Applications & Pathways

With the global energy structure shifting towards clean and efficient hydrogen energy the safety management issues of hydrogen refueling stations are becoming increasingly prominent. To address these issues a hydrogen leak localization algorithm for hydrogen refueling stations based on a combination of reinforcement learning and hidden Markov models is proposed. This method combines hidden Markov model to construct a probability distribution model for hydrogen leakage and diffusion simulates the propagation probability of hydrogen in different grid cells and uses reinforcement learning to achieve fast and accurate localization of hydrogen leakage events. The outcomes denoted that the training accuracy reached 95.2% with an F1 value of 0.961 indicating its high accuracy in hydrogen leak localization. When the wind speed was 0.8 m/s the mean square error of the raised method was 0.03 and when the wind speed was 1.0 m/s the mean square error of the raised method was 0.04 proving its good robustness. After 50 localization experiments the proposed algorithm achieves a localization success rate of 93.7% and an average computation time of 42.8 s further demonstrating its high accuracy and computational efficiency. The proposed hydrogen leakage location algorithm has improved the accuracy and efficiency of hydrogen leakage location providing scientific basis and technical guarantee for the safe operation of future hydrogen refueling stations.

The global aviation sector is essential for connecting people cultures and economies but it significantly contributes to greenhouse gases (GHG) exacerbating environmental concerns. This systematic literature review examines the transformation of waste into Sustainable Aviation Fuels (SAF) highlighting their potential to reduce the aviation industry’s carbon footprint. The review explores waste-to-fuel technologies such as gasification pyrolysis liquefaction and Fischer-Tropsch synthesis mainly focusing on the eight ASTM-certified bio-jet fuel production pathways demonstrating the highest readiness levels. The study covers methodologies case studies and optimszation studies identifying significant trends advancements and gaps in the literature to develop SAF from waste. Key findings reveal that some processes can significantly reduce CO2 emissions and improve sustainability but challenges persist. Despite the potential of thermochemical pathways combined with oil hydro-processing and their technological readiness the pathway’s production costs remain high and robust regulatory support is needed to scale up SAF production. Integrating pathways in a hybrid format could further offer a synergistic approach to developing SAF that combine high performance with economic and environmental sustainability. Future research should address these gaps enhance energy and economic efficiencies and explore innovative feedstocks and catalytic processes. The review provides valuable insights for environmentalists industry stakeholders engineers and policymakers supporting efforts to achieve sustainable aviation and global environmental goals.

The growing demand for sustainable solutions in the transportation sector and global decarbonization goals have fueled debate on using hydrogen as an energy source. Although hydrogen’s potential is recognized in Brazil its application in heavy-duty vehicles still faces structural and technological barriers. This study aimed to analyze the viability of hydrogen as an energy alternative for trucks in Brazil. The research adopted an exploratory qualitative approach based on the expert analysis method through semi-structured interviews with development engineers representatives of heavy-duty vehicle manufacturers and researchers specializing in hydrogen technologies. The data were organized into a thematic framework and interpreted using content analysis. The results show that although there is growing interest and ongoing initiatives challenges such as the cost of fuel cells the lack of refueling infrastructure and low technological maturity hinder large-scale adoption. From a theoretical perspective the study contributes by integrating specialized literature with practical insights from key industry players broadening the understanding of the energy transition. In practical terms it outlines some strategic paths such as expanding technological development and forming partnerships. From a social perspective it emphasizes the importance of hydrogen as a pillar for sustainable low-carbon mobility capable of positively impacting public health and mitigating climate change.

