Energy Science & Engineering最新文献

This study addresses the significant discrepancies in traditional methods for predicting the height of water-conducting fracture zones in deep-mining hard roofs, which can lead to catastrophic water inrush events. The 110,504 working face of Banji Coal Mine was chosen as the research site to systematically investigate the development characteristics of these fracture zones through a combination of theoretical analysis, field measurements, and numerical simulations. A key stratum identification model was proposed, based on the temperature-compensated elliptical stress arch theory, to better account for high ground temperatures in the overlying strata. The theoretical calculations predicted a water-conducting fracture zone height of 61.32 m and a fracture zone height of 21.25 m. The development of the fracture zone exhibited a three-stage evolution: a slow development stage, followed by a rapid expansion stage, and finally a stable penetration stage. The findings suggest that the fracture zone height is primarily governed by the fracturing of key strata within an ellipsoidal stress arch, with overburden failure influenced by mining-induced stress concentration and the structural characteristics of the overlying rock. These results provide both theoretical insights and empirical data for improving predictions of water hazards and enhancing the stability of overburden in deep mining environments.

This paper presents GRATE–DRL–AI, an Artificial Intelligence (AI)–driven algorithm designed to enhance the efficiency and accuracy of distribution system planning. Leveraging advanced AI methodologies, including graph learning, transfer learning, deep reinforcement learning (DRL), and physics-guided neural networks, this model efficiently addresses the growing complexity and uncertainties in modern distribution grids with high penetration of distributed energy resources. Case studies on the Institute of Electrical and Electronics Engineers 33-bus and 123-bus systems show that GRATE–DRL–AI reduces planning cost by up to 8.5%, achieves 99%–100% feasibility, and significantly lowers computation time (e.g., 580 s vs. 1610 s for the 342-bus system). Even under ±30% uncertainty in demand and renewable generation, feasibility remains above 99%. In addition to strong performance gains, the study also highlights limitations, such as data availability, computational requirements, and regulatory considerations, which must be addressed for real-world deployment of AI-driven planning frameworks.

Reducing harmonics in alternating current (AC) input and ripples in direct current (DC) output enhances power quality, achievable through multi-pulse converters (MPCs). This study presents the design, simulation, and analysis (in MATLAB/Simulink) of an autotransformer-based 18-pulse AC-DC converter used with a vector-controlled asynchronous motor drive (VCAMD) to improve power quality at the point of common coupling (PCC). Unlike alternative designs that require three single-phase transformers, the proposed autotransformer only utilizes two, making it a cost-effective replacement for conventional 6-pulse diode bridge rectifiers. The article covers various topologies, simulation outcomes, and comparisons. It also examines load change effects on VCAMD, analyzing total harmonic distortion (THD) and assessing harmonic reduction efficiency. Experimental results from a laboratory prototype further validate the proposed structure's effectiveness.

Hybrid Ocean Thermal Energy Conversion (H-OTEC) systems are characterized by the adoption of both open-loop and closed-loop Rankine cycles. In the closed-loop configuration, a working fluid such as ammonia is evaporated in a heat exchanger, utilizing the heat from water vapor generated in a vacuum chamber by warm surface seawater introduction. The vapor is then expanded through a turbogenerator to produce electricity before being condensed in a cold-water heat exchanger using cold water. In Malaysia, significant advancements are being made in the technology for seawater suction systems, particularly for applications in fish breeding, farming, desalination plants, and power generation. The operation of an H-OTEC Experimental system at UPM I-AQUAS, Port Dickson, Malaysia depends on surface seawater for turbine operation, necessitating the installation of a piping system spanning 336 m from the H-OTEC facility to the suction location. Challenges associated with seawater intake systems include pump cavitation due to high suction head, pipe contamination by organisms such as barnacles and algae, pump placement, strainer size, and pipe diameter intake. The primary objective of this study is to provide valuable insights, conduct field testing, and gather necessary data for the development of the first-of-its-kind surface seawater piping system for H-OTEC in the Asian region. This objective was accomplished through the installation of a centrifugal pump unit with a flow rate of 40 m³/h (600 L/min), the laying of 106 mm inner diameter parallel pipes, installation of strainers, and a booster pump connected to a 125 A HDPE pipe. The collected data provides the necessary input in establishing the layout design and location selection of the seawater intake pipe, introduce a novel helical crossflow self-cleaning suction screen water intake system, facilitate weight structure design, and enable pump sizing and suction pump analysis.

