Publications
Flame Stabilization and Blow-off of Ultra-Lean H2-Air Premixed Flames
Apr 2021
Publication
The manner in which an ultra-lean hydrogen flame stabilizes and blows off is crucial for the understanding and design of safe and efficient combustion devices. In this study we use experiments and numerical simulations for pure H2-air flames stabilized behind a cylindrical bluff body to reveal the underlying physics that make such flames stable and eventually blow-off. Results from CFD simulations are used to investigate the role of stretch and preferential diffusion after a qualitative validation with experiments. It is found that the flame displacement speed of flames stabilized beyond the lean flammability limit of a flat stretchless flame (φ = 0.3) can be scaled with a relevant tubular flame displacement speed. This result is crucial as no scaling reference is available for such flames. We also confirm our previous hypothesis regarding lean limit blow-off for flames with a neck formation that such flames are quenched due to excessive local stretching. After extinction at the flame neck flames with closed flame fronts are found to be stabilized inside a recirculation zone.
Fuzzy Logic-Based Energy Management Strategy for Hybrid Fuel Cell Electric Ship Power and Propulsion System
Oct 2024
Publication
The growing use of proton-exchange membrane fuel cells (PEMFCs) in hybrid propulsion systems is aimed at replacing traditional internal combustion engines and reducing greenhouse gas emissions. Effective power distribution between the fuel cell and the energy storage system (ESS) is crucial and has led to a growing emphasis on developing energy management systems (EMSs) to efficiently implement this integration. To address this goal this study examines the performance of a fuzzy logic rule-based strategy for a hybrid fuel cell propulsion system in a small hydrogenpowered passenger vessel. The primary objective is to optimize fuel efficiency with particular attention on reducing hydrogen consumption. The analysis is carried out under typical operating conditions encountered during a river trip. Comparisons between the proposed strategy with other approaches—control based optimization based and deterministic rule based—are conducted to verify the effectiveness of the proposed strategy. Simulation results indicated that the EMS based on fuzzy logic mechanisms was the most successful in reducing fuel consumption. The superior performance of this method stems from its ability to adaptively manage power distribution between the fuel cell and energy storage systems.
A Systematic Comparison of the Energy and Emissions Intensity of Hydrogen Production Pathways in the United Kingdom
Sep 2024
Publication
Meeting climate targets requires profound transformations in the energy system. Most energy uses should be electrified but where this is not feasible hydrogen can be part of the solution. However 98% of global hydrogen production involves greenhouse gas emissions with an average of 12 kg CO2e/kg H2. Therefore new hydrogen production pathways are needed in order to make hydrogen production compatible with climate targets. In this work we fill this gap by systematically comparing the energy and emissions intensity of 173 hydrogen production pathways suitable for the UK. Scenarios include onshore and offshore pathways and the use of repurposed infrastructure. Unlike fossil-fuel based pathways the results show that electrolytic hydrogen powered by fixed offshore wind could align with proposed emissions standards either onshore or offshore. However the embodied and fugitive emissions are important to consider for electrolytic pathways as they result in 10–50% of the total emissions intensity.
Hydrogen Refuelling Station Calibration with a Traceable Gravimetric Standard
Apr 2020
Publication
Of all the alternatives to hydrocarbon fuels hydrogen offers the greatest long-term potential to radically reduce the many problems inherent in fuel used for transportation. Hydrogen vehicles have zero tailpipe emissions and are very efficient. If the hydrogen is made from renewable sources such as nuclear power or fossil sources with carbon emissions captured and sequestered hydrogen use on a global scale would produce almost zero greenhouse gas emissions and greatly reduce air pollutant emissions. The aim of this work is to realise a traceability chain for hydrogen flow metering in the range typical for fuelling applications in a wide pressure range with pressures up to 875 bar (for Hydrogen Refuelling Station - HRS with Nominal Working Pressure of 700 bar) and temperature changes from −40 °C (pre-cooling) to 85 °C (maximum allowed vehicle tank temperature) in accordance with the worldwide accepted standard SAE J2601. Several HRS have been tested in Europe (France Netherlands and Germany) and the results show a good repeatability for all tests. This demonstrates that the testing equipment works well in real conditions. Depending on the installation configuration some systematic errors have been detected and explained. Errors observed for Configuration 1 stations can be explained by pressure differences at the beginning and end of fueling in the piping between the Coriolis Flow Meter (CFM) and the dispenser: the longer the distance the bigger the errors. For Configuration 2 where this distance is very short the error is negligible.
Detailed Analysis of a Pure Hydrogen-fueled Dual-fuel Engine in Terms of Performance and Greenhouse Gas Emissions
Sep 2024
Publication
The current study seeks to greenhouse gas emissions reduction in an existing engine under dual-fuel combustion fueled with diesel fuel and natural gas due to great concerns about global warming. This simulation study focuses on the identification of areas prone to the formation of greenhouse gas emissions in engine cylinders. The simulation results of dual-fuel combustion confirmed that the possibility of incomplete combustion and the formation of greenhouse gas emissions in high levels are not far from expected. Therefore an efficient combustion strategy along with replacing natural gas with hydrogen was considered. Only changing the combustion mode to reactivity-controlled compression ignition has led to the improvement of the natural gas burning rate and guarantees a 32 % reduction in unburned methane and 50 % carbon monoxide. To further reduce engine emissions while changing the combustion mode a part of natural gas replacement with hydrogen to the complete elimination of it was evaluated. Increasing the share of hydrogen energy in the intake air-natural gas mixture up to 54 % without exhaust gas recirculation does not lead to diesel knock. Moreover improvement of engine load and efficiency can be achieved by up to 18 % and 6 % respectively. Natural gas consumption can be reduced by up to 67 %. Meanwhile the unburned methane and carbon dioxide mass known as greenhouse gas emissions can be reduced to less than 1 % and up to 50 % respectively. Continued replacement of natural gas with hydrogen until its complete elimination guarantees a reduction of 92000 cubic meters of natural gas per year in one engine cylinder. Although the engine efficiency and load face a decrease of 0.8 % and 5.0 % respectively; the amount of carbon dioxide can be decreased by about 4.5 times. Unburned methane carbon monoxide and nitrogen oxides can be reduced to below the relevant EURO VI range while the amount of unburned hydrogen compared to the hydrogen entering the engine is about 0.5 %.
Collaborative Control Strategy of Electric–Thermal–Hydrogen-Integrated Energy System Based on Variable-Frequency Division Coefficient
Dec 2024
Publication
To address the issues of diverse energy supply demands and power fluctuations in integrated energy systems (IESs) this study takes an IES composed of power-generation units such as wind and photovoltaic units along with various energy-storage systems including electrical thermal and hydrogen storage as the research subject. A collaborative control strategy is proposed for the IES which comprehensively considers the status of diverse energy-storage systems like battery packs thermal tanks and hydrogen tanks. First a mathematical model of the IES is constructed. Then a dual-layer collaborative control strategy is designed considering different operating modes of the IES which includes a multi-energy-storage power allocation control layer based on second-order power-frequency processing and distribution and an adaptive adjustment layer for adjusting powerfrequency coefficients based on adaptive fuzzy control. Finally MATLAB is used to simulate and validate the proposed strategy. The results indicate that the collaborative control strategy based on variable-frequency coefficients optimizes the allocation of fluctuating power among multiple energy-storage systems enhances the stability of bus voltage reduces the deep charge and discharge time of battery packs and extends the service life of battery packs.