The aviation industry is responsible for approximately 2–3% of worldwide CO2 emissions and is increasingly subjected to demands for the attainment of net-zero emissions targets by the year 2050. Traditional fossil jet fuels which exhibit lifecycle emissions of approximately 89 kg CO2-eq/GJ play a substantial role in exacerbating climate change contributing to local air pollution and fostering energy insecurity. In contrast Sustainable Aviation Fuels (SAFs) derived from renewable feedstocks including biomass municipal solid waste algae or through CO2- and H2-based power-to-liquid (PtL) represent a pivotal solution for the immediate future. SAFs generally accomplish lifecycle greenhouse gas (GHG) reductions of 50–80% (≈20–30 kg CO2-eq/GJ) possess reduced sulfur and aromatic content and markedly diminish particulate emissions thus alleviating both climatic and health-related repercussions. In addition to their environmental advantages SAFs promote energy diversification lessen reliance on unstable fossil fuel markets and invigorate regional economies with projections indicating the creation of up to one million green jobs by 2030. This comprehensive review synthesizes current knowledge on SAF sustainability advantages compared to conventional aviation fuels identifying critical barriers to large-scale deployment and proposing integrated solutions that combine technological innovation supportive policy frameworks and international collaboration to accelerate the aviation industry’s sustainable transformation.

The Indonesian government has established an energy transition policy for decarbonization including the target of utilizing hydrogen for power generation through a co-firing scheme. Several studies indicate that hydrogen co-firing in gas-fired power plants can reduce CO2 emissions while improving efficiency. This study develops a simulation model for hydrogen co-firing in an M701F gas turbine at the Cilegon power plant using Aspen HYSYS. The impact of different hydrogen volume fractions (5–30%) on thermal efficiency and CO2 emissions is analyzed under varying operational loads (100% 75% and 50%). The simulation results show an increase in thermal efficiency with each 5% increment in the hydrogen fraction averaging 0.32% at 100% load 0.34% at 75% load and 0.37% at 50% load. The hourly CO2 emission rate decreased by an average of 2.16% across all operational load variations for every 5% increase in the hydrogen fraction. Meanwhile the average reduction in CO2 emission intensity at the 100% 75% and 50% operational loads was 0.017 0.019 and 0.023 kg CO2/kWh respectively.

This paper introduces a novel dual-purpose transmission system that integrates power transmission and energy storage using hydrogen ammonia and compressed air—an area largely unexplored in the literature. Unlike conventional cable transmission which requires separate storage infrastructure the proposed approach leverages the transmission medium itself as an energy storage solution enhancing system efficiency and reducing costs. By incorporating a defined storage allocation factor this study examines the delivery of offshore-generated power to onshore locations calculating the necessary media flow rates and evaluating the required transportation infrastructure including tunnels and pipelines. A comparative cost-effectiveness analysis is conducted to determine optimal conditions under which storage-integrated transmission outperforms conventional cable transmission. Various transmission powers storage fractions pressures and distances are analysed to assess feasibility and economic viability. The findings indicate that for a 75 % storage allocation factor compressed air can transmit up to 450 MW over 300 km more cost-effectively than cables while hydrogen enables 230 MW transmission beyond 310 km. Ammonia proves to be the most efficient facilitating the transmission of over 2000 MW across distances exceeding 140 km at a lower cost than cables all without requiring onshore storage. Moreover for a 500-km transmission line compressed air hydrogen and ammonia can store the equivalent of 62 58 and 152 h of wind farm output respectively significantly reducing the need for additional onshore storage. This study fills a critical research gap by optimizing offshore wind power delivery through an innovative cost-effective and scalable transmission and storage approach.

The mixing of fuel and ambient in a compression-igniting combustion engine is a critical process affecting ignition delay burn duration and cycle efficiency. This study aims to visualize and quantify hydrogen mole fraction distributions resulting from high-pressure (10 MPa) hydrogen injections into an inert pressurized (1 MPa) nitrogen ambient at room temperature. Using inverse planar laser-induced fluorescence in which the ambient rather than the jet is seeded with a fluorescent tracer two different injectors (nozzle hole sizes of 0.55 and 0.65 mm) and two different tracers (toluene and acetone) are compared. It is concluded that a non-intensified CCD camera for fluorescence detection is superior to the use of an intensified one due to the linear behavior on contrast. The two injectors produce similar jets in terms of jet penetration and angle. Jet penetration derived from inverse-LIF measurements agree with Schlieren data on nominally the same jets but the hydrogen mole fractions are generally 2.5-5 percent lower than those obtained by planar Rayleigh scattering. Quasi-steadiness and self-similarity were found for ensemble-averaged mole fraction distributions of both injectors which aligns with theory and highlights the importance of using RANS simulations or time-averaged experiments for future comparisons.

