Publications

Traditional charging stations have a single function which usually does not consider the construction of energy storage facilities and it is difficult to promote the consumption of new energy. With the gradual increase in the number of new energy vehicles (NEVs) to give full play to the complementary advantages of source-load resources and provide safe efficient and economical energy supply services this paper proposes the optimal operation strategy of a PV-charging-hydrogenation composite energy station (CES) that considers demand response (DR). Firstly the operation mode of the CES is analyzed and the CES model including a photovoltaic power generation system fuel cell hydrogen production hydrogen storage hydrogenation and charging is established. The purpose is to provide energy supply services for electric vehicles (EVs) and hydrogen fuel cell vehicles (HFCVs) at the same time. Secondly according to the travel law of EVs and HFCVs the distribution of charging demand and hydrogenation demand at different periods of the day is simulated by the Monte Carlo method. On this basis the following two demand response models are established: charging load demand response based on the price elasticity matrix and interruptible load demand response based on incentives. Finally a multi-objective optimal operation model considering DR is proposed to minimize the comprehensive operating cost and load fluctuation of CES and the maximum–minimum method and analytic hierarchy process (AHP) are used to transform this into a linearly weighted single-objective function which is solved via an improved moth–flame optimization algorithm (IMFO). Through the simulation examples operation results in four different scenarios are obtained. Compared with a situation not considering DR the operation strategy proposed in this paper can reduce the comprehensive operation cost of CES by CNY 1051.5 and reduce the load fluctuation by 17.8% which verifies the effectiveness of the proposed model. In addition the impact of solar radiation and energy recharge demand changes on operations was also studied and the resulting data show that CES operations were more sensitive to energy recharge demand changes.

Blue hydrogen is gaining attention as an intermediate step toward achieving eco-friendly green hydrogen production. However the general blue hydrogen production requires an energy-intensive process for carbon capture and storage resulting in low process efficiency. Additionally the hydrogen production processes steam methane reforming (SMR) and electrolysis emits waste heat and byproduct oxygen respectively. To solve these problems this study proposes an oxy-fuel combustion-based blue hydrogen production process that integrates fossil fuel-based hydrogen production and electrolysis processes. The proposed processes are SMR + SOEC and SMR + PEMEC whereas SMR solid oxide electrolysis cell (SOEC) and proton exchange membrane electrolysis cell (PEMEC) are also examined for comparison. In the proposed processes the oxygen produced by the electrolyzer is utilized for oxy-fuel combustion in the SMR process and the resulting flue gas containing CO2 and H2O is condensed to easily separate CO2. Additionally the waste heat from the SMR process is recovered to heat the feed water for the electrolyzer thereby maximizing the process efficiency. Techno-economic sensitivity and greenhouse gas (GHG) analyses were conducted to evaluate the efficiency and feasibility of the proposed processes. The results show that SMR + SOEC demonstrated the highest thermal efficiency (85.2%) and exergy efficiency (80.5%) exceeding the efficiency of the SMR process (78.4% and 70.4% for thermal and exergy efficiencies respectively). Furthermore the SMR + SOEC process showed the lowest levelized cost of hydrogen of 6.21 USD/kgH2. Lastly the SMR + SOEC demonstrated the lowest life cycle GHG emissions. In conclusion the proposed SMR + SOEC process is expected to be a suitable technology for the transition from gray to green hydrogen.

With an increase in the use of eco-friendly vehicles such as hybrid electric and hydrogen vehicles in response to the global climate crisis accidents related to these vehicles have also increased. Numerical analysis was performed to optimize the safety of first responders responding to hydrogen vehicle accidents wherein hydrogen jet flames occur. The influence range of the jet flame generated through a 1.8-mm-diameter nozzle was analyzed based on five discharge angles (90 75 60 45 and 30◦ ) between the road surface and the downward vertical. As the discharge angle decreases toward the road surface the risk area that could cause damage moves from the center of the vehicle to the rear; at a discharge angle of 90◦ the range above 9.5 kW/m2 was 1.59 m and 4.09 m to the front and rear of the vehicle respectively. However at a discharge angle of 30◦ it was not generated at the front but was 10.39 m to the rear. In response to a hydrogen vehicle accident first responders should perform rescue activities approaching from a diagonal direction to the vehicle front to minimize injury risk. This study can be used in future hydrogen vehicle design to develop the response strategy of the first responders.

