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The BRICS countries have been increasingly prioritizing electricity transition as a crucial step towards achieving sustainable growth, energy security, and mitigating climate change. As major emerging economies, the BRICS nations will play a significant role in the global energy landscape since their transition to renewable energy sources holds a significant implication for global energy markets and environmental sustainability. This study investigates the impact of the renewable energy transition on economic growth in BRICS nations from 1990 to 2023, employing a panel NARDL, DOLS, and FMOLS models. This study investigates the relationship between disaggregated renewable energy sources and economic growth. The findings show that renewable energy’s impact on economic growth varies across countries and depends on the type of renewable energy source. Specifically, hydropower, and wind power are found to have significant positive impacts on economic growth in some BRICS countries, while other renewables and trade openness have insignificant impacts. To foster economic growth and the expansion of renewable energy, it is essential for policymakers to focus on investments in hydropower and wind energy. Furthermore, they should encourage trade liberalization, as well as nuclear power development, and enhance regional collaboration. This study offers significant contributions to the current body of literature on the renewable energy–economic growth nexus, supplying crucial insights for both policymakers and researchers. Full article

Currently, wind turbines utilize doubly fed induction machines that incorporate a frequency converter in the rotor circuit to manage slip energy. This setup ensures a stable voltage amplitude and frequency that align with the alternating current. It is crucial to accurately determine the parameters of the equivalent circuit from the rotor side of the vector control system of the frequency converter. The objective of this study is to develop a method for the preliminary identification of the doubly fed induction machines parameters by analyzing the rotor current decay curves using Newton’s method. The numerical estimates of the equivalent circuit parameters a doubly fed induction machines with a fixed short-circuited rotor are obtained during the validation of the results on a real plant. It is along with the integral errors of deviation between the experimental rotor current decay curve and the response of the adaptive regression model. The integral errors do not exceed 4% in nearly all sections of the curves. It is considered acceptable in engineering practice. The developed algorithm for the preliminary identification for the parameters of the doubly fed induction machines substitution scheme can be applied with the configuring machines control systems, including a vector control system. Full article

This study numerically investigates clocking effects on pump–turbine hydraulic performance in pump mode. Analyzing the influence of clock position on pressure loss characteristics under three flow conditions and its correlation with internal flow. By integrating local hydraulic loss theory and vortex evolution analysis, the operational mechanism is elucidated. Key results show that the stay vane clock position significantly impacts off-design conditions, causing maximum efficiency differences of 0.855% at 0.8Q_d and 0.805% at 1.2Q_d. At the design condition, guide vane clocking position has a more pronounced effect, yielding a maximum inter-scheme efficiency difference of 0.330%. The optimal scheme positions the tongue at the guide vane trailing edge and 1/4 of the stay vane flow path, minimizing time-averaged losses and enhancing flow stability. The clocking effect alters the scale and intensity of volute dual-vortex structures, significantly increasing energy loss at vortex interfaces, with volute loss identified as the primary factor in performance variation. This work provides a theoretical foundation for applying clocking effects in pump–turbine engineering. Full article

This research introduces a two-stage, low-carbon industrial heating process, leveraging advanced waste heat recovery (WHR) technologies and exploiting waste heat (WH) to drive decentralised hydrogen production. This study is supported by a data-driven analysis of individual technologies, followed by 0D modelling of the integrated system for technical and feasibility assessment. Within 10 years, the EU industry will be supported by two main strategies to transition to low-carbon energy: (a) shifting from grid-mix electricity towards fully renewable sources, and (b) expanding low-carbon hydrogen infrastructure within industrial clusters. On the demand side, process heating in the industrial sector accounts for 70% of total energy consumption in industry. Almost one-fifth of the energy consumed to fulfil the process heat demand is lost as waste. The proposed heating solution is tailored for process heat in industry and stands apart from the dual-mode residential heating system (i.e., heat pump and gas boiler), as it is based on integrated and simultaneous operation to meet industry-level reliability at higher temperatures, focusing on WHR and low-carbon hydrogen. The solution uses a cascaded heating approach. Low- and medium-temperature WH are exploited to drive high-temperature heat pumps (HTHPs), followed by hydrogen burners fuelled by hydrogen generated on-site by electrolysers, which are powered by advanced WHR technologies. The results revealed that the deployment of the solution at scale could fulfil ~14% of the process heat demand in EU/UK industries by 2035. Moreover, with further availability of renewable energy sources and clean hydrogen, it could have a higher contribution to the total process heat demand as a low-carbon solution. The economic analysis estimates that adopting the combined heating solution—benefiting from the full capacity of WHR for the HTHP and on-site hydrogen production—would result in a levelised cost of heat of ~EUR 84/MWh, which is lower than that of full electrification of industrial heating in 2035. Full article

