United Kingdom

Ammonia production currently contributesalmost 11% of global industrial carbon dioxide emissions or1.3% of global emissions. In the context of global emissiontargets and growing demand decarbonization of this processis highly desirable. We present a method to calculate a firstestimate for the optimum size of an ammonia productionplant (at the process level) the required renewable energy(RE) supply and the levelized cost of ammonia (LCOA) forislanded operation with a hydrogen buffer. A model wasdeveloped to quantitatively identify the key variables thatimpact the LCOA (relative to a ±10 GBP/tonne change inLCOA): levelized cost of electricity (±0.89 GBP/MWh) electrolyzer capital expenditure (±65 GBP/kW) minimum Haber−Bosch (HB) load (±12% of rated power) maximum rate of HB load ramping and RE supply mix. Using 2025/2030 estimatesresults in a LCOA of 588 GBP/tonne for Lerwick Scotland. The application of the model will facilitate and improve theproduction of carbon-free ammonia in the future.

Aviation is a major contributor to transportation carbon emissions but aims to reduce its carbon footprint. Sustainable and environmentally friendly green hydrogen fuel is essential for decarbonization of this industry. Using the extremely low temperature of liquid hydrogen in aviation sector unlocks the opportunity for cryoelectric aircraft concept which exploits the advantageous properties of superconductors onboard. A significant barrier for green hydrogen adoption relates to its high cost and the immediate need for large-scale production which Proton Exchange Membrane Water Electrolyzers (PEMWE) can address through optimal dynamic performance high lifetimes good efficiencies and importantly scalability. In PEMWE the cell is a crucial component that facilitates the electrolysis process and consists of a polymer membrane and electrodes. To control the required production rate of hydrogen the output power of cell should be monitored which usually is done by measuring the cell’s potential and current density. In this paper five different machine learning (ML) models based on different algorithms have been developed to predict this parameter. Findings of the work highlight that the model based on Cascade-Forward Neural Network (CFNN) is investigated to accurately predict the cell potential of PEMWE under different anodic material and working conditions with an accuracy of 99.998 % and 0.001884 in terms of R2 and root mean square error respectively. It can predict the cell potential with a relative error of less than 0.65 % and an absolute error of below 0.01 V. The Standard deviation of 0.000061 for 50 iterations of stability analysis indicated that this model has less sensitivity to the random selection of training data. By accurately estimating different cell’s output with one model and considering its ultra-fast response CFNN model has the potential to be used for both monitoring and the designing purposes of green hydrogen production.

Shipping corridors act as the arteries of the global economy. The maritime shipping sector is also a major source of greenhouse gas emissions accounting for 2.9% of the global total. The international nature of the shipping sector combined with issues surrounding the use of battery technology means that these emissions are considered difficult to eliminate. This work explores the transition to renewable fuels by examining the use of electrofuels (in the form of liquid hydrogen methane methanol ammonia and Fischer-Tropsch fuel) to decarbonise large container ships from a technical economic and environmental perspective. For an equivalent range to current fossil fuel vessels the cargo capacity of vessels powered by electrofuels decreases by between 3% and 16% depending on the fuel of choice due to the lower energy density compared with conventional marine fuels. If vessel operators are willing to sacrifice range cargo space can be preserved by downsizing onboard energy storage which necessitates more frequent refuelling. For a realistic green hydrogen cost of €3.5/kg (10.5 €c/kWh) in 2030 the use of electrofuels in the shipping sector results in an increase in the total cost of ownership of between 124% and 731% with liquid hydrogen in an internal combustion engine being the most expensive and methanol in an internal combustion engine resulting in the lowest cost increase. Despite this we find that the increased transportation costs of some consumer goods to be relatively small adding for example less than €3.27 to the cost of a laptop. In general fuels which do not require cryogenic storage and can be used in internal combustion engines result in the lowest cost increases. For policymakers reducing the environmental impact of the shipping sector is a key priority. The use of liquid hydrogen which results in the largest cost increase offers a 70% reduction in GHG emissions for an electricity carbon intensity of 80 gCO2e/ kWh which is the greatest reduction of all fuels assessed in this work. A minimum carbon price of €400/tCO2 is required to allow these fuels to reach parity with conventional shipping operations. To meet European Union emissions reductions targets electricity with an emissions intensity below 40 gCO2e/kWh is required which suggests that for electrofuels to be truly sustainable direct connection with a source of renewable electricity is required.

