Production & Supply Chain

Photocatalysis offers an attractive strategy to upgrade H2O to renewable fuel H2. However current photocatalytic hydrogen production technology often relies on additional sacrificial agents and noble metal cocatalysts and there are limited photocatalysts possessing overall water splitting performance on their own. Here we successfully construct an efficient catalytic system to realize overall water splitting where hole-rich nickel phosphides (Ni2P) with polymeric carbon-oxygen semiconductor (PCOS) is the site for oxygen generation and electron-rich Ni2P with nickel sulfide (NiS) serves as the other site for producing H2. The electron-hole rich Ni2P based photocatalyst exhibits fast kinetics and a low thermodynamic energy barrier for overall water splitting with stoichiometric 2:1 hydrogen to oxygen ratio (150.7 μmol h−1 H2 and 70.2 μmol h−1 O2 produced per 100 mg photocatalyst) in a neutral solution. Density functional theory calculations show that the co-loading in Ni2P and its hybridization with PCOS or NiS can effectively regulate the electronic structures of the surface active sites alter the reaction pathway reduce the reaction energy barrier boost the overall water splitting activity. In comparison with reported literatures such photocatalyst represents the excellent performance among all reported transition-metal oxides and/or transition-metal sulfides and is even superior to noble metal catalyst.

Hydrogen production from electrolytic water based on Renewable Energy has been found as a vital method for the local consumption of new energy and the utilization of hydrogen energy. In this paper the hydrogen production power supply matching the working characteristics of electrolytic water production was investigated. Through the analysis of the correlation between the electrolysis current and temperature of the proton exchange membrane electrolyzer and the electrolyzer port voltage energy efficiency and hydrogen production speed it was concluded that the hydrogen production power supply should be characterized by low output current ripple high output current and wide range voltage output. To meet the requirements of the system of hydrogen production from electrolytic water based on new energy a hydrogen production power supply scheme was proposed based on Y which is the type three is the phase staggered parallel LLC topology. In the proposed scheme the cavity with three is the phase staggered parallel output is resonated to meet the operating characteristics (high current and low ripple) of the electrolyzer and pulse frequency control is adopted to achieve resonant soft in the switching operation and increase conversion efficiency. Lastly a simulation model and a 6kW experimental prototype were built to verify the rationality and feasibility of the proposed scheme.

Hydrogen has emerged as a promising new energy source that can be produced in renewable mode for example from biomass derivatives reforming or water splitting. However the conventional catalysts used for hydrogen production in renewable mode suffer from limitations in activity selectivity and/or stability. To overcome these limitations nanostructured catalysts with multicomponent active phases particularly trimetallic catalysts are being explored. This catalyst formulation significantly enhances catalyst activity and effectively suppresses the undesired production of CO CH4 or coke during the reforming of biomass derivatives for hydrogen formation. Moreover the success of this approach extends to water splitting catalysis where trimetallic based catalysts have demonstrated good performance in hydrogen production. Notably trimetallic catalysts composed of Ni Fe and a third metal prove to be highly efficient in water splitting bypassing the problems associated with traditional catalysts. That is the high material costs of state-of-the-art catalysts as well as the limited activity and stability of alternative ones. Furthermore theoretical methods play a vital role in understanding catalyst activity and/or selectivity as well as in the design of catalysts with improved characteristics. These enable a comprehensive study of the complete reaction mechanism on a target catalyst and help in identifying potential reaction descriptors allowing for efficient screening and selection of catalysts for enhanced hydrogen production. Overall this critical review shows how the exploration of trimetallic catalysts combined with the insights from theoretical methods holds great promise in advancing hydrogen production through renewable means paving the way for sustainable and efficient energy solutions.