Fuel cells and electric batteries are competing technologies for the energy transition in heavy transportation. We explore the conditions for the survival of a unique technology in the long term. Learning by doing suggests focusing on a single technology while differentiation and decreasing return to scale (cost convexity) favor diversification. Exogenous technical change also plays a role. The interaction between these factors is analyzed in a general model. It is proved that in absence of convexity and exogenous technical change only one technology is used for the whole transition. We then apply this framework to analyze the competition between fuel-cell electric buses (FCEBs) and battery electric buses (BEB) in the European bus sector. There are both learning by doing and exogenous technical change. The model is calibrated and solved. It is shown that the existence of a niche for FCEBs critically depends on the speed at which cost reductions are achieved. The speed depends both on the size of the niche and the rate of learning by doing for FCEBs. Public policies to decentralize the socially optimal trajectory in terms of taxes (carbon) and subsidies (learning by doing) are derived.

Large-scale production of hydrogen using clean electricity from renewable energy sources (RESs) is gaining more momentum in attempts to foster the growth of the nascent hydrogen energy market. However the inherited intermittency of RESs constitutes a significant challenge for the reliable and economic operation of electrolysers and consequently the overall hydrogen production plant. This paper proposes a power allocation control strategy to regulate the operation of a multi-unit electrolyser plant fed by a solar power system for improved efficiency and economic hydrogen production. Proper implementation of the proposed control strategy can decrease the number of switching times increase hydrogen production raise the efficiency and extend the operational lifespan of the utilised electrolyser units. A solar-hydrogen system comprising a 1 MW electrolyser plant and a battery system is designed and implemented in MATLAB/Simulink environment to validate the efficacy of the proposed control strategy in improving the performance and reliability of an Industrial Green Hydrogen Hub (IGHH). The simulation results showed an improvement of 52.85% in the daily production of hydrogen with an increase of 71.088 kg/day a 68.67% improvement in the efficiency and an enhancement of more than 80% in the utilisation factor of the IGHH compared to other control techniques (traditional choppy control).

Renewable hydrogen is widely considered a key technology to achieve net zero emissions in industrial production processes. This paper presents a structured bibliometric analysis examining current and future applications of hydrogen as feedstock and fuel across industries quantifying demand for different industrial processes and identifying greenhouse gas emissions reduction potential against the context of current fossil-based practices. The findings highlight significant focus on hydrogen as feedstock for steel ammonia and methanol production and its use in high-to medium-temperature processes and a general emphasis on techno-economic and technological evaluations of hydrogen applications across industries. However gaps exist in research on hydrogen use in sectors like cement glass waste pulp and paper ceramics and aluminum. Additionally the analysis reveals limited attention in the identified literature to hydrogen supply chain efficiencies including conversion and transportation losses as well as geopolitical and raw material challenges. The analysis underscores the need for comprehensive and transparent data to align hydrogen use with decarbonization goals optimize resource allocation and inform policy and investment decisions for strategic deployment of renewable hydrogen.

This work formed part of the H21 programme whose objective is to reach the point whereby it is feasible to convert the existing natural gas (NG) distribution network to 100% hydrogen (H2) and provide a contribution to decarbonising the UK’s heat and power sectors with the focus on decarbonised fuel at point of use. Hydrogen has an ATEX Gas Group of IIC compared to IIA for natural gas which means further precautions are necessary to prevent the ignition of hydrogen during network operations. Both electrostatic and friction ignition risks were considered. Network operations considered include electrostatic precautions for polyethylene (PE) pipe and cutting and drilling of metallic pipes. As a result of the updated basis of safety from ignition considerations existing flow stopping methods were reviewed to see if they were compatible. Commonly used flow stopping methods were tested under laboratory conditions with hydrogen following the methodologies specified in the Gas Industry Standards (GIS). A new basis of safety for flow stopping has been proposed that looks at the flow past the secondary stop as double isolations are recommended for use with hydrogen.

