Publications

The world is facing an urgent global climate challenge and hydrogen (H2) is increasingly valued as a carbon-free energy carrier that can play a prominent role in decarbonising economies. However the environmental impact of the different methods for hydrogen production are sometimes overlooked. This work provides a comprehensive overview of the environmental impacts and costs of a diverse range of methods for producing hydrogen. Ninety nine life cycle assessments (LCAs) of hydrogen production published between 2015 and 2022 are categorised by geography production method energy source goal and scope and compared by data sources and methodology. A meta-analysis of methodological choices is used to identify a subset of mutually comparable studies whose results are then compared initially by global warming potential (GWP) then low-GWP scenarios are compared by other indicators. The results show that the lowest GWP is achieved by methods that are currently more expensive (~US $4–9/kg H2) compared to the dominant methods of producing hydrogen from fossil fuels (~US $1–2/kg H2). The research finds that data are currently limited for comparing environmental indicators other than GWP such as terrestrial acidification or freshwater eutrophication. Recommendations are made for future LCAs of hydrogen production.

Recently major problems related to fuel consumption and greenhouse gas (GHG) emissions have arisen in the transportation sector. Therefore developing transportation modes powered by alternative fuels has become one of the main targets for car manufacturers and governments around the world. This study aimed to investigate the economic prospects of using hydrogen fuel cell technology in taxi fleets in Westbank. For this purpose a model that could predict the number of taxis was developed and the expected economic implications of using hydrogen fuel cell technology in taxi fleets were determined based on the expected future fuel consumption and future fuel cost. After analysis of the results it was concluded that a slight annual increase in the number of taxis in Palestine is expected in the future due to the government restrictions on issuing new taxi permits in order to get this sector organized. Furthermore using hydrogen fuel cells in taxi fleets is expected to become more and more feasible over time due to the expected future increase in oil price and the expected significant reduction in hydrogen cost as a result of the new technologies that are expected to be used in the production and handling of hydrogen.

In this podcast David Ledesma talks to Aliaksei Patonia and Veronika Lenivova about Hydrogen pipelines and high-voltage direct current (HVDC) transmission lines and how Hydrogen pipelines offer the advantage of transporting larger energy volumes but existing projects are dwarfed by the vast networks of HVDC transmission lines. The podcast discusses how advocates for hydrogen pipelines see potential in expanding these networks capitalizing on hydrogen’s physical similarities to natural gas and the potential for cost savings. However hydrogen’s unique characteristics such as its small molecular size and compression requirements present construction challenges. On the other hand HVDC lines while less voluminous excel in efficiently transmitting green electrons over long distances. They already form an extensive global network and their efficiency makes them suitable for various applications. Yet intermittent renewable energy sources pose challenges for both hydrogen and electricity systems necessitating solutions like storage and blending.

The podcast can be found on their website.

One of the methods for mitigating the duck curve phenomenon in photovoltaic (PV) energy systems is storing surplus energy in the form of hydrogen. However there is a lack of studies focused on residential PV systems that assess the impact of hydrogen storage on the reduction of energy flow imbalance to and from the national grid. This study presents an analysis of hydrogen energy storage based on real-world data from a household PV installation. Using simulation methods grounded in actual electricity consumption and hourly PV production data the research identified the storage requirements including the required operating hours and the capacity of the hydrogen tank. The analysis was based on a 1 kW electrolyzer and a fuel cell representing the smallest and most basic commercially available units and included a sensitivity analysis. At the household level—represented by a singlefamily home with an annual energy consumption and PV production of approximately 4–5 MWh over a two-year period—hydrogen storage enabled the production of 49.8 kg and 44.6 kg of hydrogen in the first and second years respectively. This corresponded to the use of 3303 kWh of PV-generated electricity and an increase in self-consumption from 30% to 64%. Hydrogen storage helped to smooth out peak energy flows from the PV system decreasing the imbalance from 5.73 kWh to 4.42 kWh. However while it greatly improves self-consumption its capacity to mitigate power flow imbalance further is constrained; substantial improvements would necessitate a much larger electrolyzer proportional in size to the PV system’s output.

Underground Hydrogen Storage (UHS) provides a large-scale and safe solution to balance the fluctuations in energy production from renewable sources and energy consumption but requires a proper and detailed characterization of the candidate reservoirs. The scope of this study was to estimate the hydrogen diffusion coefficient for real caprock samples from two natural gas storage reservoirs that are candidates for underground hydrogen storage. A significant number of adsorption/desorption tests were carried out using a Dynamic Gravimetric Vapor/Gas Sorption System. A total of 15 samples were tested at the reservoir temperature of 45 °C and using both hydrogen and methane. For each sample two tests were performed with the same gas. Each test included four partial pressure steps of sorption alternated with desorption. After applying overshooting and buoyancy corrections the data were then interpreted using the early time approximation of the solution to the diffusion equation. Each interpretable partial pressure step provided a value of the diffusion coefficient. In total more than 90 estimations of the diffusion coefficient out of 120 partial pressure steps were available allowing a thorough comparison between the diffusion of hydrogen and methane: hydrogen in the range of 1 × 10−10 m2 /s to 6 × 10−8 m2 /s and methane in the range of 9 × 10−10 m2 /s to 2 × 10−8 m2 /s. The diffusion coefficients measured on wet samples are 2 times lower compared to those measured on dry samples. Hysteresis in hydrogen adsorption/desorption was also observed.

The main results highlighted in this article underline the critical significance of hydrogen technologies in the move towards carbon neutrality. This research focuses on several key areas including the production storage safety and usage of hydrogen alongside innovative approaches for assessing hydrogen purity and production-related technologies. This study emphasizes the vital role of hydrogen storage technology for the future utilization of hydrogen as an energy carrier and the advancement of technologies that facilitate effective safe and cost-efficient hydrogen storage. Furthermore bibliometric analysis has been instrumental in identifying primary research fields such as hydrogen storage hydrogen production efficient electrocatalysts rotary engines utilizing hydrogen as fuel and underground hydrogen storage. Each domain is essential for realizing a sustainable hydrogen economy reflecting the significant research and development efforts in hydrogen technologies. Recent trends have shown an increased interest in underground hydrogen storage as a method to enhance energy security and assist in the transition towards sustainable energy systems. This research delves into the technical economic and environmental facets of employing geological formations for large-scale seasonal and long-term hydrogen storage. Ultimately the development of hydrogen technologies is deemed crucial for meeting sustainable development goals particularly in terms of addressing climate change and reducing greenhouse gas emissions. Hydrogen serves as an energy carrier that could substantially lessen reliance on fossil fuels while encouraging the adoption of renewable energy sources aiding in the decarbonization of transport industry and energy production sectors. This in turn supports worldwide efforts to curb global warming and achieve carbon neutrality.