This paper presents a novel literature survey on leveraging electrolysis for grid frequency stabilization in power systems with high penetration of renewable energy sources (RESs) uniquely integrating global research findings with specific insights into the Polish energy context—a region facing acute grid challenges due to rapid RES growth and infrastructure limitations. The intermittent nature of wind and solar power exacerbates frequency fluctuations necessitating dynamic demand-side management solutions like hydrogen production via electrolysis. By synthesizing over 30 studies the survey reveals key results: electrolysis systems particularly PEM and alkaline electrolyzers can reduce frequency deviations by up to 50% through fast frequency response (FFR) and primary reserve provision as demonstrated in simulations and real-world pilots (e.g. in France and the Netherlands); however economic viability requires enhanced compensation schemes with current models showing unprofitability without subsidies. Technological advancements such as transistor-based rectifiers improve efficiency under partial loads while integration with RES farms mitigates overproduction issues as evidenced by Polish cases where 44 GWh of solar energy was curtailed in March 2024. The survey contributes actionable insights for policymakers and engineers including recommendations for deploying electrolyzers to enhance grid resilience support hydrogen-based transportation and facilitate Poland’s target of 50.1% RESs by 2030 thereby advancing the green energy transition amid rising instability risks like blackouts in RES-heavy systems.

Maintaining frequency stability is one of the biggest challenges facing future power systems due to the increasing penetration levels of inverter-based renewable resources. This investigation experimentally validates the frequency provision capabilities of a real Polymer Electrolyte Membrane (PEM) hydrogen electrolyser (HE) using a power hardware-in-the-loop (PHIL) setup. The PHIL consists of a custom 3-level interleaved buck converter and a hardware platform for real-time control of the converter and conducting grid simulation associated with the modelling of the future Iberian Peninsula (IP) and Continental Europe (CE) systems. The investigation had the aim of validating earlier simulation work and testing new responses from the electrolyser when providing different frequency services at different provision volumes. The experimental results corroborate earlier simulation results and capture extra electrolyser dynamics as the double-layer capacitance effect which was absent in the simulations. Frequency Containment Reserve (FCR) and Fast Frequency Response (FFR) were provided successfully from the HE at different provision percentages enhancing the nadir and the rate of change of frequency (RoCoF) in the power system when facing a large disturbance compared to conventional support only. The results verify that HE can surely contribute to frequency services paving the way for future grid support studies beyond simulations.

Green hydrogen is widely recognised as a key enabler for decarbonising heavy industry and long-haul transport. However producing it cost-competitively from variable renewable energy sources presents design challenges. In this study a mixed-integer linear programming (MILP) optimisation framework is developed to minimise the levelised cost of hydrogen (LCOH) from renewable-powered electrolysers. The analysis covers all European countries and explores how wind and solar resource availability influences the optimal sizing of renewable generators electrolysers hydrogen storage and batteries under both current and future scenarios. Results show that renewable resource quality strongly affects system design and hydrogen costs. At present solar-only systems yield LCOH values of 7.4–24.7 €/kg whereas wind-only systems achieve lower costs (5.1–17.1 €/kg) due to higher capacity factors and reduced storage requirements. Hybrid systems combining solar and wind emerge as the most cost-effective solution reducing average LCOH by 57 % compared to solar-only systems and 25 % compared to wind-only systems effectively narrowing geographical cost disparities. In the future scenario LCOH declines to 3–4 €/kg confirming renewable hydrogen’s potential to become economically competitive throughout Europe. A key contribution of this work is the derivation of design guidelines by correlating renewable resource quality with technical energy and economic indicators.