Optimization Operation Strategy for Comprehensive Energy System Considering Multi-Mode Hydrogen Transportation
Dec 2024
Publication
The transformation from a fossil fuel economy to a low-carbon economy has reshaped the way energy is transmitted. As most renewable energy is obtained in the form of electricity using green electricity to produce hydrogen is considered a promising energy carrier. However most studies have not considered the transportation mode of hydrogen. In order to encourage the utilization of renewable energy and hydrogen this paper proposes a comprehensive energy system optimization operation strategy considering multi-mode hydrogen transport. Firstly to address the shortcomings in the optimization operation of existing systems regarding hydrogen transport modeling is conducted for multi-mode hydrogen transportation through hydrogen tube trailers and pipelines. This model reflects the impact of multi-mode hydrogen delivery channels on hydrogen utilization which helps promote the consumption of new energy in electrolysis cells to meet application demands. Based on this the constraints of electrolyzers combined heat and power units hydrogen fuel cells and energy storage systems in integrated energy systems (IESs) are further considered. With the objective of minimizing the daily operational cost of the comprehensive energy system an optimization model for the operation considering multi-mode hydrogen transport is constructed. Lastly based on simulation examples the impact of multi-mode hydrogen transportation on the operational cost of the system is analyzed in detail. The results indicate that the proposed optimization strategy can reduce the operational cost of the comprehensive energy system. Hydrogen tube trailers and pipelines will have a significant impact on operational costs. Properly allocating the quantity of hydrogen tube trailers and pipelines is beneficial for reducing the operational costs of the system. Reasonable arrangement of hydrogen transportation channels is conducive to further promoting the green and economic operation of the system.
Towards a Synthetic Positive Energy District (PED) in ˙Istanbul: Balancing Cost, Mobility, and Environmental Impact
Oct 2024
Publication
The influence of mobility modes within Positive Energy Districts (PEDs) has gained limited attention despite their crucial role in reducing energy consumption and greenhouse gas emissions. Buildings in the European Union (EU) account for 40% of energy consumption and 36% of greenhouse gas emissions. In comparison transport contributes 28% of energy use and 25% of emissions with road transport responsible for 72% of these emissions. This study aims to design and optimize a synthetic PED in Istanbul that integrates renewable energy sources and public mobility systems to address these challenges. The renewable energy sources integrated into the synthetic PED model include solar energy hydrogen energy and regenerative braking energy from a tram system. Solar panels provided a substantial portion of the energy while hydrogen energy contributed to additional electricity generation. Regenerative braking energy from the tram system was also utilized to further optimize energy production within the district. This system powers a middle school 10 houses a supermarket and the tram itself. Optimization techniques including Linear Programming (LP) for economic purposes and the Weighted Sum Method (WSM) for environmental goals were applied to balance cost and CO2 emissions. The LP method identified that the PED model can achieve cost competitiveness with conventional energy grids when hydrogen costs are below $93.16/MWh. Meanwhile the WSM approach demonstrated that achieving a minimal CO2 emission level of 5.74 tons requires hydrogen costs to be $32.55/MWh or lower. Compared to a conventional grid producing 97 tons of CO2 annually the PED model achieved reductions of up to 91.26 tons. This study contributes to the ongoing discourse on sustainable urban energy systems by addressing key research gaps related to the integration of mobility modes within PEDs and offering insights into the optimization of renewable energy sources for reducing emissions and energy consumption.
Prediction of Transient Hydrogen Flow of Proton Exchange Membrane Electrolyzer Using Artificial Neural Network
Aug 2023
Publication
A proton exchange membrane (PEM) electrolyzer is fed with water and powered by electric power to electrochemically produce hydrogen at low operating temperatures and emits oxygen as a by-product. Due to the complex nature of the performance of PEM electrolyzers the application of an artificial neural network (ANN) is capable of predicting its dynamic characteristics. A handful of studies have examined and explored ANN in the prediction of the transient characteristics of PEM electrolyzers. This research explores the estimation of the transient behavior of a PEM electrolyzer stack under various operational conditions. Input variables in this study include stack current oxygen pressure hydrogen pressure and stack temperature. ANN models using three differing learning algorithms and time delay structures estimated the hydrogen mass flow rate which had transient behavior from 0 to 1 kg/h and forecasted better with a higher count (>5) of hidden layer neurons. A coefficient of determination of 0.84 and a mean squared error of less than 0.005 were recorded. The best-fitting model to predict the dynamic behavior of the hydrogen mass flow rate was an ANN model using the Levenberg–Marquardt algorithm with 40 neurons that had a coefficient of determination of 0.90 and a mean squared error of 0.00337. In conclusion optimally fit models of hydrogen flow from PEM electrolyzers utilizing artificial neural networks were developed. Such models are useful in establishing an agile flow control system for the electrolyzer system to help decrease power consumption and increase efficiency in hydrogen generation.
Pressure Dependence of CO2 Effect on Hydrogen-assisted Fatigue Crack Growth in Two Pipeline Steels
Oct 2024
Publication
This study investigated the pressure-dependent CO2 effect on the hydrogen embrittlement of X80 and GB20# pipeline steels by combining experiments and first-principles calculations. Results revealed that the CO2 effect enhanced the fatigue crack growth for GB20# steel in 10 MPa CO₂-enriched hydrogen mixtures. However the improved degree by the CO₂ effect at 10 MPa was less pronounced than at 0.4 MPa which was found for the first time. This was attributed to the decreased adsorption rate of CO₂ on iron as hydrogen pressure increased. Therefore in high-pressure CO₂-enriched hydrogen mixtures CO2 could not significantly accelerate the inherent rapid hydrogen uptake at high pressure.
Thermodynamic and Transport Properties of Hydrogen Containing Streams
Jul 2020
Publication
he use of hydrogen (H2) as a substitute for fossil fuel which accounts for the majority of the world’s energy is environmentally the most benign option for the reduction of CO2 emissions. his will require gigawatt-scale storage systems and as such H2 storage in porous rocks in the subsurface will be required. ccurate estimation of the thermodynamic and transport properties of H2 mixed with other gases found within the storage system is therefore essential for the efcient design for the processes involved in this system chain. In this study we used the established and regarded GERG-2008 Equation of State (EoS) and SuperRPP model to predict the thermo-physical properties of H2 mixed with CH4 N2 CO2 and a typical natural gas from the North-Sea. he data covers a wide range of mole fraction of H2 (10–90 Mole%) pressures (0.01–100MPa) and temperatures (200–500K) with high accuracy and precision. Moreover to increase ease of access to the data a user-friendly software (H2Themobank) is developed and made publicly available.
Conceptual Design-optimisation of a Subsonic Hydrogen-powered Long-range Blended-wing-body Aircraft
Nov 2024
Publication
The adoption of liquid hydrogen (LH2) holds promise for decarbonising long-range aviation. LH2 aircraft could weigh less than Jet-A aircraft thereby reducing the thrust requirement. However the lower volumetric energy density of LH2 can adversely impact the aerodynamic performance and energy consumption of tube-wing aircraft. In a first this work conducts an energy performance modelling of a futuristic (2030+) LH2 blendedwing-body (BWB) aircraft (301 passengers and 13890 km) using conceptual aircraft design-optimisation approach employing weight-sizing methods while considering the realistic gravimetric and volumetric energy density effects of LH2 on aircraft design and the resulting reduction in aircraft thrust requirement. This study shows that at the design point the futuristic LH2 BWB aircraft reduces the specific energy consumption (SEC MJ/ tonne-km) by 51.7–53.5% and 7.3–10.8% compared to (Jet-A) Boeing 777-200LR and Jet-A BWB respectively. At the off-design points this study shows that by increasing the load factor for a given range and/or increasing range for all load factor cases the SEC (or energy efficiency) of this LH2 BWB concept improves. The results of this work will inform future studies on use-phase emissions and contrails modelling LH2 aircraft operations for contrail reduction estimation of operating costs and lifecycle climate impacts.