With the increasing adoption of renewable energy sources such as solar and wind power it is essential to achieve carbon neutrality. However several shortcomings including their intermittence pose significant challenges to the stability of the electrical grid. This study explores hydrogen-based technologies such as fuel cells and water electrolysis systems as an effective solution to improve frequency stability and address the problems of power grid reliability. Using power system analysis programs modeling and simulations performed on IEEE-25 Bus and Jeju Island systems demonstrate the potential of these technologies to mitigate reductions reduce transmission constraints and stabilize frequencies. The results show that hydrogen-based systems are important factors enabling sustainable energy transition.

This study develops a comprehensive framework for assessing the sustainability performance of wind power systems integrated with hydrogen storage (WPCHS). Unlike previous works that mainly emphasized economic or environmental indicators our approach incorporates a balanced set of economic environmental and social criteria supported by expert evaluation. To address the uncertainty in human judgment we introduce an interval-valued fuzzy TOPSIS model that provides a more realistic representation of expert assessments. A case study in Manjil Iran demonstrates the application of the model highlighting that project A4 outperforms other alternatives. The findings show that both economic factors (e.g. levelized cost of energy) and social aspects (e.g. poverty alleviation) strongly influence project rankings. Compared with earlier studies in Europe and the Middle East this work contributes by extending the evaluation scope beyond financial and environmental metrics to include social sustainability thereby enhancing decision-making relevance for policymakers and investors.

Australia has set a new climate target of reducing emissions by 62–70% below 2005 levels by 2035 with sustainable aviation fuel (SAF) central to achieving this goal. This review critically examines techno-economic analysis (TEA) and life cycle assessment (LCA) of Powerto-Liquid (PtL) electrofuels (e-fuels) which synthesize atmospheric CO2 and renewable hydrogen (H2) via Fischer-Tropsch (FT) synthesis. Present PtL pathways require ~0.8 kg of H2 and 3.1 kg of CO2 per kg SAF with ~75% kerosene yield. While third-generation feedstocks could cut greenhouse gas emissions by up to 93% (as low as 8 gCO2e/MJ) real world reductions have been limited (~1.5%) due to variability in technology rollout and feedstock variability. Integrated TEA–LCA studies demonstrate up to 20% energy efficiency improvements and 40% cost reductions but economic viability demands costs below $3/kg. In Australia abundant solar resources vast transport networks and supportive policy frameworks present both opportunities and challenges. This review provides the first comprehensive assessment of PtL-FT SAF for Australian conditions highlighting that large-scale development will require technological advancement feedstock development infrastructure investment and coordinated policy support.

Hydrogen-based direct reduction of iron ore is a promising route to reduce CO2 emissions in steelmaking where uniform particle flow inside shaft furnaces is essential for efficient operation. In this study a full-scale three-dimensional Discrete Element Method (DEM) model of a shaft furnace was developed to investigate the effects of a diverter device on granular flow. By systematically varying the radial width and top/bottom diameters of the diverter particle descent velocity residence time compressive force distribution and collision energy dissipation were analyzed. The results demonstrate that introducing a diverter effectively suppresses funnel flow prolongs residence time and improves radial flow uniformity. Among the tested configurations the smaller central diameter diverter showed the most favorable performance achieving a faster and more uniform descent reduced compressive force concentration and lower collision energy dissipation. These findings highlight the critical role of diverter design in regulating particle dynamics and provide theoretical guidance for optimizing shaft furnace structures to enhance the efficiency of hydrogen-based direct reduction processes.

