methane conversion of 16.6 % and energy costs of 10.6 kJ L− 1 . This performance provides a new benchmark for electrified H2 production with a potential to utilise renewable electricity. In addition carbon materials are produced. The characterizations show difference in the morphology of the materials collected in different reactor zones.

Hydrogen’s increasing potential as an alternative fuel for heavy-duty transport has led to the conversion of conventional diesel compression-ignition engines to spark-ignition hydrogen operation. Hydrogen’s broad flammability range enables leaner operation achieving both higher engine efficiency and near-zero emissions. In particular direct injection hydrogen combustion improves volumetric efficiency and reduces problems including pre-ignition and knock related to hydrogen port-fuel injection. In the present work we performed an optical investigation of direct injection (DI) hydrogen combustion under leaner mixture conditions. The study was conducted using a heavy-duty optical diesel engine modified for spark-ignition operation. Bottom-view natural flame luminosity and OH-PLIF imaging were conducted along with in-cylinder pressure measurements. Experiments were conducted at three air-excess ratios (3 3.4 and 3.8) with spark timings (ST) varied from − 15 ◦CA aTDC to − 30 ◦CA aTDC. Hydrogen injection ended at − 30 ◦CA aTDC with the start of injection adjusted accordingly to achieve the desired lambda conditions. The maximum IMEPg corresponded to the lowest COV of the IMEPg indicating optimal spark timing for lean DI hydrogen combustion. The optimized spark timing for λ = 3 λ = 3.4 and λ = 3.8 were occurred at − 25 ◦CA aTDC − 25 ◦CA aTDC and − 30 ◦CA aTDC respectively. The corresponding COV of IMEPg values were below 5 % indicating stable combustion. The flame kernel first initiates at the spark plug and then propagates toward the piston’s outer boundary however the flame propagation does not remain as a continuous front unlike port-fuel injected hydrogen combustion. The effect of fuel stratification is evident in combustion luminosity and OH-PLIF images showing pockets of varying intensity within the combustion chamber. Natural flame luminosity images reveal incomplete flame coverage and asymmetric combustion emphasizing the need for metal engine experiments to further quantify the unburned hydrogen and associated combustion losses.

The application of OH* chemiluminescence diagnostics is becoming increasingly prevalent in the combustion characterization of hydrogen. As the current literature is lacking a systematic study of OH* chemiluminescence in non-premixed turbulent natural gas (NG) and hydrogen (H2 ) flames the present work was designed to address this research gap. Therefore extensive experiments were performed on a semi-industrial burner operating at 50–100 kW in NG/H2–Air/O2 combustion modes which were complemented by comprehensive numerical simulations including 1D laminar counterflow diffusion flamelet calculations and full 3D CFD simulations of the semi-industrial furnace setup. In this way an OH* chemistry model is presented that accurately predicts the global reaction zone characteristics and their difference between CH4 and H2 in air-fired and oxygen-fired flames. The comprehensive numerical approach in conjunction with the subsequent study of different operating conditions yielded novel insights into both combustion modeling and the underlying thermochemical phenomena providing an essential contribution to the transition of the thermal energy sector towards hydrogen as an alternative carbon-free fuel.

This study presents a comparative life cycle and economic assessment of using clean hydrogen as a sustainable alternative to natural gas and propane for corn grain drying. The study compares the environmental performance limited to GWP100 and cost-effectiveness of hydrogen from various renewable sources (hydro wind solar) and plasma pyrolysis of natural gas against conventional fossil fuels under two delivery scenarios: pipeline and trucking. A life cycle assessment is conducted using Open LCA to quantify the carbon intensity of each fuel from cradle to combustion at multiple energy requirements based on four burner efficiencies across each scenario. In parallel economic analysis is conducted by calculating the fuel cost required per ton of dried corn grains at each efficiency across both scenarios. The results indicate that green hydrogen consistently outperforms current fuels in terms of emissions but it is generally more expensive at lower burner efficiencies and in trucking scenarios. However the cost competitiveness of green hydrogen improves significantly at higher efficiency and with pipeline infrastructure development it can become more economical when compared to propane. Hydrogen produced via plasma pyrolysis offers high environmental and economic costs due to its electricity and natural gas requirements. Sensitivity analysis further explores the impact of a 50% reduction in hydrogen production and transportation costs revealing that hydrogen could become a viable option for grain drying in both pipeline and trucking scenarios. This study highlights the long-term potential of hydrogen in reducing carbon emissions and offers insights into the economic feasibility of hydrogen adoption in agricultural drying processes. The findings suggest that strategic investments in hydrogen infrastructure could significantly enhance the sustainability of agricultural practices paving the way for a greener future in food production.

