Green Hydrogen Research Articles

Overview of Main Electrolyzer Technologies and Power Electronic Converter Topologies for Enabling Hydrogen Production Through Water Electrolysis

ABSTRACTThis manuscript offers an in‐depth exploration of electrolysis, focusing on the various types of electrolyzers and providing a detailed analysis of their respective advantages and disadvantages. Additionally, it presents a comprehensive review of DC–DC and AC–DC converters, highlighting their essential roles in green hydrogen production and explaining their functionality and applications in detail. Furthermore, the manuscript examines the diverse power electronic systems used in green hydrogen production, underscoring the crucial importance of converters. The investigation also covers effective strategies for integrating these technologies, with the goal of optimizing the green hydrogen production process. This study aims to significantly advance knowledge in sustainable technologies, emphasizing the pivotal role of power electronics in electrolysis, fostering the generation of renewable energy, and reinforcing the commitment to a greener and more sustainable future.

Footprint family of China's coal-based synthetic natural gas industry

China's increasing demand for natural gas and concerns related to energy security have expanded the coal-based synthetic natural gas (CBSNG) industry. The accompanying intensive environmental and economic impacts are evaluated based on static design or simulated data, but their industrialized performance at both the project-specific and national levels remains unclear. The objective of this study is to estimate an energy-water-pollutant-carbon-economic footprint family of China's CBSNG industry. To this end, a comprehensive accounting methodology for the multiple footprints of CBSNG was developed and the first-hand dynamic operation and economic data of four commercialized projects were surveyed. Accompanied by the technology learning curve, scenarios towards 2035 were designed to predict future trajectories of these footprints. The results show that the project-specific energy-water-pollutant-carbon footprints generally reduced by 10 to 30 % from 2020 to 2022, while the economic footprints increased slightly. The total energy-water-pollutant-carbon footprints, driven by scale expansion, increased by less than 10 % and the total economic footprint increased by over 30 %. They were predicted to approximately double by 2025 and increase fivefold by 2035, which suggests the deployment of green hydrogen and a circular economy, optimization of spatial layout, and fortification of separate statistics and economic policies for sustainability.

Unlocking OER potential: Tailoring layered double perovskites through self-reconstruction

The sluggish rate of the anode oxygen evolution reaction (OER) is a major bottleneck for green hydrogen production, making a room-temperature alkaline water electrolyser critical to unlocking the full potential of this technology. Using a perovskite oxide as an electrochemical matrix and forming a self-assembled oxyhydroxide (OOH) layer on the surface via a self-reconstruction activation process (SRAP) is a promising strategy to enhance OER catalytic activity. However, the mechanistic details and long-term impact of SRAP, especially its relationship to catalytic activity, oxygen collection efficiency, and catalyst dissolution, are not fully understood. To address this knowledge gap, we used layered double perovskite (LDP) PrBa0·75Ca0·25Co1·5Fe0·5O5+δ(PBCCF) and PrBa0·75Ca0·25Co1·5Fe0·4Ni0·1O5+δ (PBCCFN) as model electrochemical catalysts and then triggered SRAP. Subsequently, chronoamperometry (CA), rotating ring disk electrode (RRDE) and in-situ electrochemical quartz crystal microbalance (EQCM) were used to study the effect of the Ni-doping on PBCCF SRAP in terms of catalytic activity, oxygen collection efficiency and catalyst stability. The results showed that the OER catalytic current of the LDP PBCCF and PBCCFN was enhanced via SRAP and the oxygen collection efficiency can be maintained, suggesting that the increase in catalytic current is attributed to OER catalytic activity increase rather than electrochemical catalyst dissolution. Additionally, the effect of the catalytic activity enhancement was more significant in PBCCFN. More importantly, the stability of the LDP PBCCF and PBCCFN after SRAP are higher than simple perovskite Ba0·5Sr0·5Co0·8Fe0·2O3-δ (BSCF) because of the increase in the redeposition rate. The observations suggest that using LDP PBCCF and PBCCFN as matrices followed by triggering SRAP can provide valuable insights for designing LDP based OER electrocatalysts.