This article takes the perspective of Hydrogen Load Aggregator (HLA) to optimize the declaration strategy of peak shaving market improve the flexible regulation capability of power system and HLA economy as the research objectives and proposes an optimization strategy method for HLA to participate in peak shaving market. Firstly an improved Convolutional Neural Networks–Long Short-Term Memory (CNN-LSTM) time series prediction model is developed to address peak shaving demand uncertainty. Secondly a bidding strategy model incorporating dynamic pricing is constructed by comprehensively considering electrolyzer regulation costs market supply–demand relationships and system constraints. Thirdly a market clearing model for peak shaving markets with HLA participation is designed through analysis of capacity contribution and marginal costs among different regulation resources. Finally the capacity allocation model is designed with the goal of minimizing the total cost of peak shaving among various stakeholders within HLA and the capacity won by HLA in the peak shaving market is reasonably allocated. Simulations conducted on a Python3.12-based experimental platform demonstrate the following: the improved CNN-LSTM model exhibits strong adaptability and robustness the bidding model effectively enhances HLA market competitiveness and the clearing model reduces system operator costs by 5.64%.

Due to the environmental impact of fossil fuels renewable energy such as wind and solar energy is rapidly developed. In energy systems energy storage units are important which can regulate the safe and stable operation of the power system. However different energy storage methods have different environmental and economic impacts in renewable energy systems. This paper proposed three different energy storage methods for hybrid energy systems containing different renewable energy including wind solar bioenergy and hydropower meanwhile. Based on Homer Pro software this paper compared and analyzed the economic and environmental results of different methods in the energy system through the case of a residential community in Baotou City. The result showed that (1) the use of batteries as energy storage in communities posed the lowest energy costs whose NPC was $197396 and LCOE was $0.159 consisting of 20 batteries 19.3 kW PV 6 wind turbines a 12.6 kW converter. (2) Lower fuel cell prices mean lower NPC and the increase in the Electric Load Scaled Average implied a decrease in LCOE and the increase of the NPC. (3) The use of fuel cells also had impacts on the environment such as resulting CO2 and SO2.

Crude oil accounts for approximately 40% of global energy consumption and the refining sector is a major contributor to greenhouse gas (GHG) emissions particularly through the production of hard-to-abate fuels such as aviation fuel and fuel oil. This study disaggregates the refinery into its key process units to identify decarbonization opportunities along the entire production chain. Units are categorized into combustion-based processes— including crude and vacuum distillation hydrogen production coking and fluid catalytic cracking—and non-combustion processes which exhibit lower emission intensities. The analysis reveals that GHG emissions can be reduced by up to 60% with currently available technologies without requiring major structural changes. Electrification residual heat recovery renewable hydrogen for desulfurization and process optimization through digital twins are identified as priority measures many of which are also economically viable in the short term. However achieving full decarbonization and alignment with net-zero targets will require the deployment of carbon capture technologies. These results highlight the significant potential for emission reduction in refineries and reinforce their strategic role in enabling the transition toward low-carbon fuels.

This paper presents a method for gas turbine performance calculations with alternative fuels with a particular focus on their use in aircraft engines. The effects of various alternative aviation fuels on fuel consumption CO2 emissions and contrail formation are examined in a comparative study. We use the GasTurb performance software and calculate heat release and hot section gas properties using a chemical equilibrium solver. Fuels with complex compositions are included in the calculation via surrogates of a limited number of known species that mimic the relevant properties of the real fuel. An automated method is used for the fuel surrogate formulation. We compare the results of this rigorous approach with the simplified approach of calculating the heat release using an alternative fuel’s heating value while still using the gas properties of conventional Jet A-1. The results show that the latter approach systematically overpredicts fuel consumption by up to 0.2% for aromaticsfree synthetic kerosene (e.g. “biofuels”). Overall aircraft engines running on alternative fuels tend to be more fuel efficient due to their often higher hydrogen contents and thus fuel heating values. We find reductions in fuel consumption of up to 2.8% during cruise when using aromatics-free synthetic kerosene. We further assess how alternative fuels affect contrail formation based on the Schmidt-Appleman criterion. Contrails can form 200 m lower under cruise conditions when burning aromatics-free synthetic kerosene instead of Jet A-1 with identical thrust requirements and under the same atmospheric conditions mainly due to their higher hydrogen content. In summary we present a flexible yet easy-to-use method for studying fuel effects in performance calculations that avoids small but systematic errors by rigorously calculating the heat release and hot section gas properties for each fuel.