Hydrogen is a promising clean energy source that can be a promising alternative to fossil fuels without toxic emissions. It can be generated from formic acid (FA) through an FA dehydrogenation reaction using an active catalyst. Activated carbon-supported palladium (Pd/C) catalyst has superior activity properties for FA dehydrogenation and can be reused after deactivation. This study focuses on predicting the FA conversion to H2 (%) in the presence of Pd/C using machine learning techniques and experimental data (1544 data points). Six different machine learning algorithms are employed including random forest (RF) extremely randomized trees (ET) decision tree (DT) K nearest neighbors (KNN) support vector machine (SVM) and linear regression (LR). Temperature time FA concentration catalyst size catalyst weight sodium formate (SF) concentration and solution volume are considered as the input data while the FA conversion to H2 (%) is the target value. Based on the train and test outcomes the ET is the most accurate model for the prediction of FA conversion to H2 (%) and its accuracy is assessed by root mean squared error (RMSE) R-squared (R2 ) and mean absolute error (MAE) which are 3.16 0.97 and 0.75 respectively. In addition the results reveal that solution volume is the most significant feature in the model development process that affects the amount of FA conversion to H2 (%). These techniques can be used to assess the efficiency of other catalysts in terms of type size weight percentage and their effects on the amount of FA conversion to H2 (%). Moreover the results of this study can be used to optimize the energy cost and environmental aspects of the FA dehydrogenation process.

Solid oxide electrolysis cells (SOEC) system has potential to offer an efficient green hydrogen production technology. However the significant cost of this technology is related to the high operating temperatures materials and thermal management including the waste heat. Recovering the waste heat can be conducted through techniques to reduce the overall energy consumption. This approach aims to improve accuracy and efficiency by recovering and reusing the heat that would otherwise be lost. In this paper thermal energy models are proposed based on waste heat recovery methodologies to utilize the heat from outlet fluids within the SOEC system. The mathematical methods for calculating thermal energy and energy transfer in SOEC systems have involved the principles of heat transfer. To address this different simplified thermal models are developed in Simulink Matlab R2025b. The obtained results for estimating proper thermal energy for heating incoming fluids and recycled heat are discussed and compared to determine the efficient and potential thermal model for improvement the waste heat recovery.

By turning a waste stream into a clean energy source green hydrogen generation from wastewater provides a dual solution to energy and environmental problems. This study presents a thorough bibliometric analysis of research trends in the field of green hydrogen generation from wastewater between 2010 and 2024. A total of 221 publications were extracted from Scopus database and VOSviewer (1.6.20) was used as a visualization tool to identify influential authors institutions collaborations and thematic focus areas. The analysis revealed a significant increase in research output with a peak of 122 publications in 2024 with a total of 705 citations. China had the most contributions with 60 publications followed by India (30) and South Korea (26) indicating substantial regional involvement in Asia. Keyword co-occurrence and coauthorship network mapping revealed 779 distinct keywords grouped around key themes like electrolysis hydrogen evolution reactions and wastewater treatment. Significantly this work was supported by contributions from 115 publication venues with the International Journal of Hydrogen Energy emerging as the most active and cited source (40 articles 539 citations). The multidisciplinary aspect of the area was highlighted by keyword co-occurrence analysis which identified recurring themes including electrolysis wastewater treatment and hydrogen evolution processes. Interestingly the most-cited study garnered 131 citations and discussed the availability of unconventional water sources for electrolysis. Although there is growing interest in the field it is still in its initial phases indicating a need for additional research particularly in developing countries. This work offers a basic overview for researchers and policymakers who are focused on promoting the sustainable generation of green hydrogen from wastewater.

The high efficiency light weight and reliability of hydrogen energy electrochemical equipment are among the future development directions. Membrane electrode assemblies (MEAs) and electrolyzers as key components have structures and strengths that determine the efficiency of their power generation and the hydrogen production efficiency of electrolyzers. This article summarizes the evolution of membrane electrode and electrolyzer structures and their power and efficiency in recent years highlighting the significant role of integrated structures in promoting proton transport and enhancing performance. Finally it proposes the development direction of integrating electrolyte and electrode manufacturing using phase-change methods.