Blending hydrogen to existing fuel mix represents a major opportunity for decarbonisation. One important consideration for this application is the chemical interaction between hydrogen and hydrocarbon fuels arising from their different combustion chemistries and varying considerably with combustion processes. This paper conducted an exploratory study of hydrogen’s impact on autoignition in several combustion processes where hydrogen is used as a blending component or the main fuel. Case studies are presented for spark ignition engines (H2/natural gas) compression ignition engines (H2/diesel) moderate or intense low-oxygen dilution (MILD) combustors (H2/natural gas) and rotational detonation engines (H2/natural gas). Autoignition reactivity as a function of the hydrogen blending level is investigated numerically using the ignition delay iso-contours and state-of-the-art kinetic models at time scales representative of each application. The results revealed drastically different impact of hydrogen blending on autoignition due to different reaction temperature pressure and time scale involved in these applications leaving hydrocarbon interacting with hydrogen at different ignition branches where the negative pressure/temperature dependency of oxidation kinetics could take place. The resulted non-linear and at times non-monotonic behaviours indicate a rich topic for combustion chemistry and also demonstrates ignition delay iso-contour as a useful tool to scope autoignition reactivity for a wide range of applications.

This review presents a state-of-the-art of geochemical geomechanical and hydrodynamic modelling studies in the Underground Hydrogen Storage (UHS) domain. Geochemical modelling assessed the reactivity of hydrogen and res pective fluctuations in hydrogen losses using kinetic reaction rates rock mineralogy brine salinity and the integration of hydrogen redox reactions. Existing geomechanics studies offer an array of coupled hydromechanical models suggesting a decline in rock failure during the withdrawal phase in aquifers compared to injection phase. Hydrodynamic modelling evaluations indicate the critical importance of relative permeability hysteresis in determining the UHS performance. Solubility and diffusion of hydrogen gas appear to have minimal impact on UHS. Injection and production rates cushion gas deployment and reservoir heterogeneity however significantly affect the UHS performance stressing the need for thorough modelling and experimental studies. Most of the current UHS modelling efforts focus on assessing the hydrodynamic aspects which are crucial for understanding the viability and safety of UHS. In contrast the lesser-explored geochemical and geomechanical considerations point to potential research gaps. A variety of modelling software tools such as CMG Eclipse COMSOL and PHREEQC evaluated those UHS underlying effects along with a few recent applications of datadriven-based Machine Learning (ML) techniques for enhanced accuracy. This review identified several unresolved challenges in UHS modelling: pronounced lack of expansive datasets leading to a gap between model predictions and their practical reliability; need robust methodologies capable of capturing natural subsurface heterogeneity while upscaling from precise laboratory data to field-scale conditions; demanding intensive computational resources and novel strategies to enhance simulation efficiency; and a gap in addressing geological uncertainties in subsurface environments suggesting that methodologies from oil reservoir simulations could be adapted for UHS. This comprehensive review offers a critical synthesis of the prevailing approaches challenges and research gaps in the domain of UHS thus providing a valuable reference document for further modelling efforts facilitating the informed advancements in this critical domain towards the realization of sustainable energy solutions.

Based on the concept of sustainable development to promote the development and application of renewable energy and enhance the capacity of renewable energy consumption this paper studies the design and optimization of renewable energy hydrogen production systems. For this paper six different scenarios for grid-connected and off-grid renewable energy hydrogen production systems were designed and analyzed economically and technically and the optimal grid-connected and off-grid systems were selected. Subsequently the optimal system solution was optimized by analyzing the impact of the load data and component capacity on the grid dependency of the grid-connected hydrogen production system and the excess power rate of the off-grid hydrogen production system. Based on the simulation results the most matched load data and component capacity of different systems after optimization were determined. The grid-supplied power of the optimized grid-connected hydrogen production system decreased by 3347 kWh and the excess power rate of the off-grid hydrogen production system decreased from 38.6% to 10.3% resulting in a significant improvement in the technical and economic performance of the system.

Hydrogen is widely considered as the energy carrier of the future but the rather high energy losses for its production are often neglected. The major current hydrogen production technology is steam methane reforming of fossil gas but there is a growing interest in producing hydrogen sustainably from water using electrolysis. This article examines four main hydrogen production chains and two transportation options (pipeline and ship) from North Africa to Europe analyzing the costs and environmental impacts of each. The core objective is to determine the most promising hydrogen provision method and location from an economic and ecological point of view including the required transport. An important finding of this analysis is that both options importing green hydrogen and producing it in Europe may be relevant for a decarbonized energy system. The emphasis should be on green hydrogen to achieve carbon emission reductions. If blue hydrogen is also considered attention should be paid to the often-neglected methane emissions upstream.

With the rapid development of hydrogen pipelines their safety issues have become increasingly prominent. In order to evaluate the properties of pipeline materials under a highpressure hydrogen environment this study investigates the hydrogen embrittlement sensitivity of X70 welded pipe in a 10 MPa high-pressure hydrogen environment using slow strain rate testing (SSRT) and low-cycle fatigue (LCF) analysis. The microstructure slow tensile and fatigue fracture morphology of base metal (BM) and weld metal (WM) were characterized and analyzed by means of ultra-depth microscope scanning electron microscope (SEM) electron backscattering diffraction (EBSD) and transmission electron microscope (TEM). Results indicate that while the high-pressure hydrogen environment has minimal impact on ultimate tensile strength (UTS) for both BM and WM it significantly decreases reduction of area (RA) and elongation (EL) with RA reduction in WM exceeding that in BM. Under the nitrogen environment the slow tensile fracture of X70 pipeline steel BM and WM is a typical ductile fracture while under the high-pressure hydrogen environment the unevenness of the slow tensile fracture increased and a large number of microcracks appeared on the fracture surface and edges with the fracture mode changing to ductile fracture + quasicleavage fracture. In addition the high-pressure hydrogen environment reduces the fatigue life of the BM and WM of X70 pipeline steel and the fatigue life of the WM decreases more than that of the BM as well. Compared to the nitrogen environment the fatigue fracture specimens of BM and WM in the hydrogen environment showed quasi-cleavage fracture patterns and the fracture area in the instantaneous fracture zone (IFZ) was significantly reduced. Compared with the BM of X70 pipeline steel although the effective grain size of the WM is smaller WM’s microstructure with larger Martensite/austenite (M/A) constituents and MnS and Al-rich oxides contributes to a heightened embrittlement sensitivity. In contrast the second-phase precipitation of nanosized Nb V and Ti composite carbon-nitride in the BM acts as an effective irreversible hydrogen trap which can significantly reduce the hydrogen embrittlement sensitivity

Hydrogen energy technologies are envisioned to play a critical supporting role in global decarbonisation. While low-carbon hydrogen is primarily targeted for reducing industrial emissions alongside decarbonising parts of the transport sector environmental benefits could also be achieved in the residential context. Presently gasdependent countries such as Japan and the United Kingdom are assessing the feasibility of deploying hydrogen home appliances as part of their national energy strategies. However prospects for the transition will hinge on consumer acceptance alongside an array of other socio-technical factors. To support potential ambitions for large-scale and sustained technology diffusion this study advances a Unified Theory of Domestic Hydrogen Acceptance. Through an integrative comparative literature review targeting hydrogen and domestic energy studies the paper proposes a novel Domestic Hydrogen Acceptance Model (DHAM) which accounts for the cognitive and emotional dimensions of human perceptions. Through this dual interplay the proposed framework can increase the predictive power of hydrogen acceptance models.