The heat transfer performance of the thermal management system plays a crucial role in the hydrogen-powered aviation engine cycle. As an exceptional fuel the thermophysical parameters of hydrogen change drastically with temperature in the trans-critical state. While previous studies on heat transfer enhancement mainly focused on changing the geometrical structure few studies have been conducted on realizing heat transfer enhancement based on the properties of the fluid itself. Utilizing the drastic changes in thermophysical parameters of hydrogen in the trans-critical state to achieve heat transfer enhancement could greatly contribute to the thermal management system of the hydrogen-powered cycle. In this study a trans-critical process control method for heat transfer enhancement based on multidirectional impact flow distribution is proposed. The distributions and variation patterns of temperature density specific heat capacity and equivalent thermal conductivity along the flow directions were investigated the flow and heat transfer performance of the channel optimized by the proposed method was numerically simulated and the control of the trans-critical process and the mechanism of heat transfer enhancement were analyzed. The effects of the key design parameters such as flow distribution ratio number and spacing of gaps on the flow and heat transfer performance of the heat transfer unit were comparatively analyzed by taking various factors into account and finally a relatively optimal combination of key design parameters was obtained.

Green hydrogen offers a promising yet underexplored pathway for agricultural decarbonisation requiring technological readiness and coordinated action from policymakers industry and farmers. This paper integrates techno-economic modelling with stakeholder engagement (semi-structured interviews and an expert workshop) to assess its potential. Analyses were conducted for farms of 123 hectares and clusters of 10 farms complemented by seven interviews and a workshop with nine sector experts. Findings show both opportunities and barriers. While on-farm hydrogen production is technically feasible it remains economically uncompetitive due to high levelised costs shaped by seasonal demand variability and low utilisation of electrolysers and storage. Pooling demand across multiple users is essential to improve cost-effectiveness. Stakeholders identified three potential business models: fertiliser production via ammonia synthesis cooperative-based models and local refuelling stations. Of these cooperative hydrogen hubs emerged as the most promising enabling clusters of farms to jointly invest in renewable-powered electrolysers storage and refuelling facilities thereby reducing costs extending participation to smaller farms and mitigating risks through collective investment. By linking techno-economic feasibility with stakeholder perspectives and business model considerations the results contribute to socio-technical transition theory by showing how technological institutional and social factors interact in shaping hydrogen adoption in agriculture. With appropriate policy support cooperative hubs could lower costs ease concerns over affordability and complexity and position hydrogen as a practical driver of agricultural decarbonisation and rural resilience. Keywords: green

This study employs computational thermodynamics to evaluate the feasibility of replacing methane with hydrogen as both burner fuel and reductant during blister copper deoxidation aiming to enhance deoxidation efficiency and reduce CO2 emissions. A comprehensive thermodynamic model was developed using FactSage 8.3 for dilute Cu–O and Cu–S–O melts containing trace impurities (Fe Ni Pb Zn) incorporating methane thermal decomposition and temperature-dependent variations in liquid copper density with oxygen and sulfur content. Model parameters were optimized against over 105 deoxidation simulation data points yielding temperature- and composition-dependent expressions for rapid density estimates. Benchmarking against existing literature models demonstrated improved accuracy. Key findings include: (1) increasing impurities contents from electronics waste recycling (Fe Ni Pb Zn) reduces oxygen activity deteriorating the deoxidation efficiency; (2) under global equilibrium methane provides greater reducing power per mole than hydrogen due to full thermal cracking but real-world mass transfer limitations render hydrogen more consistently effective up to 1200 C with methane gas needing to achieve at least 472 C to match hydrogen’s performance; (3) adiabatic flame equilibrium studies show that O2/H2 ratios of 0.5 to 1 yield liquid copper oxygen activities comparable to industrial O2/CH4 ratios of 2 to 3 supporting the direct substitution of methane with hydrogen in oxy-fuel anode furnace burners without compromising metal quality.