The transportation sector plays an important role in the current effort towards the control of global warming. Against this backdrop electrification is currently attracting attention as the life cycle environmental performance of different powertrain technologies is critically assessed. In this study a life cycle analysis of the public transportation buses was performed. The scope of the analysis is to compare the energy and global warming performances of the different powertrain technologies in the city fleet: diesel full electric and hydrogen buses. Real world monitored data were used in the analysis for the energy consumptions of the buses and to produce hydrogen in Bolzano. Compared to the traditional diesel buses the electric vehicles showed a 43% reduction of the non-renewable primary energy demand and a 33% of the global warming potential even in the worst consequential scenario considered. The switch to hydrogen buses leads to very different environmental figures: from very positive if it contributes to a further penetration of renewable electricity to hardly any difference if hydrogen from steam-methane reforming is used to clearly negative ones (approximately doubling the impacts) if a predominantly fossil electricity mix is used in the electrolysis.

As energy system research into high shares of renewables has developed so have the perspectives of the fundamental nature of a highly renewable economy. Early energy system transition research suggested that current fossil fuel energy systems would transition to a ‘Hydrogen Economy’ whereas more recent insights suggest that a ‘Power-to-X Economy’ may be a more appropriate term as renewable electricity will become both the most important primary and final energy carrier through various Power-to-X conversion routes across the energy system. This paper provides a detailed overview on research insights of recent years on the core elements of the Power-to-X Economy and the role of hydrogen based on latest research results. These results suggest that by 2050 upwards of 61737 TWhLHV of hydrogen will be required to fully defossilise the global energy-industry system. Hydrogen therefore emerges as a central intermediate energy carrier and its relevance is driven by significant cost reductions in renewable electricity especially of solar photovoltaics and wind power. Efficiency and cost drivers position direct electrification as the primary solution for defossilisation of the global energy-industry system; however electron-to-molecule routes are essential for the large subset of remaining energy-related demands including chemical production marine and aviation fuels and steelmaking.

This study presents a novel web-based decision support system (DSS) that optimizes the locations of hydrogen refueling stations (HRSs) and hydrogen supply chains (HSCs). The system is developed with a design science approach that identifies key design requirements and features through interviews and literature reviews. Based on the findings a system architecture and data model were designed incorporating scenario management optimization model visualization and data management components. The DSS provides a two-stage solution model that links demand to HRSs and production facilities to HRSs. A prototype is demonstrated with a plan for 2025 and 2030 in the Republic of Korea where 450 to 660 stations were deployed nationwide and linked to production facilities. User evaluation confirmed the effectiveness of the DSS in solving optimization problems and its potential to assist the government and municipalities in planning hydrogen infrastructure.

In recent years the use and development of hydrogen as a carbon-free energy carrier have grown. However as hydrogen is flammable with air safety issues are raised. In the case of ignition especially in confined space the flame can accelerate and reach the detonation regime causing severe structural damage [1].<br/>To assess these safety issues it is required to understand the fluid-structure interaction in the case of a detonation impacting a deformable structure and to quantify and model this interaction [2]. At the CEA (Commissariat à l’énergie atomique et aux energies alternatives) a combustion tube experimental facility [3] for studying the fluid-structure interaction in the case of hydrogen combustion has been developed. Several Photomultipliers and Pressure sensors are placed along the tube to monitor the flame acceleration and the detonation location. A fluid-structure interaction (FSI) module or a non-deformable flange can be placed at the end of the tube. Post-processing of the sensor’s signal will provide insight into the occurring phenomena inside the tube.<br/>Several experimental campaigns have been conducted with various initial conditions and configurations at the end of the tube. In this contribution the experiments resulting in a detonation are presented. First the recorded pressure and velocities will be compared to theoretical values coming from combustion models [4] [5]. Secondly the impulse before and after reflection for thin plate and non-deformable flange will be compared to quantify the energy transmitted to the plate and the influence of the fluid-structure interaction on the reflected shock.