This paper describes the performance of explosion free in fire self-venting (TPRD-less) composite tanks of Type IV in fires of realistic intensity HRR/A=1 MW/m2 in conditions of first responders’ intervention. This breakthrough safety technology does not require the use of thermally activated pressure relief devices (TPRD). It provides microleaks-no-burst (LNB) performance of high-pressure hydrogen storage tanks in a fire. Two fire intervention strategies are investigated one is the removal of a vehicle with LNB tank from the fire and another is the extinction of the fire. The removal from the fire scenario is investigated for one carbon-carbon and one carbon-basalt double-composite wall tank prototype. The fire extinction scenario is studied for four carbon-basalt prototypes. All six prototypes of 7.5 L volume and nominal working pressure of 70 MPa demonstrated safe release of hydrogen through microchannels of the composite wall after melting a liner. The technology allows fire brigades to apply standard intervention strategies and tactics at the fire scene with hydrogen vehicles if LNB tanks are used in the vehicle.

This study aims to explore the techno-economic potential of harnessing waste heat from a Small Modular Reactor (SMR) to fuel Direct Air Carbon Capture (DACC) and High Temperature Steam Electrolysis (HTSE) technologies. The proposed system’s material flows and energy demands are modelled via the ASPEN Plus v12.1 where results are utilised to provide estimates of the Levelised Cost of DACC (LCOD) and Levelised Cost of Hydrogen (LCOH). The majority of thermal energy and electrical utilities are assumed to be supplied directly by the SMR. A sensitivity analysis is then performed to investigate the effects of core operational parameters of the system. Key results indicate levelised costs of 4.66 $/kgH2 at energy demands of 34.37 kWh/kgH2 and 0.02 kWh/kgH2 thermal for HTSE hydrogen production and 124.15 $/tCO2 at energy demands of 31.67 kWh/tCO2 and 126.33 kWh/tCO2 thermal for carbon capture; parameters with most impact on levelised costs are air intake and steam feed for LCOD and LCOH respectively. Both levelised costs i.e. LCOD and LCOH would decrease with the production scale. The study implies that an integrated system of DACC and HTSE provided the best cost-benefit results however the cost-benefit analysis is heavily subjective to geography politics and grid demand.

The HyDeploy2 project seeks to address a key issue for UK energy customers: how to reduce the carbon they emit in heating their homes. The UK has a world class gas grid delivering heat conveniently and safely to more than 83% of homes. Emissions can be reduced by lowering the carbon content of gas through blending with hydrogen. This delivers carbon savings without customers requiring disruptive and expensive changes in their homes. It also provides the platform for deeper carbon savings by enabling wider adoption of hydrogen across the energy system.

This paper aims to present an overview of the current state of hydrogen storage methods and materials assess the potential benefits and challenges of various storage techniques and outline future research directions towards achieving effective economical safe and scalable storage solutions. Hydrogen is recognized as a clean secure and costeffective green energy carrier with zero emissions at the point of use offering significant contributions to reaching carbon neutrality goals by 2050. Hydrogen as an energy vector bridges the gap between fossil fuels which produce greenhouse gas emissions global climate change and negatively impact health and renewable energy sources which are often intermittent and lack sustainability. However widespread acceptance of hydrogen as a fuel source is hindered by storage challenges. Crucially the development of compact lightweight safe and cost-effective storage solutions is vital for realizing a hydrogen economy. Various storage methods including compressed gas liquefied hydrogen cryocompressed storage underground storage and solid-state storage (material-based) each present unique advantages and challenges. Literature suggests that compressed hydrogen storage holds promise for mobile applications. However further optimization is desired to resolve concerns such as low volumetric density safety worries and cost. Cryo-compressed hydrogen storage also is seen as optimal for storing hydrogen onboard and offers notable benefits for storage due to its combination of benefits from compressed gas and liquefied hydrogen storage by tackling issues related to slow refueling boil-off and high energy consumption. Material-based storage methods offer advantages in terms of energy densities safety and weight reduction but challenges remain in achieving optimal stability and capacities. Both physical and material-based storage approaches are being researched in parallel to meet diverse hydrogen application needs. Currently no single storage method is universally efficient robust and economical for every sector especially for transportation to use hydrogen as a fuel with each method having its own advantages and limitations. Moreover future research should focus on developing novel materials and engineering approaches in order to overcome existing limitations provide higher energy density than compressed hydrogen and cryo-compressed hydrogen storage at 70 MPa enhance costeffectiveness and accelerate the deployment of hydrogen as a clean energy vector.