Separation of H2 from CO2 is crucial in industry since they are the products of water gas shift reaction. In addition the demand for pure H2 as well as the potential reuse of CO2 as reactant are increasing as a consequence of the transition from fossil fuels to decarbonization processes. In this scenario this work aims to propose a possible solution to get simultaneously pure H2 and CO2 meeting the world’s requirements in terms of reduction of CO2 emissions and transition to cleaner energy. A simulated plant combining Pd-based and SAPO-34 membrane modules is able to provide pure H2 with a final recovery higher than 97%. In addition the entire CO2 fed to SAPO-34 unit is recovered in the permeate stream with a concentration of 97.7%. A cost analysis shows that feed gas gives a higher contribution than compression heat exchange and membranes (e.g. 70 20 3 and 7% respectively). Net profit and net present value are positive within a specific feed gas price range (e.g. net profit up to 0.10 and 0.155 $/Nm3 depending on the labour cost set) showing that the process can be cost-effective and profitable. H2 purification cost ranges between 2.6 and 7.8 $/kg.

This article discusses the potential of using the double-Wiebe function to model combustion in a compression-ignition engine fueled by diesel fuel or its substitutes such as hydrotreated vegetable oil (HVO) and rapeseed methyl ester (RME) and hydrogen injected into the engine intake manifold. The hydrogen amount ranged from 0 to 35% of the total energy content of the fuels burned. It was found that co-combustion of liquid fuel with hydrogen is characterized by two distinct combustion phases: premixed and diffusion combustion. The premixed phase occurring just after ignition is characterized by a rapid combustion rate which increases with an increase in hydrogen injected. The novelty in this work is the modified formula for a double-Wiebe function and the proposed parameters of this function depending on the amount of hydrogen added for co-combustion with liquid fuel. To model this combustion process the modified double-Wiebe function was proposed which can model two phases with different combustion rates. For this purpose a normalized HRR was calculated and based on this curve coefficients for the double-Wiebe function were proposed. Satisfactory consistency with the experiment was achieved at a level determined by the coefficient of determination (R-squared) of above 0.98. It was concluded that the presented double-Wiebe function can be used to model combustion in 0-D and 1-D models for fuels: RME and HVO with hydrogen addition.

Contemporary research into decarbonized fuels such as H2/NH3 has highlighted complex challenges with applied combustion with marked changes in thermochemical properties leading to significant issues such as limited operational range flashback and instability particularly when attempts are made to optimize emissions production in conventional lean-premixed systems. Non-premixed configurations may address some of these issues but often lead to elevated NOx production particularly when ammonia is retained in the fuel mixture. Optimized fuel injection and blending strategies are essential to mitigate these challenges. This study investigates the application of a 75 %/25 %mol H2/NH3 blend in a swirl-stabilized combustor operated at elevated conditions of inlet temperature (500 K) and ambient pressure (0.11–0.6 MPa). A complex nonmonotonic relationship between swirl number and increasing ambient combustor pressure is demonstrated highlighting the intricate interplay between swirling flow structures and reaction kinetics which remains poorly understood. At medium swirl (SN = 0.8) an increase in pressure initially reduces NO emissions diminishing past ~0.3 MPa with an opposing trend evident for high swirl (SN = 2.0) as NO emissions fall rapidly when combustor pressure approaches 0.6 MPa. High-fidelity numerical modeling is presented to elucidate these interactions in detail. Numerical data generated using Detached Eddy Simulations (DES) were validated against experimental results to demonstrate a change in flame anchoring on the axial shear layer and marked change in recirculated flow structure successfully capturing the features of higher swirl number flows. Favorable comparisons are made with optical data and a reduction in NO emissions with increasing pressure is demonstrated to replicate changes to the swirling flame chemical kinetics. Findings provide valuable insights into the combustion behavior of hydrogen-rich ammonia flames contributing to the development of cleaner combustion technologies.

