Production & Supply Chain

Previous studies have demonstrated the potential benefit of a future hydrogen economy in terms of reducing CO2 emissions. The hydrogen leakage rate and the green hydrogen fraction in the mix were identified as key factors in maximising the climate benefit of this energy transition. This study highlights the importance of blue hydrogen production hypotheses for a climate-beneficial transition to a hydrogen economy. The benefits are substantial when blue hydrogen is produced properly using an efficient CO₂ sequestration hydrogen production plant and minimizing the rate of upstream CH₄ leakage. The rate of hydrogen leakage remains an important parameter to consider throughout the entire value chain. Based on various scenarios of the development of a 21st century hydrogen economy we estimate significant CO₂ emission reductions of 266–418 GtCO₂eq (up to 395–675 GtCO2eq in the case of a “high hydrogen demand” scenario) between 2030 and 2100. This cumulative reduction in CO₂ emissions translates into a reduction in global warming of 0.12–0.19 °C (0.18–0.30 °C for a “high hydrogen demand”) by the end of the century.

Ammonia (NH3) decomposition offers a pathway for water purification and green hydrogen production yet conventional catalysts often suffer from poor stability due to agglomeration. This study presents a novel (FeCoNiCuMn)O high-entropy ceramic (HEC) catalyst synthesized via fast-moving bed pyrolysis (FMBP) which prevents aggregation and enhances catalytic performance. The HEC catalyst applied as an anode in electrochemical oxidation (EO) demonstrated a uniform spinel (AB2O4) structure confirmed by XRD XRF and ICP-OES. Electronic structure characterization using UPS and LEIPS revealed a bandgap of 4.722 eV with EVBM and ECBM values facilitating redox reactions. Under 9 V and 50 mA/cm² current density the HEC electrode achieved 99% ammonia decomposition within 90 min and retained over 90% efficiency after four cycles. Surface analysis by XPS and HAXPES indicated oxidation state variations confirming catalyst activity and stability. Gas chromatography identified H2 N2 and O2 as the main products with ~64.7% Faradaic efficiency for H2 classifying it as green hydrogen. This dual-function approach highlights the (FeCoNiCuMn)O HEC anode as a promising and sustainable solution for wastewater treatment and hydrogen production.

A two-stage system is used for hydrogen (H2) and methane (CH4) production from sucrose wastewater. The H2- producing reactor is operated at pH temperature (T) and hydraulic retention time (HRT) of 5.5 35 ◦C 24 h respectively. While operating conditions of 7–8 pH 35 ◦C T and 144 h HRT are used to conduct the CH4 production stage. The effects of two different parameters as sucrose concentration (5 10 and 20 g/L) and addition of ferrous ions (60 and 120 mg/L) are investigated. Both H2 and CH4 productions are increased at high sucrose concentrations. However the optimum H2 and CH4 yields of 163.2 mL-H2/g-sucrose and 211.8 mL-CH4/g-TVS are obtained at 5 g-sucrose/L. At 5 g-sucrose/L addition of Fe2+ increases the H2 yield to 192.5 and 176.2 mLH2/g-sucrose corresponding to 60 and 120 mg-Fe2+/L respectively. Higher removal efficiencies and total energy recovery are measured using the two-stage system than the single-stage reactor.

While hydrogen production through pure water splitting remains a key focus in solar hydrogen research photocatalytic seawater splitting presents a more sustainable alternative better aligned with global development goals amid increasing freshwater scarcity. Nevertheless the deactivation of the photocatalyst by the corrosion of various ions present in seawater as well as the chloride ions’ redox side reaction limits the practical use of the photocatalytic seawater splitting process. In this context sulfur has emerged as a crucial component in photocatalytic composites for seawater splitting owing to its unique chemical properties. It acts as a chlorine-repulsive agent effectively suppressing chloride ion oxidation which mitigates corrosion enhances structural stability and significantly improves overall photocatalytic performance in saline environments. This review offers a thorough explanation of the basic ideas of solar-driven seawater splitting delves into various synthesis strategies and explores recent advancements in sulfur-based composites for efficient hydrogen generation using seawater. Optimizing synthesis techniques and incorporating strategies like doping cocatalyst and heterojunctions significantly enhance the performance of sulfur-based photocatalysts for seawater splitting. Future advances include integrating AI-guided material discovery sustainable use of industrial sulfur waste and precise control of sacrificial agents to ensure long-term efficiency and stability.

