Publications

Eco-design is an innovative design methodology that focuses on minimizing the environmental footprint of industries including aviation right from the conceptual and development stages. However rising industrial demand calls for a more comprehensive strategy wherein beyond environmental considerations competitiveness becomes a critical factor supported by additional pillars of sustainability such as economic viability circularity and social impact. By incorporating sustainability as a primary design driver at the initial design stages this study suggests a shift from eco-driven to sustainability-driven design approaches for aircraft components. This expanded strategy considers performance and safety goals environmental impact costs social factors and circular economy considerations. To provide the most sustainable design that balances all objectives these aspects are rigorously quantified and optimized during the design process. To efficiently prioritize different variables methods such as multi-criteria decision-making (MCDM) are employed and a sustainability index is developed in this framework to assess the overall sustainability of each design alternative. The most sustainable design configurations are then identified through an optimization process. A typical aircraft component namely a hat-stiffened panel is selected to demonstrate the proposed approach. The study highlights how effectively sustainability considerations can be integrated from the early stages of the design process by exploring diverse material combinations and geometric configurations. The findings indicate that the type of fuel used and the importance given to the sustainability pillars—which are ultimately determined by the particular requirements and goals of the user—have a significant impact on the sustainability outcome. When equal prioritization is given across the diverse dimensions of sustainability the most sustainable option appears to be the full thermoplastic component when kerosene is used. Conversely when hydrogen is considered the full aluminum component emerges as the most sustainable choice. This trend also holds when environmental impact is prioritized over the other aspects of sustainability. However when costs are prioritized the full thermoplastic component is the most sustainable option whether hydrogen or kerosene is used as the fuel in the use phase. This innovative approach enhances the overall sustainability of aircraft components emphasizing the importance and benefits of incorporating a broader range of sustainability factors at the conceptual and initial design phases.

Introduction: The transition towards electrolysis-produced hydrogen in refineries and chemical industries is expected to have a potent impact on the local energy system of which these industries are part. In this study three urban areas with hydrogen-intense industries are studied regarding how the energy system configuration is affected if the expected future hydrogen demand is met in each node individually as compared to forming a “Hydrogen Valley” in which a pipeline can be used to trade hydrogen between the nodes.<br/>Method: A technoeconomic mixed-integer linear optimization model is used to study the investments in and dispatch of the included technologies with an hourly time resolution while minimizing the total system cost. Four cases are investigated based on the availability of offshore wind power and the possibility to invest in a pipeline.<br/>Results: The results show that investments in a pipeline reduces by 4%–7% the total system cost of meeting the demands for electricity heating and hydrogen in the cases investigated. Furthermore investments in a pipeline result in greater utilization of local variable renewable electricity resources as compared to the cases without the possibility to invest in a pipeline.<br/>Discussion: The different characteristics of the local energy systems of the three nodes in local availability of variable renewable electricity grid capacity and available storage options compared to local demands of electricity heating and hydrogen are found to be the driving forces for forming a Hydrogen Valley.

Due to hydrogen’s beneficial characteristics as a sustainable energy carrier the application of pulsing electric fields has been researched for its effectiveness during water electrolysis. Although there have been conflicting findings on the benefits of the application of pulsing electric fields this research highlights the potential it has to enhance the efficiency of water electrolysis while providing clarity on past discrepancies. This research achieves this by identifying distinctive energy flow profiles that result from various power input waveforms along with subsequent hydrogen production rates and efficiencies while also utilising a novel method of measuring the capacitance of the electrolyte to detect shifts in the molecular energy. The results indicate that pulsing electric fields can increase efficiency by up to 20 % or decrease efficiency by over 40 % depending on the energy flow profiles of the electrical molecular and electrochemical dynamics. Furthermore the use of pulsing electric fields also enabled load adaptability by allowing the electrolyser to operate effectively throughout a range of power inputs. For example the power input could be increased to cause a 279 % increase in hydrogen production without compromising efficiency; while conversely enabling electrolysis at >65 % efficiency using power input levels which were otherwise too low to drive electrochemical reactions. This study provides another step towards making renewable hydrogen viable as a sustainable energy carrier by identifying factors which influence and are influenced by changing electrical molecular and electrochemical dynamics while also providing a foundation for further research into more efficient use of energy to produce hydrogen gas.