This article proposes a novel open-circuit switch fault diagnosis method (FDM) for a three-level interleaved buck converter (TLIBC) in a hydrogen production system based on the water electrolysis process. The control algorithm is suitably modified to ensure the same hydrogen production despite the fault. The TLIBC enables the interfacing of the power source (i.e. low-carbon energy sources) and electrolyzer while driving the hydrogen production of the system in terms of current or voltage. On one hand the TLIBC can guarantee a continuity of operation in case of power switch failures because of its interleaved architecture. On the other hand the appearance of a power switch failure may lead to a loss of performance. Therefore it is crucial to accurately locate the failure in the TLIBC and implement a fault-tolerant control strategy for performance purposes. The proposed FDM relies on the comparison of the shape of the input current and the pulse width modulation (PWM) gate signal of each power switch. Finally an experimental test bench of the hydrogen production system is designed and realized to evaluate the performance of the developed FDM and fault-tolerant control strategy for TLIBC during post-fault operation. It is implemented with a real-time control based on a MicroLabBox dSPACE (dSPACE Paderborn Germany) platform combined with a TI C2000 microcontroller. The obtained simulation and experimental results demonstrate that the proposed FDM can detect open-circuit switch failures in one switching period and reconfigure the control law accordingly to ensure the same current is delivered before the failure.

Today hydrogen is already widely regarded as up-and-coming source of energy. It is essential to meet energy needs while reducing environmental pollution since it has a high energy capacity and does not emit carbon oxide when burned. However for the widespread application of hydrogen energy it is necessary to search new technical solutions for both its production and storage. A promising effective and cost-efficient method of hydrogen generation and storage can be the use of solid materials including nanomaterials in which chemical or physical adsorption of hydrogen occurs. Focusing on the recommendations of the DOE the search is underway for materials with high gravimetric capacity more than 6.5% wt% and in which sorption and release of hydrogen occurs at temperatures from −20 to +100 ◦C and normal pressure. This review aims to summarize research on hydrogen generation and storage using silicon nanostructures and silicon composites. Hydrogen generation has been observed in Si nanoparticles porous Si and Si nanowires. Regardless of their size and surface chemistry the silicon nanocrystals interact with water/alcohol solutions resulting in their complete oxidation the hydrolysis of water and the generation of hydrogen. In addition porous Si nanostructures exhibit a large internal specific surface area covered by SiHx bonds. A key advantage of porous Si nanostructures is their ability to release molecular hydrogen through the thermal decomposition of SiHx groups or in interaction with water/alkali. The review also covers simulations and theoretical modeling of H2 generation and storage in silicon nanostructures. Using hydrogen with fuel cells could replace Li-ion batteries in drones and mobile gadgets as more efficient. Finally some recent applications including the potential use of Si-based agents as hydrogen sources to address issues associated with new approaches for antioxidative therapy. Hydrogen acts as a powerful antioxidant specifically targeting harmful ROS such as hydroxyl radicals. Antioxidant therapy using hydrogen (often termed hydrogen medicine) has shown promise in alleviating the pathology of various diseases including brain ischemia–reperfusion injury Parkinson’s disease and hepatitis.

Developing cleaner processes via newer technologies will accelerate advancement toward more sustainable energy systems. Hydrogen is an energy carrier and an intermediate molecule in chemical processes. This research investigates an innovative hydrogen production process utilizing a non-thermal Cold Atmospheric Pressure Plasma-based Reformer (CAPR). Exploring environmentally friendly and economically viable pathways for hydrogen production is crucial for addressing climate change and reducing the carbon footprint of industrial processes. The study investigates the conversion of natural gas to hydrogen at ambient temperature and pressure highlighting the ability of plasma-based technology to operate without direct CO2 emissions.<br/>Initially through experimental studies natural gas was passed through the CAPR where the plasma's energetic discharges initiate the reforming process. Subsequently the produced hydrogen along with other light hydrocarbons enters the separation system for producing purified hydrogen. The research focuses on techno-economic analyses and sensitivity assessments to determine the levelized cost of producing hydrogen via a nanosecond plasma-based refining plant and benchmark technologies. Sensitivity analyses identify two primary factors that significantly affect the levelized cost of hydrogen production in a plasma-based reforming system.<br/>The research suggests that instead of producing carbon dioxide and capturing the emitted CO2 utilize processes that do not emit direct CO2. CAPR shows potential for cost competitiveness with conventional hydrogen production methods including steam methane reforming (SMR) and electrolysis. The findings underscore the need for further research to optimize the system's performance and cost-effectiveness positioning CAPR as a potentially transformative technology for the chemical process industry.