Energy transition is crucial for climate change mitigation and Sustainable Development Goals (SDGs) and has been a key government focus in Colombia since 2022 which must carefully consider its energy roadmap. This study evaluates three potential scenarios for achieving nearly 100% renewable energy by 2035: replacing fossil fuels with biofuels using hydrogen for transport and industrial heat and relying entirely on renewable electricity. This paper discusses these scenarios’ technical economic and social challenges including the need for substantial investments in renewable energy technologies and energy storage systems to replace fossil fuels. The discussion highlights the importance of balancing energy security environmental concerns and economic growth while addressing social priorities such as poverty eradication and access to healthcare and education. The results show that while the Colombian government’s energy transition goals are commendable a rapid energy transition requires 4 to 8 times the government’s projected 34 billion USD investment making it economically unfeasible. Notably focusing on wind photovoltaic and green hydrogen systems which need storage is too costly. Furthermore replacing fossil fuels in transport is impractical though increasing biofuel production could partially substitute fossil fuels. Less energy-intensive alternatives like trains and waterway transport should be considered to reduce energy demand and carbon footprint.

While renewable energy deployment has accelerated in recent years fossil fuels continue to play a dominant role in electricity generation worldwide. This necessitates the development of transitional strategies to mitigate greenhouse gas emissions from this sector while gradually reducing reliance on fossil fuels. This study investigates the potential of blending green hydrogen with natural gas as a transitional solution to decarbonize Jordan’s electricity sector. The research presents a comprehensive techno-economic and environmental assessment evaluating the compatibility of the Arab Gas Pipeline and major power plants with hydrogen–natural gas mixtures considering blending limits energy needs environmental impacts and economic feasibility under Jordan’s 2030 energy scenario. The findings reveal that hydrogen blending between 5 and 20 percent can be technically achieved without major infrastructure modifications. The total hydrogen demand is estimated at 24.75 million kilograms per year with a reduction of 152.7 thousand tons of carbon dioxide per annum. This requires 296980 cubic meters of water per year equivalent to only 0.1 percent of the National Water Carrier’s capacity indicating a negligible impact on national water resources. Although technically and environmentally feasible the project remains economically constrained requiring a carbon price of $1835.8 per ton of carbon dioxide for economic neutrality.

The urgent need to mitigate climate change has elevated green hydrogen as a sustainable alternative to fossil fuels while green cryptocurrencies have emerged to address the environmental concerns of traditional cryptocurrency mining. This study investigates the dynamic correlation between the green hydrogen market and selected green cryptocurrencies (Cardano Stellar Hedera Algorand and Chia) from July 2021 to April 2024 utilizing the Dynamic Conditional Correlation GARCH (DCC-GARCH) model with robustness checks using EGARCH and GJR-GARCH specifications. Our findings reveal significant correlations with peaks reaching up to 50% in 2022 a period likely influenced by the Russia-Ukraine conflict. Subsequently a decline in these correlations was observed in 2023. These results underscore the interconnectedness of sustainability-driven markets suggesting potential contagion effects during periods of global instability. The high persistence of correlation shocks (α + β values approaching unity) indicates that correlation regimes tend to be long- lasting with important implications for portfolio diversification and risk management strategies. Robustness checks using EGARCH and GJR-GARCH specifications confirmed qualitatively similar patterns reinforcing the validity of our findings into the evolving landscape of green finance and energy

The transport of natural gas blended with hydrogen is a key strategy for the low-carbon energy transition. However the influence mechanism of its thermo-physical property variations on centrifugal compressor performance remains insufficiently understood. This study systematically investigates the effects of the hydrogen blending ratio (HBR 0–30%) inlet temperature and rotational speed on key compressor parameters (pressure ratio polytropic efficiency and outlet temperature) through numerical simulations. In order to evaluate the influence of hydrogen blending on the performance and stability of centrifugal compressors a three-dimensional model of the compressor was established and the simulation conducted was verified with the experimental data. Results indicate that under constant inlet conditions both the pressure ratio and outlet temperature decrease with increasing HBR while polytropic efficiency remains relatively stable. Hydrogen blending significantly expands the surge margin shifting both surge and choke lines downward and consequently reducing the stable operating range by 27.11% when hydrogen content increases from 0% to 30%. This research provides theoretical foundations and practical guidance for optimizing hydrogen-blended natural gas centrifugal compressor design and operational control.

