Renewable hydrogen is increasingly promoted as a key component of sustainable low-emission energy systems; however, its realistic role remains highly dependent on national system conditions. This review examines under what circumstances renewable hydrogen can effectively contribute to Poland’s low-emission energy transition, given its coal-dominated electricity mix, energy-intensive industrial structure, and evolving regulatory environment. The article adopts a system-oriented review approach that integrates recent European Union and national policy developments, including RED III and related delegated acts, with technological pathways, infrastructure readiness, safety considerations, and sectoral demand. Particular attention is given to electricity–hydrogen–industry coupling and the system-level conditions that determine the technical feasibility, efficiency losses, and economic viability of renewable hydrogen deployment. The review demonstrates that renewable hydrogen in Poland is unlikely to become a universal decarbonization solution. Its effective deployment is conditional on accelerated renewable electricity expansion, coordinated development of hydrogen transport and storage infrastructure, and regulatory alignment with EU frameworks. In the short and medium term, the highest system value lies in substituting fossil-based hydrogen in existing industrial applications, while in the longer-term hydrogen may support system flexibility and the decarbonization of hard-to-electrify sectors. Technology-neutral policy approaches may facilitate early market formation but risk reinforcing technology lock-in effects if maintained in the long term. These findings suggest that renewable hydrogen should be positioned as a complementary element of Poland’s low-emission energy system, requiring targeted, system-integrated policy and investment strategies rather than broad, technology-neutral deployment.

The large-scale integration of wind turbine generators (WTGs) and photovoltaic (PV) generation increases operational uncertainty and can exacerbate stability limitations in weak transmission networks, motivating the use of green hydrogen energy storage systems (HESS). This paper presents a probabilistic planning framework for the joint siting and sizing of HESS to support hybrid WTG–PV integration under stochastic wind, solar irradiance, and load conditions. The proposed framework explicitly couples Monte Carlo-based probabilistic power flow with weak-grid security constraints by enforcing FVSI-based voltage-stability limits and an SSI-based system-strength requirement within the optimization loop, rather than treating these indices as post-analysis checks. The planning problem is formulated using a weighted-sum scalarization to minimize life-cycle carbon footprint and active power losses, subject to security constraints based on the Fast Voltage Stability Index (FVSI) and a system-strength constraint expressed through a System Strength Index (SSI). To solve the resulting constrained, nonlinear optimization problem, a sequential hybrid metaheuristic that couples Whale Optimization (exploration) with Osprey Optimization (exploitation) is developed. The framework is implemented in MATLAB using MATPOWER and evaluated on a modified IEEE 39-bus system. Simulation results report an annual carbon footprint of 22.16 Mt CO2eq/yr, an improvement of 9.2% and 5.3% relative to PSO and GA/PSO baselines, respectively, while increasing the weakest-bus SSI to 4.68 (bus 7). The resulting HESS design comprises a 296.9 MW electrolyzer, a 262.7 MW fuel cell, and 28,012 kg of hydrogen storage.

ABSTRACT The escalating generation of multilayer packaging waste presents significant environmental challenges due to their complex laminated structure comprising paperboard, polyethylene, and aluminum foil. This study presents a novel integrated hydrolysis-calcination pathway for complete valorization of Aluminun multilayer pakaging waste, achieving simultaneous production of green hydrogen and β-alumina solid electrolyte. Following hot water separation of the paperboard fraction, the LDPE/aluminum laminate undergoes alkaline hydrolysis, generating hydrogen gas with a yield of 97.5% (215 mL from 5.9 g waste) while preserving intact LDPE film for direct mechanical recycling. Kinetic analysis reveals that increasing NaOH concentration reduces activation energy from 26.2 kJ/mol (1M) to 12.7 kJ/mol (4M). The resulting sodium aluminate solution is transformed into pure β-alumina (NaAl₁₁O₁₇) phase via controlled precipitation at pH 9 and calcination at 1000°C. Comprehensive characterization (XRD, SEM-EDS, FTIR, TGA, photoluminescence) confirms good material quality suitable for advanced energy storage applications. This zero-waste process exemplifies circular economy principles, converting challenging multilayer packaging into four high-value products: renewable hydrogen fuel, advanced battery electrolyte material, recycled polymers, and cellulosic feedstock.

Interlinkages between cryptocurrency classes and the hydrogen economy: New diversification insights from a partial correlation-based connectedness approach

Coordinated frequency regulation scheme for renewable integrated green hydrogen hubs

Magnesium-doping modulates the electronic structure of copper sulfide nanoparticles in nitrogen-doped hierarchical porous carbon for efficient overall water splitting.

Spatially coupled Ni2P/CoP-8 heterostructures with superwetting interfaces for high current density overall water splitting.