Gotland has been designated by the Swedish government as a pilot region for the transition to a sustainable, fossil-free energy system by 2030. This transformation emphasizes local renewable energy production and system independence. Within this context, this study investigates the role of industrial waste heat as a resource to improve energy efficiency and support sector integration between electricity, heating, and industry. A mixed-methods approach was used, combining techno-economic energy system modeling, life cycle assessment, spatial GIS data, and stakeholder input. The study develops and analyzes future carbon-neutral energy scenarios for Gotland’s energy system. Industrial waste heat can significantly reduce primary energy demand, particularly in scenarios with expanded industry, carbon capture, and increased sector integration—such as through district heating. In such cases, up to 3000–4000 GWh/year of low-temperature industrial residual heat becomes available, offering substantial potential to improve overall energy efficiency. The scenarios highlight synergies and trade-offs across environmental, economic, and social dimensions, emphasizing the importance of coordinated planning. Scenarios with offshore wind enable energy exports and industrial growth but raise challenges related to emissions and public acceptance, while scenarios without cement production reduce environmental impact but weaken local economic resilience. Limitations of the study include the exclusion of global supply chain impacts and assumptions about future technological costs. The study underscores the need for integrated planning, regulatory innovation, and stakeholder collaboration to ensure a just and resilient transition for Gotland. Full article

Intermediate-temperature solid oxide fuel cells (IT-SOFCs) have attracted attention due to their potential to overcome the trade-off between the performance and lifetime of SOFC devices. However, the guiding principle for effective material design, which can reduce operating temperatures and overcome performance decreases caused by excessive overpotential on the anode surface, has not been clearly established. In the present work, we studied the reported Schottky anomaly, which has been observed exclusively in yttria-stabilized zirconia (YSZ). To investigate this phenomenon, a small amount (less than 1200 ppm) of trivalent cations (Rh³⁺ or Fe³⁺), chemically similar to Y³⁺ in Y₂O₃, was doped onto the YSZ surface in the anode layer. Then, the current density observed from the SOFC device at 973 K was found to be nine-times higher than the SOFC device with an undoped anode. The surface first-principles calculations in the present work indicate that this performance enhancement is caused by the delocalized electrons induced by trivalent cation doping in the vicinity of the three-phase boundary and the promotion of surface oxygen diffusion in YSZ. Based on all experimental data, the effective material design guiding principle was obtained for utilizing the unique physical property of YSZ for applications such as IT-SOFCs. Full article

To investigate the movement law of top coal and the influencing factors of coal caving ratio in fully mechanized top coal caving faces, this study adopts the theory of dispersoid mechanics. First, a top coal flow model was established without considering the influence of the support. Then, the effect of the support was analyzed, and it was found that the sliding resistance of the top coal body increases with the square of both the support width and the top coal thickness. Furthermore, the positive stress on the coal particles was derived through a microelement force analysis, and a theoretical formula for arching probability was proposed. The mobility of top coal was evaluated using a flow factor, and the influence of lump size on arching tendency was quantitatively analyzed. Based on these insights, several measures to improve top coal flowability and recovery rate were proposed, including increasing mining height, enlarging the coal caving opening, enhancing the initial support force, extending the caving step, and applying multiple alternating loads to pre-break top coal. These strategies provide a theoretical basis and practical guidance for enhancing top coal caving efficiency. Full article