To reduce the amount of harmful gases produced by fossil fuels more environmentally friendly and sustainable alternatives are being proposed around the world. As a result technologies for manufacturing hydrogen fuel cells and producing green hydrogen are becoming more widespread with an impact on energy production and environmental protection. In many countries around the world and in Africa in particular leaders scientists and populations are considering switching from fossil fuels to so-called green energies. Hydrogen is therefore an interesting alternative that deserves to be explored especially since both rural and urban populations have shown an interest in using it in the near future which would reduce pollution and the proliferation of greenhouse gases thereby mitigating global warming. The aim of this paper is to determine the hybrid energy system best suited to addressing the energy problem in the study area and then to make successive substitutions of different energy sources starting with the most polluting in order to assess the possibilities for transitioning the energy used in the area to green hydrogen. To this end this study began with a technical and economic analysis which based on climatic parameters led to the proposal of a PV/DG-BATTery system configuration with a Net Present Cost (NPC) of USD 19267 and an average Cost Of Energy (COE) of USD 0.4 and with a high proportion of CO2 emissions compared with the PV/H2GEN-BATT and H2GEN systems. The results of replacing fossil fuel generators with hydrogen generators are beneficial in terms of environmental protection and lead to a reduction in energy-related expenses of around 2.1 times the cost of diesel and a reduction in mass of around 2.7 times the mass of diesel. The integration of H2GEN at high duty percentages increases the Cost Of Energy whether in a hybrid PV/H2GEN system or an H2GEN system. This shows the interest in the study country in using favorable duty proportions to make the use of hydrogen profitable.

From an environmental standpoint carbon-free energy carriers such as ammonia and hydrogen are essential for future energy systems. However their hightemperature chemical behavior remains insufficiently understood posing challenges for the development and optimization of advanced combustion technologies. Ammonia in particular is globally available and cost-effective especially for energy-intensive industries. The addition of ammonia or hydrogen to methane significantly reduces the accuracy of existing predictive models. Therefore validated and detailed data are urgently needed to enable reliable design and performance predictions. This review highlights the compatibility of ammonia with existing combustion infrastructure facilitating a smoother transition to more sustainable heating methods without the need for entirely new systems. Applications in high-temperature heating processes such as metal processing ceramics and glass production and power generation are of particular interest. This review focuses on the systematic assessment of alternative fuel mixtures comprising ammonia and hydrogen as well as natural gas with particular consideration of existing safety-related parameters and combustion characteristics. Fundamental quantities such as the laminar burning velocity are discussed in the context of their relevance for fuel mixtures and their scalability toward turbulent flame propagation which is of critical importance for industrial burner and reactor design. The influence of fuel composition on ignition limits is examined as these are essential parameters for safety margin definitions and operational boundary conditions. Furthermore flame stability in mixed-fuel systems is addressed to evaluate the practical feasibility and robustness of combustion under varying process conditions. A detailed overview of current diagnostic and analysis methods follows encompassing both pollutant measurement techniques and the detection of key radical species. These diagnostics form the experimental basis for reaction kinetics modeling and mechanism validation. Given the importance of emission formation in combustion systems a dedicated subsection summarizes major emission trends even though a comprehensive treatment would exceed the scope of this review. Thermal radiation effects which are highly relevant for heat transfer and system efficiency in large-scale applications are then reviewed. In parallel current developments in numerical simulation approaches for industrial-scale combustion systems are presented including aspects of model accuracy boundary conditions and computational efficiency. The review also incorporates insights from materials engineering particularly regarding high-temperature material performance corrosion resistance and compatibility with combustion products. Based on these interdisciplinary findings operational strategies for high-temperature furnaces are outlined and selected industrial reference systems are briefly presented. This integrated approach aims to support the design optimization and safe operation of next-generation combustion technologies utilizing carbon-free or low-carbon fuels.