High-performance porous 3D Ni skeleton electrodes for the oxygen evolution reaction

A key component of green hydrogen production technologies is the fabrication of large-scale porous transport layer (PTL) for use in anion electrolyte membrane water electrolysers (AEMWEs). One strategy to achieve that goal is to manufacture Ni-based 3D electrode skeletons that can be further catalyzed to achieve high current densities at low overpotentials. In the present work, shock-wave induced spray (SWIS) and cold spray (CS) deposition techniques were used to prepare 20 cm2 Ni-based electrode skeletons. In our experimental conditions, the porosity of coatings prepared using the SWIS deposition system and Ni powders with particle sizes D50 = 32 and 75 μm never exceeded 28%. Higher porosity could only be achieved using the CS deposition system and a spheroidal Ni–Al powder, whose particles consist of an aluminum core encapsulated in a nickel shell. After Al leaching in an alkaline solution, the resulting electrodes showed good mechanical and structural integrity with up to 41% porosity. The electrochemical active surface area of the most porous electrodes is a factor of 2100 larger than a polished Ni plate, and it has superaerophobic properties with a captive air bubble contact angle of 151°. During 1 h of electrolysis, the overpotential at 100 mA cm−2 of the most active leached Ni–Al cold spray deposited electrode was 330 mV, compared to 380 mV for a Ni foam electrode.

Carbon abatement costs of green hydrogen across end-use sectors

Carbon abatement costs of green hydrogen across end-use sectors

The Role of Public-Private Investment Partnerships in Overcoming Challenges and Seizing Opportunities in Poland’s Renewable Energy Sector

Poland’s renewable energy sector is undergoing a significant transformation as the country strives to reduce its reliance on coal and align with European Union (EU) climate targets. However, this transition faces several challenges, including regulatory instability, financial constraints, and outdated infrastructure. PPPs have emerged as a vital mechanism for overcoming these barriers, offering a collaborative approach that blends public financial support with private sector expertise and innovation. This paper explores the critical role of PPPs in addressing Poland’s renewable energy challenges, such as financing large-scale projects, stabilizing regulatory frameworks, and modernizing the energy grid. It also examines the opportunities for growth in offshore wind, solar energy, and green hydrogen production, highlighting how PPPs can help Poland capitalize on these emerging sectors. Through effective collaboration between the public and private sectors, Poland is poised to accelerate its clean energy transition and position itself as a leader in renewable energy development within Central and Eastern Europe.

Efficient and durable OER electrocatalysts through vacancy engineering and core-shell structure design in acidic environment

The electrocatalytic conversion of water into green hydrogen energy through overall water splitting advances sustainable energy goals. However, it is limited by the slow kinetics of the oxygen evolution reaction (OER) and durability challenges at high potentials. Here, we rationally develop a series of Mn-doped RuO2-coated Ru (Mn-Ru@RuO2) catalysts involving unique core-shell structures and abundant lattice distortions induced by oxygen defects. The optimal Mn-Ru@RuO2 sample demonstrated robust activity, achieving a low overpotential of 220 mV at 10 mA cm−2. Notably, this sample exhibited minimal degradation after 220 h and a 25.5-fold increase in mass activity (1.37 A mgRu−1) compared to commercial RuO2 at an overpotential of 300 mV. These results suggest that regulated oxygen deficiencies and optimal Ru3+/Ru4+ ratios facilitate the lattice oxygen oxidation (LOM) mechanism and the formation of a high concentration of ∗OH radicals, enhancing acidic OER performance. Additionally, the unique core-shell structures effectively prevent over-oxidation of the RuO2 shell, ensuring superior durability. This research not only breaks the trade-off of electrochemical activity and durability, but also provides valuable insights into the design of highly efficient and stable electrocatalysts.

Unlocking development of green hydrogen production through techno-economic assessment of wind energy by considering wind resource variability: A case study

Generating hydrogen from renewable energy sources is widely recognized as an effective strategy for addressing critical challenges in the energy sector while contributing to the reduction of greenhouse gas emissions. This study aims to assess the wind energy potential for electricity and hydrogen production in five locations on Sumba Island using 10 years (2011–2020) of data from the NASA's POWER Project. A wind variability assessment was performed on five wind turbines ranging from 500 kW to 1.5 MW and using electrolysis technology. The results indicated a hydrogen production potential of 25–57 tons per year. Economic analysis of hydrogen production for Haharu reveals an attractive internal rate of return (IRR) of 43% with a payback period (PBP) of 2.25 years and a net present value (NPV) of 1.3 MM USD, the levelized cost of electricity (LCOE) of 0.0241 USD/kWh, and the levelized cost of Hydrogen (LCOH) of 1.01 USD/kg. Sensitivity analysis underscores the critical influence of investment and revenue on project profitability, highlighting their substantial impact on determining a project's success or failure. These findings emphasize the potential of Sumba Island as a hub for sustainable energy production to meet the growing demand for clean and renewable energy sources.