The global transition towards clean energy sources is becoming essential to reduce reliance on conventional fuels and mitigate carbon emissions. In the future the clean energy storage landscape green hydrogen and green ammonia (powered by renewable energy sources) are emerging as key players. This study explores the prospectives and feasibility of producing and storing offshore green hydrogen and green ammonia. The potential power output of Hornsea one and Hornsea two winds farms in the United Kingdom was calculated using real wind data. The usable electricity from the Hornsea one wind farm was 5.83 TWh/year and from the Hornsea two wind farm it was 6.44 TWh/year harnessed to three different scenarios for the production and storage of green ammonia and green hydrogen. Scenario 1 fulfil the requirement of green hydrogen storage for flexible ammonia production but consumes more energy for green hydrogen compression. Scenario 2 does not offer any hydrogen storage which is not favourable in terms of flexibility and market demand. Scenario 3 offers both a direct routed supply of produced hydrogen for green ammonia synthesis and a storage facility for green hydrogen storage. Detailed mathematical calculations and sensitivity analysis was performed based on the total energy available to find out the energy storage capacity in terms of the mass of green hydrogen and green ammonia produced. Sensitivity analysis in the case of scenario 3 was conducted to determine the optimal percentage of green hydrogen going to the storage facility. Based on the cost evaluation of three different presented scenarios the levelized cost of hydrogen (LCOH) is between USD 5.30 and 5.97/kg and the levelized cost of ammonia (LCOA) is between USD 984.16 and USD 1197.11/tonne. These prices are lower compared to the current UK market. The study finds scenario 3 as the most appropriate way in terms of compression energy savings flexibility for the production and storage capacity that depends upon the supply and demand of these green fuels in the market and a feasible amount of green hydrogen storage.

The decarbonization of the maritime sector represents a priority in the energy policy agendas of the majority of Countries worldwide and the International Maritime Organization (IMO) has recently revised its strategy aiming for an ambitious zero-emissions scenario by 2050. In these regards there is a broad consensus on hydrogen as one of the most promising clean energy vectors for maritime transport and a key towards that goal. However to date an international regulatory framework for the use of hydrogen on-board of ships is absent this posing a severe limitation to the adoption of hydrogen technologies in this sector. To cope with this issue this paper presents a preliminary gap assessment analysis for the International Code of Safety for Ship Using Gases or other Low-flashpoint Fuels (IGF Code) with relation to hydrogen as a fuel. The analysis is structured according to the IGF Code chapters and a bottom-up approach is followed to review the code content and assess its relevance to hydrogen. The risks related to hydrogen are accounted for in assessing the gaps and providing a first level set of recommendations for IGF Code updates. By this means this work settles the basis for further research over the identified gaps towards the identification of a final set of recommendations for the IGF Code update.

: This article investigates how safety culture impacts the safety performance of blue hydrogen projects. Blue hydrogen refers to decarbonized hydrogen produced through natural gas reforming with carbon capture and storage (CCS) technology. It is crucial to decide on a suitable safety policy to avoid potential injuries financial losses and loss of public goodwill. The system dynamics approach is a suitable tool for studying the impact of factors controlling safety culture. This study examines the interactions between influencing factors and implications of various strategies using what-if analyses. The conventional risk and safety assessments fail to consider the interconnectedness between the technical system and its social envelope. After identifying the key factors influencing safety culture a system dynamics model will be developed to evaluate the impact of those factors on the safety performance of the facility. The emphasis on safety culture is directed by the necessity to prevent major disasters that could threaten a company’s survival as well as to prevent minor yet disruptive incidents that may occur during day-to-day operations. Enhanced focus on safety culture is essential for maintaining an organization’s long-term viability. H2-CCS is a complex socio-technical system comprising interconnected subsystems and sub-subsystems. This study focuses on the safety culture sub-subsystem illustrating how human factors within the system contribute to the occurrence of incidents. The findings from this research study can assist in creating effective strategies to improve the sustainability of the operation. By doing so strategies can be formulated that not only enhance the integrity and reliability of an installation as well as its availability within the energy networks but also contribute to earning a good reputation in the community that it serves.