Hydrogen as a primary carbon-free energy carrier is confronted by challenges in storage and transportation. However liquid organic hydrogen carriers (LOHCs) present a promising solution for storing and transporting hydrogen at ambient temperature and atmospheric pressure. Unlike circular energy carriers such as methanol ammonia and synthetic natural gas LOHCs do not produce by-products during hydrogen recovery. LOHCs only act as hydrogen carriers and the carriers can also be recycled for reuse. Although there are considerable advantages to LOHCs there are also some drawbacks especially relative to the energy consumption during the dehydrogenation step of the LOHC recycling. This review summarizes the recent progresses in LOHC technologies focusing on catalyst developments process and reactor designs applications and techno-economic assessments (TEA). LOHC technologies can potentially offer significant benefits to Australia especially in terms of hydrogen as an export commodity. LOHCs can help avoid capital costs associated with infrastructure such as transportation vessels while reducing hydrogen loss during transportation such as in the case of liquid hydrogen (LH2). Additionally it minimises CO2 emissions as observed in methane and methanol reforming. Thus it is essential to dedicate more efforts to explore and develop LOHC technologies in the Australian context.

Hydrogen Economy and Cyclic Economy are advocated together with the use of perennial (solar wind hydro geo-power SWHG) and renewable (biomass) energy sources for defossilizing anthropic activities and mitigating climate change. Each option has intrinsic limits that prevent a stand-alone success in reaching the target. Humans have recycled goods (metals water paper and now plastics) to a different extent since very long time. Recycling carbon (which is already performed at the industrial level in the form of CO2 utilization and with recycling paper and plastics) is a key point for the future. The conversion of CO2 into chemicals and materials is carried out since the late 1800s (Solvay process) and is today performed at scale of 230 Mt/y. It is time to implement on a scale of several Gt/y the conversion of CO2 into energy products possibly mimicking Nature which does not use hydrogen. In the short term a few conditions must be met to make operative on a large scale the production of fuels from recycled-C namely the availability of low-cost: i. abundant pure concentrated streams of CO2 ii. non-fossil primary energy sources and iii. non-fossil-hydrogen. The large-scale production of hydrogen by Methane Steam Reforming with CO2 capture (Blue-H2) seems to be a realistic and sustainable solution. Green-H2 could in principle be produced on a large scale through the electrolysis of water powered by perennial primary sources but hurdles such as the availability of materials for the construction of long-living robust electrochemical cells (membranes electrodes) must be abated for a substantial scale-up with respect to existing capacity. The actual political situation makes difficult to rely on external supplies. Supposed that cheap hydrogen will be available its direct use in energy production can be confronted with the indirect use that implies the hydrogenation of CO2 into fuels (E-fuels) an almost ready technology. The two strategies have both pros and cons and can be integrated. E-Fuels can also represent an option for storing the energy of intermittent sources. In the medium-long term the direct co-processing of CO2 and water via co-electrolysis may avoid the production/transport/ use of hydrogen. In the long term coprocessing of CO2 and H2O to fuels via photochemical or photoelectrochemical processes can become a strategic technology.

South Korea has drawn up plans to reduce greenhouse gases by 29.7 million tons by supplying 4.5 million electric and hydrogen cars by 2030 to implement the “2050 carbon neutrality” goal. This article gathers data on public preferences for electric cars (ECs) over hydrogen cars (HCs) in the commercial vehicle transportation sector through a survey of 1000 people. Moreover the strength of the preference was evaluated on a five-point scale. Of all respondents 60.0 percent preferred ECs and 21.0 percent HCs the former being 2.86 times greater than the latter. On the other hand the strength of the preference for HCs was 1.42 times greater than that for ECs. Factors influencing the preference for ECs over HCs were also explored through adopting the ordered probit model which is useful in examining ordinal preference rather than cardinal preference. The analyzed factors which are related to respondents’ characteristics experiences and perceptions can be usefully employed for developing strategies of promoting carbon neutrality in the commercial vehicle transportation sector and preparing policies to improve public acceptance thereof.

Hydrogen Fuel Cell Electric Vehicles (HFC EVs) represent an alternative to replace current internal combustion engine vehicles. The use of these vehicles with storage of compressed gaseous hydrogen (CGH2) in confined spaces such as tunnels underground car parks etc. creates new challenges to ensure the protection of people and property and to keep the risk at an acceptable level. The HYTUNNEL-CS project sponsored by the FCH-JU was launched to develop validated hazard and risk assessment tools for the behavior of hydrogen leaks in tunnels. Among the experiments carried out in support of the validation tools the CEA has conducted tests on gas dispersion in a full-scale tunnel geometry. In the tests carried out hydrogen is replaced by helium under a pressure of 70 MPa in a 78 liter tank. The car is simulated by a flat plate called chassis and the discharges are made either downwards under the chassis or upwards to take into account a rollover of the car during the accident. Different thermally activated pressure relief device (TPRD) diameters are examined as well as different orientations of the discharge. Finally the mixing transient of helium with air is measured for distances between -50 and +50m from the release. Performing CFD simulations of such an under-expanded jet in an environment as large as a road tunnel demands a compressible flow solver and so a large computational cost. To optimize this cost a notional nozzle approach is generally used to replace the under-expanded jet by a subsonic jet that has the same concentration dilution behavior. The physics at the injection point is then not resolved and a model of these boundary conditions has to be implemented. This article first reviews the main experimental results. Then a model of boundary conditions is proposed to have a subsonic hydrogen jet that matches the dilution characteristics of an under-expanded jet. Furthermore this model is implemented in the TRUST LES computer code and in the Neptune-CFD RANS computer code in order to simulate some helium dispersion experiments. Finally results from the CFD simulations are compared to the experimental results and the effect of the exact shape of the tunnel is also assessed by comparing simulations with idealized flat walls and real scanned walls.

Accelerated decarbonisation of steelmaking oil refining and petrochemical industries is essential for climate change mitigation. Drawing on three longitudinal case studies of these industries in the UK this synthesis article makes a comparative analysis of their varying low-carbon reorientation speeds. The paper uses the triple embeddedness framework to analyse five factors (policy support international competition financial health technical feasibility corporate strategy and mindset) that explain why UK oil refineries have in recent years been comparatively the fastest in their low-carbon reorientation and UK steelmakers the slowest. We find that policy support has been more beneficial for refining and petrochemicals than for steel although recent government deals with steelmakers addressed this imbalance. International competition has been high for steel and petrochemicals and comparatively lower for refining (meaning that decarbonisation costs are less detrimental for international competitiveness). Financial performance has comparatively been worst for steel and best for oil refining which shapes the economic feasibility of low-carbon options. Hydrogen and carbon-capture-and-storage are technologically feasible for refining and petrochemicals while Electric Arc Furnaces are technically feasible for steelmakers but face wider feasibility problems (with scrap steel supply electricity grids and electricity prices) which is why we question the recent government deals. Corporate strategy and perceptions changed in oil refining with firms seeing economic opportunities in decarbonisation while steelmakers and petrochemical firms still mostly see decarbonisation as a burden and threat. The paper ends with comparative conclusions a discussion of political considerations and future outlooks for the three UK industries policy and research.