Research progress on 5-hydroxymethylfurfural electrocatalytic or photocatalytic oxidation coupling with hydrogen production

Biomass and hydrogen serve as crucial alternatives to fossil fuels, addressing climate change and the shortage of fossil fuels. Hydrogen offers high energy density and emits no carbon, while biomass is abundant and renewable. Nevertheless, green hydrogen production via electrocatalysis or photocatalysis faces challenges such as slow kinetics and low efficiency. Oxidation catalysis of biomass derivatives, particularly 5-hydroxymethylfurfural (HMF), has the potential to substitute for the oxygen evolution reaction (OER) in hydrolysis, leading to a significant increase in hydrogen evolution and the production of valuable products such as 2,5-diformylfuran (DFF), 5-hydroxymethyl-2-furancarboxylic acid (HMFCA), and 2,5-furan dicarboxylic acid (FDCA). This review explores recent advancements in electrocatalytic, photocatalytic, and photoelectrocatalytic HMF oxidation coupled with hydrogen production. This study provides a theoretical basis and practical guidance for catalyzing HMF oxidation coupled with hydrogen production through a detailed analysis of the reaction mechanism of HMF oxidation coupled with hydrogen generation and the performance of bifunctional catalysts.

Natural Hydrogen, the Ultimate Green Energy: Current Status and Prospects

Natural hydrogen is green hydrogen that is naturally produced on Earth, that is, an energy source that does not emit carbon without using additional energy for production. Since carbon is emitted from the existing gray hydrogen and blue hydrogen, green hydrogen with perfect eco-friendliness has been required. Natural hydrogen is produced through four mechanisms: serpentinization, radioactive decomposition, magma gas removal, and rock destruction and can exist in the dissolved ․ content of fluid mammals. Representative sites discovered to date include Mali, Africa, Brazil, and Australia, and each topography has different characteristics. Although reserves are estimated using geochemical and geophysical exploration technologies, the reliability is not high because the deep hydrogen flow in various geological environments is not considered. Based on this, this study drew the following conclusions. 1) Hydrogen can realize carbon neutrality with high energy content and independence, but 2) economic feasibility cannot be evaluated due to the uncertainty of the reserves and current reserves of natural hydrogen. Therefore, 3) for commercial use, leakage detection technology is required along with an understanding of the mechanism for generating natural hydrogen.

Future pathways for green hydrogen: Analyzing the nexus of renewable energy consumption and hydrogen development in Chinese cities

Hydrogen energy offers a promising pathway for achieving zero-carbon urban energy consumption. This study quantitatively analyzes the patterns of hydrogen energy development and its linked to electricity consumption in China's urban areas. It investigates the spatial relationships between hydrogen energy expansion, the potential for green hydrogen production, and overall energy use. Utilizing a coupling coordination degree (CCD) model and a panel vector autoregressive (PVAR) model, the research explores the dynamic interactions between urban hydrogen energy development and the transition to renewable energy sources. In line with Chinese government policy, the study also conducts a scenario analysis of green hydrogen production by 2030, proposing a consumption strategy that balances environmental sustainability with economic growth. The key conclusions are as follows: (1) There is a spatial mismatch between the locations where hydrogen energy is being developed and where the potential for green hydrogen production is greatest. Cities with higher electricity consumption demonstrate stronger synergies in the coordinated development of hydrogen and renewable energy. (2) The development of hydrogen energy significantly accelerates the transition to renewable energy consumption in urban areas, with this impact being more substantial than that of the utilization capacity alone. (3) Hydrogen production in the Plan Scenario is significantly higher than in the Pessimistic Scenario, underscoring the critical importance of implementing renewable hydrogen projects in provinces with high production potential. Future trends in green hydrogen consumption at the provincial level indicate that addressing the challenges of efficient inter-provincial transportation of hydrogen energy remains essential.

Prospects for a large-scale green hydrogen storage methods development in Poland – a review

Prospects for a large-scale green hydrogen storage methods development in Poland – a review

Doping-mediated interface engineered Ni3S2: Economically viable electrochemical methanol-mediated water splitting