In light of increased international efforts to combat climate change sustainable infrastructure is shifting toward green hydrogen produced through renewable-powered electrolysis. Still it is challenging to forecast the production of green hydrogen because environmental and system factors are variable both in time and space. We introduce a new system that utilizes a Spatio-Temporal Graph Convolutional Network (STGCN) and a novel algorithm the Ninja Optimization Algorithm (NiOA) to address this issue. Using the framework binary NiOA performs feature selection while continuous NiOA optimizes both the model architecture and the number of variables in the data simultaneously. It is clear from the research that forecasting results have shown significant improvement. The STGCN model achieved an R2 of 0.8769 and an MSE of 0.00375 whereas the STGCN with NiOA reached an R2 of 0.9815 and an MSE of only 7.48 × 10−8. Due to these improvements adaptive metaheuristics show even greater promise in delivering more accurate forecasting and reduced computational requirements for addressing critical environmental issues. The suggested strategy can be followed repeatedly providing a solid framework for the effective modeling of renewable energy systems and making green hydrogen projects more dependable.

As hydrogen gains prominence in energy systems its adoption as an energy source for fuel cell electric vehicles (FCEVs) necessitates the establishment of hydrogen refueling stations (HRS). These stations contain critical compo-nents including nozzles storage tanks heat exchangers and compressors which must be certified by regulatory agen-cies to ensure safety and public trust. Current certification processes are fragmented and manually intensive creating inefficiencies and limiting transparency across the infrastructure lifecycle. In this paper we propose a blockchain-based solution that creates a secure and auditable network for certifying key HRS components. The system integrates an EVM-compatible blockchain decentralized storage and a modular suite of smart contracts (SCs) that formalize registration bidding accreditation certification and governance. Each contract encodes a distinct actor-driven work-flow enabling traceable and role-specific operations. A Decentralized Application (DApp) interface supports real-time and role-based interaction across the ecosystem. We present and evaluate the SCs and their underlying algorithms us-ing gas usage analysis load testing and security auditing. Load testing across the certification lifecycle shows stable transaction throughput and predictable cost profiles under increasing actor activity. A static security analysis con-firms resilience against common vulnerabilities. Our cost analysis indicates that while the framework is technically deployable on public blockchains the execution costs of certain functions make it more cost-effective for private blockchains or Layer 2 networks. We also compare our framework with existing systems to highlight its novelty and technical advantages. Our SCs DApp interface and load testing scripts are publicly available on GitHub.

Given the Kenyan challenges in energy availability accessibility and affordability exploring green hydrogen as a sustainable energy solution is supreme. This study aimed to assess the potential of green hydrogen production a transformative clean energy technology and its implications for Kenya's future energy. The specific objectives were to identify the drivers of change that could accelerate green hydrogen adoption and policy recommendations. The study employed a scenario planning approach focusing on four key steps: defining the scenario and time horizon identifying drivers of change and developing and applying scenarios. The diffusion of innovation theory guided the study. Twelve key critical drivers of change were identified with societal and industry acceptance of green hydrogen and compatibility with existing energy infrastructure being the strongest drivers of change from cross-impact analysis results. The study outlined four plausible future scenarios for adoption: Successful Production (best scenario) Low Production Chaotic Transition and Rejection of Green Hydrogen Production (worst scenario). Major opportunities include advancements in hydrogen production export potential and job creation. Cost competitiveness analysis is essential comparing Kenya's hydrogen with traditional fuels and African peers. Economic models suggest that Kenya's renewable energy can lower costs enhancing its position in clean energy innovation. However critical challenges involve regulatory uncertainty ethical concerns public misconceptions about green hydrogen safety and financial barriers due to high initial investment costs. The study recommended that the Kenyan government invest in renewable energy infrastructure formulate a comprehensive national hydrogen policy and establish an enabling environment to attract private investment. In conclusion green hydrogen production stands as a strategic pillar for Kenya’s sustainable energy transition and further research should focus on strengthening regulatory frameworks and enhancing public engagement to unlock its full potential.

Hydrogen will play a critical role in decarbonizing diverse economic sectors. However given limited sustainable resources and the energy-intensive nature of its production prioritizing its applications will be essential. Here we analyse approximately 2000 (low-carbon) hydrogen projects worldwide encompassing operational and planned initiatives until 2043 quantifying their greenhouse gas (GHG) emissions and mitigation potential from a life cycle perspective. Our results demonstrate the variability in GHG emissions of hydrogen applications depending on the geographical location and hydrogen source used. The most climate-effective hydrogen applications include steel-making biofuels and ammonia while hydrogen use for road transport power generation and domestic heating should be discouraged as more favourable alternatives exist. Planned low-carbon hydrogen projects could generate 110 MtH2 yr−1 emit approximately 0.4 GtCO2e yr−1 and potentially reduce net life cycle GHG emissions by 0.2–1.1 GtCO2e yr−1 by 2043 depending on the substituted product or service. Addressing the current hydrogen implementation gap and prioritizing climate-effective applications are crucial for meeting decarbonization goals.

