Publications
Impacts of Intermittency on Low-temperature Electrolysis Technologies: A Comprehensive Review
May 2024
Publication
By offering promising solutions to two critical issues – the integration of renewable energies into energy systems and the decarbonization of existing hydrogen applications – green hydrogen production through water electrolysis is set to play a crucial role in addressing the major challenges of the energy transition. However the successful integration of renewable energy sources relies on gaining accurate insights into the impacts that intermittent electrical supply conditions induce on electrolyzers. Despite the rising importance of addressing intermittency issues to accelerate the widespread adoption of renewable energy sources the state-of-the-art lacks research providing an in-depth understanding of these concerns. This paper endeavors to offer a comprehensive review of existing research focusing on proton exchange membrane (PEM) and alkaline electrolysis technologies operating under intermittent operation. Despite growing interest over the last ten years the review underscores the scarcity of industrial-scale databases for quantifying these impacts.
Assessing the Cost-effectiveness of Carbon Neutrality for Light-duty Vehicle Sector in China
Nov 2023
Publication
China’s progress in decarbonizing its transportation particularly vehicle electrification is notable. However the economically effective pathways are underexplored. To find out how much cost is necessary for carbon neutrality for the light-duty vehicle (LDV) sector this study examines twenty decarbonization pathways combining the New Energy and Oil Consumption Credit model and the China-Fleet model. We find that the 2060 zero-greenhouse gas (GHG) emission goal for LDVs is achievable via electrification if the battery pack cost is under CNY483/kWh by 2050. However an extra of CNY8.86 trillion internal subsidies is needed under pessimistic battery cost scenarios (CNY759/kWh in 2050) to eliminate 246 million tonnes of CO2-eq by 2050 ensuring over 80% market penetration of battery electric vehicles (BEVs) in 2050. Moreover the promotion of fuel cell electric vehicles is synergy with BEVs to mitigate the carbon abatement difficulties decreasing up to 34% of the maximum marginal abatement internal investment.
Efficiency and Consistency Enhancement for Alkaline Electrolyzers Driven by Renewable Energy Sources
May 2023
Publication
Low-cost alkaline water electrolysis from renewable energy sources (RESs) is suitable for large-scale hydrogen production. However fluctuating RESs lead to poor performance of alkaline water electrolyzers (AWEs) at low loads. Here we explore two urgent performance issues: inefficiency and inconsistency. Through detailed operation process analysis of AWEs and the established equivalent electrical model we reveal the mechanisms of inefficiency and inconsistency of low-load AWEs are related to the physical structure and electrical characteristics. Furthermore we propose a multi-mode self-optimization electrolysis converting strategy to improve the efficiency and consistency of AWEs. In particular compared to a conventional dc power supply we demonstrate using a lab-scale and large-scale commercially available AWE that the maximum efficiency can be doubled while the operation range of the electrolyzer can be extended from 30–100% to 10–100% of rated load. Our method can be easily generalized and can facilitate hydrogen production from RESs.
Entropy Production and Filling Time in Hydrogen Refueling Stations: An Economic Assessment
Aug 2024
Publication
A multi-objective optimization is performed to obtain fueling conditions in hydrogen stations leading to improved filling times and thermodynamic efficiency (entropy production) of the de facto standard of operation which is defined by the protocol SAE J2601. After finding the Pareto frontier between filling time and total entropy production it was found that SAE J2601 is suboptimal in terms of these process variables. Specifically reductions of filling time from 47 to 77% are possible in the analyzed range of ambient temperatures (from 10 to 40 °C) with higher saving potential the hotter the weather conditions. Maximum entropy production savings with respect to SAE J2601 (7% for 10 °C 1% for 40 °C) demand a longer filling time that increases with ambient temperature (264% for 10 °C 350% for 40 °C). Considering average electricity prices in California USA the operating cost of the filling process can be reduced between 8 and 28% without increasing the expected filling time.
Mechanical Testing Methods for Assessing Hydrogen Embrittlement in Pipeline Steels: A Review
Oct 2025
Publication
As the transport of gaseous hydrogen and its use as a low carbon-footprint energy vector become increasingly likely scenarios both the scientific literature and technical standards addressing the compatibility of pipeline steels with high-pressure hydrogen environments are rapidly expanding. This work presents a detailed review of the most relevant hydrogen embrittlement testing methodologies proposed in standards and the academic literature. The focus is placed on testing approaches that support design-oriented assessments rather than simple alloy qualification for hydrogen service. Particular attention is given to tensile tests (conducted on smooth and notched specimens) as well as to J-integral and fatigue tests performed following the fracture mechanics’ approach. The influences of hydrogen partial pressure and deformation rate are critically examined as these parameters are essential for ensuring meaningful comparisons across different studies.