Potential Domestic Energy System Vulnerabilities from Major Exports of Green Hydrogen: A Case Study of Australia
Aug 2023
Publication
Australia has clear aspirations to become a major global exporter of hydrogen as a replacement for fossil fuels and as part of the drive to reduce CO2 emissions as set out in the National Hydrogen Strategy released in 2019 jointly by the federal and state governments. In 2021 the Australian Energy Market Operator specified a grid forecast scenario for the first time entitled “hydrogen superpower”. Not only does Australia hope to capitalise on the emerging demand for zero-carbon hydrogen in places like Japan and South Korea by establishing a new export industry but it also needs to mitigate the built-in carbon risk of its export revenue from coal and LNG as major customers such as Japan and South Korea move to decarbonise their energy systems. This places hydrogen at the nexus of energy climate change mitigation and economic growth with implications for energy security. Much of the published literature on this topic concentrates on the details of what being a major hydrogen exporter will look like and what steps will need to be taken to achieve it. However there appears to be a gap in the study of the implications for Australia’s domestic energy system in terms of energy security and export economic vulnerability. The objective of this paper is to develop a conceptual framework for the implications of becoming a major hydrogen exporter on Australia’s energy system. Various green hydrogen export scenarios for Australia were compared and the most recent and comprehensive was selected as the basis for further examination for domestic energy system impacts. In this scenario 248.5 GW of new renewable electricity generation capacity was estimated to be required by 2050 to produce the additional 867 TWh required for an electrolyser output of 2088 PJ of green hydrogen for export which will comprise 55.9% of Australia’s total electricity demand at that time. The characteristics of comparative export-oriented resources and their interactions with the domestic economy and energy system are then examined through the lens of the resource curse hypothesis and the LNG and aluminium industries. These existing resource export frameworks are reviewed for applicability of specific factors to export-oriented green hydrogen production with applicable factors then compiled into a novel conceptual framework for exporter domestic implications from large-scale exports of green hydrogen. The green hydrogen export superpower (2050) scenario is then quantitatively assessed using the established indicators for energy exporter vulnerability and domestic energy security comparing it to Australia’s 2019 energy exports profile. This assessment finds that in almost all factors exporter vulnerability is reduced and domestic energy security is enhanced by the transition from fossil fuel exports to green hydrogen with the exception of an increase in exposure of the domestic energy system to international market forces.
Research on Energy Management of Hydrogen Fuel Cell Bus Based on Deep Reinforcement Learning Considering Velocity Control
Aug 2023
Publication
In the vehicle-to-everything scenario the fuel cell bus can accurately obtain the surrounding traffic information and quickly optimize the energy management problem while controlling its own safe and efficient driving. This paper proposes an energy management strategy (EMS) that considers speed control based on deep reinforcement learning (DRL) in complex traffic scenarios. Using SUMO simulation software (Version 1.15.0) a two-lane urban expressway is designed as a traffic scenario and a hydrogen fuel cell bus speed control and energy management system is designed through the soft actor–critic (SAC) algorithm to effectively reduce the equivalent hydrogen consumption and fuel cell output power fluctuation while ensuring the safe efficient and smooth driving of the vehicle. Compared with the SUMO–IDM car-following model the average speed of vehicles is kept the same and the average acceleration and acceleration change value decrease by 10.22% and 11.57% respectively. Compared with deep deterministic policy gradient (DDPG) the average speed is increased by 1.18% and the average acceleration and acceleration change value are decreased by 4.82% and 5.31% respectively. In terms of energy management the hydrogen consumption of SAC–OPT-based energy management strategy reaches 95.52% of that of the DP algorithm and the fluctuation range is reduced by 32.65%. Compared with SAC strategy the fluctuation amplitude is reduced by 15.29% which effectively improves the durability of fuel cells.
Life Cycle Assessment Comparison of Orchard Tractors Powered by Diesel and Hydrogen Fuel Cell
Sep 2024
Publication
To reduce the impact of the agricultural sector on the environment human health and resource depletion several steps should be taken to develop innovative powertrain systems. The agricultural sector must be involved in this innovation since diesel-powered tractors are an important source in terms of pollution. In this context fuel-cell systems have gained importance making them one of the possible substitutes due to their characteristics featuring almost zero local emissions low refueling time and high efficiency. However to effectively assess the sustainability of a fuel-cell tractor a cradle-to-grave life cycle assessment comprising production use phase and end of life must be performed. This article presents a comparative analysis according to different impact categories of the life cycle impacts of a traditional diesel-powered tractor and a fuel-cell hybrid tractor designed considering operative requirements and functional constraints. The study was conducted according to the LCA technique (defined by ISO 14040 and ISO 14044 standards) combining secondary data mainly derived from studies and reports available in the literature with the use of the Ecoinvent 3.0 database. The results are presented according to ten different impact categories defined by ReCiPe 2016 v 1.03 at the midpoint level. The findings obtained showed that the fuel-cell tractor allows for a relevant reduction in all the considered categories. The highest-impact reduction more than 92% was obtained in the human toxicity non-carcinogenic category while the lowest reduction around 4.55% was observed for the fossil fuel scarcity category mainly due to the adoption of gray hydrogen which is produced from fossil fuels. As for the climate change category the fuel-cell tractor showed a reduction of more than 34% in the life cycle impact. Finally the authors also considered the case of green hydrogen produced using solar energy. In this case further reductions in the impact on climate change and fossil fuel resource depletion were obtained. However for the other impact categories the results were worse compared to using gray hydrogen.
Safety of Hydrogen Storage Technologies
Oct 2024
Publication
While hydrogen is regularly discussed as a possible option for storing regenerative energies its low minimum ignition energy and broad range of explosive concentrations pose safety challenges regarding hydrogen storage and there are also challenges related to hydrogen production and transport and at the point of use. A risk assessment of the whole hydrogen energy system is necessary to develop hydrogen utilization further. Here we concentrate on the most important hydrogen storage technologies especially high-pressure storage liquid hydrogen in cryogenic tanks methanol storage and salt cavern storage. This review aims to study the most recent research results related to these storage techniques by describing typical sensors and explosion protection measures thus allowing for a risk assessment of hydrogen storage through these technologies.
A Review of Hydrogen Production via Seawater Electrolysis: Current Status and Challenges
Oct 2024
Publication
Seawater electrolysis represents a promising green energy technology with significant potential for efficient energy conversion. This study provides an in-depth examination of the key scientific challenges inherent in the seawater-electrolysis process and their potential solutions. Initially it analyzes the potential issues of precipitation and aggregation at the cathode during hydrogen evolution proposing strategies such as self-cleaning cathodes and precipitate removal to ensure cathode stability in seawater electrolysis. Subsequently it addresses the corrosion challenges faced by anode catalysts in seawater introducing several anti-corrosion strategies to enhance anode stability including substrate treatments such as sulfidation phosphidation selenidation and LDH (layered double hydroxide) anion intercalation. Additionally this study explores the role of regulating the electrode surface microenvironment and forming unique coordination environments for active atoms to enhance seawater electrolysis performance. Regulating the surface microenvironment provides a novel approach to mitigating seawater corrosion. Contrary to the traditional understanding that chloride ions accelerate anode corrosion certain catalysts benefit from the unique coordination environment of chloride ions on the catalyst surface potentially enhancing oxygen evolution reaction (OER) performance. Lastly this study presents the latest advancements in the industrialization of seawater electrolysis including the in situ electrolysis of undiluted seawater and the implementation of three-chamber dual anion membranes coupled with circulating electrolyte systems. The prospects of seawater electrolysis are also explored.
A Comprehensive Literature Review on Hydrogen Tanks: Storage, Safety, and Structural Integrity
Oct 2024
Publication
In recent years there has been a significant increase in research on hydrogen due to the urgent need to move away from carbon-intensive energy sources. This transition highlights the critical role of hydrogen storage technology where hydrogen tanks are crucial for achieving cleaner energy solutions. This paper aims to provide a general overview of hydrogen treatment from a mechanical viewpoint and to create a comprehensive review that integrates the concepts of hydrogen safety and storage. This study explores the potential of hydrogen applications as a clean energy alternative and their role in various sectors including industry automotive aerospace and marine fields. The review also discusses design technologies safety measures material improvements social impacts and the regulatory landscape of hydrogen storage tanks and safety technology. This work provides a historical literature review up to 2014 and a systematic literature review from 2014 to the present to fill the gap between hydrogen storage and safety. In particular a fundamental feature of this work is leveraging systematic procedural techniques for performing an unbiased review study to offer a detailed analysis of contemporary advancements. This innovative approach differs significantly from conventional review methods since it involves a replicable scientific and transparent process which culminates in minimizing bias and allows for highlighting the fundamental issues about the topics of interest and the main conclusions of the experts in the field of reference. The systematic approach employed in the paper was used to analyze 55 scientific articles resulting in the identification of six primary categories. The key findings of this review work underline the need for improved materials enhanced safety protocols and robust infrastructure to support hydrogen adoption. More importantly one of the fundamental results of the present review analysis is pinpointing the central role that composite materials will play during the transition toward hydrogen applications based on thin-walled industrial vessels. Future research directions are also proposed in the paper thereby emphasizing the importance of interdisciplinary collaboration to overcome existing challenges and facilitate the safe and efficient use of hydrogen.
