Abstract

Accurate load forecasting is crucial for efficient energy management, particularly due to the increasing adoption of renewable energy sources and the growing need for grid stability. This study introduces an autoregressive transformer encoder-decoder model that advances residential electricity load prediction and synthesis. Unlike the conventional models, our proposed model utilizes temperature and calendar information as primary inputs and can generate an electricity load without relying on the past load. This model’s design is rooted in the observation that temperature and calendar context sufficiently capture residential electricity consumption dynamics. By excluding the reliance on past load data, our model is able to synthesize electricity load for arbitrary temperature and calendar scenarios in addition to effectively predicting the future load. This synthesizing capability is invaluable for optimizing the planning and operation of residential energy systems, including photovoltaic systems and batteries. Experimental results using real-world electricity load data of residential buildings demonstrate the effectiveness of our transformer-based model, offering a robust framework for future load prediction and synthesis under varying conditions.

Abstract

As an emerging micro- or small-scale energy conversion technology, free-piston engine generator (FPEG) features the advantages of high efficiency, high volumetric power density, and multi-fuel adaptability potential. To solve the issues that the previous FPEG prototype (developed in the authors’ group) had, in this work, we developed a new FPEG prototype with a compact structure that is capable of operating at a higher frequency. Some preliminary experimental results are obtained from the new prototype. The results indicate that there is no significant operation inconsistency between the two free-piston engines, and achieving continuous combustion in both of the engines will be the subject of future research.

Abstract

This research aims to propose sustainable urban development strategies that harmonise decarbonisation with urban residents’ well-being through Geographic Information Systems (GIS) scenario analysis. Modern urbanisation enhances quality of life but escalates energy consumption, greenhouse gas emissions, and environmental degradation. In urban areas, CO2 emissions from transportation, industrial activities, and households significantly contribute to global warming, while overcrowding deteriorates living conditions and impacts health and well-being.
Decarbonisation is essential to address these environmental issues, but enhancing urban well-being is equally crucial. This study utilises GIS to explore urban development pathways that balance decarbonisation and well-being. Scenarios evaluate the impact of increased green spaces on CO2 absorption, enhanced public transportation on reducing private vehicle usage, and energy-efficient buildings on lowering energy consumption and emissions.
The study includes practical interventions in The Nihonbashi Initiative Project, comparing sustainable measures such as greening projects, energy efficiency improvements, and well-being initiatives against a control office floor. Spatial analyses assess the environmental and well-being impacts, providing empirical data for sustainable urban planning. Building owners in the area collaborate to promote energy management, with an expected energy savings effect of approximately 10%. This collaborative effort aims to create a model for sustainable urban development that balances decarbonisation and resident well-being.
Expected outcomes throughout the investigation include the development of a new model for sustainable urban development that integrates renewable energy, green space enhancement, and low-carbon transportation. The study contributes a novel framework for GIS-based scenario analysis, advancing the understanding of achieving decarbonisation and well-being concurrently in urban environments, bridging theory and practice with evidence-based insights.

Abstract

As investment in the construction of UGS increases around the world, the operational efficiency and safety of UGS have attracted attention, which includes some problems that need to be faced. Currently, the dissolution of cushion gas in reservoir fluids has been little discussed. However, with the promotion of the use of CO2 cushion gas, the impact of dissolution is one of the problems that has to be faced. We aim to show with this study that the dissolved consumption of cushion gas is critical as this affects the total gas volume. We considered two different scenario models, with and without chemical capture reactions. Through simulation, it was found that the increase in pressure increased the solubility of CO2, but the total dissolved amount decreased. The increase in reservoir temperature reduces the solubility of CO2 and also leads to a decrease in the total dissolved amount. In addition, chemical capture will affect the solubility of CO2 to a certain extent, and its extent is related to pressure. A reduction in dissolved gas means an increase in free gas, potentially making the reservoir more sensitive to gas injection pressure. Therefore, chemical capture and hydration dissolution factors become key considerations in cushion gas design and UGS operation. This research helps promote efficient operation of UGS.