The development of power quality control systems and methods is a credible step for the modernization of the power grid. In this context, this paper presents novel approaches for the control of power quality and voltage of the power grid using power converters connected to photovoltaic battery systems. The photovoltaic system permits to generate the required power to adjust the grid voltage. Indeed, a three-level neutral point clamped (NPC) converter, connecting the PV-batteries to the power grid, plays the function of a static compensator (STATCOM) in the case of a fault causing power grid voltage variation. The NPC converter is controlled by a direct current vector control method based on a hysteresis controller. The amplitude and phase of the NPC converter reference currents are generated based on the irradiation value, the battery state of charge, and the grid voltage. In addition to the NPC converter, the proposed approach uses three DC–DC converters with the aim to extract the maximum power from the PV system and control the charge–discharge of the batteries. The bidirectional converter associated with the batteries and the four-quadrant chopper connected to the NPC converter are controlled by proportional integral (PI) regulators in aim to maintain the voltage and state of charge of the batteries within the acceptable range. To coordinate the different scenarios, a power management system is proposed in this paper to generate adequate control signals for the control of the different power converters. PI closed-loop controllers have been proposed to ensure the highest performance and stability of voltage regulation in the power grid. The different control methods have been implemented and verified in MATLAB-Simulink environment. The results prove the effectiveness of the proposed approach to regulate the voltage and the grid power quality. The results demonstrate that the proposed system is capable of maintaining the grid voltage within ±10% of the nominal value, even under fault conditions, with a voltage regulation efficiency of 98%. Additionally, the power quality improvements are quantified, showing a reduction in total harmonic distortion (THD) of the grid current to below 3%, ensuring compliance with international power quality standards.

The escalating global demand for energy, coupled with pressing environmental anxieties, necessitates the strategic integration of renewable resources with advanced thermodynamic cycles. This paper analyzes the proposed sustainable hybrid power systems combining heliostat-based solar thermal plants, molten salt thermal storage, and supercritical CO₂ Brayton cycles, augmented by green methanol synthesis. This study undertakes a multi-faceted evaluation of the proposed systems, assessing their viability based on energy, exergy, environmental, and economic metrics. This assessment is facilitated by sophisticated, AI-driven multi-objective optimization algorithms. Concurrently, a bibliometric mapping of the research domain was performed using VOSviewer to visualize the scholarly landscape. The results reveal promising configurations with improved thermal performance, enhanced energy storage strategies, and significant emission reductions, offering a viable path toward sustainable industrial-scale energy solutions. The optimized configurations achieved a thermal efficiency of more than 45%, exergy efficiency of more than 40%, and CO₂₂ emission reduction of more than 80% compared to conventional fossil-based systems. These results validate the proposed models technical viability and environmental advantage, offering a promising pathway toward scalable, sustainable energy systems.

Indonesia's considerable geothermal resources present tremendous potential for energy production, yet restricted investor interest hampers development. This study evaluates the economic viability of a proposed 330 MW geothermal power plant in Gunung Kembar to encourage investment and facilitate Indonesia's 2060 Nationally Determined Contributions (NDC). Four scenarios were modeled using RETScreen, each differing in carbon credit pricing and project duration. Scenario I implement a carbon credit price of $2 per metric ton of CO₂ over a 25-year period, resulting in a Net Present Value (NPV) of $22 million and a Levelized Cost of Electricity (LCOE) of 0.091 USD/kWh. Scenario II elevates the credit price to $18, resulting in an NPV of $23.5 million. In Scenario III, prolonging the project lifespan to 30 years yielded a NPV of $30.6 million and a LCOE of 0.088 USD/kWh. Scenario IV, featuring a credit price of $50 and a term of 30 years, attained the highest NPV at $67.9 million and an LCOE of 0.088 USD/kWh. Scenario IV demonstrates the most economic potential, indicating that elevated carbon price may augment project profitability and stimulate renewable investment in Indonesia.