Hydrogen flames are much thinner than hydrocarbon flames. They have a higher propensity to wrinkle and are subject to thermo-diffusive instabilities in lean conditions. The large scale experiments of Sherman under partially vented conditions have shown that the transition to detonation is possible with only modest flame acceleration to approximately 200 m/s which is much lower than the commonly accepted limits corresponding to choked flames. At present the reason for this transition is not known. Vented H2-air explosions have also demonstrated the role played by expansion/flame interactions in deforming the flame. The state of the art on flame burning rate enhancement by expansion waves will be provided along with the recent experimental and numerical results of head on interaction of flames with an expansion wave conducted in our group. We show that the expansion wave interaction can generate local burning rate increases by more than an order of magnitude. The role of thermo-diffusive instability is also assessed. The mechanism of flame deformation is via the vorticity generation by the misaligned pressure gradient controlled by the expansion wave and the density gradient of the flame. Expansion waves originating from the unburned gas severely elongate the cells until the flame folds burn out. Expansion waves originating from the burned gas side first invert the flames then elongate them by the same mechanism. The rate of elongation is controlled by the volumetric expansion of the gas and the curvature-enhanced growth.

In many industries low-carbon hydrogen will substitute fossil fuels in the course of the transformation to climate neutrality. This paper contributes to understanding this transformation. This paper provides an overview of energy- and emission-intensive industry sectors with great potential to defossilize their production processes with hydrogen. An assessment of future hydrogen demand for various defossilization strategies in Germany that rely on hydrogen as a feedstock or as an energy carrier to a different extent in the sectors steel chemicals cement lime glass as well as pulp and paper is carried out. Results indicate that aggregate industrial hydrogen demand in those industries would range between 197 TWh and 298 TWh if production did not relocate abroad for any industry sector. The range for hydrogen demand is mainly due to differences in the extent of hydrogen utilization as compared to alternative transformation paths for example based on electrification. The attractiveness of production abroad is then assessed based on the prospective comparative cost advantage of relocating parts of the value chain to excellent production sites for low-carbon hydrogen. Case studies are provided for the steel industry as well as the chemical industry with ethylene production through methanol and the production of urea on the basis of ammonia. The energy cost of the respective value chains in Germany is then compared to the case of value chains partly located in regions with excellent conditions for renewable energies and hydrogen production. The results illustrate that at least for some processes – as ammonia production – relocation to those favorable regions may occur due to substantial comparative cost advantages.

This paper presents work undertaken by the HSE as part of the Hytunnel-CS project a consortium investigating safety considerations for fuel cell hydrogen (FCH) vehicles in tunnels and similar confined spaces. The test programme investigating hydrogen dispersion in tunnels involved simulating releases analogous to Thermally activated Pressure Relief Devices (TPRDs) typically found on hydrogen vehicles into the HSE Tunnel facility. The releases were scaled and based upon four scenarios: cars buses and two different train designs. The basis for this scaling was the size of the tunnel and the expected initial mass flow rates of the releases scenarios. The results of the 12 tests completed have been analysed in two ways: the initial mass flow rates of the tests were calculated based upon facility measurements and the Able-Noble equations of state for comparison to the intended initial flow rate; and observations of the hydrogen dispersion in the tunnel were made based on 15 hydrogen sensors arrayed along the tunnel. The calculated mass flow rates showed reasonable agreement with the intended initial conditions showing that the scaling methodology can be used to interpret the data based on the full-scale tunnel of interest. Observations of the hydrogen dispersion show an initial turbulent mixing followed by a movement of the mixed hydrogen/air cloud down the tunnel. No vertical stratification of the cloud was observed but this effect could be possible in longer tunnels or tunnels with larger diameters. Higher ventilation rates in the tunnel resulted in a reduction of the residence time of the hydrogen and a slight increase in the dilution.

A reliable and sustainable energy source is essential for human survival and progress. Hydrogen energy is both clean and environmentally friendly which highlights the need for the development of effective photocatalysts to enhance the efficiency of photocatalytic hydrogen production. Near-infrared (NIR) light makes up a significant part of the solar spectrum and possesses strong penetration capabilities. Therefore it is important to enhance research on photocatalysis that utilizes both NIR and visible light. Metal-organic frameworks (MOFs) possess outstanding photocatalytic characteristics and are utilized in various applications for the photocatalytic generation of hydrogen. Consequently this minireview examines the fundamental characteristics of MOFs focusing on their classification the mechanisms of hydrogen production and the use of MOFs composites in photocatalytic hydrogen production. It discusses MOFs materials that feature type I II III Z and S heterojunctions along with strategies for modifying MOFs through elemental doping and the addition of co-catalysts. The study investigates methods to expand the photo-response range through up-conversion reduce the band gap of photocatalyst materials and utilize plasmon resonance and photothermal effects. This minireview lays the groundwork for achieving photocatalysis that responds to near-infrared and visible light thereby enhancing photocatalytic efficiency for hydrogen production. Finally the guidance and obstacles for upcoming studies on MOFs materials in the context of photocatalytic hydrogen production are examined.

Direct air capture (DAC) is considered one of the mitigation strategies in most of the future scenarios trying to limit global temperature to 1.5 ◦C. Given the high expectations placed on DAC for future decarbonisation this study presents an extensive review of DAC technologies exploring a number of techno-economic aspects including an updated collection of the current and planned DAC projects around the world. A dedicated analysis focused on the production of synthetic methane methanol and diesel from DAC and electrolytic hydrogen in the European Union (EU) is also performed where the carbon footprint is analysed for different scenarios and energy sources. The results show that the maximum grid carbon intensity to obtain negative emissions with DAC is estimated at 468 gCO2e/kWh which is compliant with most of the EU countries’ current grid mix. Using only photovoltaics (PV) and wind negative emissions of at least −0.81 tCO2e/tCO2 captured can be achieved. The maximum grid intensities allowing a reduction of the synthetic fuels carbon footprint compared with their fossil-fuels counterparts range between 96 and 151 gCO2e/kWh. However to comply with the Renewable Energy Directive II (REDII) sustainability criteria to produce renewable fuels of non-biological origin the maximum stays between 30.2 to 38.8 gCO2e/kWh. Only when using PV and wind is the EU average able to comply with the REDII threshold for all scenarios and fuels with fuel emissions ranging from 19.3 to 25.8 gCO2e/MJ. These results highlight the importance of using renewable energies for the production of synthetic fuels compliant with the EU regulations that can help reduce emissions from difficult-to-decarbonise sectors.

Green hydrogen has become a central topic in discussions about the global energy transition seen as a promising solution for decarbonizing economies and meeting climate goals. As part of the process of decarbonization green hydrogen can replace fossil fuels currently in use helping to reduce emissions in sectors vital to the global economy such as industry and transport as well as in the power and heat sectors. Whilst there is significant potential for green hydrogen there are also challenges. The upfront costs for infrastructure and technology are high and the availability and accessibility of the renewables needed for production varies by region. Green hydrogen production and storage technologies are continuously evolving and being promoted as the demand for hydrogen in many applications grows. Considering this this paper presents the main methods for its production and storage as well as its economic impact. Hence the trend of governments and international organizations is to invest in research and development to make this technology more accessible and efficient given the carbon reduction targets.