By passing the delegated acts supplementing the revised Renewable Energy Directive the European Commission has recently set a regulatory benchmark for the classifcation of green hydrogen in the European Union. Controversial reactions to the restricted power purchase for electrolyser operation refect the need for more clarity about the efects of the delegated acts on the cost and the renewable characteristics of green hydrogen. To resolve this controversy we compare diferent power purchase scenarios considering major uncertainty factors such as electricity prices and the availability of renewables in various European locations. We show that the permission for unrestricted electricity mix usage does not necessarily lead to an emission intensity increase partially debilitating concerns by the European Commission and could notably decrease green hydrogen production cost. Furthermore our results indicate that the transitional regulations adopted to support a green hydrogen production ramp-up can result in similar cost reductions and ensure high renewable electricity usage.

The turbocharged dual-fuel engine is modeled and connected online to optimiser platform for transient input variation of input parameters decided by designed algorithms. This task is undertaken to enable intelligent control of the propulsion system including the Hydrogen injection instantly to reduce the thermal irreversibility. Therefore two methods of optimisation are applied to data collected from a turbocharged dual fuel operated propulsion system with direct diesel fuel injection and hydrogen port injection. This study investigates the application of multi-objective game theory (MOGT) and non-dominated sorting genetic algorithm II (NSGA-II) for optimising the performance of a diesel-hydrogen dual-fuel engine. The system is designed in 1D framework with input variability of the turbocharger efficiency hydrogen mass injection air compression ratio (Rp) and start of combustion (SoC). The objective is to set maximized the volume work while minimising the entropy generation and NO emission. The first populations in the optimisation procedures are initialised with uniform Latin hypercube and random space filler design of experiment (DoE) for both optimisers. The MOGT can find the best solution faster than NSGA-II with slightly better result. The statistics showed that MOGT generates 12 more unfeasible designs that do not meet the constraint limit on NO emission. The findings indicate that for different optimisation algorithms there are some factors with different effect direction and size on the objectives. Addi tionally it is discovered that although MOGT solution makes higher objective function value the NSGA-II optimal solution leads to better engine efficiency and lower fuel consumption.

The transition to low-carbon energy systems requires efficient hydrogen production methods that minimise CO2 emissions. This study presents a techno-economic assessment of hydrogen production via methane pyrolysis utilising a novel liquid metal bubble column reactor (LMBCR) designed for CO2-free hydrogen and solid carbon outputs. Operating at 20 bar and 1100 ◦C the reactor employs a molten nickel-bismuth alloy as both catalyst and heat transfer medium alongside a sodium bromide layer to enhance carbon purity and facilitate separation. Four operational scenarios were modelled comparing various heating and recycling configurations to optimise hydrogen yield and process economics. Results indicate that the levelised cost of hydrogen (LCOH) is highly sensitive to methane and electricity prices CO2 taxation and the value of carbon by-products. Two reactor configurations demonstrate competitive LCOHs of 1.29 $/kgH2 and 1.53 $/kgH2 highlighting methane pyrolysis as a viable low-carbon alternative to steam methane reforming (SMR) with carbon capture and storage (CCS). This analysis underscores the potential of methane pyrolysis for scalable economically viable hydrogen production under specificmarket conditions.

The integration of wind and solar energy with green hydrogen technologies represents an innovative approach toward achieving sustainable energy solutions. This review examines state-ofthe-art strategies for synthesizing renewable energy sources aimed at improving the efficiency of hydrogen (H2 ) generation storage and utilization. The complementary characteristics of solar and wind energy where solar power typically peaks during daylight hours while wind energy becomes more accessible at night or during overcast conditions facilitate more reliable and stable hydrogen production. Quantitatively hybrid systems can realize a reduction in the levelized cost of hydrogen (LCOH) ranging from EUR 3.5 to EUR 8.9 per kilogram thereby maximizing the use of renewable resources but also minimizing the overall H2 production and infrastructure costs. Furthermore advancements such as enhanced electrolysis technologies with overall efficiencies rising from 6% in 2008 to over 20% in the near future illustrate significant progress in this domain. The review also addresses operational challenges including intermittency and scalability and introduces system topologies that enhance both efficiency and performance. However it is essential to consider these challenges carefully because they can significantly impact the overall effectiveness of hydrogen production systems. By providing a comprehensive assessment of these hybrid systems (which are gaining traction) this study highlights their potential to address the increasing global energy demands. However it also aims to support the transition toward a carbon-neutral future. This potential is significant because it aligns with both environmental goals and energy requirements. Although challenges remain the promise of these systems is evident.