Hydrogen UK - Supply Chain Strategic Assessment: Phase I
Mar 2025
Publication
The UK Hydrogen Supply Chain Strategic Assessment – Phase II report is developed as an appendix to the UK Hydrogen Supply Chain Strategic Assessment – Phase I report published in September 2024. Whereas the Phase I report prioritised the supply side elements of the hydrogen supply chain i.e. power industry storage electrolytic production CCUS enabled production and networks the Phase II focuses on demand side elements in the hydrogen supply chain i.e. fuel cell systems (including cars vans heavy goods vehicles & non road mobile machinery rail marine) and hydrogen refuelling systems. The Phase II adopts the same approach as carried out in Phase I by utilising analysis based on feedback from survey questionnaires interviews with key industrial stakeholders and internal research.
The paper can be found on their website.
The paper can be found on their website.
Simulation of a Solar-based Small-scale Green Hydrogen Production Unit in Iran: A Techno-economic-feasibility Analysis
Aug 2025
Publication
Based on the global efforts to reduce fossil fuel dependence and its environmental concerns green hydrogen has been considered a promising pathway towards sustainable energy transition. Iran is considered a promising location for green hydrogen production due to its considerable solar energy potential. While global interest in green hydrogen continues to grow studies that explore the techno-economic feasibility of small-scale solar-based green hydrogen systems tailored to Iran’s diverse climatic conditions are still relatively limited. This study aims to assess the technical and economic feasibility of small-scale green hydrogen production based on solar energy (photovoltaics) in six cities of Iran including Isfahan Kerman Kermanshah Shiraz Tehran and Zahedan by examining whether such systems can be financially viable despite their relatively high unit costs. The study employs TRNSYS for dynamic simulation of the hydrogen production system and RETScreen for economic analysis. The results indicate that the system has an annual energy production capacity ranging from 831.52 to 1062.22 MWh across the studied locations. The system's hydrogen production rate was between 16800 and 21114 kg/year. Based on the results the lowest levelized cost of hydrogen (LCOH) was recorded in Shiraz at $6.43/kg H₂ while Tehran experienced the highest value ($8.81/kg H₂). Among the evaluated cities Shiraz demonstrated the most favorable financial performance with an internal rate of return (IRR) of 18.5% and a payback period of 8 years. These findings can be useful for policymakers in Iran and the MENA region in investment planning related to the clean energy transition.
The European Hydrogen Market Landscape - November 2024
Nov 2024
Publication
This report aims to summarise the status of the European hydrogen market landscape. It is based on the information available at the European Hydrogen Observatory (EHO) initiative the leading source of data on hydrogen in Europe exploring the basic concepts latest trends and role of hydrogen in the energy transition. The data presented in this report is based on research conducted until the end of September 2024. This report contains information on current hydrogen production and trade distribution and storage end-use cost and technology manufacturing as of the end of 2023 except if stated otherwise in Europe. A substantial portion of the data gathering was carried out within the framework of Hydrogen Europe's efforts for the European Hydrogen Observatory. Downloadable spreadsheets of the data can be accessed on the website: https://observatory.clean-hydrogen.europa.eu/. The production and trade section provides insights into hydrogen production capacity and production output by technology in Europe and into international hydrogen trade (export and import) to and between European countries. The section referring to distribution and storage presents the location and main attributes of operational dedicated hydrogen pipelines and storage facilities as well as publicly accessible and operational hydrogen refuelling stations in Europe. The end-use section provides information on annual hydrogen consumption per end-use in Europe the deployment of hydrogen fuel cell electric vehicles in Europe the current and future hydrogen Valleys in Europe and the leading scenarios for future hydrogen demand in Europe in 2030 2040 and 2050 by sector. The cost chapter offers a comprehensive examination of the levelised cost of hydrogen production by technology and country. This chapter also gives estimations of renewable hydrogen break-even prices for different end-use applications in addition to electrolyser cost components by technology. Finally a chapter on technologies manufacturing explores data on the European electrolyser manufacturing capacity and sales and the fuel cell market.