This research delineates a pivotal advancement in the domain of sustainable energy systems with a focused emphasis on the integration of renewable energy sources—predominantly wind and solar power—into the hydrogen production paradigm. At the core of this scientific endeavor is the formulation and implementation of a deep-learning-based framework for short-term localized weather forecasting specifically designed to enhance the efficiency of hydrogen production derived from renewable energy sources. The study presents a comprehensive evaluation of the efficacy of fully connected neural networks (FCNs) and convolutional neural networks (CNNs) within the realm of deep learning aimed at refining the accuracy of renewable energy forecasts. These methodologies have demonstrated remarkable proficiency in navigating the inherent complexities and variabilities associated with renewable energy systems thereby significantly improving the reliability and precision of predictions pertaining to energy output. The cornerstone of this investigation is the deployment of an artificial intelligence (AI)-driven weather forecasting system which meticulously analyzes data procured from 25 distinct weather monitoring stations across Latvia. This system is specifically tailored to deliver short-term (1 h ahead) forecasts employing a comprehensive sensor fusion approach to accurately predicting wind and solar power outputs. A major finding of this research is the achievement of a mean squared error (MSE) of 1.36 in the forecasting model underscoring the potential of this approach in optimizing renewable energy utilization for hydrogen production. Furthermore the paper elucidates the construction of the forecasting model revealing that the integration of sensor fusion significantly enhances the model’s predictive capabilities by leveraging data from multiple sources to generate a more accurate and robust forecast. The entire codebase developed during this research endeavor has been made available on an open access GIT server.

The abundant plastic wastes become an imperative global issue and how to handle these organic wastes gains growing scientific and industrial interest. Recently converting plastic wastes into hydrogen fuel has been investigated and the “waste-to-value” practice accelerates the circular economy. To accelerate the development of plastic-to-hydrogen conversion in this review recent advances in plastic-to-hydrogen conversion via thermochemical photocatalytic and electrocatalytic routes are analyzed. All of the thermo- photo- and electrochemical processes can transform different plastic wastes into hydrogen and the hydrogen production efficiency depends heavily on the selected techniques operating parameters and applied catalysts. The application of rational-designed catalysts can promote the selective production of hydrogen from plastic feedstocks. Further studies on process optimization cost-effective catalyst design and mechanism investigation are needed.

In recent years there has been a significant increase in the adoption of autonomous vehicles for marine and submarine missions. The advancement of emerging imaging navigation and communication technologies has greatly expanded the range of operational capabilities and opportunities available. The ENDURUNS project is a European research endeavor focused on identifying strategies for achieving minimal environmental impact. To measure these facts this article evaluates the product impacts employing the Life Cycle Assessment methodology for the first time following the ISO 14040 standard. In this analysis the quantitative values of Damage and Environmental Impact using the Eco-Indicator 99 methodology in SimaPro software are presented. The results report that the main contributors in environmental impact terms have been placed during the manufacturing phase. Thus one of the challenges is accomplished avoiding the use phase emissions that are the focus to reduce nowadays in the marine industry.

The global energy landscape is experiencing a transformative shift with an increasing emphasis on sustainable and clean energy sources. Hydrogen remains a promising candidate for decarbonization energy storage and as an alternative fuel. This study explores the landscape of hydrogen pricing and demand dynamics by evaluating three collaboration scenarios: market-based pricing cooperative integration and coordinated decision-making. It incorporates price-sensitive demand environmentally friendly production methods and market penetration effects to provide insights into maximizing market share profitability and sustainability within the hydrogen industry. This study contributes to understanding the complexities of collaboration by analyzing those structures and their role in a fast transition to clean hydrogen production by balancing economic viability and environmental goals. The findings reveal that the cooperative integration strategy is the most effective for sustainable growth increasing green hydrogen’s market share to 19.06 % and highlighting the potential for environmentally conscious hydrogen production. They also suggest that the coordinated decision-making approach enhances profitability through collaborative tariff contracts while balancing economic viability and environmental goals. This study also underscores the importance of strategic pricing mechanisms policy alignment and the role of hydrogen hubs in achieving sustainable growth in the hydrogen sector. By highlighting the uncertainties and potential barriers this research offers actionable guidance for policymakers and industry players in shaping a competitive and sustainable energy marketplace.

Green hydrogen (H2 ) has emerged as a promising energy carrier for decarbonizing the industrial building and transportation sectors. However current green H2 production technologies face challenges that limit cost reduction and scaling up. Platinum-group metals (PGMs) including platinum and iridium present exceptional electrocatalytic properties for water splitting but their high cost is a significant barrier. This directly impacts the overall cost of electrolyzers thus increasing green H2 production costs. The present work covers the fundamentals of water electrolysis the currently available technologies focusing on proton-exchange membrane electrolyzers and the critical role of electrocatalysts discussing potential strategies for reducing the PGM content and consequently decreasing green H2 cost.

Positive Energy Districts can be defined as connected urban areas or energy-efficient and flexible buildings which emit zero greenhouse gases and manage surpluses of renewable energy production. Energy storage is crucial for providing flexibility and supporting renewable energy integration into the energy system. It can balance centralized and distributed energy generation while contributing to energy security. Energy storage can respond to supplement demand provide flexible generation and complement grid development. Photovoltaics and wind turbines together with solar thermal systems and biomass are widely used to generate electricity and heating respectively coupled with energy system storage facilities for electricity (i.e. batteries) or heat storage using latent or sensible heat. Energy storage technologies are crucial in modern grids and able to avoid peak charges by ensuring the reliability and efficiency of energy supply while supporting a growing transition to nondepletable power sources. This work aims to broaden the scientific and practical understanding of energy storage in urban areas in order to explore the flexibility potential in adopting feasible solutions at district scale where exploiting the space and resource-saving systems. The main objective is to present and critically discuss the available options for energy storage that can be used in urban areas to collect and distribute stored energy. The concerns regarding the installation and use of Energy Storage Systems are analyzed by referring to regulations and technical and environmental requirements as part of broader distribution systems or as separate parts. Electricity heat energy and hydrogen are the most favorable types of storage. However most of them need new regulations technological improvement and dissemination of knowledge to all people with the aim of better understanding the benefits provided.

In light of the Italian Hydrogen Roadmap goals the 2030 national RES installation targets need to be redefined. This work aims to propose a more appropriate RES installation deployment on national scale by matching the electrolysers capacity and the green hydrogen production goals. The adopted approach envisages the power-to-gas value chain priority for the green hydrogen production as a means of balancing system. Thus the 2030 Italian energy system has been modelled and several RES installation scenarios have been simulated via EnergyPLAN software. The simulation outputs have been integrated with a breakdown model for the overgeneration RES share detection in compliance with the PV dispatching priority of the Italian system. Therefore the best installation solutions have been detected via multi-objective optimization model based on the green hydrogen production additional installation cost critical energy excess along with the Levelized Cost of Hydrogen (LCOH). Higher wind technology installations provide more competitive energy and hydrogen costs. The most suitable scenarios show that the optimal LCOH and hydrogen production values respectively equal to 3.6 €/kg and 223 ktonH2 arise from additional PV/wind installations of 35 GW on top of the national targets.

The International Energy Agency (IEA) established the "H2 Implementing Agreement (HIA)" to promote H2 transition in various economic sectors. Today less than one percent of the world's H2 production is “Green”. Lack of regulations high production costs and inadequate infrastructure are significant impediments. The U.S. Department of Energy set a "111-target" which translates into $1/kg-H2 in the next decade. Many countries in the Middle East and North Africa (MENA) region have announced ambitious plans to produce green H2. Through techno-economic metrics and the impact of economies of scale this study investigates H2@Scale production. H2 Production Analysis and the System Advisor Model developed by the U.S. Department of Energy were used for analysis. The results demonstrate a significant decrease in the levelized cost of H2 (LCOH) when the production volume is scaled up. It was determined that the key cost drivers are capital cost energy installed balance of the plant and mechanical and electrical subsystems. The studied location is found promising for scaled production and developing its commodity status. The findings could serve as a benchmark for key stakeholders investors policymakers and the developer of relevant strategies in the infrastructure and H2 value chain.