Thermo-chemical conversion of waste plastics offers a sustainable strategy for integrated waste management and clean energy generation. To address the challenges of low gas yield and rapid catalyst deactivation due to coking in conventional gasification processes an innovative three-stage chemical looping gasification (CLG) system specifically designed for enhanced hydrogen-rich syngas production was proposed in this work. A comparative analysis between conventional gasification and the staged CLG system were firstly conducted coupled with online gas analysis for mechanistic elucidation. The influence of Fe/Al molar ratios in oxygen carriers and their cyclic stability were systematically examined through multicycle experiments. Results showed that the three-stage CLG in the presence of Fe1Al2 demonstrated exceptional performance achieving 95.23 mmol/gplastic of H2 and 129.89 mmol/gplastic of syngas respectively representing 1.32-fold enhancement over conventional method. And the increased H2/CO ratio (2.68-2.75) reflected better syngas quality via water-gas shift. Remarkably the oxygen carrier maintained nearly 100% of its initial activity after 7 redox cycles attributed to the incorporation of Al2O3 effectively mitigating sintering and phase segregation through metal-support interactions. These findings establish a three-stage CLG configuration with Fe-Al oxygen carriers as an efficient platform for efficient hydrogen production from waste plastics contributing to sustainable waste valorisation and carbon-neutral energy systems.

This paper investigates the circularity of green hydrogen and resource recovery from brine using an integrated approach based on alkaline water electrolysis (AWE). Traditional AWE employs highly alkaline electrolytes which can lead to electrode corrosion undesirable side reactions and gas cross-over issues. Conversely indirect brine electrolysis requires pre-treatment steps which negatively impact both techno-economics and environmental sustainability. In response this study proposes an innovative brine electrolysis process utilizing solid electrolytes (SELs). The process includes an on-site brine treatment facility leveraging a self-driven phase transition technique and incorporates a hydrophobic membrane as part of a membrane distillation (MD) system to facilitate the gas pathway. Polyvinyl alcohol (PVA) and tetraethylammonium hydroxide (TEAOH)-based electrolytes combined with potassium hydroxide (KOH) at various concentrations function as a self-wetted electrolyte (SWE). This design partially disperses water vapor while effectively preventing the intrusion of contaminated ions into the SWE and electrode-catalyst interfaces. PVA-TEAOH-KOH-30 wt% SWE demonstrated the highest ion conductivity (112.4 mScm−1) and excellent performance with a current density of 375 mAcm−2. Long-term electrolysis confirmed with a nine-fold brine in volume concentration factor (VCF) demonstrated stable performance without MD membrane wetting. The Cl−/ClO− and Br− concentrations in the SWE were reduced by five orders of magnitude compared to the original brine. This electrolyzer supports the circular use of resources with hydrogen as an energy carrier and concentrated brine and oxygen as valuable by-products aligning with the sustainable development goals (SDGs) and net-zero emissions by 2050.