Upscaling of the renewable hydrogen economy: A study on complex adaptive systems

A cross-regional analysis of policies, regulations, and incentives from the United States, the European Union, China, and Australia for shaping hydrogen economy

Intensified steam reforming of a simulated bio-oil for renewable hydrogen production over CeO2-promoted Ni/CaO bifunctional material: Experimental kinetics and reactor modeling

The production of hydrogen fuel via water electrolysis has emerged as one of the energy conversion technique to alleviate the global energy scarcity. The search for non-noble metal based active electrocatalyst to accelerate water electrolysis process has become one of the challenging task. Here, a suitable and facile one-step solvothermal method has been followed for the growth of Cd based pristine metal organic frameworks (MOFs) onto nickel foam (NF). The binder-free three-dimensional (3D) Cd (II)-BPFA-MOF/NF electrode exhibits an excellent performance toward urea-assisted water splitting. The electrocatalyst Cd (II)-BPFA-MOF/NF showed an overpotential of 148 and 420 mV at benchmark current density of 10 mA cm-2 in 1 M KOH medium for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. At the same time, Cd (II)-BPFA-MOF/NF exhibit only 1.59 V for urea oxidation reaction (UOR) at benchmark current density in 1 M KOH and 0.33 M urea medium. The Cd (II)-BPFA-MOF/NF || Cd (II)-BPFA-MOF/NF bifunctional electrodes demands only 1.54 V potential to achieve a current density of 10 mA cm-2 toward urea-assisted overall water splitting reaction (UOWS) with remerkable long-term stability. Therefore, this work represents application of a waste to wealth approach toward Cd-based sustainable electrocatalyst for renewable hydrogen production.

High-rate ammonium removal and recovery and hydrogen production from wastewater using microbial electrolysis cell.

Renewable Hydrogen storage pathways for decentralized energy systems in remote Indian communities: A review of technologies, optimization strategies, and policy perspectives

Next-generation control for electrolyzers: a review of GPT-based AI frameworks in renewable hydrogen systems

Decarbonizing power generation is accomplished through coupling renewable energy with long term energy storage, primarily through the use of a hydrogen electricity coupling system. This paper considers the effectiveness in mitigation of carbon emissions, power quality enhancement and balancing supply demand variability of such systems. Smoothing of energy availability over time is achieved when we store hydrogen, and the initial carbon emissions decrease when we install it. Power quality metrics such as voltage stability, harmonic distortion, and reactive power management are acceptable in the system and the system is technically viable. The findings reveal a potential of mid-century carbon neutral goals are revealed by hydrogen as a reliable energy vector. Basically, the study gives a hydrogen-electricity coupling model that integrates wind, solar, biomass, and other renewable energy sources, hydrogen production, storage, and grid power delivery as one operational structure. The simulations conducted on MATLAB/Simulink showed with good quality and fast response that the system possessed stable power quality and performed energy conversion efficiently with whatever the variable renewable input conditions were.

The transition to net-zero emissions hinges on circular economy strategies that valorize waste and enhance resource efficiency. Among X-to-liquid (XTL) technologies, the Fischer-Tropsch (FT) process stands out for converting biomass, waste, and CO2 into hydrocarbons and chemicals, especially when powered by renewable hydrogen. Cobalt-based catalysts are preferred in FT synthesis due to their efficiency and CO2 tolerance, yet their catalytic performance is closely tied to their polymorphic structuresface-centered cubic (FCC), hexagonal close-packed (HCP), and stacking-faulted intergrowths thereof. HCP cobalt has been shown to exhibit high activity and selectivity for higher hydrocarbons and oxygenates, particularly when transformed into cobalt carbide (Co2C), which forms more readily at low H2/CO ratios. This study presents a quantitative analysis of cobalt polymorphs and stacking faults in Mn-promoted Co/TiO2 FT catalysts from in situ powder X-ray diffraction (XRD) data and X-ray Diffraction Computed Tomography (XRD-CT) data from spent catalysts in order to obtain a more complete correlation of structural features with catalytic performance. By modeling stacking fault probabilities using supercell simulations, the proportion of faulted FCC and HCP domains was determined across varying Mn loadings (0-5%). Increased Mn loading was found to decrease stacking faults in the FCC phase while increasing them in HCP, promoting the formation of HCP domains and ultimately Co2C under reaction conditions. Notably, the 3% Mn-loaded sample showed a marked rise in HCP content and Co2C formation, correlating with the highest observed alcohol and olefin selectivity. These findings highlight a critical structure-function relationship: Mn facilitates a transformation from FCC to HCP and then to Co2C, this final transition driven by similar stacking sequences and metal-support interactions. The findings show that Mn promotion not only stabilizes smaller Co particles and enhances its dispersion, but also modulates the distribution of Co polymorphs and stacking faults, leading to altered catalytic behavior. This highlights the importance of stacking fault characterization for optimizing FT catalyst design and performance, and suggests pathways to more efficient and selective carbon-neutral fuel production through engineered polymorphic and interfacial structures.