Abstract

The kinetic characteristics of methane conversion to hydrates in deep-sea cold seep sediments have a significant impact on hydrate accumulation and resource distribution. Consequently, they have important implications for the assessment of carbon sequestration and hydrate extraction potential. Nevertheless, the impact of clay minerals in cold seep sediments on the kinetics of methane hydrate formation in sandy environments remains uncertain. To investigate this, quartz sand was employed to simulate a sandy environment, allowing the effect of varying levels of calcium-based montmorillonite on the kinetics of methane hydrate formation in porous media to be studied. The results demonstrated that the initial rate of hydrate formation increased, while the final methane consumption decreased as the mass fraction of calcium-based montmorillonite (MMT) increased in comparison to the pure quartz sand system. The observed effects were mainly attributed to the high specific surface area of MMT and its capacity for adsorbing water. This work contributes to our understanding of the mechanism by which calcium-based montmorillonite affects the transformation of hydrates at varying water contents. Furthermore, it provides scientific support for the estimation of marine carbon sink capacity and carbon sequestration.

Abstract

Lithium-ion batteries serve as crucial energy storage carriers due to their numerous superior properties. However, metal impurities introduced during the manufacturing process can affect battery performance. The intrinsic impacts of these impurities have not yet been fully elucidated. In this study, pouch cells containing copper particle impurities are investigated. The results show that cells with impurities not only experienced micro-short circuits but also exhibited higher polarization compared to normal cells. Various material characterization techniques reveal that the increase in impedance is due to factors such as cracking of the anode graphite layer and localized lithium plating on the anode. Furthermore, the experiments reveal that the aluminum current collector in the short-circuit area dissolves and diffuses to the anode surface, forming deposits, while deposits also form around the impurity particles in the cathode. These phenomena can further degrade battery performance. The findings of this study enhance the understanding of the deep-seated effects of impurities in lithium-ion cells and provide theoretical insights for the manufacturing and detection methods of internal impurities in lithium-ion cells.

Abstract

The study of methane hydrate formation kinetics in various ionic solution systems helps to understand the hydrate formation characteristics in deep-sea cold seep environments, providing insights into methane conversion. The ionic composition and ratio in seawater play an important role in the nucleation and growth of methane hydrate. In this study, we investigated the formation behaviors of methane hydrate in varied ionic solutions and in-situ seawater. It was found that, compared with in pure water system, the inhibition of hydrate formation in the solutions was in the following order: NaCl ＞ seawater ＞ MgCl2 ＞ CaCl2 ＞ SrCl2. The experimental results of this study can provide a reference for further exploration of methane hydrate formation in cold seep environments, and can also contribute to an effective response to the challenge of climate change and the goal of carbon neutrality.

Abstract

Marine microorganisms play a vital role in the ocean’s cycling of organic matter and nutrients. Here, we conducted a 150-day simulation experiment to investigate cold seep sedimentary microbial diversity under different pressure conditions (0.1–14 MPa) and the roles of various influencing factors. The results showed that the level of pressure affected the reaction rates of metabolic processes, especially those involved in the carbon cycle. The microbial diversity tended to decrease and then increase with increasing pressure. An environmental pressure of 7 MPa was the dividing line between stochastic and deterministic processes. The microbial community diversity was primarily influenced by sulfate ion (SO42−), total organic carbon (TOC), and total inorganic carbon (TIC).

Abstract

The reformer is a key component in MRFC for on-site H2 production and operation of HT-PEMFC. In this study, a segmented reformer was designed using heat transfer structure optimization to control the temperature segmentation of the reaction zone, achieving high conversion rate and low CO outlet molar fraction. The multi-objective optimization of methanol conversion rate and CO output molar fraction was conducted to determine the optimal structures with the NSGA-II optimization algorithm. Under the optimal structure, the methanol conversion rate of the segmented reformer reaches 99.6%, with a CO outlet mole fraction of 1.3%. For the output power, the MRFC with the segmented reformer can generate output power of 302 W, which provides reference significance for the commercialization of MRFC.

Abstract

The recent transition in the power system brings challenges like load and demand imbalance, intermittent renewable energy recourses, and the risk of lumping load from power-to-X applications. The battery energy storage system (BESS) is a viable solution for short-term and long-term balancing. Combined with the upcoming major load type of the electrolyzer, we propose the lab-field multi-energy system platform for validating a demonstration of a virtual power plant for grid-connection synergies. Based on the field tests, we summarize the characteristics of the redox flow BESS, lithium-ion BESS, and electrolyzer. The response time of these components varies from one second for the redox flow BESS to a few hours for the electrolyzer. As these components have different response times, efficiency, and capacity, our work provides a reference for the hardware performance and lays the foundation for further implementation and optimization.