Hydrogen Carriers: Scientific Limits and Challenges for the Supply Chain, and Key Factors for Techno-Economic Analysis
Aug 2023
Publication
Hydrogen carriers are one of the keys to the success of using hydrogen as an energy vector. Indeed sustainable hydrogen production exploits the excess of renewable energy sources after which temporary storage is required. The conventional approaches to hydrogen storage and transport are compressed hydrogen (CH2 ) and liquefied hydrogen (LH2 ) which require severe operating conditions related to pressure (300–700 bar) and temperature (T < −252 ◦C) respectively. To overcome these issues which have hindered market penetration several alternatives have been proposed in the last few decades. In this review the most promising hydrogen carriers (ammonia methanol liquid organic hydrogen carriers and metal hydrides) have been considered and the main stages of their supply chain (production storage transportation H2 release and their recyclability) have been described and critically analyzed focusing on the latest results available in the literature the highlighting of which is our current concern. The last section reviews recent techno-economic analyses to drive the selection of hydrogen carrier systems and the main constraints that must be considered. The analyzed results show how the selection of H2 carriers is a multiparametric function and it depends on technological factors as well as international policies and regulations.
Hydrogen Strategy Update to the Market: December 2024
Dec 2024
Publication
Low carbon hydrogen is essential to achieve the Government’s Clean Energy Superpower and Growth Missions. It will be a crucial enabler of a low carbon and renewables-based energy system and will help to deliver new clean energy industries which can support good jobs in our industrial heartlands and coastal communities. Hydrogen presents significant growth and economic opportunities across the UK by enhancing our energy security providing flexible cleaner energy for our power system and helping to decarbonise vital UK industries. Hydrogen has a critical role in helping to achieve our Clean Energy Superpower Mission. It can provide flexible low carbon power generation meaning we can use hydrogen to produce electricity during extended periods of low renewable output. Hydrogen can also provide interseasonal energy storage through conversion of electricity into hydrogen and then back into electricity at times of need using a combination of hydrogen production storage and hydrogen to power. To advance our Clean Energy and Growth Missions hydrogen also has a unique role in transitioning crucial UK industries away from oil and gas and towards a clean homegrown source of fuel. Hydrogen can decarbonise hard-to-abate sectors like chemicals and heavy transport complementing our wider electrification efforts and accelerating our progress to net zero. Using our strong domestic expertise and favourable geology geography and infrastructure backing UK hydrogen can unlock significant economic opportunities and new low carbon jobs of the future. Government has an ambitious range of policies in place to incentivise and support industry to invest in low carbon hydrogen. The recent Hydrogen Skills Workforce Assessment an industry-led study undertaken by the Hydrogen Skills Alliance estimated that the UK hydrogen economy could support 29000 direct jobs and 64500 indirect jobs by 2030. Since establishing in Summer 2024 this Government has already made significant progress in delivering the UK hydrogen economy. This includes confirming support for the 11 successful Hydrogen Allocation Round 1 projects announcing up to £21.7 billion of available funding to launch the UK’s new carbon capture utilisation and storage industry and publishing our hydrogen to power consultation response with an aim to establish a new hydrogen to power business model. We have also launched three new bodies – the National Energy System Operator Great British Energy and the National Wealth Fund – which will help to deliver a world-class energy system including for low carbon hydrogen. This December 2024 Hydrogen Strategy Update to the Market sets out the key milestones achieved by the Department for Energy Security and Net Zero in 2024 to deliver the hydrogen economy and an ambitious forward look at our next steps and upcoming opportunities. To achieve net zero and create a thriving and resilient energy landscape we are already working at considerable pace to deliver a world-leading UK hydrogen sector.
Techno-economic Assessment of Hydrogen Supply Solutions for Industrial Site
Sep 2024
Publication
In Austria one of the highest priorities of hydrogen usage lies in the industrial sector particularly as a feedstock and for high-temperature applications. Connecting hydrogen producers with consumers is challenging and requires comprehensive research to outline the advantages and challenges associated with various hydrogen supply options. This study focuses on techno-economic assessment of different supply solutions for industrial sites mainly depicted in two categories: providing hydrogen by transport means and via on-site production. The technologies needed for the investigation of these scenarios are identified based on the predictions of available technologies in near future (2030). The transportation options analyzed include delivering liquid hydrogen by truck liquid hydrogen by railway and gaseous hydrogen via pipeline. For on-site low-carbon hydrogen production a protonexchange membrane (PEM) electrolysis was selected as resent research suggests lower costs for PEM electrolysis compared to alkaline electrolysis (AEL). The frequency of deliveries and storage options vary by scenario and are determined by the industrial demand profile transport capacity and electrolyser production capacity. The assessment evaluates the feasibility and cost-effectiveness of each option considering factors such as infrastructure requirements energy efficiency and economic viability. At a hydrogen demand of 80 GWh the transport options indicate hydrogen supply costs in the range of 14–24 ct/kWh. In contrast the scenarios investigating on-site production of hydrogen show costs between 29 and 49 ct/ kWh. Therefore transport by truck rail or pipeline is economically advantageous to own-production under the specific assumptions and conditions. However the results indicate that as energy demand increases on-site production becomes more attractive. Additionally the influence of electricity prices and the hydrogen production/import price were identified as decisive factors for the overall hydrogen supply costs.
Design and Performance Optimization of a Radial Turbine Using Hydrogen Combustion Products
Dec 2024
Publication
The combustion of hydrogen increases the water content of the combustion products affecting the aerodynamic performance of turbines using hydrogen as a fuel. This study aims to design a radial turbine using the differential evolution (DE) algorithm to improve its characteristics and optimize its aerodynamic performance through an orthogonal experiment and analysis of means (ANOM). The effects of varying water content in combustion products ranging from 12% to 22% on the performance of the radial turbine are also investigated. After optimization the total–static efficiency of the radial turbine increased to 89.12% which was 1.59% higher than the preliminary design. The study found that flow loss in the impeller primarily occurred at the leading edge trailing edge and the inlet of the suction surface tip and outlet. With a 10% increase in water content the enthalpy dropped Mach number increased and turbine power increased by 4.64% 1.71% and 2.41% respectively. However the total static efficiency and mass flow rate decreased by 0.71% and 2.13% respectively. These findings indicate that higher water content in hydrogen combustion products enhances the turbine’s output power while reducing the combustion products’ mass flow rate.
Modelling of Hydrogen Blending into the UK Natural Gas Network Driven by a Solid Oxide Fuel Cell for Electricity and District Heating System
Aug 2023
Publication
A thorough investigation of the thermodynamics and economic performance of a cogeneration system based on solid oxide fuel cells that provides heat and power to homes has been carried out in this study. Additionally different percentages of green hydrogen have been blended with natural gas to examine the techno-economic performance of the suggested cogeneration system. The energy and exergy efficiency of the system rises steadily as the hydrogen blending percentage rises from 0% to 20% then slightly drops at 50% H2 blending and then rises steadily again until 100% H2 supply. The system’s minimal levelised cost of energy was calculated to be 4.64 £/kWh for 100% H2. Artificial Neural Network (ANN) model was also used to further train a sizable quantity of data that was received from the simulation model. Heat power and levelised cost of energy estimates using the ANN model were found to be extremely accurate with coefficients of determination of 0.99918 0.99999 and 0.99888 respectively.