Hydrogen is commonly used as feedstock in industrial processes and is regarded as a potential future energy carrier. However its reactivity and low density make it difficult to handle and store safely. Indoor hydrogen dispersion can cause a fire or explosion hazard if encountering an ignition source. Safety practices often use time expensive modelling techniques to estimate risk associated with hydrogen. A neural network based surrogate model could efficiently replace Computational Fluid Dynamics (CFD) modelling in safety studies. To lower the dimensionality of this surrogate model a dimensional analysis based on Buckingham’s Pi-theorem is proposed. The dimensional analysis examines stratified filling and highlights the functional parameters involved in the process. Stratified filling occurs for buoyancy dominated releases and is characterized by layers of decreasing concentration starting at the ceiling of the enclosure and developing towards the bottom. The study involves four dimensional cases that were simulated using Computational Fluid Dynamics (CFD) to demonstrate the usefulness of the proposed dimensionless time and dimensionless volume. The setup considered in this paper consists of a parallelepiped enclosure with standard atmospheric conditions a single release source and one pressure outlet to ensure constant pressure during the release. The results of the CFD simulations show a distinct pattern in the relation of hydrogen molar fraction and dimensionless time. The pattern depends on the dimensionless height of the measurement location. A five-parameter logistic (5PL) function is proposed to fit the data from the CFD models. Overall the paper provides insights into the functional parameters involved in the evolution of hydrogen mass fractions during stratified filling. It provides a nondimensional surrogate model to compute the evolution of the local concentrations of hydrogen during the development of stratification layers.

Converting renewable electricity via water electrolysis into green hydrogen and hydrogen-based products will shape a global trade in power-to-x (PtX) products. The European Union's renewable hydrogen import target of 10 million tonnes by 2030 reflects the urgent need for PtX imports by sea to early high-demand countries like Germany. This study evaluates the cost efficiency and greenhouse gas (GHG) emissions of four hydrogen carrier ship import options considering a reconversion to H2 at the import terminal for a final delivery to offtakers via a H2 pipeline network in 2030. This includes ammonia a liquid organic hydrogen carrier (LOHC) system based on benzyltoluene (BT) and a novel CO2/e-methane and CO2/e-methanol cycle where CO2 is captured at the reconversion plant and then shipped back to the PtX production site in a nearly closed carbon loop. The GHG emission accounting includes well-to-wake emissions of the marine fuels and direct emissions of the carbon capture plant. Two GW-scale case studies reveal the impact of a short and long-distance route from Tunisia and Australia to Germany whereas the specific PtX carriers are either fuelled by its PtX cargo as a renewable marine fuel or by conventional heavy fuel oil (HFO). Ammonia outperforms the other PtX routes as the total hydrogen supply cost range between 5.07 and 7.69 for Australia (low: NH3 HFO high: LOHC HFO) and 4.78–6.21 € per kg H2 for Tunisia (low: NH3 HFO high: CH4 HFO) respectively. The ammonia routes achieve thereby GHG intensities of 31 % and 86 % below the EU threshold of 3.4 kg CO2(e) per kg H2 for renewable hydrogen. LOHC though unless switching to low-emission fuels and the CO2/e-methanol cycle exceed the GHG threshold at shipping distances of 12300 and 16600 km. The hydrogen supply efficiencies vary between 57.9 and 78.8 %LHV (low: CH4 PtX-fuelled high: NH3 HFO) with a PtX marine fuel consumption of up to 15 % LHV for the Australian methanol route whereas high uncertainties remain for the ammonia and methanol reconversion plant efficiencies. The CO2 cyle enables a cost-efficient CO2 supply easing the near-term shortage of climate-neutral CO2 sources at the cost of high GHG emissions for long-distance routes.

With the aim of reducing carbon emissions and seeking independence from Russian gas in the wake of the conflict in Ukraine the use of hydrogen in the European Union is expected to rise in the future. In this regard hydrogen transport via pipeline will become increasingly crucial either through the utilization of existing natural gas infrastructure or the construction of new dedicated hydrogen pipelines. This study investigates the effects of hydrogen blending in existing pipelines on the European energy system by the year 2050 by introducing hydrogen blending sensitivities to the Global Energy System Model (GENeSYS-MOD). Results indicate that hydrogen demand in Europe is inelastic and limited by its high costs and specific use cases with hydrogen production increasing by 0.17% for 100%-blending allowed compared to no blending allowed. The availability of hydrogen blending has been found to impact regional hydrogen production and trade with countries that can utilize existing natural gas pipelines such as Norway experiencing an increase in hydrogen and synthetic gas exports from 44.0 TWh up to 105.9 TWh in 2050 as the proportion of blending increases. Although the influence of blending on the overall production and consumption of hydrogen in Europe is minimal the impacts on the location of production and dependence on imports must be thoroughly evaluated in future planning efforts.

Developing an effective energy transition roadmap is crucial in the face of global commitments to achieve net zero emissions. While renewable power generation systems are expanding challenges such as curtailments and grid constraints can lead to energy loss. To address this surplus electricity can be converted into green hydrogen serving as a key component in the energy transition. This research explores the use of renewable solar energy for powering a proton exchange membrane electrolyser to produce green hydrogen while a downdraft gasifier fed by municipal solid waste generates hydrogen-enriched syngas. The blended fuel is then used to feed a Solid Oxide Fuel Cell (SOFC) system. The study investigates the impact of hydrogen content on the performance of the fuel cell-based power plant from thermodynamics and exergoeconomic perspectives. Multiobjective optimisation using a genetic algorithm identifies optimal operating conditions for the system. Results show that blending hydrogen with syngas increases combined heat and power efficiency by up to 3% but also raises remarkably the unit product cost and reduces carbon dioxide emissions. Therefore the optimal values for hydrogen content current density temperatures and other parameters are determined. These findings contribute to the design and operation of an efficient and sustainable energy generation system.

This work studies the efficiency and long-term viability of powered hydrogen production. For this purpose a detailed exploration of hydrogen production techniques has been undertaken involving data collection information authentication data organization and analysis. The efficiency trends environmental impact and hydrogen production costs in a landscape marked by limited data availability were investigated. The main contribution of this work is to reduce the existing data gap in the field of hydrogen production by compiling and summarizing dispersed data. The findings are expected to facilitate the decision-making process by considering regional variations energy source availability and the potential for technological advancements that may further enhance the economic viability of electrolysis. The results show that hydrogen production methods can be identified that do not cause significant harm to the environment. Photolysis stands out as the least serious offender producing 0 kg of CO2 per kg of H2 while thermolysis emerges as the major contributor to emissions with 20 kg of CO2 per kg of H2 produced.