Hydrogen production is increasingly vital for global decarbonization but remains a waterand energy-intensive process especially in arid regions. Despite growing attention to its climate benefits limited research has addressed the environmental impacts of water sourcing. This study employs a life cycle assessment (LCA) approach to evaluate three water supply strategies for hydrogen production: (1) seawater desalination without brine treatment (BT) (2) desalination with partial BT and (3) freshwater purification. Scenarios are modeled for the United Arab Emirates (UAE) Australia and Spain representing diverse electricity mixes and water stress conditions. Both electrolysis and steam methane reforming (SMR) are evaluated as hydrogen production methods. Results show that desalination scenarios contribute substantially to human health and ecosystem impacts due to high energy use and brine discharge. Although partial BT aims to reduce direct marine discharge impacts its substantial energy demand can offset these benefits by increasing other environmental burdens such as marine eutrophication especially in regions reliant on carbon-intensive electricity grids. Freshwater scenarios offer lower environmental impact overall but raise water availability concerns. Across all regions feedwater for SMR shows nearly 50% lower impacts than for electrolysis. This study focuses solely on the environmental impacts associated with water sourcing and treatment for hydrogen production excluding the downstream impacts of the hydrogen generation process itself. This study highlights the trade-offs between water sourcing brine treatment and freshwater purification for hydrogen production offering insights for optimizing sustainable hydrogen systems in water-stressed regions.

Minimizing carbon dioxide emissions is crucial due to the generation of energy from fossil fuels. The significance of carbon capture and storage (CCS) technology which is highly successful in mitigating carbon emissions has increased. On the other hand hydrogen is an important energy carrier for storing and transporting energy and technologies that rely on hydrogen have become increasingly promising as the world moves toward a more environmentally friendly approach. Nevertheless the integration of CCS technologies into power production processes is a significant challenge requiring the enhancement of the combined power generation–CCS process. In recent years there has been a growing interest in process intensification (PI) which aims to create smaller cleaner and more energy efficient processes. The goal of this research is to demonstrate the process intensification potential and to model and simulate a hybrid integrated–intensified adsorptive-membrane reactor process for simultaneous carbon capture and hydrogen production. A comprehensive multi-scale multi-phase dynamic computational fluid dynamics (CFD)-based process model is constructed which quantifies the various underlying complex physicochemical phenomena occurring at the pellet and reactor levels. Model simulations are then performed to investigate the impact of dimensionless variables on overall system performance and gain a better understanding of this cyclic reaction/separation process. The results indicate that the hybrid system shows a steady-state cyclic behavior to ensure flexible operating time. A sustainability evaluation was conducted to illustrate the sustainability improvement in the proposed process compared to the traditional design. The results indicate that the integrated–intensified adsorptive-membrane reactor technology enhances sustainability by 35% to 138% for the chosen 21 indicators. The average enhancement in sustainability is almost 57% signifying that the sustainability evaluation reveals significant benefits of the integrated–intensified adsorptive-membrane reactor process compared to HTSR + LTSR.

Simultaneous saccharification and fermentation (SSF) and pre-hydrolysis with SSF (PSSF) were used to produce hydrogen from the biomass of Chlorella sp. SSF was conducted using an enzyme mixture consisting of 80 filter paper unit (FPU) g-biomass−1 of cellulase 92 U g-biomass−1 of amylase and 120 U g-biomass−1 of glucoamylase at 35 ◦C for 108 h. This yielded 170 mL-H2 g-volatile-solids−1 (VS) with a productivity of 1.6 mL-H2 g-VS−1 h −1 . Pre-hydrolyzing the biomass at 50 ◦C for 12 h resulted in the production of 1.8 g/L of reducing sugars leading to a hydrogen yield (HY) of 172 mL-H2 g-VS−1 . Using PSSF the fermentation time was shortened by 36 h in which a productivity of 2.4 mL-H2 g-VS−1 h −1 was attained. To the best of our knowledge the present study is the first report on the use of SSF and PSSF for hydrogen production from microalgal biomass and the HY obtained in the study is by far the highest yield reported. Our results indicate that PSSF is a promising process for hydrogen production from microalgal biomass.