The Bio Steel Cycle: 7 Steps to Net-Zero CO2 Emissions Steel Production
Nov 2022
Publication
CO2 emissions have been identified as the main driver for climate change with devastating consequences for the global natural environment. The steel industry is responsible for ~7–11% of global CO2 emissions due to high fossil-fuel and energy consumption. The onus is therefore on industry to remedy the environmental damage caused and to decarbonise production. This desk research report explores the Bio Steel Cycle (BiSC) and proposes a seven-step-strategy to overcome the emission challenges within the iron and steel industry. The true levels of combined CO2 emissions from the blast-furnace and basic-oxygen-furnace operation at 4.61 t of CO2 emissions/t of steel produced are calculated in detail. The BiSC includes CO2 capture implementing renewable energy sources (solar wind green H2 ) and plantation for CO2 absorption and provision of biomass. The 7-step-implementation-strategy starts with replacing energy sources develops over process improvement and installation of flue gas carbon capture and concludes with utilising biogas-derived hydrogen as a product from anaerobic digestion of the grown agrifood in the cycle. In the past CO2 emissions have been seemingly underreported and underestimated in the heavy industries and implementing the BiSC using the provided seven-steps-strategy will potentially result in achieving net-zero CO2 emissions in steel manufacturing by 2030.
Greenhouse Gas Reduction Potential and Economics of Green Hydrogen via Water Electrolysis: A Systematic Review of Value-Chain-Wide Decarbonization
May 2024
Publication
Green hydrogen generated via water electrolysis has become an essential energy carrier for achieving carbon neutrality globally because of its versatility in renewable energy consumption and decarbonization applications in hard-to-abate sectors; however there is a lack of systematic analyses of its abatement potential and economics as an alternative to traditional technological decarbonization pathways. Based on bibliometric analysis and systematic evaluation methods this study characterizes and analyzes the literature on the Web of Science from 1996 to 2023 identifying research hotspots methodological models and research trends in green hydrogen for mitigating climate change across total value chain systems. Our review shows that this research theme has entered a rapid development phase since 2016 with developed countries possessing more scientific results and closer partnerships. Difficult-to-abate sectoral applications and cleaner production are the most famous value chain links and research hotspots focus on three major influencing factors: the environment; techno-economics; and energy. Green hydrogen applications which include carbon avoidance and embedding to realize carbon recycling have considerable carbon reduction potential; however uncertainty limits the influence of carbon reduction cost assessment indicators based on financial analysis methods for policy guidance. The abatement costs in the decarbonization sector vary widely across value chains electricity sources baseline scenarios technology mixes and time scenarios. This review shows that thematic research trends are focused on improving and optimizing solutions to uncertainties as well as studying multisectoral synergies and the application of abatement assessment metrics.
Advancements in Hydrogen Production, Storage, Distribution and Refuelling for a Sustainable Transport Sector: Hydrogen Fuel Cell Vehicles
Jul 2023
Publication
Hydrogen is considered as a promising fuel in the 21st century due to zero tailpipe CO2 emissions from hydrogen-powered vehicles. The use of hydrogen as fuel in vehicles can play an important role in decarbonising the transport sector and achieving net-zero emissions targets. However there exist several issues related to hydrogen production efficient hydrogen storage system and transport and refuelling infrastructure where the current research is focussing on. This study critically reviews and analyses the recent technological advancements of hydrogen production storage and distribution technologies along with their cost and associated greenhouse gas emissions. This paper also comprehensively discusses the hydrogen refuelling methods identifies issues associated with fast refuelling and explores the control strategies. Additionally it explains various standard protocols in relation to safe and efficient refuelling analyses economic aspects and presents the recent technological advancements related to refuelling infrastructure. This study suggests that the production cost of hydrogen significantly varies from one technology to others. The current hydrogen production cost from fossil sources using the most established technologies were estimated at about $0.8–$3.5/kg H2 depending on the country of production. The underground storage technology exhibited the lowest storage cost followed by compressed hydrogen and liquid hydrogen storage. The levelised cost of the refuelling station was reported to be about $1.5–$8/kg H2 depending on the station's capacity and country. Using portable refuelling stations were identified as a promising option in many countries for small fleet size low-to-medium duty vehicles. Following the current research progresses this paper in the end identifies knowledge gaps and thereby presents future research directions.
Green Hydrogen Cooperation between Egypt and Europe: The Perspective of Locals in Suez and Port Said
Jun 2024
Publication
Hydrogen produced by renewable energy sources (green hydrogen) is at the centrepiece of European decarbonization strategies necessitating large imports from third countries. Egypt potentially stands out as major production hub. While technical and economic viability are broadly discussed in literature analyses of local acceptance are absent. This study closes this gap by surveying 505 locals in the Suez Canal Economic Zone (Port Said and Suez) regarding their attitudes towards renewable energy development and green hydrogen production. We find overall support for both national deployment and export to Europe. Respondents see a key benefit in rising income thereby strongly underlying the economic argument. Improved trade relationships or improved political relationships are seen as potential benefits of export but as less relevant for engaging in cooperation putting a spotlight on local benefits. Our study suggests that the local population is more positive than negative towards the development and scaling up of green hydrogen projects in Egypt.
An Overview of Different Water Electrolyzer Types for Hydrogen Production
Oct 2024
Publication
While fossil fuels continue to be used and to increase air pollution across the world hydrogen gas has been proposed as an alternative energy source and a carrier for the future by scientists. Water electrolysis is a renewable and sustainable chemical energy production method among other hydrogen production methods. Hydrogen production via water electrolysis is a popular and expensive method that meets the high energy requirements of most industrial electrolyzers. Scientists are investigating how to reduce the price of water electrolytes with different methods and materials. The electrolysis structure equations and thermodynamics are first explored in this paper. Water electrolysis systems are mainly classified as high- and low-temperature electrolysis systems. Alkaline PEM-type and solid oxide electrolyzers are well known today. These electrolyzer materials for electrode types electrolyte solutions and membrane systems are investigated in this research. This research aims to shed light on the water electrolysis process and materials developments.
Ignore Variability, Overestimate Hydrogen Production - Quantifying the Effects of Electrolyzer Efficiency Curves on Hydrogen Producton from Renewable Energy Sources
May 2024
Publication
This study investigates the impact of including (or neglecting) the variable efficiency of hydrogen electrolyzers as a function of operating power in the modelling of green hydrogen produced from variable renewable energy sources. Results show that neglecting the variable electrolyzer efficiency as is commonly done in studies of green hydrogen leads to significant overestimation of hydrogen production in the range of 5–24%. The effects of the time resolution used in models are also investigated as well as the impact of including the option for the electrolyzer to switch to stand-by mode instead of powering down and electrolyzer ramp rate constraints. Results indicate that these have a minor effect on overall hydrogen production with the use of hour resolution data leading to overestimation in the range of 0.2–2% relative to using 5-min data. This study used data from three solar farms and three wind in Australia from which it is observed that wind farms produced 55% more hydrogen than the solar farms. The results in this study highlight the critical importance of including the variable efficiency of electrolyzers in the modelling of green hydrogen production. As this industry scales continuing to neglect this effect would lead to the overestimation of hydrogen production by tens of megatonnes.
Assessing the Potential of Hybrid Systems with Batteries, Fuel Cells and E-Fuels for Onboard Generation and Propulsion in Pleasure Vessels
Dec 2024
Publication
Electro-fuels (E-fuels) represent a potential solution for decarbonizing the maritime sector including pleasure vessels. Due to their large energy requirements direct electrification is not currently feasible. E-fuels such as synthetic diesel methanol ammonia methane and hydrogen can be used in existing internal combustion engines or fuel cells in hybrid configurations with lithium batteries to provide propulsion and onboard electricity. This study confirms that there is no clear winner in terms of efficiency (the power-to-power efficiency of all simulated cases ranges from 10% to 30%) and the choice will likely be driven by other factors such as fuel cost onboard volume/mass requirements and distribution infrastructure. Pure hydrogen is not a practical option due to its large storage necessity while methanol requires double the storage volume compared to current fossil fuel solutions. Synthetic diesel is the most straightforward option as it can directly replace fossil diesel and should be compared with biofuels. CO2 emissions from E-fuels strongly depend on the electricity source used for their synthesis. With Italy’s current electricity mix E-fuels would have higher impacts than fossil diesel with potential increases between +30% and +100% in net total CO2 emissions. However as the penetration of renewable energy increases in electricity generation associated E-fuel emissions will decrease: a turning point is around 150 gCO2/kWhel.