Synergistic Effects of Air Pollution and Carbon Reduction Policies in China’s Iron and Steel Industry
Oct 2025
Publication
As an energy-intensive sector China’s iron and steel industry is crucial for achieving “Dual Carbon” goals. This study fills the research gap in systematically comparing the synergistic effects of multiple policies by evaluating five key measures (2020–2023) in ultra-low-emission retrofits and clean energy alternatives. Using public macro-data at the national level this study quantified cumulative reductions in air pollutants (SO2 NOx PM VOCs) and CO2. A synergistic control effect coordinate system and a normalized synergistic emission reduction equivalent (APeq) model were employed. The results reveal significant differences: Sintering machine desulfurization and denitrification (SDD) showed the highest APeq but increased CO2 emissions in 2023. Dust removal equipment upgrades (DRE) and unorganized emission control (UEC) demonstrated stable co-reduction effects. While electric furnace short-process steelmaking (ES) and hydrogen metallurgy (HM) showed limited current benefits they represent crucial deep decarbonization pathways. The framework provides multi-dimensional policy insights beyond simple ranking suggesting balancing short-term pollution control with long-term transition by prioritizing clean alternatives.
Renewable Energy Storage in a Poly-Generative System Fuel Cell/Electrolyzer, Supporting Green Mobility in a Residential Building
Oct 2025
Publication
The European Commission through the REPowerEU plan and the “Fit for 55” package aims to reduce fossil fuel dependence and greenhouse gas emissions by promoting electric and fuel cell hybrid electric vehicles (EV-FCHEVs). The transition to this mobility model requires energy systems that are able to provide both electricity and hydrogen while reducing the reliance of residential buildings on the national grid. This study analyses a poly-generative (PG) system composed of a Solid Oxide Fuel Cell (SOFC) fed by biomethane a Photovoltaic (PV) system and a Proton Exchange Membrane Electrolyser (PEME) with electric vehicles used as dynamic storage units. The assessment is based on simulation tools developed for the main components and applied to four representative seasonal days in Rende (Italy) considering different daily travel ranges of a 30-vehicle fleet. Results show that the PG system provides about 27 kW of electricity 14.6 kW of heat and 3.11 kg of hydrogen in winter spring and autumn and about 26 kW 14 kW and 3.11 kg in summer; it fully covers the building’s electrical demand in summer and hot water demand in all seasons. The integration of EV batteries reduces grid dependence improves renewable self-consumption and allows for the continuous and efficient operation of both the SOFC and PEME demonstrating the potential of the proposed system to support the green transition.
Review and Evaluation of Hydrogen and Air Heat Exchangers for Fuel Cell-Powered Electric Aircraft Propulsion
Mar 2025
Publication
Hydrogen fuel cell systems are a viable option for electrified aero engines due to their efficiency and environmental benefits. However integrating these systems presents challenges notably in terms of overall system weight and thermal management. Heat exchangers are crucial for the effective thermal management system of electric propulsion systems in commercial electrified aviation. This paper provides a comprehensive review of various heat exchanger types and evaluates their potential applications within these systems. Selection criteria are established based on the specific requirements for air and hydrogen heat exchangers in electrified aircraft. The study highlights the differences in weighting criteria for these two types of heat exchangers and applies a weighted point rating system to assess their performance. Results indicate that extended surface microchannel and printed circuit heat exchangers exhibit significant promise for aviation applications. The paper also identifies key design challenges and research needs particularly in enhancing net heat dissipation increasing compactness improving reliability and ensuring effective integration with aircraft systems.
Evaluating the Role of Hydrogen as an Energy Carrier: Perspectives on Low-Emission Applications
Oct 2025
Publication
Application of low-emission hydrogen production methods in the decarbonization process remains a highly relevant topic particularly in the context of sustainable hydrogen value chains. This study evaluates hydrogen applications beyond industry focusing on its role as an energy carrier and applying multi-criteria decision analysis (MCDA) to assess economics environmental impact efficiency and technological readiness. The analysis confirmed that hydrogen use for heating was the most competitive non-industrial application (ranking first in 66%) with favorable efficiency and costs. Power generation placed among the top two alternatives in 75% of cases. Transport end-use was less suitable due to compression requirements raising emissions to 272–371 g CO2/kg H2 and levelizing the cost of hydrogen (LCOH) to 13–17 EUR/kg. When H2 transport was included new pipelines and compressed H2 clearly outperformed other methods for short- and long-distances adding only 3.2–3.9% to overall LCOH. Sensitivity analysis confirmed that electricity price variations had a stronger influence on LCOH than capital expenditures. Comparing electrolysis technologies yielded that proton-exchange membrane and solid oxide reduced costs by 12–20% and CO2 emissions by 15–25% compared to alkaline. The study highlights heating end-use and compressed hydrogen and pipeline transport proving MCDA to be useful for selecting scalable pathways.