The growing energy crisis and increasing threat of climate change are driving the need to take action regarding the use of alternative fuels in transport including public transport. Hydrogen is undoubtedly a fuel which is environmentally friendly and constitutes an alternative to fossil fuels. The wider deployment of hydrogen-powered vehicles involves the need to adapt infrastructure to support the operation of these vehicles. Such infrastructure includes refuelling stations for hydrogen-powered vehicles. The widespread use of hydrogen-powered vehicles is dependent on the development of a network of hydrogen refuelling stations. The aim of this article is to propose the conceptual location of infrastructure for fuelling public transport vehicles with hydrogen in selected cities of the West Pomeranian Voivodeship in particular the cities of Szczecin and Koszalin. The methodology used to determine the number of refuelling stations is described and the concept of the location for the refuelling stations has been proposed. Based on a set assumptions it was stated that two stations may be located in the Voivodeship in 2025 and seven stations in 2040. The research results will be of interest to infrastructure developers public transport companies and municipalities involved in making decisions related to the purchase and operation of hydrogen-powered buses.

The chemical industry faces major challenges worldwide. Since 1950 production has increased 50-fold and is projected to continue growing particularly in Asia. It is one of the most energy- and resource-intensive industries contributing significantly to greenhouse gas emissions and the depletion of finite resources. This development exceeds planetary boundaries and calls for a sustainable transformation of the industry. The key transformation areas are as follows: (1) Non-Fossil Energy Supply: The industry must transition away from fossil fuels. Renewable electricity can replace natural gas while green hydrogen can be used for high-temperature processes. (2) Circularity: Chemical production remains largely linear with most products ending up as waste. Sustainable product design and improved recycling processes are crucial. (3) Non-Fossil Feedstock: To achieve greenhouse gas neutrality oil gas and coal must be replaced by recycling plastics renewable biomaterials or CO2-based processes. (4) Sustainable Chemical Production: Energy and resource savings can be achieved through advancements like catalysis biotechnology microreactors and new separation techniques. (5) Sustainable Chemical Products: Chemicals should be designed to be “Safe and Sustainable by Design” (SSbD) meaning they should not have hazardous properties unless essential to their function. (6) Sufficiency: Beyond efficiency and circularity reducing overall material flows is essential to stay within planetary boundaries. This shift requires political economic and societal efforts. Achieving greenhouse gas neutrality in Europe by 2050 demands swift and decisive action from industry governments and society. The speed of transformation is currently too slow to reach this goal. Science can drive innovation but international agreements are necessary to establish a binding framework for action.

Injection timing in low-pressure hydrogen direct injection (H2LPDI) engines plays a critical role in optimising gas jet structure and mixture formation due to the complex and transient nature of ambient air flow and density inside the cylinder. This study systematically investigates the macroscopic characteristics of gas jet development at five distinct injection timings from 210 to 120 ◦CA bTDC with the intake valve closure (IVC) as a reference point in a motored inline four-cylinder spark-ignition engine at 2000 rpm and 160 Nm load using low-pressure injection of 3.5 MPa. Optical access was made with two endoscopes: one for high-speed imaging and the other for laser insertion to realise laser shadowgraph imaging of the gas jet delivered using a side-mounted outwardopening pintle nozzle injector. The experimental results reveal spatial and temporal variations in jet morphology penetration spreading angle and mixture dispersion as a function of injection timing. Pre-IVC injection (210 ◦CA bTDC) produced a narrow mean cone angle of ~40◦ and the highest penetration-rate proxy (0.49) whereas postIVC injection (120 ◦CA bTDC) retained a wider ~53◦ cone yet reduced the penetration rate to 0.28 while increasing the sheet-based mixing index from − 0.084 to − 0.106. Pre-IVC injection occurring under low ambient pressure and with active intake airflow was found to produce elongated jets with enhanced penetration and mixing rates though accompanied by substantial cyclic variations. Conversely post-IVC injection was strongly influenced by a fully developed tumble flow which redirected the jet trajectory towards the pent-roof and facilitated mixing through increased turbulence. However the elevated air density constrained the jet penetration. At-IVC injection resulted in a more uniform and stable jet structure. However the lack of convective flow constrained the overall mixing effectiveness. Quantitative analysis of jet spreading angle pixel intensity gradient and centroid movement using 100 consecutive cycles confirms the critical role of injection timing in shaping the gas jet development as suggested by the images.