Review of Common Hydrogen Storage Tanks and Current Manufacturing Methods for Aluminium Tank Liners
Aug 2023
Publication
With the growing concern about climate issues and the urgent need to reduce carbon emissions hydrogen has attracted increasing attention as a clean and renewable vehicle energy source. However the storage of flammable hydrogen gas is a major challenge and it restricts the commercialisation of fuel cell electric vehicles (FCEVs). This paper provides a comprehensive review of common on-board hydrogen storage tanks possible failure mechanisms and typical manufacturing methods as well as their future development trends. There are generally five types of hydrogen tanks according to different materials used with only Type III (metallic liner wrapped with composite) and Type IV (polymeric liner wrapped with composite) tanks being used for vehicles. The metallic liner of Type III tank is generally made from aluminium alloys and the associated common manufacturing methods such as roll forming deep drawing and ironing and backward extrusion are reviewed and compared. In particular backward extrusion is a method that can produce near net-shape cylindrical liners without the requirement of welding and its tool designs and the microstructural evolution of aluminium alloys during the process are analysed. With the improvement and innovation on extrusion tool designs the extrusion force which is one of the most demanding issues in the process can be reduced significantly. As a result larger liners can be produced using currently available equipment at a lower cost.
Greenhouse Gas Emissions of a Hydrogen Engine for Automotive Application through Life-Cycle Assessment
May 2024
Publication
Hydrogen combustion engine vehicles have the potential to rapidly enter the market and reduce greenhouse gas emissions (GHG) compared to conventional engines. The ability to provide a rapid market deployment is linked to the fact that the industry would take advantage of the existing internal combustion engine production chain. The aim of this paper is twofold. First it aims to develop a methodology for applying life-cycle assessment (LCA) to internal combustion engines to estimate their life-cycle GHG emissions. Also it aims to investigate the decarbonization potential of hydrogen engines produced by exploiting existing diesel engine technology and assuming diverse hydrogen production routes. The boundary of the LCA is cradle-to-grave and the assessment is entirely based on primary data. The products under study are two monofuel engines: a hydrogen engine and a diesel engine. The hydrogen engine has been redesigned using the diesel engine as a base. The engines being studied are versatile and can be used for a wide range of uses such as automotive cogeneration maritime off-road and railway; however this study focuses on their application in pickup trucks. As part of the redesign process certain subsystems (e.g. combustion injection ignition exhaust gas recirculation and exhaust gas aftertreatment) have been modified to make the engine run on hydrogen. Results revealed that employing a hydrogen engine using green hydrogen (i.e. generated from water electrolysis using wind-based electricity) might reduce GHG emission by over 90% compared to the diesel engine This study showed that the benefits of the new hydrogen engine solution outweigh the increase of emissions related to the redesign process making it a potentially beneficial solution also for reconditioning current and used internal combustion engines.
Thermodynamic Evaluation and Carbon Footprint Analysis of the Application of Hydrogen-Based Energy-Storage Systems in Residential Buildings
Sep 2016
Publication
This study represents a thermodynamic evaluation and carbon footprint analysis of the application of hydrogen based energy storage systems in residential buildings. In the system model buildings are equipped with photovoltaic (PV) modules and a hydrogen storage system to conserve excess PV electricity from times with high solar irradiation to times with low solar irradiation. Short-term storages enable a degree of self-sufficiency of approximately 60% for a single-family house (SFH) [multifamily house (MFH): 38%]. Emissions can be reduced by 40% (SFH) (MFH: 30%) compared to households without PV modules. These results are almost independent of the applied storage technology. For seasonal storage the degree of self-sufficiency ranges between 57 and 83% (SFH). The emission reductions highly depend on the storage technology as emissions caused by manufacturing the storage dominate the emission balance. Compressed gas or liquid organic hydrogen carriers are the best options enabling emission reductions of 40%.
Hydrogen from Waste Gasification
Feb 2024
Publication
Hydrogen is a versatile energy vector for a plethora of applications; nevertheless its production from waste/residues is often overlooked. Gasification and subsequent conversion of the raw synthesis gas to hydrogen are an attractive alternative to produce renewable hydrogen. In this paper recent developments in R&D on waste gasification (municipal solid waste tires plastic waste) are summarised and an overview about suitable gasification processes is given. A literature survey indicated that a broad span of hydrogen relates to productivity depending on the feedstock ranging from 15 to 300 g H2/kg of feedstock. Suitable gas treatment (upgrading and separation) is also covered presenting both direct and indirect (chemical looping) concepts. Hydrogen production via gasification offers a high productivity potential. However regulations like frame conditions or subsidies are necessary to bring the technology into the market.
Shorter Message, Stronger Framing Increases Societal Acceptance for Hydrogen
Feb 2024
Publication
With the question of ‘can short messages be effective in increasing public support for a complex new technology (hydrogen)?‘ this study uses a representative national survey in Australia to analyze the differences and variations in subjective support for hydrogen in response to four differently framed short messages. The findings of this study show that short messages can increase social acceptance but the effects depend on how strongly the message is framed in terms of its alignment with either an economic or environmental values framework. Furthermore the effects depend on the social and cultural context of the receiver of the message.
Can an Energy Only Market Enable Resource Adequacy in a Decarbonized Power System? A Co-simulation with Two Agent-based-models
Feb 2024
Publication
Future power systems in which generation will come almost entirely from variable Renewable Energy Sources (vRES) will be characterized by weather-driven supply and flexible demand. In a simulation of the future Dutch power system we analyze whether there are sufficient incentives for market-driven investors to provide a sufficient level of security of supply considering the profit-seeking and myopic behavior of investors. We cosimulate two agent-based models (ABM) one for generation expansion and one for the operational time scale. The results suggest that in a system with a high share of vRES and flexibility prices will be set predominantly by the demand’s willingness to pay particularly by the opportunity cost of flexible hydrogen electrolyzers. The demand for electric heating could double the price of electricity in winter compared to summer and in years with low vRES could cause shortages. Simulations with stochastic weather profiles increase the year-to-year variability of cost recovery by more than threefold and the year-to-year price variability by more than tenfold compared to a scenario with no weather uncertainty. Dispatchable technologies have the most volatile annual returns due to high scarcity rents during years of low vRES production and diminished returns during years with high vRES production. We conclude that in a highly renewable EOM investors would not have sufficient incentives to ensure the reliability of the system. If they invested in such a way to ensure that demand could be met in a year with the lowest vRES yield they would not recover their fixed costs in the majority of years.
Geomechanics of Hydrogen Storage in a Depleted Gas Field
Feb 2024
Publication
We perform a simulation study of hydrogen injection in a depleted gas reservoir to assess the geomechanical impact of hydrogen storage relative to other commonly injected gases (methane CO2). A key finding is that the differences in hydrogen density compressibility viscosity and thermal properties compared to the other gases result in significantly less thermal perturbation at reservoir level. The risks of fault reactivation and wellbore fractures due to thermally-induced stress changes are significantly lower when storing hydrogen compared to results observed in CO2 scenarios. This implies that hydrogen injection and production has a much smaller geomechanical footprint with benefits for operational safety. We also find that use of nitrogen cushion gas ensures efficient deliverability and phase separation in the reservoir. However in this study a large fraction of cushion gas was back-produced in each cycle demonstrating the need for further studies of the surface processing requirements and economic implications.