Potential carbon neutrality of the global trucking shipping and aviation sectors by 2050 could be achieved by substituting fossil fuels with renewable hydrogen and synthetic fuels. To investigate the economic impact of fuel substitution over time a holistic cost model is developed and applied to three case studies in Norway an early adopter of carbon-neutral freight transport. The model covers the value chains from local electricity and fuel production (hydrogen ammonia Fischer–Tropsch e-fuel) to fuel consumption for long-haul trucking short-sea shipping and mid-haul aviation. The estimates are internally consistent and allow cross-mode and cross-fuel comparisons that set this work apart from previous studies more narrowly focused on a given transport mode or fuel. The model contains 150 techno-economic parameters to identify which components along the value chains drive levelized costs. This paper finds a cost reduction potential for renewable fuels of 41% to 68% until 2050 but carbon-neutral transport will suffer asymmetric cost disadvantages. Fuel substitution is most expensive in short-sea shipping followed by mid-haul aviation and long-haul trucking. Cost developments of electricity direct air capture of carbon vehicle expenses and fuel-related payload losses are significant drivers.

Green hydrogen a critical element in the shift towards sustainable energy is traditionally produced by electrolysis powered by solar photovoltaic (PV) systems. This research explores the potential of underexploited photovoltaic thermal (PV-T) systems for efficient green hydrogen generation. This paper compares this advanced technology performance and economic viability against conventional PV setups. This paper uses TRNSYS simulation software to analyze two distinct solar-based hydrogen production configurations – PV and PV-T – across diverse climatic conditions in Doha Tunis and Stuttgart. The paper’s findings indicate that PV-T significantly outperforms PV in hydrogen generation across diverse climates (Doha Tunis Stuttgart). For instance in Doha PV-T systems increase hydrogen output by 78% in Tunis by 59% and in Stuttgart by 25%. An economic assessment reveals PV panels as the most cost-effective option with hydrogen production costs ranging from $4.92/kg to $9.66/kg across the studied locations. For PV-T collectors the hydrogen cost range from $6.66/kg to $16.80/kg across the studied locations. Nevertheless this research highlights the potential of PV-T technology to enhance the efficiency and economic viability of green hydrogen production. These findings offer valuable insights for policymakers investors and researchers pursuing more efficient solutions for sustainable energy.

Alkaline water electrolysis is a key technology for large-scale hydrogen production. In this process safety and efficiency are among the most essential requirements. Hence optimization strategies must consider both aspects. While experimental optimization studies are the most accurate solution model-based approaches are more cost and time-efficient. However validated process models are needed which consider all important influences and effects of complete alkaline water electrolysis systems. This study presents a dynamic process model for a pressurized alkaline water electrolyzer consisting of four submodels to describe the system behavior regarding gas contamination electrolyte concentration cell potential and temperature. Experimental data from a lab-scale alkaline water electrolysis system was used to validate the model which could then be used to analyze and optimize pressurized alkaline water electrolysis. While steady-state and dynamic solutions were analyzed for typical operating conditions to determine the influence of the process variables a dynamic optimization study was carried out to optimize an electrolyte flow mode switching pattern. Moreover the simulation results could help to understand the impact of each process variable and to develop intelligent concepts for process optimization

Purpose: The purpose of the hydrogen supply and demand data stream is to provide an overview of the hydrogen market in Europe and to track industry’s progress in deploying clean hydrogen technologies. Scope: Data about hydrogen production capacity and consumption in EU countries together with Switzerland Norway Iceland and the United Kingdom. Hydrogen production capacity is presented by country and by production technology whereas the hydrogen consumption data is presented by country and by end-use sector. The analysis undertaken for this report was completed using data reflecting end of 2020. Key Findings: The current hydrogen market (on both the demand and supply side) is dominated by refining and ammonia industries with four countries (DE NL PL ES) responsible for more than half of hydrogen consumption. Hydrogen is overwhelmingly produced by reforming of fossil fuels (mostly natural gas). Clean hydrogen production capacities are currently insignificant with hydrogen produced from natural gas coupled with carbon capture at 0.42% and hydrogen produced from water electrolysis at 0.14% of total production capacity.

Underground hydrogen storage will be an essential part of the future hydrogen infrastructure to provide flexibility and security of supply. Storage in porous reservoirs should complement storage in salt caverns to be able to meet the projected high levels of required storage capacities. To assess its techno-economic feasibility a case study of hydrogen storage in a depleted gas field in the Netherlands is developed. Subsurface modelling is performed and various surface facility design concepts are investigated to calculate the levelized cost of hydrogen storage (LCOHS). Our base case with hydrogen as cushion gas results in an LCOHS of 0.79 EUR/kg (range of 0.58–1.04 EUR/kg). Increasing the number of full-cycle equivalents from 1 to 6 lowers the storage cost to 0.25 EUR/kg. The investment cost of the cushion gas represents 76% of the total cost. With nitrogen as cushion gas LCOHS is reduced to 0.49 EUR/kg (range of 0.42–0.56 EUR/kg).

In the new scenario where the transportation sector must be decarbonized to limit global warming fuel cellpowered aerial vehicles have been selected as a strategic target application to compose part of the urban fleet to minimize road transport congestion and make goods and personal transportation fast and efficient. To address the necessity of clean and efficient urban air transport this work consists of the conceptual development of a lightweight rotary-winged transport vehicle using a hydrogen-based fuel cell propulsion system and the optimization of its energy balance. For that purpose the methods for integrating the coupled aerodynamic and propulsion system sizing and optimization was developed with the aim of designing concepts capable of carrying 0 (unmanned aerial vehicle — Design 1) and 1 (Aerotaxi — Design 2) passengers for a distance of 300 km at a cruise altitude of 500 m with a minimum climbing rate capability of 6 m s−1 at 1000 m. The results show how these designs with the desired performance specifications can be obtained with a vehicle mass ranging from 416 to 648 kg depending on the application and with specific range and endurance respectively within 46.2–47.8 km/kg and 20.4–21.3 min/kg for design 1 and 33.3–33.8 km/kg and 12.5–13.9 min/kg for design 2.

Hydrogen is one of the main energy carriers playing a prominent role in the future decarbonization of the economy. However several aspects regarding the transport and storage of this gas are challenging. The intermediary conversion of hydrogen into high-density energy molecules may be a crucial step until technological conditions are ready to attain a significant reduction in fossil fuel use in transport and the industrial sector. The process of transforming hydrogen into methane by anaerobic digestion is reviewed showing that this technology is a feasible option for facilitating hydrogen storage and transport. The manuscript focuses on the role of anaerobic digestion as a technology driver capable of fast adaptation to current energy needs. The use of thermophilic systems and reactors capable of increasing the contact between the H2 -fuel and liquid phase demonstrated outstanding capabilities attaining higher conversion rates and increasing methane productivity. Pressure is a relevant factor of the process allowing for better hydrogen solubility and setting the basis for considering feasible underground hydrogen storage concomitant with biological methanation. This feature may allow the integration of sequestered carbon dioxide as a relevant substrate.

Defossilisation of the current fossil fuels dominated global energy system is one of the key goals in the upcoming decades to mitigate climate change. Sharp reduction in the costs of solar photovoltaics wind power and battery technologies enables a rapid transition of the power and some segments of the transport sectors to sustainable energy resources. However renewable electricity-based fuels and chemicals are required for the defossilisation of hard-to-abate segments of transport and industry. The global demand for carbon dioxide as raw material for the production of e-fuels and e-chemicals during a global energy transition to 100% renewable energy is analysed in this research. Carbon dioxide capture and utilisation potentials from key industrial point sources including cement mills pulp and paper mills and waste incinerators are evaluated. According to this study’s estimates the demand for carbon dioxide increases from 0.6 in 2030 to 6.1 gigatonnes in 2050. Key industrial point sources can potentially supply 2.1 gigatonnes of carbon dioxide and thus meet the majority of the demand in the 2030s. By 2050 however direct air capture is expected to supply the majority of the demand contributing 3.8 gigatonnes of carbon dioxide annually. Sustainable and unavoidable industrial point sources and direct air capture are vital technologies which may help the world to achieve ambitious climate goals.