Electrochemical water splitting is the front runner to meet the global green hydrogen demand. The development of a noble metal-free earth-abundant electrocatalyst is desired to rationalize an economically viable electrochemical water-splitting system. The sluggish anodic oxygen evolution reaction (OER) is the bottleneck of the electrochemical water-splitting system. Herein, to improve OER kinetics, group VIB elements such as chromium (Cr), molybdenum (Mo), and tungsten (W) doped nickel sulfides (Ni3S2) nanosheets (NSs) are synthesized by two-step hydrothermal method to modulate the intrinsic electrocatalytic activity of the pure Ni3S2. Among all the doped samples, the Cr-doped Ni3S2 catalyst exhibited excellent OER with an ultra-low overpotential of 248 mV and MOR with a potential of 1.36 V @ 10 mA cm−2 vs RHE achieving a lower Tafel slope of 95.5 mV/dec and 46.4 mV/dec and outstanding durability with negligible degradation respectively. Furthermore, the Pt/C||Cr-Ni3S2 (1.48 V) system outperforms commercial Pt/C||RuO2 (1.53 V @ 10 mA cm−2) in a two-electrode configuration. The methanol-mediated hybrid water splitting system only warranted a cell voltage of 1.38 V to attain 10 mA cm−2 for the Pt/C||Cr-Ni3S2 system in the presence of 0.1 M methanol (MeOH). The methanol oxidation reaction (MOR) mediated the hybrid water electrolyzer system demonstrates reduced operation cell voltage while additionally electro-synthesizing formate as a value-added chemical. The overall work is motivated to rationalize the importance of doping-mediated interface-engineered catalyst synthesis to improve the electrocatalytic efficiency of the hybrid water electrolyzer.

Methods for Enhancing Electrolysis for Hydrogen Production: The Benefits of Applying Magnetic Fields

The electrolysis of water is one of the most promising ways of producing green hydrogen. This produces hydrogen using electricity and does not generate additional carbon dioxide like the more conventional reforming of fossil fuels. However, making electrolysis competitive with conventional methods for hydrogen production is a challenge because of the cost of electricity and because of inefficiencies and costs in electrolysis systems. Initially this review looks at the basic design of water electrolysis and asks where energy is lost. Then, a selection of the latest results in the area of magnetic field-enhanced water electrolysis are examined and discussed, in particular focusing on the empirical results of magnetic field-assisted electrolysis with the aim of comparing findings and identifying limitations of current studies such that recommendations can be made for advanced design of hydrogen producing electrolysis systems.

Evaluation of Green and Blue Hydrogen Production Potential in Saudi Arabia

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 two cases of Steam Methane Reforming (SMR) with different percentages of carbon capture. The two BHP scenarios were compared with a base case scenario of hydrogen production from natural gas without CCS/U (gray hydrogen). 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 the three SMR cases 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.

Thermodynamic and Economic Analysis of the Green Ammonia Synthesis System Driven by Synergistic Hydrogen Production Using Alkaline Water Electrolyzers and Proton Exchange Membrane Electrolyzers

Green ammonia and hydrogen from renewable energy sources have emerged as crucial players during the transition of the chemical industry from a fossil energy‐dominated economy to one that is environmentally friendly. This work proposes a green ammonia synthesis system driven by synergistic hydrogen generation using alkaline water electrolyzers (AWE) and proton exchange membrane electrolyzers (PEMEC). The effects of hydrogen‐production ratios of PEMEC and AWE on the thermodynamic and economic performance of the system are compared and analyzed via multi‐objective optimization. The findings showed that an increase in the amount of hydrogen produced by PEMEC improves the system's energy efficiency, but the payback period is delayed because of the PEMEC high initial investment cost. The techno‐economic performance of the system at a 1:1 ratio of PEMEC to AWE hydrogen production are investigated considering the system level heat integration based on the pinch point analysis method to maximize the heat recovery. The results show that increasing the operational temperature, the pressure of the electrolyzer, and the ammonia synthesis pressure will enhance the system's thermal performance. Economic analysis shows that reducing electricity prices and electrolyzer investment costs will be the key to achieving the economic feasibility of the green ammonia system.

Design considerations and preliminary hydrodynamic analysis of an offshore decentralised floating wind-hydrogen system

Despite the number of works on the techno-economics of offshore green hydrogen production, there is a lack of research on the design of floating platforms to concomitantly support hydrogen production facilities and wind power generation equipment. Indeed, previous studies on offshore decentralised configuration for hydrogen production, implicitly assume that a floating platform designed for wind power generation (FOWT) can be also suitable as a floating wind hydrogen system (FWHS). This work proposes a novel design for an offshore decentralised FWHS, and analyses the effects of the integration of the hydrogen facilities on the platform's dynamics and how this in turn affects the performances of the wind turbine and the hydrogen equipment. Our findings indicate that despite the reduction in platform's stability, the performance of the wind turbine is barely affected. Regarding the hydrogen system, our results aim at contributing to further assessment and design of this equipment for offshore conditions.