Accidental release from a hydrogen car tank in a confined space like a tunnel poses safety concerns. This Computational Fluid Dynamics (CFD) study focuses on the first seconds of such a release which are the most critical. Hydrogen leaks through a Thermal Pressure Relief Device (TPRD) forms a high-speed jet that impinges on the street spreads horizontally recirculates under the chassis and fills the area below it in about one second. The “fresh-air entrainment effect” at the back of the car changes the concentrations under the chassis and results in the creation of two “tongues” of hydrogen at the rear corners of the car. Two other tongues are formed near the front sides of the vehicle. In general after a few seconds hydrogen starts moving upwards around the car mainly in the form of buoyant blister-like structures. The average hydrogen volume concentrations below the car have a maximum of 71% which occurs at 2 s. The largest “equivalent stoichiometric flammable gas cloud size Q9” is 20.2 m3 at 2.7 s. Smaller TPRDs result in smaller hydrogen flow rates and smaller buoyant structures that are closer to the car. The investigation of the hydrogen dispersion during the initial stages of the leak and the identification of the physical phenomena that occur can be useful for the design of experiments for the determination of the TPRD characteristics for potential safety measures and for understanding the further distribution of the hydrogen cloud in the tunnel.

Transitioning to a sustainable energy future necessitates innovative storage solutions for renewable energies where hydrogen (H₂) emerges as a pivotal energy carrier for its low emission potential. This paper explores unlined rock caverns (URCs) as a promising alternative for underground hydrogen storage (UHS) overcoming the geographical and technical limitations of UHS methods like salt rock caverns and porous media. Drawing from the experiences of natural gas (NG) and compressed air energy storage (CAES) in URCs we explore the viability of URCs for storing hydrogen at gigawatt-hour scales (>100 GWh). Despite challenges such as potential uplift failures (at a depth of approximately less than 1000 m) and hydrogen reactivity with storage materials at typical conditions (below temperatures of 100◦C and pressures of 15 MPa) URCs present a flexible scalable option closely allied with green hydrogen production from renewable sources. Our comprehensive review identifies critical design considerations including hydraulic containment and the integrity of fracture sealing materials under UHS conditions. Addressing identified knowledge gaps particularly around the design of hydraulic containment systems and the interaction of hydrogen with cavern materials will be crucial for advancing URC technology. The paper underscores the need for further experimental and numerical studies to refine URC suitability for hydrogen storage highlighting the role of URCs in enhancing the compatibility of renewable energy sources with the grid.

Hydrogen embrittlement (HE) poses a significant challenge for high-strength steels. Although HE of wrought steels has been extensively studied it remains limited in steels processed by additive manufacturing (AM). The present work (i) compares the HE susceptibility of AISI 4340 ultra-high-strength steel fabricated by selective laser melting (SLM) with its wrought counterpart; (ii) investigates the predominant factors and possible HE mechanisms in the AM-fabricated material; and (iii) correlates microstructures produced with different SLM processing parameters to HE susceptibility of the steel. Generally conventionally processed AISI 4340 steel is used with a tempered martensitic structure to ensure the ultrahigh strength and therefore is susceptible to HE. In contrast SLM-fabricated 4340 exhibits a uniform refined bainitic microstructure. How this change of microstructure influences the HE susceptibility of the steel is unknown and needs investigation. Our results demonstrate that at the same level of strength the SLM-fabricated 4340 steel exhibits significantly lower HE susceptibility than its wrought counterpart. The SLM-fabricated steel showed a higher hydrogen diffusion rate. Furthermore the refined microstructure of the SLM-fabricated steel contributes to enhanced ductility even with hydrogen. These findings indicate that AM of high-strength steels has strong potential to improve HE resistance providing a pathway to solve this long-term problem. This study highlights the critical role of microstructure in influencing HE and offers valuable insights for developing steels for hydrogen applications.