In order to improve energy utilization efficiency and the flexibility of resource transfer in oceanic-island-group microgrids a water–electricity–hydrogen flexible scheduling strategy based on a multi-rate hydrogen-powered ship is proposed. First the characteristics of the seawater desalination unit (SDU) proton exchange membrane electrolyzer (PEMEL) and battery system (BS) in consuming surplus renewable energy on resource islands are analyzed. The variable-efficiency operation characteristics of the SDU and PEMEL are established and the effect of battery life loss is also taken into account. Second a spatiotemporal model for the multi-rate hydrogen-powered ship is proposed to incorporate speed adjustment into the system optimization framework for flexible resource transfer among islands. Finally with the goal of minimizing the total cost of the system a flexible water–electricity–hydrogen hybrid resource transfer model is constructed and a certain island group in the South China Sea is used as an example for simulation and analysis. The results show that the proposed scheduling strategy can effectively reduce energy loss promote renewable energy absorption and improve the flexibility of resource transfer.

Access to renewable energy is vital for rural development and climate change mitigation. The intermittency of renewable sources necessitates efficient energy storage especially in off-grid applications. This study evaluates the technical economic and environmental performance of an off-grid hybrid system for the rural settlement of Soma Turkey. Using HOMER Pro 3.14.2 software a system consisting of solar wind battery and hydrogen components was modeled under four scenarios with Cyclic Charging (CC) and Load Following (LF) control strategies for optimization. Life cycle assessment (LCA) and hydrogen leakage impacts were calculated separately through MATLAB R2019b analysis in accordance with ISO 14040 and ISO 14044 standards. Scenario 1 (PV + wind + battery + H2) offered the most balanced solution with a net present cost (NPC) of USD 297419 with a cost of electricity (COE) of USD 0.340/kWh. Scenario 2 without batteries increased hydrogen consumption despite a similar COE. Scenario 3 with wind only achieved the lowest hydrogen consumption and the highest efficiency. In Scenario 4 hydrogen consumption decreased with battery reintegration but COE increased. Specific CO2 emissions ranged between 36–45 gCO2-eq/kWh across scenarios. Results indicate that the control strategy and component selection strongly influence performance and that hydrogen-based hybrid systems offer a sustainable solution in rural areas.

To advance the hydrogen energy-driven low-altitude aviation sector it is imperative to establish sophisticated risk assessment frameworks tailored for hydrogen-powered aircraft. Such methodologies will deliver fundamental guidelines for the preliminary design phase of onboard hydrogen systems by leveraging rigorous risk quantification and scenario-based analytical models to ensure operational safety and regulatory compliance. In this context this study proposes a comprehensive hazard and operability analysis-fuzzy dynamic Bayesian network (HAZOP-FDBN) framework which quantifies risk without relying on historical data. This framework systematically maps the risk factor relationships identified in HAZOP results into a dynamic Bayesian network (DBN) graphical structure showcasing the risk propagation paths between subsystems. Expert knowledge is processed using a similarity aggregation method to generate fuzzy probabilities which are then integrated into the FDBN model to construct a risk factor relationship network. A case study on low-altitude aircraft hydrogen storage systems demonstrates the framework’s ability to (1) visualize time-dependent failure propagation mechanisms through bidirectional probabilistic reasoning and (2) quantify likelihood distributions of system-level risks triggered by component failures. Results validate the predictive capability of the model in capturing emergent risk patterns arising from subsystem interactions under low-altitude operational constraints thereby providing critical support for safety design optimization in the absence of historical failure data.