In practical applications, precise tuning of current controllers is essential for achieving desirable dynamic performance and stability margins. Traditional tuning techniques rely heavily on accurate plant parameter identification. However, this process is often challenged by inherent nonlinearities and unmodeled dynamics in motor systems. To address this issue, this paper proposes a current loop parameter tuning algorithm based on open-loop frequency sweeping. As the swept Bode diagram reveals nonlinear factors typically neglected during modeling, it provides a basis for control parameter correction. A pulse-sine voltage injection method is first introduced to identify motor parameters, serving as initial values for the controller. By analyzing the magnitude and phase characteristics of the open-loop transfer function, the delay time constant in the high-frequency range can be accurately identified, and mismatched parameters in the low-to-mid frequency range can be corrected. This method does not rely on complex model structures or extensive online adaptation mechanisms. Experimental results on a mechanical test platform demonstrate that the proposed tuning strategy significantly enhances the current loop’s closed-loop bandwidth and dynamic performance. Full article

This paper studies the collaborative inertia-frequency regulation strategies for the high renewable energy penetrated low inertia power system. Firstly, a systematic investigation is conducted to reveal the dominant dynamic characteristics and the possible challenges for such systems, and then proved the effectiveness of virtual inertia. Subsequently, a novel Laguerre-based model predictive control strategy is accordingly pro-posed, which ensures a better system states convergence ability and a reduced computational burden. The controller takes into account the system’s dual-mode feature to ensure timely response for both the inertia and the frequency support. Then, the regulation quality, operational burden and the cost are mathematically defined. The control trajectory is determined by the rolling optimization. The Gravity Searching Algorithm is utilized to determine the optimal control parameters. Finally, the proposed control strategy is validated through five case studies, demonstrating enhanced robustness, superior dynamic performance and cost-effective operation. This study provides new insights for the analysis and control strategies of the high RE penetrated low inertia systems. Full article

Global discussion on energy security remains deeply embedded in social, political, and economic discourse, especially in light of ongoing geopolitical instability and disruptions in supply chains. The aim of this study is to assess the degree of differentiation in the energy security of EU countries and to distinguish typological groups of the studied facilities based on the level of this phenomenon in 2023. This article uses a three-stage research procedure to assess the energy security of EU countries. In the first stage, statistical data were collected for 21 diagnostic features belonging to three groups: energy production and consumption, energy imports and exports, and economic and social factors. Next, using the TOPSIS method, three synthetic measures were constructed: separately for each group of features, taking into account features from the first and second groups, and taking into account features from all three groups. Based on these measures, typological groups of countries were identified using the three-median method. In the final stage, the impact of socio-economic characteristics on energy security was assessed. The results presented in this paper confirm the varied level of energy security in EU countries and indicate that it is linked not only to categories directly related to the energy economy but also to the level of socio-economic development of a given country. The top places in the ranking are occupied by countries such as Sweden, Finland, the Netherlands and Austria, while the last places in the ranking include Malta, Greece, Cyprus and Ireland. Full article

In this study, a 3D model is developed to simulate multi-hole leakage scenarios in buried pipelines transporting hydrogen-blended natural gas (HBNG). By introducing three parameters—the First Dangerous Time (FDT), Ground Dangerous Range (GDR), and Farthest Dangerous Distance (FDD)—to characterize the diffusion hazard of the gas mixture, this study further analyzes the effects of the number of leakage holes, hole spacing, hydrogen blending ratio (HBR), and soil porosity on the diffusion hazard of the gas mixture during leakage. Results indicate that gas leakage exhibits three distinct phases: initial independent diffusion, followed by an intersecting accelerated diffusion stage, and culminating in a unified-source diffusion. Hydrogen exhibits the first two phases, whereas methane undergoes all three and dominates the GDR. Concentration gradients for multi-hole leakage demonstrate similarities to single-hole scenarios, but multi-hole leakage presents significantly higher hazards. When the inter-hole spacing is small, diffusion characteristics converge with those of single-hole leakage. Increasing HBR only affects the gas concentration distribution near the leakage hole, with minimal impact on the overall ground danger evolution. Conversely, variations in soil porosity substantially impact leakage-induced hazards. The outcomes of this study will support leakage monitoring and emergency management of HBNG pipelines. Full article

