Production & Supply Chain

This study presents an experimental approach to modelling PEM electrolysers for green hydrogen production using solar energy. The objective is to implement a temperature steady-state electrolyser model to assess the optimal coupling configuration with a photovoltaic plant and estimate the yearly hydrogen production capacity. The research focuses on the energy consumption of ancillary systems under different load conditions developing a steady-state operational model that improves hydrogen production predictions by accounting for these consumptions. The model based on polynomial equations captures the non-linear variation in energy costs under partial load conditions. PEM electrolysers produce hydrogen above 3.0 quality (99.9% purity) and it is feasible to integrate purification processes to reach 5.0 quality (99.999% purity). While small-scale systems include purification large-scale facilities separate it enabling process optimisation. Two models are introduced to estimate hydrogen mass flow depending on purity: a base-purity model and a high-purity model that includes drying and pressure swing adsorption. Both are based on experimental data from a five-year-old small-scale electrolyser and are applicable to large-scale systems at partial load. Due to test conditions the model applied to large-scale facilities underestimates hydrogen production affected by energy losses from a non-optimised purification process and electrolyser degradation. Model validation with large-scale operational data from the literature shows the model captures plant behaviour well despite the consistent underestimation described above. The model is applied to several European locations to identify optimal photovoltaic-to-electrolyser ratios. Oversizing factors between 1.4 and 2 are needed to cover ancillary consumption. The levelised cost remains comparable for both purity levels despite higher energy demands for high-purity hydrogen due to the greater cost of the electrolyser over the photovoltaic plant.

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.

Hydrogen (H2) is an attractive fuel due to its high specific energy and zero direct carbon emissions. Membraneless electrolyzers (MEs) offer a lower-cost route to hydrogen production but their operation is complex and current efficiencies are modest. Although multi-objective optimization is widely used its heavy compute demands and weak integration with modern learning methods limit scalability and adaptability. We introduce a practical ML-guided way to design Tesla-valve (TV) membraneless electrolyzers by building diodicity (Di) directly into the geometry search. Using multilayer-perceptron surrogates trained on 150 high-fidelity simulations (R2 > 0.95) we link four design knobs (We Wc Wd Di) to pressure drop (Δp) and ohmic loss. A Genetic Algorithm (GA)-based multi-objective search over realistic ranges delivers 60 Pareto-optimal designs that make the Δp–ohmic trade-off explicit; TOPSIS then selects a balanced geometry (We = 1.708 mm Wc = 0.200 mm Wd = 1.012 mm Di = 1.618) with ohmic loss 4.069 V and Δp 6.169 Pa. The approach delivers faster lower-cost design maps and is supported by experimental checks pointing to an actionable route for scalable interpretable optimization of sustainable hydrogen production.

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 rational design of Cu-based catalysts with tailored interfacial structures and electronic states remains challenging yet essential for advancing hydrogen production via methanol steam reforming (MSR). Here we developed a samarium-mediated strategy to construct a 30Sm-CuAl catalyst. The introduction of Sm promotes Cu dispersion and induces strong metal-support interactions resulting in the formation of Sm2O3- encapsulated Cu nanoparticles enriched with Cu+ -O-Sm interfaces. The optimized 30Sm-CuAl demonstrates exceptional MSR performance achieving a hydrogen production rate of 1126 mmol gcat− 1 h− 1 at 250◦C. Mechanistic studies revealed that the reaction follows the formate pathway in xSm-CuAl with formate accumulation identified as the primary reason for the deactivation of 30Sm-CuAl. Dynamic regeneration of 30SmCuAl through redox treatment restores its activity thereby enabling cyclic operation. These findings provide insights into rare-earth oxide regulation of Cu-based catalysts and lay the foundation for targeted resolution of formate intermediate accumulation to enhance MSR stability.

A well-developed hydrogen infrastructure is a key element for the global energy transition. The strategic implementation of this infrastructure is challenging due to the wide range of different criteria which need to be considered and analyzed. This paper presents a novel multi-criteria analysis framework for the optimal localization of power-to-gas (PtG) plants. The framework considers criteria such as renewable energy availability hydrogen demand proximity to existing gas infrastructure and groundwater availability. A techno-economic model is integrated into the framework to evaluate the levelized cost of hydrogen (LCOH) for different electrolyzer technologies. Applying the developed framework to Germany the potential of northern and northwestern Germany as suitable locations becomes apparent. In addition LCOH for PtG plants at selected locations in Germany are evaluated depending on the year of commissioning. The large differences between present LCOH ranging from 16.8 €/kg to 9.1 €/kg illustrate the importance of an integrated techno-economic model.

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.

The development of durable and efficient catalysts capable of driving both hydrogen and oxygen evolution reactions is essential for advancing sustainable hydrogen production through overall water electrolysis. In this study we developed a corrosion-mediated approach where Ni ions originate from the self-corrosion of the nickel foam (NF) substrate to construct Pt-modified NiFe layered double hydroxide (Pt-NiFeOxHy@NiFe-LDH) under ambient conditions. The obtained catalyst exhibits a hierarchical architecture with abundant defect sites which favor the uniform distribution of Pt clusters and optimized electronic configuration. The Pt-NiFeOxHy@NiFe-LDH catalyst constructed through the interaction between Pt sites and defective NiFe layered double hydroxide (NiFe-LDH) demonstrates remarkable hydrogen evolution reaction (HER) activity delivering an overpotential as low as 29 mV at a current density of 10 mA·cm−2 and exhibiting a small tafel slope of 34.23 mV·dec−1 in 1 M KOH together with excellent oxygen evolution reaction (OER) performance requiring only 252 mV to reach 100 mA·cm−2 . Moreover the catalyst demonstrates outstanding activity and durability in alkaline seawater maintaining stable operation over long-term tests. The Pt-NiFeOxHy@NiFe-LDH electrode when integrated into a two-electrode system demonstrates operating voltages as low as 1.42 and 1.51 V for current densities of 10 and 100 mA·cm−2 respectively and retains outstanding stability under concentrated alkaline conditions (6 M KOH 70 ◦C). Overall this work establishes a scalable and economically viable pathway toward high-efficiency bifunctional electrocatalysts and deepens the understanding of Pt-LDH interfacial synergy in promoting water-splitting catalysis.

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.

An industrially relevant method for obtaining hydrogen from hydrocarbons without emitting carbon into the atmosphere involves ethanol-steam reforming followed by carbon capture. Herein we present a detailed conceptual process using ethanol-stream reforming to produce blue hydrogen integrated with a carbon capture plant followed by a techno-economic analysis. In the first step the Aspen plus-based simulation of ethanolstream reforming reactions is performed to optimize the reforming reactor geometrical parameters for a 10 t/ day of hydrogen production. Afterward the carbon capture system was designed with a standalone absorber and stripper which were subsequently integrated for solvent makeup calculation. Considering the target value of hydrogen production the optimized reactor diameter and length were found to be 0.18 and 2 m respectively corresponding to reactant flow (200 t/day) and heat duty (3.14 MW) at optimal circumstances. Absorber and stripper packing heights of 12.2 m and 5 m respectively with column diameters of 1.22 m and 2.60 m are required to extract 95 % CO2 from the reformed product stream. The techno-economic analysis indicates that the cost of producing one kilogram of H2 is $3.5. The computed internal rate of return is 16.6 % the discounted payback period is 6 years and the net present value is $13 million.