Bioenergy with carbon capture and storage (BECCS) technology is expected to support net-zero targets by supplying low carbon energy while providing carbon dioxide removal (CDR). BECCS is estimated to deliver 20 to 70 MtCO2 annual negative emissions by 2050 in the UK despite there are currently no BECCS operating facility. This research is modelling and demonstrating the flexibility scalability and attainable immediate application of BECCS. The CDR potential for two out of three BECCS pathways considered by the Intergovernmental Panel on Climate Change (IPCC) scenarios were quantified (i) modular-scale CHP process with post-combustion CCS utilising wheat straw and (ii) hydrogen production in a small-scale gasifier with pre-combustion CCS utilising locally sourced waste wood. Process modelling and lifecycle assessment were used including a whole supply chain analysis. The investigated BECCS pathways could annually remove between − 0.8 and − 1.4 tCO2e tbiomass− 1 depending on operational decisions. Using all the available wheat straw and waste wood in the UK a joint CDR capacity for both systems could reach about 23% of the UK’s CDR minimum target set for BECCS. Policy frameworks prioritising carbon efficiencies can shape those operational decisions and strongly impact on the overall energy and CDR performance of a BECCS system but not necessarily maximising the trade-offs between biomass use energy performance and CDR. A combination of different BECCS pathways will be necessary to reach net-zero targets. Decentralised BECCS deployment could support flexible approaches allowing to maximise positive system trade-offs enable regional biomass utilisation and provide local energy supply to remote areas.

The concept of the “hydrogen economy” was first coined by Prof. John Bockris during a talk he gave in 1970 at the General Motors Technical Center. Bockris’s talk introduced the vision of a world economy in which energy was carried in the form of hydrogen resulting in zero emissions at its point of use—be that as a chemical feedstock or as a fuel for industrial or domestic heating for power generation in a gas turbine or in a fuel cell “engine” for transport applications. Despite several waves of significant interest and investment however due to the relative costs and technological immaturity of hydrogen technologies the hydrogen economy was never delivered at scale nor was there sufficient motivation to create the technology needed to overcome these hurdles.<br/>But today as the world seeks to transition to a truly net-zero carbon economy hydrogen has returned to the fore as a key energy carrier—not as a hydrogen economy but as “hydrogen in the economy” synergistically working alongside low- to zero-carbon electricity to decarbonize those parts of the economy that are too expensive or too difficult to be directly decarbonized with electricity. These include:<br/>♦ Transport applications in which large amounts of energy are needed on the vehicle such as planes trains shipping long-distance trucks and heavy-duty vehicles;<br/>♦ Industrial applications such as steelmaking and cement manufacturing;<br/>♦ Long-term energy storage for days to weeks at a time;<br/>♦ The production of green chemicals such as green ammonia and green methanol;<br/>♦ Industrial (and potentially residential) heating.

In the latest OIES podcast from the Hydrogen Programme James Henderson talks to Abdurahman Alsulaiman about his latest paper entitled “Navigating Turbulence: Hydrogen’s Role in the Decarbonisation of the Aviation Sector.” In the podcast we discuss the current balance of fuels in the aviation sector the importance of increasing efficiency of aero-engines and the impact of increasing passenger miles travelled. The podcast then considers different decarbonisation options for the sector focussing on a change of engine technology to allow the use of alternative fuels such as hydrogen or electricity but also looking at the potential for hydrogen to play an important role in the development of Sustainable Aviation Fuels (SAFs) for use with current engine technology. We also look at Low Carbon Aviation Fuels which are essentially existing fuels derived from a significantly decarbonised supply chain and assess whether they have an important role to play as the aviation sector targets a net zero outcome.

The podcast can be found on their website.

As climate change intensifies determining a developing region’s role in achieving net-zero emissions worldwide is crucial. However regional efforts considering historical emissions remain underexplored. Here we assess energy system changes technology adoption and investments needed for developing regions including five major- and minor-emitting nations. Our analysis using an integrated assessment model shows a large gap in regional efforts toward global net-zero emissions stemming from the necessary shift of energy systems to low-carbon resources. The use of new technologies like electric vehicles hydrogen and carbon capture varies by region with the highest adoption required between 2020 and 2030. Financing this shift needs an average gross domestic product (GDP) investment rise of 0.464% in minor-emitting regions and up to 2.1% in major-emitting regions by 2085. Our results could guide policies and support setting quantifiable targets for developing nations. The findings are key to facilitating strategic technology use and finance mobilization to achieve a carbon-neutral future.