To enable a sustainable and socially accepted hydrogen and methanol economy it is crucial to prioritize green and water-conscious production. In this review we reveal that there is a significant research gap regarding comprehensive assessments of such production methods. We present an innovative process chain consisting of adsorption-based direct air capture solid oxide electrolysis and methanol synthesis to address this issue. To allow future comprehensive techno-economic assessments we perform a systematic literature review and harmonization of the techno-economic parameters of the process chain’s technologies. Based on the conducted literature review we find that the long-term median specific energy demand of adsorption-based direct air capture is expected to decrease to 204 kWhel/tCO2 and 1257 kWhth/tCO2 while the capture cost is expected to decrease to 162 €2024/tCO2 with a relative high uncertainty. The evaluated sources expect a future increase in system efficiency of solid oxide electrolysis to 80% while the purchase equipment costs are expected to decrease significantly. Finally we demonstrate the feasibility of the process chain from a technoeconomic perspective and show a potential reduction in external heat demand of the DAC unit of up to 34% when integrated in the process chain.

Chemical looping hydrogen generation (CLHG) from biomass is a promising technology for producing carbonnegative hydrogen. However achieving autothermal operation without sacrificing hydrogen yield presents a significant thermodynamic challenge. This study proposes and evaluates a novel thermal management strategy that enables a self-sustaining process by balancing the system’s heat load with its internal exothermic reactions. A comprehensive analysis was conducted using process simulation to assess the system’s thermodynamic performance identify key sources of inefficiency through exergy analysis and determine its economic viability via a detailed techno-economic assessment. The results show that a 200 MWth CLHG plant can produce 2.06 t-H2/h with a hydrogen production efficiency and exergy efficiency of 34.46 % and 44.4 % respectively. The exergy analysis identified the fuel reactor as the largest source of thermodynamic inefficiency accounting for 66.4 % of the total exergy destruction. The techno-economic analysis yielded a base-case minimum selling price (MSP) of hydrogen of 2.63 USD/kg a rate competitive with other carbon-capture-enabled hydrogen production methods. Sensitivity analysis confirmed that the MSP is most influenced by biomass price and discount rate. Crucially the system’s carbon-negative nature allows it to leverage carbon pricing schemes which can significantly improve its economic performance. Under the EU’s current carbon price the MSP falls to 0.98 USD/kg-H2 and it can become negative in regions with higher carbon taxes suggesting profitability from carbon credits alone. This study demonstrates that the proposed CLHG system is a technically robust and economically compelling pathway for clean hydrogen production particularly in regulatory environments that incentivize carbon capture.

This study presents a thermodynamic equilibrium analysis of hydrogen-rich syngas production via biomass–methane co-pyrolysis employing the Gibbs free energy minimization method. A critical temperature threshold at 700 ◦C is identified below which methanation and carbon deposition are thermodynamically favored and above which cracking and reforming reactions dominate enabling high-purity syngas generation. Methane addition shifts the reaction pathway towards increased reduction significantly enhancing carbon and H2 yields while limiting CO and CO2 emissions. At 1200 ◦C and a 1:1 methane-tobiomass ratio cellulose produces 50.84 mol C/kg 119.69 mol H2/kg and 30.65 mol CO/kg; lignin yields 78.16 mol C/kg 117.69 mol H2/kg and 19.14 mol CO/kg. The H2/CO ratio rises to 3.90 for cellulose and 6.15 for lignin with energy contents reaching 43.16 MJ/kg and 52.91 MJ/kg respectively. Notably biomass enhances methane conversion from 25% to over 53% while sustaining a 67% H2 selectivity. These findings demonstrate that syngas composition and energy content can be precisely controlled via methane co-feeding ratio and temperature offering a promising approach for sustainable tunable syngas production.

Alkaline water electrolysis (AWE) is the most mature electrochemical technology for hydrogen production from renewable electricity. Thus its mathematical modeling is an important tool to provide new perspectives for the design and optimization of energy storage and decarbonization systems. However current models rely on numerous empirical parameters and neglect variations of temperature and concentration alongside the electrolysis cell which can impact the application and reliability of the simulation results. Thus this study proposes a simple four-parameter semi-empirical model for AWE system analysis which relies on minimal fitting data while providing reliable extrapolation results. In addition the effect of model dimensionality (i.e. 0D 1/2D and 1D) are carefully assessed in the optimization of an AWE system. The results indicate that the proposed model can accurately reproduce literature data from four previous works (R 2 ≥ 0.98) as well as new experimental data. In the system optimization the trade-offs existing in the lye cooling sizing highlight that maintaining a low temperature difference in AWE stacks (76-80°C) leads to higher efficiencies and lower hydrogen costs.