Renewable energy sources, particularly solar photovoltaics (PVs), are rapidly expanding to achieve carbon neutrality. Integrated photovoltaic (IPV) solutions in underutilized spaces offer a viable option for countries with land constraints and public opposition. Vertical PV (VPV) systems, featuring bifacial solar modules installed vertically, facing east and west, present a promising alternative. In contrast to conventional tilted PV (CPV) systems, which peak around midday, VPV systems generate more power in the morning and afternoon. This mitigates issues such as the duck curve and curtailment caused by midday overgeneration. Moreover, combining VPV and CPV systems can increase the solar hosting capacity of a distribution line (DL) for PV-system interconnections, driving research interest. This study assessed the hosting-capacity improvements from VPV systems by analyzing voltage fluctuations and thermal constraints using OpenDSS software (Version 9.1.1.1). The potential substitution effect of a smart inverter-based energy-storage system (ESS) was also explored. The analysis, based on real-grid conditions in South Korea, incorporated actual DL data, generation and demand profiles, and operational data from both VPV and CPV systems. Worst-case scenarios were simulated to evaluate their impact on grid stability. The results demonstrate that VPV systems can increase hosting capacity by up to 23% and ensure stable grid operation by reducing power-generation uncertainties. Full article

Aquifer Thermal Energy Storage (ATES) is a promising technology for the seasonal storage of heat, thereby bridging the temporal gap between summer surpluses and peak winter demand. However, the efficiency of conventional ATES systems is severely compromised in aquifers with high groundwater flow velocities, as advective heat transport leads to significant storage losses. This study explores a novel three-well concept that implements an active hydraulic barrier, created by an additional extraction well upstream of the ATES doublet. This well effectively disrupts the regional groundwater flow, thereby creating a localized zone of stagnant or significantly reduced flow velocity, to protect the stored heat. A comprehensive parametric study was conducted using numerical simulations in FEFLOW. The experiment systematically varied three key parameters: groundwater flow velocity, the distance of the third well and its pumping rate. The performance of the system was evaluated based on its thermal recovery efficiency and a techno-economic analysis. The findings indicate that the hydraulic barrier effectively enhances heat recovery, surpassing twice the efficiency observed in a conventional two-well configuration (100 m/a). The analysis reveals a critical trade-off between hydraulic containment and thermal interference through hydraulic short-circuiting. The techno-economic assessment indicates that the three-well concept has the potential to generate significant cost and CO₂e savings. These savings greatly exceed the additional capital and operational costs in comparison to a traditional doublet system in the same conditions. In conclusion, the three-well ATES system can be considered a robust technical and economic solution for expanding HT-ATES to sites with high groundwater velocities; however, its success depends on careful, model-based design to optimize these competing effects. Full article

Solar photovoltaic (PV) power is an important force in promoting the transformation of the energy structure. An increase in PV panel temperature reduces open-circuit voltage and fill factor, thereby increasing the recombination of internal charge carriers and leading to a decrease in the output power of PV systems. When PV panels operate in the environment, high solar intensity may rapidly heat PV panels to very high temperature levels, converting a significant proportion of solar energy into waste heat. Waste heat further reduces the efficiency of PV panels. Therefore, effective cooling methods are important in improving the electrical performance and reliability of PV systems. For different types of PV panel cooling methods, many research works have been conducted. Aiming at providing a relatively valuable reference for future work on PV panel cooling methods, this paper presents a comprehensive review of existing research on cooling methods for PV panels. Relevant issues of eight types of PV panel cooling methods are introduced, including working principles, typical research, advantages, disadvantages, existing problems, and future research directions. Full article

This paper proposes novel designs of dual-layer flower-shaped heave plates, featuring both aligned and staggered configurations with three, six, and nine petals. Numerical simulations were conducted to study the hydrodynamic effects of these various heave plate designs integrated with the OC4 DeepCwind semisubmersible floating offshore wind turbine platform under prescribed heave oscillations. The overset mesh technique was employed to treat the floating platform’s motions. Comprehensive assessments of vertical force, radiated wave patterns, vorticity fields, added mass, and damping coefficients were conducted. The results revealed that the novel flower-shaped staggered heave plates significantly outperformed conventional circular plates in terms of damping coefficients. Specifically, the damping coefficient of flower-shaped staggered heave plates was greater than that of circular heave plates, while the aligned configuration exhibited a lower damping coefficient. The damping coefficient increased with a reduction in the number of petals for the staggered heave plates. Among the evaluated designs, the dual-layer flower-shaped staggered heave plates with three petals demonstrated the highest effectiveness in attenuating heave motion of the floating platform. The utilization of novel dual-layer flower-shaped staggered heave plates is therefore a promising practice aimed at damping the heave motion of platforms in rough seas. Full article