This article presents a comprehensive review of the current landscape and prospects of large-scale hydrogen storage technologies with a focus on both onshore and offshore applications and flexibility. Highlighting the evolving technological advancements it explores storage and compression techniques identifying potential research directions and avenues for innovation. Underwater hydrogen storage and hybrid metal hydride com pressed gas tanks have been identified for offshore buffer storage as well as exploration of using metal hydride slurries to transport hydrogen to/from offshore wind farms coupled with low pressure high flexibility elec trolyser banks. Additionally it explores the role of metal hydride hydrogen compressors and the integration of oxyfuel processes to enhance roundtrip efficiency. With insights into cost-effectiveness environmental and technology considerations and geographical factors this review offers insights for policymakers researchers and industry stakeholders aiming to advance the deployment of large-scale hydrogen storage systems in the transition towards sustainable energy.

This study aimed to compare hydrogen ammonia methanol and waste-derived biofuels as shipping fuels using life cycle assessment to establish what potential they have to contribute to the shipping industry’s 100% greenhouse gas emission reduction target. A novel approach was taken where the greenhouse gas emissions associated with one year of global shipping fleet operations was used as a common unit for comparison therefore allowing the potential life cycle greenhouse gas emission reduction from each fuel option to be compared relative to Paris Agreement compliant targets for international shipping. The analysis uses life cycle assessment from resource extraction to use within ships with all GHGs evaluated for a 100-year time horizon (GWP100). Green hydrogen waste-derived biodiesel and bio-methanol are found to have the best decarbonisation po tential with potential emission reductions of 74–81% 87% and 85–94% compared to heavy fuel oil; however some barriers to shipping’s decarbonisation progress are identified. None of the alternative fuels considered are currently produced at a large enough scale to meet shipping’s current energy demand and uptake of alternative fuel vessels is too slow considering the scale of the challenge at hand. The decarbonisation potential from alternative fuels alone is also found to be insufficient as no fuel option can offer the 100% emission reduction required by the sector by 2050. The study also uncovers several sensitives within the life cycles of the fuel options analysed that have received limited attention in previous life cycle investigations into alternative shipping fuels. First the choice of allocation method can potentially double the life cycle greenhouse gas emissions of e-methanol due to the carbon ac counting challenges of using waste carbon dioxide streams during fuel production. This leads to concerns related to the true impact of using carbon dioxide captured from fossil-fuelled processes to produce a combustible product due to the resultant high downstream emissions. Second nitrous oxide emissions from ammonia combustion are found to be highly sensitive due to high greenhouse gas potency potentially offsetting any greenhouse reduction potential compared to heavy fuel oil. Further uncertainties are highlighted due to limited available data on the rate of nitrous oxide production from ammonia engines. The study therefore highlights an urgent need for the shipping sector to consider these factors when investing in new ammonia and methanol engines; failing to do so risks jeopardizing the sector’s progress towards decarbonisation. Finally whilst alternative fuels can offer good decarbonisation potential (particularly waste derived biomethanol and bio-diesel and green hydrogen) this cannot be achieved without accelerated investment in new and retrofit vessels and new fuel supply chains: the research concludes that existing pipeline of vessel orders and fuel production facilities is insufficient. Furthermore there is a need to integrate alternative fuel uptake with other decarbonisation strategies such as slow steaming and wind propulsion.

In recent years the intensification of human activities has led to an increase in waste production and energy demand. The treatment of pollutants contained in wastewater coupled to energy recovery is an attractive solution to simultaneously reduce environmental pollution and provide alternative energy sources. Hydrogen represents a clean energy carrier for the transition to a decarbonized society. Hydrogen can be generated by photosynthetic water splitting where oxygen and hydrogen are produced and the process is driven by the light energy absorbed by the photocatalyst. Alternatively hydrogen may be generated from hydrogenated pollutants in water through photocatalysis and the overall reaction is thermodynamically more favourable than water splitting for hydrogen. This review is focused on recent developments in research surrounding photocatalytic and photoelectrochemical hydrogen production from pollutants that may be found in wastewater. The fundamentals of photocatalysis and photoelectrochemical cells are discussed along with materials and efficiency determination. Then the review focuses on hydrogen production linked to the oxidation of compounds found in wastewater. Some research has investigated hydrogen production from wastewater mixtures such as olive mill wastewater juice production wastewater and waste activated sludge. This is an exciting area for research in photocatalysis and semiconductor photoelectrochemistry with real potential for scale up in niche applications.