The Kingdom of Saudi Arabia has rich renewable energy resources specifically wind and solar in addition to geothermal beside massive natural gas reserves. This paper investigates the potential of both green and blue hydrogen production for five selected cities in Saudi Arabia. To accomplish the said objective a techno-economic model is formulated. Four renewable energy scenarios are evaluated for a total of 1.9 GW installed capacity to reveal the best scenario of Green Hydrogen Production (GHP) in each city. Also Blue Hydrogen Production (BHP) is investigated for three cases of Steam Methane Reforming (SMR) with different percentages of carbon capture. The economic analysis for both GHP and BHP is performed by calculating the Levelized Cost of Hydrogen (LCOH) and cash flow. The LCOH for GHP range for all cities ($3.27/kg -$12.17/kg)) with the lowest LCOH is found for NEOM city (50% PV and 50% wind) ($3.27/kg). LCOH for BHP are $0.534/kg $0.647/kg and $0.897/kg for SMR wo CCS/U SMR 55% CCS/U and SMR 90% CCS/U respectively.

Proton exchange membrane water electrolyzer (PEMWE) represents a promising technology for the sustainable production of hydrogen which is capable of efficiently coupling to intermittent electricity from renewable energy sources (e.g. solar and wind). The technology with compact stack structure has many notable advantages including large current density high hydrogen purity and great conversion efficiency. However the use of expensive electrocatalysts and construction materials leads to high hydrogen production costs and limited application. In this review recent advances made in key materials of PEMWE are summarized. First we present a brief overview about the basic principles thermodynamics and reaction kinetics of PEMWE. We then describe the cell components of PEMWE and their respective functions as well as discuss the research status of key materials such as membrane electrocatalysts membrane electrode assemblies gas diffusion layer and bipolar plate. We also attempt to clarify the degradation mechanisms of PEMWE under a real operating environment including catalyst degradation membrane degradation bipolar plate degradation and gas diffusion layer degradation. We finally propose several future directions for developing PEMWE through devoting more efforts to the key materials.

The present work aims to develop a novel integrated energy system to produce clean hydrogen power and biochar. The Palmaria palmata a type of seaweed and hydrogen sulfide from the industrial gaseous waste streams are taken as potential feedstock. A combined thermochemical approach is employed for the processing of both feedstocks. For clean hydrogen production the zinc sulfide thermochemical cycle is employed. Both stoichiometric and non-stoichiometric equilibrium-based models of the proposed plant design are developed in the Aspen Plus software and a comprehensive thermodynamic analysis of the system is also performed by evaluating energy and exergy efficiencies. The study further explores the modeling simulation and parametric analyses of various subsections to enhance the hydrogen and biochar production rate. The parametric analyses show that the first step of the thermochemical cycle (sulfurization reaction) follows stoichiometric pathway and the ZnO to H2S ratio of 1 represents the optimal point for reactant conversion. On the other hand the second step of the thermochemical cycle (regeneration reaction) does not follow a stoichiometric pathway and ZnS conversion of 12.87% is achieved at a high temperature of 1400oC. It is found that a hydrogen production rate of 0.71 mol/s is achieved with the introduction of 0.27 mol/s of H2S. The energy and exergy efficiencies of the zinc sulfide thermochemical cycle are found to be 65.23% and 35.58% respectively. A biochar production rate of 0.024 kg/s is obtained with the Palmaria palmata fed rate of 0.097 kg/s. The Palmaria to biochar energy and exergy efficiencies are found to be 55.43% and 45.91% respectively. The overall energy and exergy efficiencies of the proposed plant are determined to be 72.88% and 50.03% respectively.