In the quest to achieve “double carbon” goals the urgency to develop an efficient Integrated Energy System (IES) is paramount. This study introduces a novel approach to IES by refining the conventional Power-to-Gas (P2G) system. The inability of current P2G systems to operate independently has led to the incorporation of hydrogen fuel cells and the detailed investigation of P2G’s dual-phase operation enhancing the integration of renewable energy sources. Additionally this paper introduces a carbon trading mechanism with a refined penalty–reward scale and a detailed pricing tier for carbon emissions compelling energy suppliers to reduce their carbon footprint thereby accelerating the reduction in system-wide emissions. Furthermore this research proposes a flexible adjustment mechanism for the heat-to-power ratio in cogeneration significantly enhancing energy utilization efficiency and further promoting conservation and emission reductions. The proposed optimization model in this study focuses on minimizing the total costs including those associated with carbon trading and renewable energy integration within the combined P2G-Hydrogen Fuel Cell (HFC) cogeneration system. Employing a bacterial foraging optimization algorithm tailored to this model’s characteristics the study establishes six operational modes for comparative analysis and validation. The results demonstrate a 19.1% reduction in total operating costs and a 22.2% decrease in carbon emissions confirming the system’s efficacy low carbon footprint and economic viability.

Fuel cell electric vehicles (FCEVs) provide a viable answer to transportation issues caused by fossil fuel limitations and environmental concerns. This review presents a thorough evaluation of the most recent advances in FCEV durability research. It addresses 4 major topics: component upgrades technical control techniques test optimization and durability prediction. Upgrades to components include improved catalysts bipolar plates gas diffusion layers proton exchange membranes and plant balancing. Technical control solutions include power energy temperature ventilation and control management. Stress acceleration and cold start tests are examples of test optimization whereas durability prediction requires parameter selection real-time monitoring dynamic modeling and lifespan prediction. This review also makes some novel recommendations targeted at improving the endurance of FCEVs. These include measures for raising public awareness lowering prices while increasing performance improving subsystems for greater durability updating health diagnostics to prevent performance deterioration and implementing supporting regulations to encourage industry upgrading. These findings are expected to accelerate the adoption of FCEVs and the transition to a more sustainable transportation system.

Multi-energy microgrids (MEMGs) with green hydrogen have attracted significant research attention for their benefits such as energy efficiency improvement carbon emission reduction as well as line congestion alleviation. However the complexities of multi-energy networks coupled with diverse uncertainties may threaten MEMG’s operation. In this paper a data-driven methodology is proposed to achieve effective MEMG operation considering the green hydrogen technique and congestion management. First a detailed MEMG modelling approach is developed coupling with electricity green hydrogen natural gas and thermal flows. Different from conventional MEMG models hydrogen-enriched compressed natural gas (HCNG) models and weatherdependent power flow are thoroughly considered in the modelling. Meanwhile the power flow congestion problem is also formulated in the MEMG operation which could be mitigated through HCNG integration. Based on the proposed MEMG model a reinforcement learning-based method is designed to obtain the optimal solution of MEMG operation. To ensure the solution’s safety a soft actor-critic (SAC) algorithm is applied and modified by leveraging the Lagrangian relaxation and safety layer scheme. In the end case studies are conducted and presented to validate the effectiveness of the proposed method.

In the future the development of a zero-carbon economy will require large-scale hydrogen storage. This article addresses hydrogen storage capacities a critical issue for large-scale hydrogen storage in geological structures. The aim of this paper is to present a methodology to evaluate the potential for hydrogen storage in depleted natural gas reservoirs and estimate the capacity and energy of stored hydrogen. The estimates took into account the recoverable reserves of the reservoirs hydrogen parameters under reservoir conditions and reservoir parameters of selected natural gas reservoirs. The theoretical and practical storage capacities were assessed in the depleted natural gas fields of N and NW Poland. Estimates based on the proposed methodology indicate that the average hydrogen storage potential for the studied natural gas fields ranges from 0.01 to 42.4 TWh of the hydrogen energy equivalent. Four groups of reservoirs were distinguished which differed in recovery factor and technical hydrogen storage capacity. The issues presented in the article are of interest to countries considering large-scale hydrogen storage geological research organizations and companies generating electricity from renewable energy sources.