Hydrogen is poised to play a pivotal role in achieving net-zero targets and advancing green economies. However a range of complex operational challenges hinders its planning production delivery and adoption. At the same time numerous drivers within the hydrogen value chain present significant opportunities. This paper investigates the intricate relationships between these drivers and barriers associated with hydrogen supply chain (HSC). Utilising expert judgment in combination Grey-DEMATEL technique we propose a framework to assess the interplay of HSC drivers and barriers. Gaining insight into these relationships not only improves access to hydrogen but also foster innovation in its development as a low-carbon resource. The use of prominence scores and net influence rankings for each driver and barrier in the framework provides a comprehensive understanding of their relative significance and impact. Our findings demonstrate that by identifying and accurately mapping these attributes clear cause-and-effect relationships can be established contributing to a more nuanced understanding of the HSC. These insights have broad implications across operational policy scholarly and social domains. For instance this framework can aid stakeholders in recognizing the range of opportunities available by addressing key barriers to hydrogen adoption.

Hydrogen spark-ignition direct-injection engines result in no carbon emissions at use but NOX remains a challenge. This study demonstrates that with lean combustion (ϕ < 0.38) in-cylinder NOX can be reduced to a quarter of the current maritime regulatory limit. An original contribution of this work is the use of speciesresolved emissions formation across multiple engine load conditions. A novel chemically detailed combustion modelling framework was developed in CHEMKIN-Pro incorporating the evolution of the CRECK C1–C3 NOX mechanism for improved high-pressure accuracy. The framework was extensively validated using crank-angleresolved data across 9–18 bar loads. The model accurately reproduced pressure traces heat release angles and NOX. Mechanistic analysis revealed a shift from thermal Zeldovich NOX to intermediate-species (notably N2Odriven) as equivalence ratio and pressure varied. The findings highlighted the use of a high-fidelity chemical kinetic modelling framework not only to match experimental results but to gain physically grounded insight into actionable near-zero emission strategies.

The research focuses on enhancing hydrogen production using a blend of municipal solid waste (MSW) with Biomass and mixed plastic waste (MPW) under the Bioenergy with Carbon Capture Utilisation and Storage (BECCUS) concept. The key challenges include optimising the feedstock blends and gasification process parameters to maximise hydrogen yield and carbon dioxide capture. This study introduces a novel approach that employs sorption-enhanced gasification and a high-temperature regenerator reactor. Using this method syngas streams with high hydrogen contents of up to 93 mol% and 66 mol% were produced respectively. Thermodynamic simulations with Aspen Plus® validated the integrated system for achieving high-purity hydrogen (99.99 mol%) and effective carbon dioxide isolation. The system produced 70.33 molH2 /kgfeed when using steam as a gasifying agent while 37.95 molH2 /kgfeed was produced under air gasification conditions. Case I employed a mixture of MSW and wood residue at a ratio of 1:1.25 with steam and calcium oxide added at 2:1 and 0.92:1 respectively resulting in 68.80 molH2 /kgfeed and a CO2 capture efficiency of 92 %. Case II utilised MSW and MPW at a 1:1 ratio with steam and calcium oxide at 2:1 and 0.4:1 respectively producing 100.17 molH2 /kgfeed and achieving a 90.09 % CO2 capture efficiency. The optimised parameters significantly improve hydrogen yield and carbon capture offering valuable insights for BECCUS applications.

Green hydrogen is likely to play a major role in decarbonising the aviation industry. It is crucial to understand the effects of microstructure on hydrogen redistribution which may be implicated in the embrittlement of candidate fuel system metals. We have developed a multiscale finite element modelling framework that integrates micromechanical and hydrogen transport models such that the dominant microstructural effects can be efficiently accounted for at millimetre length scales. Our results show that microstructure has a significant effect on hydrogen localisation in elastically anisotropic materials which exhibit an interesting interplay between microstructure and millimetre-scale hydrogen redistribution at various loading rates. Considering 316L stainless steel and nickel a direct comparison of model predictions against experimental hydrogen embrittlement data reveals that the reported sensitivity to loading rate may be strongly linked with rate-dependent grain scale diffusion. These findings highlight the need to incorporate microstructural characteristics in hydrogen embrittlement models.