Hydrogen-based fuels are potential candidates to help international shipping achieve net-zero greenhouse gas (GHG) emissions by around 2050. This paper quantifies the environmental impacts of liquid hydrogen liquid ammonia and methanol used in a Post-Panamax container ship from 2020 to 2050. It considers cargo capacity changes electricity decarbonization and hydrogen production transitions under two International Energy Agency scenarios: the Stated Policies Scenario (STEPS) and the Net Zero Emissions by 2050 Scenario (NZE). Results show that compared to the existing HFO ship hydrogen-based propulsion systems can decrease cargo weight capacity by 0.3 % to 25 %. In the NZE scenario hydrogen-based fuels can reduce GHG emissions per tonne-nautical mile by 48 %–65 % compared to heavy fuel oil by 2050. Even with fully renewable hydrogenbased fuels 18 %–31 % of GHG emissions would still remain. Using hydrogen-based fuels in internal combustion engines requires attention to minimize environmental trade-offs.

Global renewable hydrogen trade is expected to play a key role in decarbonizing future energy systems. Yet hydrogen exporters may deviate from perfectly competitive behaviour to influence prices similarly to the existing fossil fuel market with important implications for consumer welfare and the pace of the energy transition. This study develops a global renewable hydrogen trade model that captures potential strategic interactions among exporters using a Stackelberg game-theoretic framework. The model is formulated as an Equilibrium Problem with Equilibrium Constraints (EPEC) and solved under three alternative equilibria: a profitmaximizing Nash equilibrium a cost-minimizing Nash equilibrium and a welfare-maximizing benchmark representing perfect competition. Results indicate that producers may strategically reduce their export quantities by up to 40 % relative to perfect competition to maximize profits. Such behaviour raises prices to a minimum of 4.5 USD/kg in 2050 across major import markets thereby significantly eroding consumer surplus. Strategic behaviour of dominant exporters also shifts trade flows reshaping the global allocation of hydrogen supply. Sensitivity analysis further reveals that financing costs play a key role in shaping strategic producers’ behaviour with lower financing costs helping to reduce prices and stimulate demand. These findings highlight the implications of imperfect competition in global hydrogen trade and suggest that policy measures may be needed to mitigate potential negative consequences.

This study investigates the cost-optimal capacity and operation of water electrolyzers in global net-zero CO2 energy systems. The production costs of hydrogen are largely determined by the electrolyzer capacity factor (i.e. full-load hours); therefore a global energy system model with an hourly temporal resolution was employed to consider the intermittency of variable renewable energy (VRE) and the dynamics of power system operations. Proton exchange membrane electrolysis is assumed in this study. The optimization results suggest three main findings. First water electrolysis is estimated to be a cost-effective option for achieving net-zero CO2 emissions. Under default technology assumptions the global installed capacity is projected to reach 2719 GW by 2050 with the majority of hydrogen consumed in the industry sector. Scaling up the supply chain is essential to realize this pathway. Second hydrogen and hydrogen-based fuels are economically competitive with negative emission technologies (NETs). A modest deployment of CO2 storage and NETs provides favorable conditions for water electrolysis deployment—and vice versa. Third flexible operation is critical to the widespread deployment of water electrolysis. In the default case the global weighted average capacity factor of electrolyzers is estimated at 37 % in 2050 to follow VRE output fluctuations. The results also indicate that limited operational flexibility may significantly hinder the cost-competitiveness of electrolyzer deployment.

In 2023 global carbon dioxide emissions reached 40 billion tonnes 60 % more than in 1990 intensifying climate concerns. This study explores hydrogen-natural gas blending as a transitional strategy for decarbonization across several regions and energy sectors – residential commercial industrial and agricultural. A multi-regional analysis framework evaluates integration of 20 % by volume low-carbon hydrogen blending into natural gas systems by identifying hydrogen producers importers and exporters based on production and import costs. Applied to Canada 528 scenarios (2026–2050) assess inter-regional hydrogen trade within Canadian provinces. The lowest-cost scenario involves Alberta exporting hydrogen produced through autothermal reforming with 91 % carbon capture and storage and British Columbia producing its own. The grid electrolysis scenario achieves the highest GHG reductions with a 4.5 % GHG mitigation in Canada with full energy system representation. These findings provide insights for policymakers and stakeholders in advancing hydrogen infrastructure and decarbonization strategies.