Hydrogen embrittlement is a phenomenon that affects the mechanical properties of steels intended for hydrogen transportation. One affected by this embrittlement is the Ductile to Brittle Transition Temperature (DBTT) which characterizes the change in the failure mode of the steel from ductile to brittle. This temperature is conventionally defined and compared to the operating temperature as an acceptability criterion for codes. Transition temperature does not depend only on the material but also on specimen geometry particularly the thickness. Generally the transition temperature is defined for the conservative reason by Charpy impact test. Standard Charpy specimens are straight beams with a thickness of 10 mm. For thin pipes it is impossible to extract these standard specimens. One uses in this case Mini-Charpy specimens with a reduced thickness due to pipe curvature. This paper aims to quantify the effect of hydrogen embrittlement on the transition temperature of pipe steel (API 5L X65) using two types of Charpy specimens.

The idea of supporting the Sustainable Development Goals (SDGs) has inspired researchers around the world to explore more environmentally friendly energy generation and production methods especially those related to solar and hydrogen energy. Among the various available sustainable energy technologies photo(electro)catalytic hydrogen production has been competitively explored benefiting from its versatile platform to utilize solar energy for green hydrogen production. Nevertheless the bottleneck of this photo(electro)catalytic system lies within its high voltage required for water electrolysis (>1.23 V) which affects the economic prospects of this sustainable technology. In this regard coupling the photo(electro)catalytic system with a solar-powered photovoltaic (PV) system (PV-PEC) to unleash the fascinating properties and readiness of this system has heightened attention among the scientific community. In this context this review begins by elucidating the basic principles of PV-PEC systems followed by an exploration of various types of solar PV technology and the different types of semiconductors used as photocatalysts in the PEC system. Subsequently the main challenges faced by the PV-PEC system are presented covering areas such as efficiency stability and cost-effectiveness. Finally this review delves into recent research related to PV-PEC systems discussing the advancements and breakthroughs in this promising technology. Furthermore this review provides a forecast for the future prospects of the PV-PEC system highlighting the potential for its continued development and widespread implementation as a key player in sustainable hydrogen production.

New flow metering challenges are presented by the energy transition program since the available and new infrastructures might be used to transport energy using energy vectors such as hydrogen-enriched natural gas mixtures including blends never adopted before in current distribution lines. In this framework it is necessary to have the possibility to verify the performance of flowmeters which are currently calibrated using natural gas and nitrogen as reference fluids even when operating with fluids that are not yet in use. For this reason a commercial clamp-on ultrasonic flowmeter was used to measure the speed of sound in a mixture of hydrogen and iso-butane after being calibrated using helium as reference fluid. Helium is actually much more expensive than nitrogen but in our case it is advantageous because in the temperature and pressure ranges considered in this work the speeds of sound of helium are more comparable with those of the binary mixture of hydrogen and isobutane than the speeds of sound of nitrogen under the same thermodynamic conditions. A specifically developed control apparatus was designed to adjust the temperature and the pressure of the gas filling a DN50-PN100 spool where the ultrasonic meter was mounted on. The instrument was calibrated for temperatures between (270 and 320) K and for pressures up to 3 MPa by using the prediction of the reference equation of state for helium of Ortiz-Vega et al. The measurements of the speed of sound were obtained in a binary mixture containing mainly hydrogen with a small content of iso-butane since for these compounds new results are necessary to validate and improve the predictions of thermodynamic models installed in flowmeters and in flow computers. The expanded relative uncertainty was evaluated to be of 0.09% ( = 2) that was estimated by considering the contributions of the main influence quantities repeatability and reproducibility of the measurements. The obtained results were compared with the AGA-8-92DC and GERG-2008 equations of state and found to be consistent with the values predicted by both models demonstrating the feasibility of using a clamp-on ultrasonic flowmeter to determine the speed of sound and possibility to verify the performance of flowmeter installed on the gas networks using the speed of sound as transfer quantity.