Within the framework of “dual carbon” intending to enhance the use of green energies and minimize the emissions of carbon from energy systems this study suggests a cost-effective low-carbon scheduling model that accounts for stepwise carbon trading for an integrated electricity heat gas cooling and hydrogen energy system. Firstly given the clean and low-carbon attributes of hydrogen energy a refined two-step operational framework for electricity-to-gas conversion is proposed. Building upon this foundation a hydrogen fuel cell is integrated to formulate a multi-energy complementary coupling network. Second a phased carbon trading approach is established to further explore the mechanism’s carbon footprint potential. And then an environmentally conscious and economically viable power dispatch model is developed to minimize total operating costs while maintaining ecological sustainability. This objective optimization framework is effectively implemented and solved using the CPLEX solver. Through a comparative analysis involving multiple case studies the findings demonstrate that integrating electrichydrogen coupling with phased carbon trading effectively enhances wind and solar energy utilization rates. This approach concurrently reduces the system’s carbon emissions by 34.4% and lowers operating costs by 58.6%.

Hydrogen is recognized as a key alternative fuel for mitigating greenhouse-gas emissions owing to its high fuel efficiency and carbon-free combustion. In the stratified charge combustion (SCC) mode ensuring optimal air-fuel mixing in the combustion chamber is crucial because the local equivalence ratio has a dominant influence on combustion characteristics. Therefore this study aims to build a detailed understanding of stratified hydrogen combustion under various local equivalence ratios. Laser-induced breakdown spectroscopy (LIBS) was used to measure the local equivalence ratios in hydrogen jets at different mixture-formation times (MFTs) and laserignition points (LIPs). The results showed that shorter MFTs induced highly stratified mixtures with elevated local equivalence ratios exceeding 2.0 enhancing the laminar flame speed and maximizing the conversion of chemical energy into pressure gain resulting in a representative total heat release over three times higher compared to longer MFTs. Furthermore ignition near the injector tip produced leaner mixtures with equivalence ratios around 0.3 whereas downstream LIPs generated peak local equivalence ratios around 2.0 facilitating rapid flame propagation and increased heat release by 25 %.

With the advancement of Fuel Cell Vehicles (FCVs) detecting hydrogen leaks is critically important in facilities such as hydrogen refilling stations. Despite its significance the dynamic response performance of hydrogen sensors in confined spaces particularly under ceilings has not been comprehensively assessed. This study utilizes a catalytic combustion hydrogen sensor to monitor hydrogen leaks in a confined area. It examines the effects of leak size and placement height on the distribution of hydrogen concentrations beneath the ceiling. Results indicate that hydrogen concentration rapidly decreases within a 0.5–1.0 m range below the ceiling and declines more gradually from 1.0 to 2.0 m. The study further explores the attenuation pattern of hydrogen concentration radially from the hydrogen jet under the ceiling. By normalizing the radius and concentration it was determined that the distribution conforms to a Gaussian model akin to that observed in open space jet flows. Utilizing this Gaussian assumption the model is refined by incorporating an impact reflux term thereby enhancing the accuracy of the predictive formula.

Microgrids enable the integration of renewable energy sources; however managing electricity from intermittent wind and solar power remains a significant challenge. This study investigates two storage strategies for managing surplus renewable electricity in an IEEE 84-Bus microgrid with wind turbines and photovoltaic units. The first option involves producing hydrogen via electrolyzers which is stored for later electricity generation through fuel cells. The second option involves converting surplus electricity into heat using heat pumps which is then stored in thermal energy storage systems to efficiently meet the microgrid's thermal load requirements. A scenariobased day-ahead scheduling model is proposed to optimize the microgrid's electrical and thermal load management while considering uncertainties in market prices wind speeds and solar irradiance. The resulting large-scale optimization challenge is effectively tackled using the self-adaptive charge system search algorithm. The results indicate that for the optimal utilization of excess renewable electricity heat generation via heat pumps is more cost-effective than hydrogen production primarily due to the inefficiencies in hydrogen conversion and the ability of heat pumps to produce several units of heat for each unit of electricity consumed. Moreover heat pumps prove to be more economical than natural gas combustion in boilers for meeting the thermal demands across a wide range of gas prices. These findings highlight the economic benefits of integrating heat pumps and thermal energy storage systems into renewable energy microgrids.