Routes for Hydrogen Introduction in the Industrial Hard-to-Abate Sectors for Promoting Energy Transition
Aug 2023
Publication
This paper offers a set of comprehensive guidelines aimed at facilitating the widespread adoption of hydrogen in the industrial hard-to-abate sectors. The authors begin by conducting a detailed analysis of these sectors providing an overview of their unique characteristics and challenges. This paper delves into specific elements related to hydrogen technologies shedding light on their potential applications and discussing feasible implementation strategies. By exploring the strengths and limitations of each technology this paper offers valuable insights into its suitability for specific applications. Finally through a specific analysis focused on the steel sector the authors provide in-depth information on the potential benefits and challenges associated with hydrogen adoption in this context. By emphasizing the steel sector as a focal point the authors contribute to a more nuanced understanding of hydrogen’s role in decarbonizing industrial processes and inspire further exploration of its applications in other challenging sectors.
Stable Electrolytic Hydrogen Production Using Renewable Energy
Oct 2024
Publication
The inherent intermittency of upstream solar and wind power can result in fluctuating electrolytic hydrogen production which is incompatible with the feedstock requirements of many downstream hydrogen storage and utilisation applications. Suitable backup power or storage (hydrogen or energy) strategies are thus needed in overall system design. This work conducts technoeconomic modelling to design electrolytic production systems featuring stable hydrogen output for various locations across Australia based on hourly weather data and determines the levelised cost of hydrogen (LCOH) emissions intensities and annual electrolyser usage factors. A stable truly green hydrogen supply is consistently achieved by imposing annual usage factor requirements on the system which forces the system modules (i.e. solar wind electrolyser and hydrogen storage) to be oversized in order to achieve the desired usage factor. Whilst the resultant system designs are however very location-specific a design that ensures a 100% usage factor costs approximately 22% more on average than a system design which is optimised for cost alone.
Perspectives on the Development of Technologies for Hydrogen as a Carrier of Sustainable Energy
Aug 2023
Publication
Hydrogen is a prospective energy carrier because there are practically no gaseous emissions of greenhouse gases in the atmosphere during its use as a fuel. The great benefit of hydrogen being a practically inexhaustible carbon-free fuel makes it an attractive alternative to fossil fuels. I.e. there is a circular process of energy recovery and use. Another big advantage of hydrogen as a fuel is its high energy content per unit mass compared to fossil fuels. Nowadays hydrogen is broadly used as fuel in transport including fuel cell applications as a raw material in industry and as an energy carrier for energy storage. The mass exploitation of hydrogen in energy production and industry poses some important challenges. First there is a high price for its production compared to the price of most fossil fuels. Next the adopted traditional methods for hydrogen production like water splitting by electrolysis and methane reforming lead to the additional charging of the atmosphere with carbon dioxide which is a greenhouse gas. This fact prompts the use of renewable energy sources for electrolytic hydrogen production like solar and wind energy hydropower etc. An important step in reducing the price of hydrogen as a fuel is the optimal design of supply chains for its production distribution and use. Another group of challenges hindering broad hydrogen utilization are storage and safety. We discuss some of the obstacles to broad hydrogen application and argue that they should be overcome by new production and storage technologies. The present review summarizes the new achievements in hydrogen application production and storage. The approach of optimization of supply chains for hydrogen production and distribution is considered too.
Performance Assessment of a 25 kW Solid Oxide Cell Module for Hydrogen Production and Power Generation
Jan 2024
Publication
Hydrogen produced via water electrolysis from renewable electricity is considered a key energy carrier to defossilize hard-to-electrify sectors. Solid oxide cells (SOC) based reactors can supply hydrogen not only in electrolysis but also in fuel cell mode when operating with (synthetic) natural gas or biogas at low conversion (polygeneration mode). However the scale-up of SOC reactors to the multi-MW scale is still a research topic. Strategies for transient operation depending on electricity intermittency still need to be developed. In this work a unique testing environment for SOC reactors allows reversible operation demonstrating the successful switching between electrolysis (− 75 kW) and polygeneration (25 kW) modes. Transient and steady state experiments show promising performance with a net hydrogen production of 53 kg day− 1 in SOEL operation with ca. − 75 kW power input. The experimental results validate the scaling approach since the reactor shows homogenous temperature profiles.
Multi-objective Optimization of a Hydrogen Supply Chain Network: Wind and Solid Biomass as Primary Energy Sources for the Public Transport in Sicily
Jun 2024
Publication
Europe’s heavy reliance on diesel power for nearly half of its railway lines for both goods and passengers has significant implications for carbon emissions. To address this challenge the European Union advocates for a shift towards hydrogen-based mobility necessitating the development of robust and cost-effective hydrogen supply chains at regional and national levels. Leveraging renewable energy sources such as wind farms and solid biomass could foster the transition to sustainable hydrogen-based transportation. In this study a mixed-integer linear programming approach integrated with an external heavy-duty refueling station analysis model is employed to address the optimal design of a new hydrogen supply chain. Through multi-objective optimization this study aimed to minimize the overall daily costs and emissions of the supply chain. By applying the model to a case study in Sicily different scenarios with varying supply chain configurations and wind curtailment factors were explored. The findings revealed that increasing the wind curtailment factor from 1% to 2% led to reductions of 12% and 15% in the total daily emission costs and network costs respectively. Additionally centralized biomass-based plants dominated hydrogen production accounting for 96% and 94% of the total production under 1% and 2% wind curtailment factors respectively. Furthermore transporting gaseous hydrogen via tube trailers proved more cost effective than using tanker trucks for liquid hydrogen when compressed gaseous hydrogen is required at the dispenser of forecourt refueling stations. Finally the breakdown of the levelized cost for the hydrogen refuelling station strongly depends on the form of hydrogen received at the gate namely liquid or gaseous. Specifically for the former the dispenser accounts for 60% of the total cost whereas for the latter the compressor is responsible for 58% of the total cost. This study highlights the importance of preliminary and quantitative analyses of new hydrogen supply chains through model-based optimization.
Efficient and Low-emission Approaches for Cost-effective Hydrogen, Power, and Heat Production Based on Chemical Looping Combustion
Nov 2024
Publication
Hydrogen production has recently attracted much attention as an energy carrier and sector integrator (i.e. electricity and transport) in future decarbonized smart energy systems. At the same time power production is highly valued in energy systems as other sectors like transport and heating become electrified. This work compares two different low-emission systems to produce electricity hydrogen and heat. The proposed systems are based on chemical looping combustion combined with biomass gasification (CLC-BG) and steam methane reforming (CLC-SMR) both benefiting from heat integration between chemical looping combustion and downstream processes. A full process simulation is carried out in Aspen Plus for both systems and detailed modeling is performed for chemical looping combustion. The overall thermal efficiency is calculated to be 71.1 % for CLC-BG and 76.4 % for CLC-SMR. Co-feeding methane into the biomass gasification process of CLC-BG leads to an enhanced overall efficiency. In comparison to CLC-BG CLC-SMR exhibits greater potential in terms of power and hydrogen generation resulting in a higher exergy efficiency of 58.3 % as opposed to 44.6 %. Assuming market prices of 5.2 USD/GJ for biomass and 9.1 USD/GJ for natural gas the lowest minimum hydrogen sale price is estimated to be 4 USD/kg for CLC-SMR.
Identification of Safety Critical Scenarios of Hydrogen Refueling Stations in a Multifuel Context
Sep 2023
Publication
The MultHyFuel Project funded by the Clean Hydrogen Partnership aims to achieve the effective and safe deployment of hydrogen as a carbon-neutral fuel by developing a common strategy for implementing Hydrogen Refueling Stations (HRS) in a multifuel context. The project hopes to contribute to the harmonisation of existing regulations codes and standards (RCS) by generating practical theoretical and experimental data related to HRS.<br/>This paper presents how a set of safety critical scenarios have been identified from the initial preliminary as well as detailed risk analysis of three different hydrogen refueling station configurations. To achieve this a detailed examination of each potential hazardous phenomenon (DPh) or major accident event at or near the hydrogen dispenser was carried out. Particular attention is paid to the scenarios which could affect third parties external to the refueling station.<br/>The paper presents a methodology subdivided into the following steps:<br/>♦ determination of the consequence level and likelihood of each hazardous phenomenon<br/>♦ the classification of major hazard scenarios for the 3 HRS configurations specifically those arising on the dispensing forecourt;<br/>♦ proposal of example preventative control and/or mitigation barriers that could potentially reduce the probability of occurrence and/ or consequences of safety critical scenarios and hence reducing risks to a tolerable level or to as low as reasonably practicable.