As the main body of resource aggregation Virtual Power Plant (VPP) not only needs to participate in the external energy market but also needs to optimize the management of internal resources. Different from other energy storage hydrogen energy storage systems can participate in the hydrogen market in addition to assuming the backup supplementary function of electric energy. For the Virtual Power Plant Operator (VPPO) it needs to optimize the scheduling of internal resources and formulate bidding strategies for the electric-hydrogen market based on external market information. In this study a two-stage model is constructed considering the internal and external interaction mechanism. The first stage model optimizes the operation of renewable energy flexible load extraction storage and hydrogen energy storage system based on the complementary characteristics of internal resources; the second stage model optimizes the bidding strategy to maximize the total revenue of the electricity energy market auxiliary service market and hydrogen market. Finally a typical scenario is constructed and the rationality and effectiveness of the strategy are verified. The results show that the hybrid VPP with hydrogen storage has better economic benefits resource benefits and reliability.

Fuel cell- and electric-powered trucks are promising technologies for zero-emission heavyduty transportation. Recently Fuel Cell Trucks (FCT) have gained wider acceptance as the technology of choice for long-distance trips due to their lighter weight and shorter fueling time than electric-powered trucks. Broader adoption of Fuel Cell Trucks (FCT) requires planning strategies for locating future hydrogen refueling stations (HRS) especially for fleets that transport freight along intercity and inter-country highways. Existing mathematical models of HRS placement often focus on inner-city layouts which make them inadequate when studying the intercity and intercountry FCT operation scale of FCT. Furthermore the same models rarely consider decentralized hydrogen production from renewable energy sources essential for decarbonizing the transportation sector. This paper proposes a mathematical model to guide the planning of the hydrogen infrastructure to support future long-haul FCTs. First the model uses Geographic Information System (GIS) data to determine the HRS’s optimal number and location placement. Then the model categorizes and compares potential hydrogen production sources including off-site delivery and on-site solar-to-hydrogen production. The proposed model is illustrated through a case study of the west coastal area of the United States (from Baja California Mexico to British Columbia Canada). Different geospatial scenarios were tested ranging from the current operational distance of FCEV (250km) and future releases of hydrogen FCT (up to 1500km). Results highlight the capabilities of the model in identifying the number and location of the HRS based on operation distances in addition to determining the optimal hydrogen production technology for each HRS. The findings also confirm the viability of green hydrogen production through solar energy which could play a critical role in a low-carbon transportation future.

Currently the issue of creating decarbonized energy systems in various spheres of life is acute. Therefore for gas turbine power systems including hybrid power plants with fuel cells it is relevant to transfer the existing engines to pure hydrogen or mixtures of hydrogen with natural gas. However significant problems arise associated with the possibility of the appearance of flashback zones and acoustic instability of combustion an increase in the temperature of the walls of the flame tubes and an increase in the emission of nitrogen oxides in some cases. This work is devoted to improving the efficiency of gas turbine power systems by combusting pure hydrogen and mixtures of natural gas with hydrogen. The organization of working processes in the premixed combustion chamber and the combustion chamber with a sequential injection of ecological and energy steam for the “Aquarius” type power plant is considered. The conducted studies of the basic aerodynamic and energy parameters of a gas turbine combustor working on hydrogen-containing gases are based on solving the equations of conservation and transfer in a multicomponent reacting system. A four-stage chemical scheme for the burning of a mixture of natural gas and hydrogen was used which allows for the rational parameters of environmentally friendly fuel burning devices to be calculated. The premixed combustion chamber can only be recommended for operations on mixtures of natural gas with hydrogen with a hydrogen content not exceeding 20% (by volume). An increase in the content of hydrogen leads to the appearance of flashback zones and fuel combustion inside the channels of the swirlers. For the combustion chamber of the combined-cycle power plant “Vodoley” when operating on pure hydrogen the formation of flame flashback zones does not occur.

The widespread production and use of hydrogen (H2) requires safe handling due to its wide range of flammability and low ignition energy. In confined and semi-confined areas such as garages and tunnels a hydrogen leak will create a potential accumulation of flammable gases. Hence forced ventilation is required in such confined spaces to prevent hydrogen hazards. However this practice may incur higher operating costs and could become ineffective during a power outage. Passive Autocatalytic Recombiners (PARs) are defined as safety devices for preventing hydrogen accumulation in confined spaces. PARs have been widely adopted for hydrogen mitigation in nuclear containment buildings in worst case accident scenarios where forced ventilation is not feasible. PARs are equipped with catalyst plates that self-start due to hydrogen reacting with oxygen at relatively low concentrations (<2 vol. % H2 in air). The heat generated from the reaction creates a self-sustained flow continuously supplying the catalyst surface with fresh hydrogen and oxygen. In this study a 2D transient numerical model has been developed in COMSOL Multiphysics to simulate the operation of PARs. The model was used to analyze the effect of surface reactions on the catalyst temperature flow dynamics self-start behaviour forced versus natural convective flow and steady-state hydrogen recombination rates. The model was also used to simulate carbon monoxide poisoning and its influence on the catalyst performance. Experimental data were used for model calibration and validation showing good agreement for different conditions. Overall the model provides novel insights into PARs operation such as radiation and poisoning effects on the catalyst plate. As a next step assessment of the effectiveness of PARs is underway to mitigate hydrogen hazards in selected confined and semi-confined areas including nuclear and non-nuclear applications.

Hydrogen (H2) as an energy carrier may play a role in various hard-to-abate subsectors but to maximize emission reductions supplied hydrogen must be reliable low-emission and low-cost. Here we build a model that enables direct comparison of the cost of producing net-zero hourly-reliable hydrogen from various pathways. To reach net-zero targets we assume upstream and residual facility emissions are mitigated using negative emission technologies. For the United States (California Texas and New York) model results indicate nextdecade hybrid electricity-based solutions are lower cost ($2.02-$2.88/kg) than fossil-based pathways with natural gas leakage greater than 4% ($2.73-$5.94/ kg). These results also apply to regions outside of the U.S. with a similar climate and electric grid. However when omitting the net-zero emission constraint and considering the U.S. regulatory environment electricity-based production only achieves cost-competitiveness with fossil-based pathways if embodied emissions of electricity inputs are not counted under U.S. Tax Code Section 45V guidance.

This work presents simulation results from a system where offshore wind power is used to produce hydrogen via electrolysis. Real-world data from a 2.3 MW floating offshore wind turbine and electricity price data from Nord Pool were used as input to a novel electrolyzer model. Data from five 31-day periods were combined with six system designs and hydrogen production system efficiency and production cost were estimated. A comparison of the overall system performance shows that the hydrogen production and cost can vary by up to a factor of three between the cases. This illustrates the uncertainty related to the hydrogen production and profitability of these systems. The highest hydrogen production achieved in a 31-day period was 17 242 kg using a 1.852 MW electrolyzer (i.e. utilization factor of approximately 68%) the lowest hydrogen production cost was 4.53 $/kg H2 and the system efficiency was in the range 56.1e56.9% in all cases.