Levelised Cost of Hydrogen (LCOH) Calculator Manual - Update of the May 2024 Manual
May 2025
Publication
The LCOH calculator manual explains the methodology behind the calculator in detail and demonstrates how the calculator can be used.<br/>In this second version the default prices are updated based on the latest data available in the calculator and a new use case is introduced on changing the economic lifetime and cost of capital of an electrolysis installation.
Cruel Utopia of the Seas? Multiple Risks Challenge the Singular Hydrogen Hype in Finnish Maritime Logistics
Oct 2025
Publication
To address the global climate crisis maritime logistics are undergoing a transition away from fossil-based energy sources. The transition is envisaged to be both green (involving renewables) and digital (involving various kinds of digitalization). Much of the hope rests on the new hydrogen economy involving the build-up of infrastructure for hydrogen-derived alternative fuels such as methanol and ammonia. Indeed the new hydrogen economy is often portrayed as set to revolutionize maritime transport. The hope behind the hype reflects a belief in the performativity of hypes: some technological phenomenon will eventually materialise in innovation and business practices. In this paper we critically analyse the current hydrogen hype in the field of Finnish maritime logistics as a paradigmatic case of performative techno-optimism. Based on causal network analysis and thematic analysis of expert interviews and workshop data we argue that the phenomenon of performative techno-optimism is more nuanced than hitherto presented in the related literature. We showcase a variety of stances along a spectrum ranging from radical optimism to radical pessimism. Furthermore our causal network analysis indicates that the current green and digital transition of maritime transport is caught in a systemic catch-22: transitioning to alternative fuels in maritime logistics faces a lock-in of between overly cautious demand for alternative fuels leading to overly cautious investment in supply which only secures the modest demand. Finally our thematic analysis of techno-optimist stances suggests the following two major ways out of the systemic dilemma: large-scale technological innovations and global regulatory solutions.
Sorption-enhanced Steam Reforming Technology for Promoting Hydrogen Production with In-situ CO2 Capture: Recent Advances and Prospects
Aug 2025
Publication
Sorption-enhanced steam reforming (SorESR) is an advanced thermochemical process integrating in-situ CO2 capture via solid sorbents to significantly enhance hydrogen production and purity. By coupling CO2 adsorption with steam reforming SorESR shifts the reaction equilibrium toward increased H₂ yield surpassing the limitations of conventional steam reforming (SR). The efficacy of SorESR critically depends on the physicochemical properties of the solid CO2 sorbents employed. This review critically evaluates widely studied sorbents including Ca-based Mg-based hydrotalcite-like and alkali ceramic sorbents focusing on their CO2 capture capacity reaction kinetics thermal stability and cyclic durability under SR conditions. Furthermore recent progress in multifunctional sorbent-catalysts that synergistically facilitate catalytic steam reforming alongside CO2 sorption is critically discussed. Moreover the review summarises recent performance achievements and proposes strategies to improve sorbent capacity and reaction kinetics thereby making the SorESR process more appealing for commercial applications. Large-scale SorESR implementation is expected to substantially increase hydrogen production efficiency while concurrently reducing CO2 emissions and advancing sustainable energy technologies. This review offers novel insights into the development of advanced sorbent-catalyst systems and provides new strategies for enhancing SorESR efficiency and scalability for commercial H2 Production.
System Efficiency Analysis of Direct Coupled PV-PEM Electrolyzer Systems
Oct 2025
Publication
Green hydrogen is an important technology in the energy transition with potential to decarbonize industrial processes increase renewable energy use and reduce reliance on fossil fuels yet it currently accounts for less than 1% of global hydrogen demand. One promising approach to expand production is the direct coupling of photovoltaic–electrolyzer systems. In this study overall and sub-system efficiencies were analyzed for different system setups coupling points and operating conditions such as temperature and irradiance. The highest overall system efficiencies were found to be more than 18%. The effect of varying irradiances on the coupled efficiency was not more than 5.7%. Different system designs optimized for different irradiances led to effects such as an increase in current density at the electrolyzer and thus an increase in the overvoltage which resulted in an overall efficiency loss of more than 3%. A key finding was that aligning the PV maximum power point with the electrolyzer polarization curve enables consistently high system efficiencies across the investigated irradiances. The findings were validated with two real life systems reproducing the coupling efficiencies of the model with 12%–14% including loss factors and approximately 18% for a direct coupled system respectively
Vehicle Peak Power Management System: Design, Development, and Testing of a Fuel Cell and Supercapacitor Hybrid
Oct 2025
Publication
The passive combination of fuel cells and supercapacitors possesses promising applications in the automotive industry due to its ability to decrease stack size maintain peak power capacity improve system productivity and go away with the need for additional control all without Direct current to Direct Current (DC/DC) converters. This research describes the steps to create and evaluate a fuel cell (FC) and supercapacitor (SC) passive hybrid electrical system for a 60-V lightweight vehicle. Also study offers a thorough design approach and model and experimentally to validate every passive hybrid testing station component. When both concepts are stable the voltage errors are about 2 % and 3 % respectively for fuel cells and supercapacitors. The results of the experiments provide more evidence that the passive design is effective under step loads and driving cycles. The results of the measurements match the models used to simulate the passive hybrid system if a step load voltage is used. A smaller FC stack is possible since the fuel cell controls the steady-state current. Alternatively the supercapacitors provide varying currents because of their reduced resistance. This study use a driving cycle to show that the FC stack can lower its output to 25 % of the peak power required by the load.