Green or renewable hydrogen is steadily emerging as an attractive solution in the global energy transition, offering a sustainable pathway to decarbonize hard-to-abate sectors such as steel, ammonia, and methanol, among others. Its production via water electrolysis is dominated by four main technologies: alkaline, proton exchange membrane (PEM), anion exchange membrane (AEM), and solid oxide electrolyzer cells (SOECs), each with distinct advantages and limitations. While electrolyzers operating at temperatures less than 100 °C such as alkaline and PEM are commercially mature, they suffer from lower efficiencies. In contrast, high-temperature systems such as SOECs or emerging protonic ceramic electrochemical cells (PCECs) promise superior performance but introduce complexity and durability challenges. Positioned between these extremes is intermediate-temperature water electrolysis (ITWE), operating between 100 and 400 °C, which may offer an optimal balance of efficiency, material stability, and system simplicity. Despite growing academic interest, ITWE remains largely overlooked and underexplored, particularly from a practical, deployment-oriented standpoint. This perspective presents a holistic reflection on ITWE, critically examining its thermo/electrochemistry, scientific and engineering challenges, techno-commercial promise and trade-offs, and potential deployment scenarios while proposing future directions for research and innovation in the context of large-scale green hydrogen production.

CO2 hydrogenation to green methanol using renewable hydrogen offers a promising approach for achieving a sustainable carbon cycle. Among various catalyst designs, inverse catalysts have attracted growing interest due to their unique structural advantages. However, the performance of inverse catalysts, such as ZrO2/Cu, is hindered by their hydrophilic nature, while the systematic investigations into their surface wettability remain rare. In this study, we report a non-destructive hydrophobic modification strategy for ZrO2/Cu catalyst through physical mixing with polydivinylbenzene (PDVB). The optimized ZrO2/Cu-PDVB (1:1 mass ratio) catalyst achieves a methanol space-time yield of 920.10 mgCH3OHgcat - 1h- 1 under mild conditions, outperforming the unmodified catalyst by 30%. Additionally, the optimized catalyst also demonstrates outstanding 200h thermal stability. In situ DRIFTS and related analyses reveal that the PDVB effectively promotes water desorption and diffusion, alleviating its negative impact on the rate-determining step of formate hydrogenation. This also preserves the size, metallic state of Cu particles, and the abundance of oxygen vacancies, crucial for maintaining the active ZrOx-Cu interface. This work presents a simple, scalable method for adjusting the local microenvironment of inverse catalysts, highlighting the critical yet underexplored role of hydrophobic surface engineering in optimizing water-sensitive catalytic systems.

<div>The aim of this study is to develop a methodology to significantly reduce emissions in bus fleet renewal scenarios by investigating both technical and economic aspects. This work presents a case study based on Elba Island, Italy, which investigates optimal solutions for replacing existing Diesel buses through a total cost of ownership analysis. The investigation is carried out for four different potential scenarios: renewing the fleet with Diesel buses, renewing the fleet with electric buses, adopting fuel cell buses, and implementing a hybrid solution. The latter represents a synergistic solution that integrates fuel cell buses with the development of a hydrogen refueling station driven by a proton exchange membrane electrolyzer, unlocking the techno-economic potential of self-producing green hydrogen for bus refueling. The novelty of this study is its integrated methodology that combines a total cost of ownership analysis with a tailored design of a green hydrogen production network optimized for continuous fleet operation. A constrained optimization algorithm was employed to determine the optimal configuration of key plant components, including the proton exchange membrane electrolyzer system size, the amount of photovoltaic panels and wind turbines, and the capacity of the hydrogen storage tank. The grid-based alternative offers a simple payback period under 4 years and a total cost of ownership of 6 M€, making it more cost-effective than the 6.5 M€ electric and 7.5 M€ Diesel options. These results provide a scalable, replicable roadmap for accelerating sustainable public transport adoption in similar contexts.</div>

Abstract Background On its path to achieving climate neutrality targets, the emission-intensive crude steel industry is undergoing a fundamental transformation in terms of its technologies, energy carriers and reducing agents. Such a fundamentally changing system requires an environmental assessment from a forward-looking and time-differentiating perspective. This paper proposes a dynamic prospective life cycle assessment of the transition paths of the Austrian steel industry, including a detailed evaluation of the relevant energy supply options. Methods The assessment is based on Prosperdyn , a novel dynamic inventory calculator developed by the authors as an extension to the Brightway package. It combines dynamic foreground scenarios with prospective background data, taking into account the global transformation. Compared with other available tools in this field, pathway variations can be calculated in significantly less time, enabling them to be modified according to a normative emission target. The climate impacts of steel production are assessed alongside the emissions from the construction of the electricity and hydrogen infrastructure in a dynamic impact assessment. This includes additional radiative forcing as a complementary metric to the global warming potential. Results Prosperdyn was employed to model the transition of crude steel production from blast furnaces to direct iron reduction using hydrogen by 2050. By iteratively modifying the transition path, the global warming potential will decline linearly from now until 2050, in line with the normative net-zero emission target. The final technology path meets the greenhouse gas budget and limits long-term radiative forcing. Conclusions The results demonstrate that achieving the targeted emission reductions requires a combination of ambitious measures. These include switching early to alternative reducing agents and increasing the share of secondary steel. In contrast, the source of renewable hydrogen has a minor impact on greenhouse gas emissions, but considerably affects the expected primary energy demand.