Fluidized bed systems play a crucial role in industrial processes such as combustion and gasification. In the Iron Power Cycle fluidized bed systems are essential for enabling the reduction of combusted iron back to iron making them a critical component in the regeneration step of the cycle. This study investigates the impact of operating gas velocity on conversion by performing reduction experiments at three distinct fluidization numbers (us/umf): 16 (bubbling regime) 55 (transition region) and 100 (fully turbulent regime). Experiments were conducted to determine the appropriate velocities for each regime ensuring optimal fluidization conditions across reduction temperatures ranging from 500 to 700 ⚬C. The results reveal that conversion rates increase significantly with gas velocities. At 500 ⚬C operating at approximately six times higher velocity leads to a sixfold improvement in conversion when using iron-oxide particles with a Sauter mean diameter of 61 µm. However while enhanced velocities improve reaction efficiency challenges remain at elevated temperatures (T ≥ 500 ⚬C) where iron undergoes defluidization when exposed to hydrogen. Once defluidization occurs refluidization proves impossible with either hydrogen or nitrogen raising concerns about process stability. These insights highlight the potential for optimizing fluidized bed reduction through velocity control while also underscoring the need for additional measures to mitigate unstable fluidization during high-temperature iron oxide reduction.

Dating back to more than one century ago the photocatalysis process has demonstrated great promise in addressing environmental problems and the energy crisis. Nevertheless some single or binary composite materials cannot meet the requirements of large-scale implementations owing to their limited photocatalytic efficiencies. Since 2021 dual S-scheme heterojunctionbased nanocomposites have been undertaken as highly efficient photoactive materials for green energy production and environmental applications in order to overcome limitations faced in traditional photocatalysts. Herein state-of-the-art protocols designed for the synthesis of dual S-scheme heterojunctions are described. How the combined three semiconductors in dual S-scheme heterojunctions can benefit from one another to achieve high energy production and efficient oxidative removal of various pollutants is deeply explained. Photocatalytic reaction mechanisms by paying special attention to the creation of Fermi levels (Ef ) and charge carriers transfer between the three semiconductors in dual S-scheme heterojunctions are discussed. An entire section has been dedicated to some examples of preparation and applications of double S-scheme heterojunction-based nanocomposites for several photocatalytic applications such as soluble pollutants photodegradation bacteria disinfection artificial photosynthesis H2 generation H2O2 production CO2 reduction and ammonia synthesis. Lastly the current challenges of dual S-scheme heterojunctions are presented and future research directions are presented. To sum up dual S-scheme heterojunction nanocomposites are promising photocatalytic materials in the pursuit of sustainable energy production and environmental remediation. In the future dual S-scheme heterojunctions are highly recommended for photoreactors engineering instead of single or binary photocatalysts to drive forward photocatalysis processes for practical green energy production and environmental protection.

Concerns about the competitiveness of European industry led to the publication of the Draghi report. One of his recommendations is to install regional green industrial clusters around energy-intensive companies. The report identifies three benefit categories each corresponding to typical industrial symbiosis cases: improved investment cases by shared local low-carbon energy generation improved investment cases by shared infrastructure and improved energy flows for increased resource efficiency. Industrial clusters hold untapped potential to advance the energy transition and climate neutrality. However it is still unknown how and if this potential will ever be reached nor how scalable and replicable the benefits will be. This review paper aims to take a first step in exploring the potential role of industrial clusters in the energy system by exposing the research state of the art in academic literature. A literature review is performed in line with the three benefit categories according to Draghi to understand the enablers and barriers of potential synergies and their impact on the energy system. Afterwards the scalability is assessed by positioning the European industrial clusters in the larger renewable energy landscape. To illustrate the global interest a brief reflection is made on references to industrial clusters in the policy of non-European regions. The work concludes with interesting leads for future research to further advance knowledge on the importance of industrial clusters in the energy system and to stimulate the implementation of energy synergies.