Production of Hydrogen and H2/NH3 Mixtures from Ammonia at Elevated Pressures in a Cataytic Membrane Reformer
Jul 2025
Publication
Hydrogen delivery at elevated pressures is often required for fuel cell and combustion applications to improve volumetric energy density. Catalytic membrane reformers (CMRs) integrate hydrogen production and purification from reforming liquid hydrogen carriers such as ammonia enabling direct recovery of pressurized purified hydrogen. In this study high-pressure ammonia is supplied to a catalytic membrane reformer (CMR) to enhance both performance and hydrogen recovery pressures. Increasing operating pressure in the CMR resulted in nearly doubling the hydrogen flux from 17.2 to 34 sccm cm− 2 compared to our previous work. However as the recovery pressure of the permeate increased the performance notably decreased with hydrogen recovery dropping from 98 % at atmospheric pressure to 44 % at 10 bar. Nevertheless the system demonstrated rates of ammonia conversion hydrogen flux and hydrogen recovery comparable to leading literature reports when supplying ammonia at 20 bar and recovering the permeate up to 10 bar. Additionally by using ammonia as both a feed and sweep gas we demonstrate the direct production of high-pressure NH3/H2 fuel blends including a 70:30 mixture representative of natural gas without loss in CMR performance. These results highlight the potential of CMR technology to reduce hydrogen compression costs and enable on-demand generation of ammonia-derived fuel blends.
Investigation of the Suitability of Viper: Blast CFD Software for Hydrogen and Vapor Cloud Explosions
Sep 2023
Publication
Many simplified methods for estimating blast loads from a hydrogen or vapor cloud explosion are unable to take into account the accurate geometry of confining spaces obstacles or landscape that may significantly interact with the blast wave and influence the strength of blast loads. Computation fluid dynamics (CFD) software Viper::Blast which was originally developed for the simulation of the detonation of high explosives is able to quickly and easily model geometry for blast analyses however its use for vapor cloud explosions and deflagrations is not well established. This paper describes the results of an investigation into the suitability of Viper::Blast for use in modeling hydrogen deflagration and detonation events from various experiments in literature. Detonation events have been captured with a high degree of detail and relatively little uncertainty in inputs while deflagration events are significantly more complex. An approach is proposed that may allow for a reasonable bounding of uncertainty potentially leading to an approach to CFD-based Monte Carlo analyses that are able to address a problem’s true geometry while remaining reasonably pragmatic in terms of run-time and computational investment. This will allow further exploration of practical CFD application to inform hydrogen safety in the engineering design assessment and management of energy mobility and transport systems infrastructure and operations.
Examining the Nature of Two-dimensional Transverse Waves in Marginal Hydrogen Detonations using Boundary Layer Loss Modeling with Detailed Chemistry
Sep 2023
Publication
Historically it has been a challenge to simulate the experimentally observed cellular structures and marginal behavior of multidimensional hydrogen-oxygen detonations in the presence of losses even with detailed chemistry models. Very recently a quasi-two-dimensional inviscid approach was pursued where losses due to viscous boundary layers were modeled by the inclusion of an equivalent mass divergence in the lateral direction using Fay’s source term formulation with Mirels’ compressible boundary layer solutions. The same approach was used for this study along with the inclusion of thermally perfect detailed chemistry in order to capture the correct ignition sensitivity of the gas to dynamic changes in the thermodynamic state behind the detonation front. In addition the strength of transverse waves and their impact on the detonation front was investigated. Here the detailed San Diego mechanism was applied and it has been found that the detonation cell sizes can be accurately predicted without the need to prescribe specific parameters for the combustion model. For marginal cases where the detonation waves approach their failure limit quasi-stable mode behavior was observed where the number of transverse waves monotonically decreased to a single strong wave over a long enough distance. The strong transverse waves were also found to be slightly weaker than the detonation front indicating that they are not overdriven in agreement with recent studies.
Advances in Photothermal Catalysts for Solar-driven Hydrogen Production
Nov 2024
Publication
Hydrogen is increasingly recognized as a pivotal energy storage solution and a transformative alternative to conventional energy sources. This review summarizes the evolving landscape of global H2 production and consumption markets focusing on the crucial role of photothermal catalysts (PTCs) in driving Hydrogen evolution reactions (HER) particularly with regards to oxide selenide and telluride-based PTCs. Within this exploration the mechanisms of PTCs take center stage elucidating the intricacies of light absorption localized heating and catalytic activation. Essential optimization parameters ranging from temperature and irradiance to catalyst composition and pH are detailed for their paramount role in enhancing catalytic efficiency. This work comprehensively explores photothermal catalysts (PTCs) for hydrogen production by assessing their synthesis techniques and highlighting the current research gaps particularly in optimizing catalytic stability light absorption and scalability. The energy-efficient nature of oxide selenide and telluride-based PTCs makes them prime candidates for sustainable H2 production when compared to traditional materials. By analyzing a range of materials we summarize key performance metrics including hydrogen evolution rates ranging from 0.47 mmolh− 1 g− 1 for Ti@TiO2 to 22.50 mmolh− 1 g− 1 for Mn0.2Cd0.8S/NiSe2. The review concludes with a strategic roadmap aimed at enhancing PTC performance to meet the growing demand for renewable hydrogen as well as a critical literature review addressing challenges and prospects in deploying PTCs.
Enhancing Safety through Optimal Placement of Components in Hydrogen Tractor: Rollover Angle Analysis
Feb 2024
Publication
Hydrogen tractors are being developed necessitating consideration of the variation in the center of gravity depending on the arrangement of components such as power packs and cooling modules that replace traditional engines. This study analyzes the effects of component arrangement on stability and rollover angle in hydrogen tractors through simulations and proposes an optimal configuration. Stability is evaluated by analyzing rollover angles in various directions with rotations around the tractor’s midpoint. Based on the analysis of rollover angles for Type 1 Type 2 and Type 3 hydrogen tractors Type 2 demonstrates superior stability compared to the other types. Specifically when comparing lateral rollover angles at 0◦ rotation Type 2 exhibits a 2% increase over Type 3. Upon rotations at 90◦ and 180◦ Type 2 consistently displays the highest rollover angles with differences ranging from approximately 6% to 12% compared to the other types. These results indicate that Type 2 with its specific component arrangement offers the most stable configuration among the three types of tractors. It is confirmed that the rollover angle changes based on component arrangement with a lower center of gravity resulting in greater stability. These findings serve as a crucial foundation for enhancing stability in the future design and manufacturing phases of hydrogen tractors.
Considering Carbon–Hydrogen Coupled Integrated Energy Systems: A Pathway to Sustainable Energy Transition in China Under Uncertainty
Oct 2024
Publication
The low-carbon construction of integrated energy systems is a crucial path to achieving dual carbon goals with the power-generation side having the greatest potential for emissions reduction and the most direct means of reduction which is a current research focus. However existing studies lack the precise modeling of carbon capture devices and the cascaded utilization of hydrogen energy. Therefore this paper establishes a carbon capture power plant model based on a comprehensive flexible operational mode and a coupled model of a two-stage P2G (Power-to-Gas) device exploring the “energy time-shift” characteristics of the coupled system. IGDT (Information Gap Decision Theory) is used to discuss the impact of uncertainties on the power generation side system. The results show that by promoting the consumption of clean energy and utilizing the high energy efficiency of hydrogen while reducing reliance on fossil fuels the proposed system not only meets current energy demands but also achieves a more efficient emission reduction laying a solid foundation for a sustainable future. By considering the impact of uncertainties the system ensures resilience and adaptability under fluctuating renewable energy supply conditions making a significant contribution to the field of sustainable energy transition.
No more items...