Although the conversion of end-of-lifetime fractured hydrocarbon wells to geothermal wells has gained a strong momentum in research, it is necessary to perform thorough technical assessments of well conversion before pilot testing. The objective of the study was to perform such an assessment on converting fractured horizontal hydrocarbon wells to geothermal wells based on heat transfer efficiency analysis. A mathematical model was developed in this study to simulate the transient heat transfer from shale formations to hydraulic fractures. Sensitivity analysis was performed with the model to identify key factors affecting the heat transfer processes. In all cases studied, the temperature at the exit of the fracture is significantly higher than that at the entrance of the fracture in the first month, indicating high efficiency of heat transfer. Result of this study suggests that converting fractured-horizontal hydrocarbon wells to geothermal wells is a viable process to extend the lifetime of old wells in oil and gas fields with high-geothermal gradients. However, well rotation is needed to maintain the energy productivity of reservoir.

Real-time analytics for production parameters monitoring trends for dissolved-gas allocation in petroleum reservoirs using satellite remote sensing has emerged as a precise and cost-effective tool for quantifying gas flaring across hydrocarbon production sites, enabling continuous monitoring of greenhouse gas emissions and supporting strategies to mitigate air pollution, climate change, and environmental degradation. Beyond regulatory compliance and policy development, satellite observations provide unique advantages in remote or inaccessible areas, surpassing the limitations of ground-based monitoring. This study integrates a novel algorithm with satellite imagery to quantify both associated and nonassociated flaring and to calculate gas production during hydrocarbon extraction. The approach enables dynamic gas-oil ratio (GOR) monitoring in the Main Limestone reservoir of northern Iraq, thereby improving dissolved-gas back-allocation and production control. Using daily time-series data from 2018 to 2023, the analysis demonstrates significant trends in flaring reduction from an average of 95 MMscf/d in 2018–2021 to 74 MMscf/d in 2022—largely attributed to changes in production practices. Field-wide GOR and oil production trends reveal strong temporal variability, with GOR values rising from 770 scf/stb in March 2022 to 1040 scf/stb in September, coinciding with declining oil output from 148 to 133 kstb/d. These results highlight the capacity of satellite-derived flaring estimates to uncover operational inefficiencies, inform reservoir management, and guide investment in gas-capture technologies. Model validation against 2023 production data confirms the robustness and reliability of the proposed method, demonstrating its applicability for real-time surveillance, emissions accountability, and optimized gas utilization in petroleum fields.

The power generated by Photovoltaic (PV) systems is influenced by multiple factors, with irradiance and temperature being the most significant. Under Partial Shading Conditions (PSC), uneven irradiance distribution across PV arrays leads to a substantial reduction in output power. Furthermore, the P-V characteristics of PV systems under such conditions exhibit multiple peaks, with the number of peaks increasing proportionally to the number of PV modules. Conventional Maximum Power Point Tracking (MPPT) algorithms, such as Perturb and Observe (P&O), Hill Climbing (HC), and Incremental Conductance (INC), struggle to locate the global maximum power point (GMPP) on the P-V curve in these scenarios. To address the limitations of the Coot Optimization Algorithm (COA)—specifically its slow tracking speed and significant oscillations under PSC, this paper proposes a Levy Flight-enhanced Coot Optimization Algorithm (LF-COA) for global MPPT of PV systems under shading conditions. Static and dynamic irradiance simulation experiments conducted in MATLAB/SIMULINK demonstrate that LF-COA outperforming the Modified Firefly Algorithm (MFA), Improved Particle Swarm Optimization (IPSO) algorithm, and the conventional COA in performance metrics.