This paper investigates the performance and economic viability of Combined Cycle Gas Turbines (CCGT) operating on natural gas (NG) and hydrogen within the context of evolving electricity markets. The study is structured into several sections beginning with a benchmark analysis to establish baseline performance metrics including break-even prices and price margins for CCGTs running on NG. The research then explores various base cases and sensitivity analyses focusing on different CCGT capacity factors and the uncertainties surrounding key parameters. The study also compares the performance of CCGTs across different European countries highlighting the impact of increased price fluctuations in forecasted electricity markets. Additionally the paper examines Power-to-X-to-Power (P2X2P) configurations assessing the economic feasibility of hydrogen production and its integration into CCGT operations. The analysis considers scenarios where hydrogen is sourced externally or produced on-site using renewable energy or grid electricity during off-peak hours. The results provide insights into the competitiveness and adaptability of CCGTs in a transitioning energy landscape emphasizing the potential role of hydrogen as a flexible and sustainable energy carrier.

This study presents a comprehensive framework that integrates high-resolution energy forecasting and technoeconomic modeling to assess green hydrogen production potential in Flanders Belgium. Using 15-min interval data from the Elia Group four deep learning models (LSTM BiLSTM GRU and CNN-LSTM) were developed to forecast regional photovoltaic (PV) and onshore wind energy generation. These forecasts informed the estimation of hydrogen yields and the evaluation of the levelized cost of hydrogen (LCOH) under different configurations. Results show that wind-powered hydrogen production achieves the lowest LCOH (6.63 €/kg) due to higher annual operating hours. Among electrolysis technologies alkaline electrolysis (AEL) offers the lowest cost while proton exchange membrane (PEMEL) provides greater flexibility for intermittent power sources. The hybrid PVwind system demonstrated seasonal complementarity increasing annual hydrogen yield and improving production stability. The proposed framework supports regional planning and highlights strategic investment opportunities for cost-effective green hydrogen deployment.

A potential strategy to promote the use of clean energy is the development of catalyst-coated cathodic electrodes that are economical effective and sustainable to enhance the generation of hydrogen (H2) through the electrolysis process. This study investigates the unique design and use of stainless steel (SS) coated with a CuNiZnFeOx catalyst as both anode and cathode electrodes in the alkaline electrolysis process. The electrode exhibits an improved electrochemical behavior achieving a current density of 92 mA/cm2 at an applied voltage of 2.5 V with a surface area of 36 cm2 in 1 M KOH electrolyte at 25 ◦C. Furthermore the H2 production is systematically investigated by varying electrolyte concentration applied voltage and temperature. The results demonstrate that H2 production increases significantly with enhanced electrolyte concentration (3102 mL at 2 M KOH) applied voltage (3468 mL at 3.0 V) and temperature (3202 mL at 60 ◦C) over a 300 min electrolysis time. However optimal operating conditions are determined to be 1 M KOH 2.5 V and 25 ◦C balancing performance and energy efficiency. The improved performance is primarily attributed to enhanced ionic conductivity reduced internal resistance and the synergistic catalytic activity of the Cu-integrated NiZnFeOx coating.

Hydrogen plays a central role in ensuring the fulfillment of the climate and energy goals established in the Paris Agreement. To implement sustainable and resilient hydrogen economies it is essential to analyze the entire hydrogen value chain following a Life Cycle Assessment (LCA) methodology. To determine the current methodologies approaches and research tendencies adopted when performing LCA of hydrogen energy systems a systematic literature analysis is carried out in the present study. The choices regarding the “goal and scope definition” “life cycle inventory analysis” and “life cycle impact assessment” in 70 scientific papers were assessed. Based on the collected information it was concluded that there are no similar LCA studies since specificities introduced in the system boundaries functional unit production storage transportation end-use technologies geographical specifications and LCA methodological approaches among others introduce differences among studies. This lack of harmonization triggers the need to define harmonization protocols that allow for a fair comparison between studies; otherwise the decision-making process in the hydrogen energy sector may be influenced by methodological choices. Although initial efforts have been made their adoption remains limited and greater promotion is needed to encourage wider implementation.

