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Achieving the Sustainable Development Goals (SDGs) is crucial for addressing global environmental challenges. SDG 13 calls for urgent climate action, while SDG 7 promotes sustainable energy. These objectives are particularly relevant to China, where transport-related CO2 emissions continue to rise due to urbanization, industrial growth, and increasing energy demand. This study examines the impact of economic governance, population aging, human capital, financial innovation, GDP growth, and energy transition on China’s transport-related CO2 emissions, using quarterly data from 2006Q1 to 2018Q4. The Method of Moments Quantile Regression (MMQR) is applied to analyze heterogeneous effects across different emission levels. The findings reveal that economic governance (ECOG), energy transition (ENT), and human capital (HI) significantly reduce transport CO2 emissions (TCO2E) by enhancing institutional effectiveness and promoting clean energy adoption. In contrast, population aging (POPAGE), financial innovation (FI), and GDP contribute to higher emissions by increasing energy consumption and private transport dependency. These insights highlight the need for stronger governance frameworks, sustainable financial policies, and increased investment in renewable energy. Policymakers should strengthen environmental regulations, expand green financing initiatives, and enhance public transport infrastructure to align with SDGs 7 and 13. By implementing these strategies, China can make significant progress toward reducing transport emissions, achieving carbon neutrality, and ensuring long-term sustainability.

Achieving the Sustainable Development Goals (SDGs) is crucial for addressing global environmental challenges. SDG 13 calls for urgent climate action, while SDG 7 promotes sustainable energy. These objectives are particularly relevant to China, where transport-related CO2 emissions continue to rise due to urbanization, industrial growth, and increasing energy demand. This study examines the impact of economic governance, population aging, human capital, financial innovation, GDP growth, and energy transition on China’s transport-related CO2 emissions, using quarterly data from 2006Q1 to 2018Q4. The Method of Moments Quantile Regression (MMQR) is applied to analyze heterogeneous effects across different emission levels. The findings reveal that economic governance (ECOG), energy transition (ENT), and human capital (HI) significantly reduce transport CO2 emissions (TCO2E) by enhancing institutional effectiveness and promoting clean energy adoption. In contrast, population aging (POPAGE), financial innovation (FI), and GDP contribute to higher emissions by increasing energy consumption and private transport dependency. These insights highlight the need for stronger governance frameworks, sustainable financial policies, and increased investment in renewable energy. Policymakers should strengthen environmental regulations, expand green financing initiatives, and enhance public transport infrastructure to align with SDGs 7 and 13. By implementing these strategies, China can make significant progress toward reducing transport emissions, achieving carbon neutrality, and ensuring long-term sustainability.

This paper investigates the application of utility theory in decision-making related to energy use behavior and management practice in the energy sector. By conducting a systematic literature review, this study aims to understand the theoretical and practical applications of utility theory in optimizing energy consumption and management strategies. The review targets a comprehensive collection of academic works that apply utility theory to various aspects of energy use behavior and management decisions, including efficiency initiatives, renewable energy adoption, and sustainable infrastructure development. Systematic literature review methodology is adopted, which encompasses a rigorous selection process to identify relevant studies, followed by a detailed analysis of how utility theory has been employed to influence energy-related decisions in residential, commercial, and industrial settings. The review findings were synthesized to outline the implications for both policy and practice, highlighting the role of utility theory in guiding more efficient and sustainable energy management practices. Through this exploration, the paper provides discussion to bridge the gap between economic theoretical models and practical energy management applications. It also offers insights into how decision-making influenced by utility theory can lead to enhanced energy efficiency and sustainability. The findings will offer valuable guidance for policymakers and energy managers in designing and implementing energy systems and policies that maximize utility while considering environmental and economic impacts. This paper serves for advancing the theoretical framework of utility theory and its practical application in energy management, facilitating better-informed strategies that align with global sustainability goals.

This paper investigates the application of utility theory in decision-making related to energy use behavior and management practice in the energy sector. By conducting a systematic literature review, this study aims to understand the theoretical and practical applications of utility theory in optimizing energy consumption and management strategies. The review targets a comprehensive collection of academic works that apply utility theory to various aspects of energy use behavior and management decisions, including efficiency initiatives, renewable energy adoption, and sustainable infrastructure development. Systematic literature review methodology is adopted, which encompasses a rigorous selection process to identify relevant studies, followed by a detailed analysis of how utility theory has been employed to influence energy-related decisions in residential, commercial, and industrial settings. The review findings were synthesized to outline the implications for both policy and practice, highlighting the role of utility theory in guiding more efficient and sustainable energy management practices. Through this exploration, the paper provides discussion to bridge the gap between economic theoretical models and practical energy management applications. It also offers insights into how decision-making influenced by utility theory can lead to enhanced energy efficiency and sustainability. The findings will offer valuable guidance for policymakers and energy managers in designing and implementing energy systems and policies that maximize utility while considering environmental and economic impacts. This paper serves for advancing the theoretical framework of utility theory and its practical application in energy management, facilitating better-informed strategies that align with global sustainability goals.