Bipolar Electrolysis Cells with Hydride Ion-proton Conductor Heterejunctions
Oct 2025
Publication
Protonic solid oxide electrolysis cells are pivotal for environmentally sustainable hydrogen production via water splitting but suffer from efficiency losses due to partial hole conductivity. Here we introduce a device architecture based on a hydride-ion (H− )/proton (H+ ) bipolar electrolyte which exploits electrochemical rectification at a heteroionic interface to overcome this limitation. The perovskite-type BaZr0.5In0.5O2.75 electrolyte undergoes an in situ transformation under electrolysis conditions forming an H+ -conducting hydrate layer adjacent to the anode and an H− -conducting oxyhydride layer near the cathode governed by competitive thermodynamic equilibria of hydration and hydrogenation. This bipolar configuration enables high Faradaic currents through the superior H− ion conductivity of the oxyhydride phase stabilized by cathodic potentials while facilitating continuous H+ /H− interconversion at the interface. Furthermore electrochemical hydrogenation generates an electron-depleted interfacial layer that effectively suppresses hole conduction. Consequently the cells achieve efficiencies of ∼95% at 1.0 A cm− 2 surpassing conventional H+ unipolar designs.
Ultrasonic Time-of-flight Measurement of Hydrogen Blending Ratios for Industrial Combustion Applications
Oct 2025
Publication
Hydrogen blending offers significant potential for decarbonizing natural gas-based thermal processes particularly in the steel and cement sectors. Due to its distinct combustion properties compared to natural gas – such as lower minimum air requirements and altered flame speeds – the hydrogen fraction of the fuel must be monitored for combustion control. In this study we present an ultrasonic time-of-flight measurement system for hydrogen concentrations of 0–40% in natural gas. The system is verified with test gas mixtures at laboratory scale and validated in a technical-scale setup using a real blower burner (< 60 kW). We evaluate uncertainty of the hydrogen fraction measurement and analyze the influence of varying natural gas compositions. We show that standard uncertainties below 4% can be achieved without knowledge of the specific natural gas composition. Our results provide insights for measurement system design and support the safe application of hydrogen in thermal systems for industrial processes.
Hydrogen Valleys to Foster Local Decarbonisation Targets: A Multiobjective Optimisation Approach for Energy Planning
Oct 2025
Publication
Hydrogen Valley represents localised ecosystems that enable the integrated production storage distribution and utilisation of hydrogen to support the decarbonisation of the energy system. However planning such integrated systems necessitates a detailed evaluation of their interconnections with variable renewable generation sector coupling and system flexibility. The novelty of this work lies in addressing a critical gap in system-level modelling for Hydrogen Valleys by introducing an optimization-based framework to determine their optimal configuration. This study focuses on the scenario-based multiobjective design of local hydrogen energy systems considering renewable integration infrastructure deployment and sector coupling. We developed and simulated three scenarios based on varying hydrogen pathways and penetration levels using the EnergyPLAN model implemented through a custom MATLAB Toolbox. Several decision variables such as renewable energy capacity electrolyser size and hydrogen storage were optimised to minimise CO₂ emissions total annual system cost and critical excess electricity production simultaneously. The findings show that Hydrogen Valley deployment can reduce CO₂ emissions by up to 30 % triple renewable penetration in the primary energy supply and lower the levelized cost of hydrogen from 7.6 €/kg to 5.6 €/kg despite a moderate increase in the total cost of the system. The approach highlights the potential of sector coupling and Power-to-X technologies in enhancing system flexibility and supporting green hydrogen integration. The outcome of our research offers valuable insights for policymakers and planners seeking to align local hydrogen strategies with broader decarbonisation targets and regulatory frameworks.
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