The growing demand for air connectivity coupled with the forecasted increase in passengers by 2040 implies an exigency in the aviation sector to adopt sustainable approaches for net zero emission by 2050. Sustainable Aviation Fuel (SAF) is currently the most promising short-term solution; however ensuring its overall sustainability depends on reducing the life cycle carbon footprints. A key challenge prevails in hydrogen usage as a reactant for the approved ASTM routes of SAF. The processing conversion and refinement of feed entailing hydrodeoxygenation (HDO) decarboxylation hydrogenation isomerisation and hydrocracking requires substantial hydrogen input. This hydrogen is sourced either in situ or ex situ with the supply chain encompassing renewables or non-renewables origins. Addressing this hydrogen usage and recognising the emission implications thereof has therefore become a novel research priority. Aside from the preferred adoption of renewable water electrolysis to generate hydrogen other promising pathways encompass hydrothermal gasification biomass gasification (with or without carbon capture) and biomethane with steam methane reforming (with or without carbon capture) owing to the lower greenhouse emissions the convincing status of the technology readiness level and the lower acidification potential. Equally imperative are measures for reducing hydrogen demand in SAF pathways. Strategies involve identifying the appropriate catalyst (monometallic and bimetallic sulphide catalyst) increasing the catalyst life in the deoxygenation process deploying low-cost iso-propanol (hydrogen donor) developing the aerobic fermentation of sugar to 14 dimethyl cyclooctane with the intermediate formation of isoprene and advancing aqueous phase reforming or single-stage hydro processing. Other supportive alternatives include implementing the catalytic and co-pyrolysis of waste oil with solid feedstocks and selecting highly saturated feedstock. Thus future progress demands coordinated innovation and research endeavours to bolster the seamless integration of the cutting-edge hydrogen production processes with the SAF infrastructure. Rigorous technoeconomic and life cycle assessments alongside technological breakthroughs and biomass characterisation are indispensable for ensuring scalability and sustainability

This work develops a replicable method for designing the optimal renewable hydrogen production facility applicable to any site and based on technical parameters and actual equipment costs. The solution is based on the integration of photovoltaic (PV) energy with lithium-ion battery storage systems which maximizes electrolyzer operating hours and significantly reduces the Levelized Cost of Hydrogen (LCOH). This study shows that increasing the inclination of the photovoltaic modules reduces the need for storage optimizing operation and extending the electrolyzer’s annual operating hours. In the Seville case study with current costs and efficiencies a minimum LCOH of €4.43/kg was achieved a value well below market benchmarks opening the door to a potentially competitive industrial business. The analysis confirms that electrolyzer efficiency—particularly specific power consumption—is the most important factor in reducing costs while technological progress in photovoltaics storage and equipment promises further reductions in the coming years. Overall the proposed methodology offers a practical and scalable tool to accelerate the economic viability of green hydrogen in a variety of contexts.

The increasing global demand for clean energy highlights hydrogen as a strategic energy carrier due to its high energy density and carbon-free utilization. Currently steam methane reforming (SMR) is the most widely applied method for hydrogen production; however its high CO2 emissions undermine the environmental benefits of hydrogen. Blue hydrogen production integrates carbon capture and storage (CCS) technologies to overcome this drawback in the SMR process significantly reducing greenhouse gas emissions. This study integrated a MATLAB-R2025b-based plug flow reactor (PFR) model for SMR kinetics with an Aspen HYSYS-based CCS system. The effects of reformer temperature (600–1000 ◦C) and steam-to-carbon (S/C) ratio (1–5) on hydrogen yield and CO2 emission intensity were investigated. Results show that hydrogen production increases with temperature reaching maximum conversion at 850–1000 ◦C while the optimum performance is achieved at S/C ratios of 2.5–3.0 balancing high hydrogen yield and minimized methane slip. Conventional SMR generates 9–12 kgCO2/kgH2 emissions whereas SMR + CCS reduces this to 2–3 kgCO2/kgH2 achieving more than 75% reduction. The findings demonstrate that SMR + CCS integration effectively mitigates emissions and provides a sustainable bridging technology for blue hydrogen production supporting the transition toward lowcarbon energy systems.

The paper studies and analyzes electric vehicle engines powered by hydrogen under the WLTP standard driving protocol. The driving range extension is estimated using a specific protocol developed for FCEV compared with the standard value for battery electric vehicles. The driving range is extended by 10 km averaging over the four protocols with a maximum of 11.6 km for the FTP-75 and a minimum of 7.7 km for the WLTP. This driving range extension represents a 1.8% driving range improvement on average. Applying the FCEV current weight the driving range is extended to 18.9 km and 20.4 km on average when using power source energy capacity standards for BEVs and FCEVs.