Evaluating the economic influence of water sources on green hydrogen production: A cost analysis approach

The production of green hydrogen requires significant water usage, making the economic evaluation of different water sources crucial for optimizing the Levelized Cost of Hydrogen (LCOH). This study examines the economic impact of using seawater, groundwater, grid water, industrial wastewater, and rainwater for hydrogen production through PEM electrolysis considering the water abstraction, transport, treatment, and storage costs across various plant sizes (1 MW, 10 MW, 20 MW, 50 MW, and 100 MW) were assessed and a sensitivity analysis on electricity prices was conducted. Findings reveal that while water-related costs are minimal (<2% of LCOH), transport distance significantly impacts LCOH, sometimes exceeding 10%. Future studies should integrate life cycle analysis and sustainability criteria beyond economic factors, considering social, ecological, and technical dimensions.

Techno-economic and environmental assessment of green hydrogen and ammonia production from solar and wind energy in the republic of Djibouti: A geospatial modeling approach

This study conducts a thorough economic and technical analysis to assess the viability of green hydrogen and green ammonia production using renewable energy sources in the Republic of Djibouti. We explore the economic competitiveness of utilizing wind and solar power for sustainable energy production through various measures including levelized cost of energy (LCOE), hydrogen (LCOH), and ammonia (LCOA). Our analysis incorporates sensitivity assessments and Monte Carlo simulations to predict financial feasibility and environmental impact, focusing on CO2 emission reductions. A cost mapping of electricity, green hydrogen, and green ammonia from solar and wind resources was created to find Djibouti's most cost-effective production sites. The feasibility of exporting green ammonia to neighboring countries with high fertilizer demand was also evaluated using rail and truck transport scenarios. Key findings demonstrate that Moulouhlé, endowed with robust wind and solar resources, presents a strategic site for deploying renewable energy technologies. Wind energy, with a lower LCOE of 0.066 $/kWh compared to solar's 0.093 $/kWh, emerges as a more cost-effective solution for both hydrogen and ammonia production. Notably, wind-powered hydrogen production costs are 2.25 $/kgH2, significantly lower than solar-powered costs at 4.17 $/kgH2. In terms of green ammonia, wind power achieves production costs of 399.76 $/tonNH3, outperforming solar power which stands at 537.11 $/tonNH3. Additionally, our study evaluates the logistics of exporting green ammonia, determining rail transport as a more economically viable option than trucking. This research not only underscores Djibouti's potential as a leader in green energy exportation but also aligns with global decarbonization efforts, showcasing significant CO2 savings—154.94 Mt annually from wind. This work emphasizes the importance of strategic resource utilization in Djibouti, offering insights critical for stakeholders in making informed decisions about investing in renewable energy infrastructures. The outcomes suggest a promising future for regional energy sustainability and economic resilience, fostering a transition towards low-carbon energy systems.

Microwave-assisted organic acids and green hydrogen production during mixed culture fermentation.

The integration of anaerobic digestion into bio-based industries can create synergies that help render anaerobic digestion self-sustaining. Two-stage digesters with separate acidification stages allow for the production of green hydrogen and short-chain fatty acids, which are promising industrial products. Heat shocks can be used to foster the production of these products, the practical applicability of this treatment is often not addressed sufficiently, and the presented work therefore aims to close this gap. Batch experiments were conducted in 5L double-walled tank reactors incubated at 37°C. Short microwave heat shocks of 25min duration and exposure times of 5-10min at 80°C were performed and compared to oven heat shocks. Pairwise experimental group differences for gas production and chemical parameters were determined using ANOVA and post-hoc tests. High-throughput 16SrRNA gene amplicon sequencing was performed to analyse taxonomic profiles. After heat-shocking the entire seed sludge, the highest hydrogen productivity was observed at a substrate load of 50g/l with 1.09molH2/molhexose. With 1.01molH2/molhexose, microwave-assisted treatment was not significantly different from oven-based treatments. This study emphasised the better repeatability of heat shocks with microwave-assisted experiments, revealing low variation coefficients averaging 29%. The pre-treatment with microwaves results in a high predictability and a stronger microbial community shift to Clostridia compared to the treatment with the oven. The pre-treatment of heat shocks supported the formation of butyric acid up to 10.8g/l on average, with a peak of 24.01g/l at a butyric/acetic acid ratio of 2.0. The results support the suitability of using heat shock for the entire seed sludge rather than just a small inoculum, making the process more relevant for industrial applications. The performed microwave-based treatment has proven to be a promising alternative to oven-based treatments, which ultimately may facilitate their implementation into industrial systems. This approach becomes economically sustainable with high-temperature heat pumps with a coefficient of performance (COP) of 4.3.