This study presents a techno-economic framework for assessing the potential of utilizing hybrid renewable energy sources (wind and solar) to produce green hydrogen with a specific focus on Australia. The model’s objective is to equip decision-makers in the green hydrogen industry with a reliable methodology to assess the availability of renewable resources for cost-effective hydrogen production. To enhance the credibility of the analysis the model integrates 10 min on-ground solar and wind data uses a high-resolution power dispatch simulation and considers electrolyzer operational thresholds. This study concentrates on five locations in Australia and employs high-frequency resource data to quantify wind and solar availability. A precise simulation of power dispatch for a large off-grid plant has been developed to analyze the PV/wind ratio element capacities and cost variables. The results indicate that the locations where wind turbines can produce cost-effective hydrogen are limited due to the high capital investment which renders wind farms uneconomical for hydrogen production. Our findings show that only one location—Edithburgh South Australia—under a 50% solar–50% wind scenario achieves a hydrogen production cost of 10.3 ¢USD/Nm3 which is lower than the 100% solar scenario. In the other four locations the 100% solar scenario proves to be the most cost-effective for green hydrogen production. This study suggests that precise and comprehensive resource assessment is crucial for developing hydrogen production plants that generate low-cost green hydrogen.

The electrochemical modelling of proton exchange membrane electrolyzers (PEMEZs) relies on the precise determination of several unknown parameters. Achieving this accuracy requires addressing a challenging optimization problem characterized by nonlinearity multimodality and multiple interdependent variables. Thus a novel approach for determining the unknown parameters of a detailed PEMEZ electrochemical model is proposed using the weighted mean of vectors algorithm (WMVA). An objective function based on mean square deviation (MSD) is proposed to quantify the difference between experimental and estimated voltages. Practical validation was carried out on three commercial PEMEZ stacks from different manufacturers (Giner Electrochemical Systems and HGenerators™). The first two stacks were tested under two distinct pressure-temperature settings yielding five V–J data sets in total for assessing the WMVA-based model. The results demonstrate that WMVA outperforms all optimizers achieving MSDs of 1.73366e−06 1.91934e−06 1.09306e−05 6.18248e−05 and 4.41586e−06 corresponding to improvements of approximately 88% 82.9% 82.4% 54.5% and 59.5% over the poorest-performing algorithm in each case respectively. Moreover comparative analyses statistical studies and convergence curves confirm the robustness and reliability of the proposed optimizer. Additionally the effects of temperature and hydrogen pressure variations on the electrical and physical steady-state performance of the PEMEZ are carefully investigated. The findings are further reinforced by a dynamic simulation that illustrates the impact of temperature and supplied current on hydrogen production. Accordingly the article facilitates better PEMEZ modelling and optimizing hydrogen production performance across various operating conditions.

Solid oxide electrolysers (SOEs) can decarbonise H2 supply when powered by renewable electricity but remain constrained by high electrical demand and integration penalties. Our objective is to minimise the electrical (Pel) and thermal (Qth) energy demand per mole of H2 by jointly tuning cell temperature steam fraction steam utilisation pressure and current density. Compared with prior single-variable or thermo-neutral-constrained studies we develop and validate a steady-state process-level optimisation framework that couples an Aspen Plus SOE model with electrochemical post-processing and heat caused by ohmic resistance recovery. A Box–Behnken design explores five key operating parameters to capture synergies and trade-offs between Qth and Pel energy inputs. Single-objective optimisation yields Pel = 170.1 kJ mol⁻¹ H2 a 41.4% reduction versus literature baselines. Multi-objective optimisation using an equal-weighted composite desirability function aggregating thermal and electrical demands further reduces Pel by 21.2% while balancing thermal input 4–8% lower than single-objective baselines at moderate temperature (~781 °C) and pressure (~17.5 bar). Findings demonstrate a clear process intensification advantage over previous studies by simultaneously leveraging operating parameter synergies and heat-integration. However results are bounded by steady-state perfectly mixed isothermal assumptions. The identified operating windows are mechanistically grounded targets that warrant stack-scale and plantlevel validation.