To enable climate-neutral aviation improving the energy efficiency of aircraft is essential. The research project Synergies of Highly Integrated Transport Aircraft investigates cross-disciplinary synergies in aircraft and propulsion technologies to achieve energy savings. This study examines a fuel cell electric powered configuration with distributed electric propulsion. For this a reverse-engineered ATR 72-500 serves as a reference model for calibrating the methods and ensuring accurate performance modeling. A baseline configuration featuring a state-of-the-art turboprop engine with the same entry-into-service is also introduced for a meaningful performance comparison. The analysis uses an enhanced version of the Stanford University Aerospace Vehicle Environment (SUAVE) a Python-based aircraft design environment that allows for novel energy network architectures. This paper details the preliminary aircraft design process including calibration presents the resulting aircraft configurations and examines the integration of a fuel cell-electric energy network. The results provide a foundation for higher fidelity studies and performance comparisons offering insights into the trade-offs associated with hydrogen-based propulsion systems. All fundamental equations and methodologies are explicitly presented ensuring transparency clarity and reproducibility. This comprehensive disclosure allows the broader scientific community to utilize and refine these findings facilitating further progress in hydrogen-powered aviation technologies.

Amid escalating global climate crises and the urgent imperative to meet the Paris Agreement’s carbon neutrality targets the steel industry—a leading contributor to global greenhouse gas emissions—confronts unprecedented challenges in driving sustainable industrial transformation through innovative low-carbon steelmaking technologies. This paper examines decarbonization technologies across three stages (source process and end-of-pipe) for two dominant steel production routes: the long process (BF-BOF) and the short process (EAF). For the BF-BOF route carbon reduction at the source stage is achieved through high-proportion pellet charging in the blast furnace and high scrap ratio utilization; at the process stage carbon control is optimized via bottom-blowing O2-CO2-CaO composite injection in the converter; and at the end-of-pipe stage CO2 recycling and carbon capture are employed to achieve deep decarbonization. In contrast the EAF route establishes a low-carbon production system by relying on green and efficient electric arc furnaces and hydrogen-based shaft furnaces. At the source stage energy consumption is reduced through the use of green electricity and advanced equipment; during the process stage precision smelting is realized through intelligent control systems; and at the end-of-pipe stage a closed-loop is achieved by combining cascade waste heat recovery and steel slag resource utilization. Across both process routes hydrogen-based direct reduction and green power-driven EAF technology demonstrate significant emission reduction potential providing key technical support for the low-carbon transformation of the steel industry. Comparative analysis of industrial applications reveals varying emission reduction efficiencies economic viability and implementation challenges across different technical pathways. The study concludes that deep decarbonization of the steel industry requires coordinated policy incentives technological innovation and industrial chain collaboration. Accelerating large-scale adoption of low-carbon metallurgical technologies through these synergistic efforts will drive the global steel sector toward sustainable development goals. This study provides a systematic evaluation of current low-carbon steelmaking technologies and outlines practical implementation strategies contributing to the industry’s decarbonization efforts.