Rural mini-grids in Ghana often experience substantial midday solar PV generation surpluses due to mismatches between peak production and local demand with excess energy (redundant energy) frequently curtailed once batteries are fully charged. This underutilisation limits the socio-economic benefits of renewable electrification and highlights the need for alternative long-duration storage solutions. This study investigated the technoeconomic feasibility of converting excess PV energy from a 54 kWp mini-grid in Aglakope Ghana into hydrogen via electrolysis storing it and reconverting it to electricity using fuel cells. Redundant energy generation was quantified using measured PV output and load consumption and validated using statistical error metrics (R2 = 0.955). Hydrogen production and recovery potential were modelled for different electrolyser technologies and system performance was evaluated using round-trip efficiency (RTE) levelized cost of hydrogen (LCOH) and levelized cost of storage (LCOS) with comparative analysis against additional battery capacity. The results yielded an average monthly excess energy of about 2250 kWh convertible into 43–53 kg per month of hydrogen depending on electrolyser type. The proposed hydrogen-fuel cell pathway yielded a RTE of 44.4 % LCOH of $4.97/kg and LCOS of $0.249/kWh which is about 13 % higher than lithium-ion storage benchmarks. The study findings demonstrate that hydrogen storage can complement batteries offer seasonal and multi-day storage capability and reduce renewable curtailment. Therefore wider adoption could be supported by cost reductions efficiency improvements and enabling policies positioning hydrogen-based storage as a viable pathway for resilient low-carbon rural electrification in off-grid contexts.

Proton exchange membrane water electrolysis is a core technology for green hydrogen production but its widespread adoption is hindered by a prohibitively high and uncertain life cycle cost. To address the dynamic complexity and multi-source uncertainties inherent in cost assessment this paper proposes an integrated modeling framework that combines system dynamics with an intuitionistic fuzzy bayesian network. The system dynamics model captures the macro-level feedback loops driving long-term cost evolution such as technological innovation economy-of-scale effects and other critical factors. To model and infer causal dependencies among uncertain variables that are challenging to specify precisely within the system dynamics model the intuitionistic fuzzy bayesian network is incorporated enabling quantification of relationships under conditions of incomplete data and cognitive fuzziness. Through comprehensive simulations the framework forecasts the cost evolution trajectories. Results indicate a potential 77 % reduction in the unit power cost of a 1 MW system by 2060. Uncertainty analysis revealed that the initial prediction variance for the catalyst layer was approximately 20 % significantly higher than the 6.5 % for the bipolar plate highlighting a key investment risk. A comparative analysis demonstrates that the proposed framework achieves a superior forecast accuracy with a mean absolute percentage error of 4.8 %. The proposed method provides a more accurate and robust decision support tool for long-term investment planning and policy formulation for hydrogen production through proton exchange membrane water electrolysis technology.

The sorption-enhanced steam gasification of biomass (SEBSG) is considered a prospective thermo-chemical technology for high-purity H2 production with in-situ CO2 capture. Fundamental concepts and operating conditions of SEBSG technology were summarized in this review. Considerable industrial demonstration units have been conducted on pilot scales for large-scale availability of the SEBSG process. The influence of process parameters such as reaction temperature Steam/Biomass (S/B) ratio feedstock characteristics cyclic CO2 capture capacity of CaO-based sorbents and catalysis were critically reviewed to provide theoretical recommendations for industrial operation. Bifunctional materials that have high catalytic activity and CO2 capture activity are crucial for ensuring high H2 production in the SEBSG. The application of density functional theory (DFT) and reactive force field molecular dynamic (ReaxFF MD) simulations on microcosmic reaction mechanisms in the SEBSG process such as pyrolysis WGS and reforming reactions and CO2 capture of CaO-based materials are comprehensively overviewed. Several research gaps like the exploitation of more efficient and low-cost bifunctional material integrated process economics and revelation of well-rounded mechanisms need to be filled for the following large-scale industrial applications.

Hydrogen refuelling is imperative for the emerging market of hydrogen vehicles. The pressure control valve (PCV) at the hydrogen refuelling station (HRS) plays a major role in ensuring that hydrogen delivery to the vehicle follows the prescribed refuelling protocols. A three-dimensional CFD model with a detailed resolution of PCV motion affecting heat and mass transfer is developed. The PCV motion controlling the mass flow rate is simulated using dynamic mesh. The CFD model captures refuelling from high-pressure tanks through entire HRS equipment to onboard tanks capturing pressure and temperature changes upstream and downstream of the PCV. The Joule-Thomson effect resulting in a hydrogen temperature increase at PCV is captured using the NIST real gas database. The model is validated against Test No.1 of NREL on refuelling through the entire equipment of HRS. The CFD model can be used to design HRS equipment parameters including PCV and develop efficient refuelling protocols.