Power generation is an important part of air vehicle energy management when developing long-endurance and reusable hypersonic aircraft. In order to utilize an air turbine power generation system on board, fuel-based rotating cooling has been researched to cool the turbine’s rotor blades. For fuel-cooling air turbines, each blade corresponds to a separate cooling channel. All the separate cooling channels cross together and form a distributary cavity and a confluence cavity in the center of the disk. In order to determine the flow characteristics in the distributary and confluence cavities, computational fluid dynamics (CFD) simulations using the shear–stress–transport turbulence model were carried out under the conditions of different rotating speeds and different mass flow rates. The results showed great differences between non-rotating flow and rotating flow conditions in the distributary and confluence cavities. The flow in the distributary and confluence cavities has rotational velocity, with obvious layering distribution regularity. Moreover, a high-speed rotational flow surface is formed in the confluence cavity of the original structure, due to the combined functions of centrifugal force, inertia, and the Coriolis force. Great pressure loss occurs when fluid passes through the high-speed rotational flow surface. This pressure loss increases with the increase in rotating speed and mass flow rate. Finally, four structures were compared, and an optimal structure with a separated outlet channel was identified as the best structure to eliminate this great pressure loss.

Power generation is an important part of air vehicle energy management when developing long-endurance and reusable hypersonic aircraft. In order to utilize an air turbine power generation system on board, fuel-based rotating cooling has been researched to cool the turbine’s rotor blades. For fuel-cooling air turbines, each blade corresponds to a separate cooling channel. All the separate cooling channels cross together and form a distributary cavity and a confluence cavity in the center of the disk. In order to determine the flow characteristics in the distributary and confluence cavities, computational fluid dynamics (CFD) simulations using the shear–stress–transport turbulence model were carried out under the conditions of different rotating speeds and different mass flow rates. The results showed great differences between non-rotating flow and rotating flow conditions in the distributary and confluence cavities. The flow in the distributary and confluence cavities has rotational velocity, with obvious layering distribution regularity. Moreover, a high-speed rotational flow surface is formed in the confluence cavity of the original structure, due to the combined functions of centrifugal force, inertia, and the Coriolis force. Great pressure loss occurs when fluid passes through the high-speed rotational flow surface. This pressure loss increases with the increase in rotating speed and mass flow rate. Finally, four structures were compared, and an optimal structure with a separated outlet channel was identified as the best structure to eliminate this great pressure loss.

As the presence of renewable energy production grows, so does the need to find alternative solutions for long–term energy storage. One solution may be hydrogen, and more generally, power-to-gas systems, which could allow energy storage for longer periods than batteries. However, the problem of hydrogen storage remains a limitation to the deployment of this technology. A possible solution for the hydrogen storage could be metal hydrides. In this work, a power-to-gas system based on a 2.5kW commercial electrolyzer coupled to a pair of AB2-type metal hydride cylinders with a total volume of 4L is studied. A special focus is placed on the electrolyzer power converter. In particular, the current ripple generated on the side connected to the stack and the efficiency of the converter are studied. A series of tests are carried out to verify the behavior of the system with varying types of thermal conditioning of the hydrides. The results show that the converter used is not optimized for the chosen application, and the thermal conditioning influences the hydrogen adsorption rate and thus the electrolyzer’s behavior. Finally, a technique to operate the system at maximum efficiency is proposed.

As the presence of renewable energy production grows, so does the need to find alternative solutions for long–term energy storage. One solution may be hydrogen, and more generally, power-to-gas systems, which could allow energy storage for longer periods than batteries. However, the problem of hydrogen storage remains a limitation to the deployment of this technology. A possible solution for the hydrogen storage could be metal hydrides. In this work, a power-to-gas system based on a 2.5kW commercial electrolyzer coupled to a pair of AB2-type metal hydride cylinders with a total volume of 4L is studied. A special focus is placed on the electrolyzer power converter. In particular, the current ripple generated on the side connected to the stack and the efficiency of the converter are studied. A series of tests are carried out to verify the behavior of the system with varying types of thermal conditioning of the hydrides. The results show that the converter used is not optimized for the chosen application, and the thermal conditioning influences the hydrogen adsorption rate and thus the electrolyzer’s behavior. Finally, a technique to operate the system at maximum efficiency is proposed.

The effects of an increase in output power owing to the close arrangement of vertical-axis wind turbines (VAWTs) are well known. With the ultimate goal of determining the optimal layout of a wind farm (WF) for VAWTs, this study proposes a new method for quickly calculating the flow field and power output of a virtual WF consisting of two-dimensional (2-D) miniature VAWT rotors. This new method constructs a flow field in a WF by superposing 2-D velocity numerical data around an isolated single VAWT obtained through a computational fluid dynamics (CFD) analysis. In the calculation process, the VAWTs were gradually increased one by one from the upstream side, and a calculation subroutine, in which the virtual upstream wind speed at each VAWT position was recalculated with the effects of other VAWTs, was repeated three times for each arrangement with a temporal number of VAWTs. This method includes the effects of the velocity gradient, secondary flow, and wake shift as models of turbine-to-turbine interaction. To verify the accuracy of the method, the VAWT rotor power outputs predicted by the proposed method for several types of rotor pairs, four-rotor tandem, and parallel arrangements were compared with the results of previous CFD analyses. This method was applied to four virtual WFs consisting of 16 miniature VAWTs. It was found that a layout consisting of two linear arrays of eight closely spaced VAWTs with wide spacing between the arrays yielded a significantly higher output than the other three layouts. The high-performance layout had fewer rotors in the wakes of the other rotors, and the induced flow speeds generated by the closely spaced VAWTs probably mutually enhanced their output power.