Search Results (107)

Dust accumulation on photovoltaic (PV) modules reduces power generation efficiency, and traditional water-based cleaning is impractical in arid regions. Inspired by the classical acoustic phenomenon of Chladni figures—specifically the mechanism where an acoustic standing wave field drives the regular migration and accumulation of particles—this study proposes a waterless dust removal method using low-frequency ultrasonic vibration via piezoelectric excitation. Impedance analysis identifies optimal electromechanical coupling at 28 kHz. Experiments demonstrate that higher driving voltages accelerate cleaning, with recovery rates saturating beyond 125 V. Notably, intense friction and collisions between particles within high-density dust layers consume substantial kinetic energy, significantly multiplying the required cleaning time. Macroscopic transport analysis reveals that dust removal relies on the synergy of vibration-induced adhesion decoupling and gravity-driven transport. Sufficient tangential gravity is crucial for macroscopic particle removal, and tilt angles above 30° provide the necessary downward driving force to ensure smooth particle sliding. Under optimal conditions, the system achieves an over 97% short-circuit current recovery at a low power consumption of ~10 W, providing a theoretical basis for waterless PV self-cleaning systems. Full article

In this study, we investigate the impact of electric energy storage (EES) on phase line power flow symmetry and photovoltaic (PV) energy utilization in prosumer three-phase four-wire integrated household systems. The analysis is based on high-time-resolution (1 s) experimental data collected from a real household grid and subsequent simulations of energy flows using MATLAB/Simulink software. Two converter operation strategies were evaluated: the conventional symmetric mode and the asymmetric mode developed by the authors based on an adaptive power flow management algorithm. For both strategies, the impact of EES capacity on imbalance in the distribution system operator (DSO) grid was investigated. The methodology analyzes energy flows in each phase line separately, allowing for a detailed assessment of the imbalance between phase line phenomena and their impact on local energy consumption. Key performance parameters used for the efficiency evaluation include the self-consumption and self-sufficiency rates, which quantify the share of locally generated energy consumed within the household and the degree of independence from the DSO grid. The results show that combining adaptive asymmetric inverter control with appropriately sized energy storage allows for more efficient on-site utilization of PV energy, which, at the same time, improves the load symmetry of the phase lines in the DSO grid. Full article

Against the backdrop of the global advancement of carbon neutrality goals and the energy transition in the building sector, zero-carbon buildings have emerged as pivotal enablers for achieving carbon neutrality in the construction industry. The rule-based scheduling of energy storage systems (ESS) is critical to enhancing energy efficiency and economic performance of buildings. This study takes the Jinan Zero-Carbon Operation Center Project in Shandong Province as the research object, developing a comprehensive technical framework covering the entire process from design to operation, and investigates the rule-based design and ESS scheduling strategies in response to Shandong’s newly implemented seasonal time-of-use (TOU) electricity pricing policy. First, core performance indicators are defined in accordance with national evaluation standards for zero-carbon buildings. Hourly building energy loads and photovoltaic (PV) generation profiles are simulated over a full year, which serves as the basis for determining the optimal PV installed capacity and ESS sizing. Second, an ESS scheduling strategy integrating PV generation forecasting and the seasonal TOU electricity price structure is formulated, with clear charging and discharging logic defined. Finally, the operational and economic performance of different scheduling modes are evaluated and compared through case studies. The results show that the annual PV generation ratio reaches 101.38%, with a self-consumption rate of 73% and a self-sufficiency rate of 72%, all meeting the core requirements for zero-carbon buildings. Compared with the conventional real-time scheduling mode (Mode 1), the proposed optimized mode (Mode 2) that incorporates TOU pricing and PV forecasting achieves an annual operational cost saving of 367,349 CNY, corresponding to a reduction of 47.02%. Distinct seasonal variations in core indicators are also observed: the PV generation ratio is lower in summer and winter but the self-consumption rate is higher, with the opposite trend in spring and autumn. The proposed technical framework and scheduling strategy provide practical guidance for the design and operational optimization of zero-carbon buildings and offer decision-making support for ESS operation under TOU electricity pricing policies. Full article

Despite the rapid expansion of photovoltaic (PV) installations over the past decade, challenges such as curtailments of renewable energy sources (RESs) and grid constraints continue to limit the capacity of Cyprus’ power system to accommodate higher solar penetration. In this context, grid reliability, defined as the ability to maintain stable operation by balancing supply and demand, minimizing curtailment, and reducing stress on the island network, has emerged as a critical concern. The deployment of PV-plus-storage systems offers a viable solution to enhance grid reliability while alleviating operational constraints. This paper presents a real-world case study of the first commercially deployed grid-connected PV-powered, battery-integrated electric vehicle (EV) charging station in Cyprus. Commissioned in May 2025, the system integrates a 60.32 kW_p rooftop PV array, a 100 kW/97 kWh battery energy storage system (BESS), and a 160 kW DC fast charger. A custom cloud-based energy management platform enables real-time monitoring, forecasting, and optimization under a zero-export scheme. High-resolution operational and weather data were collected between 15 May and 30 November 2025. Over this period, the integrated PV-battery system supplied 29% of the site’s total energy demand (self-sufficiency rate of 28.97%) and achieved a self-consumption rate of 98.69%. Such rates would not have been attainable with a pure PV system, given the depot’s evening-concentrated EV charging demand profile, which requires the BESS to time-shift daytime solar generation. The system reduced depot electricity costs by approximately 29%, generating €16,010 in savings and avoiding 26.47 tonnes of carbon dioxide (CO₂) emissions compared to a grid-only baseline. Beyond site-level performance, the system contributed to grid stress reduction by absorbing excess PV generation that would otherwise have been curtailed/wasted. Operational insights indicate minimal temperature-related issues, highlight the importance of automated fault detection and alerting to minimize downtime, and demonstrate how periodic operation strategies can optimize system performance and mitigate curtailment in Cyprus’s isolated grid. Full article

Bhutan’s hydropower-reliant electricity supply faces seasonal imbalances, with a winter deficit prompting costly imports from India at tariffs of up to $0.09/kWh. Despite the estimated solar potential of 12 GW, PV deployment remains limited. This study presents a demand-driven techno-economic assessment of a 150.8 kWp rooftop PV system for the Ministry of Infrastructure and Transport using high-resolution hourly load data and PVsyst simulation. Three operational configurations are evaluated: self-consumption without export, self-consumption with export, and a battery energy storage system (BESS) introduced to mitigate curtailed energy. The system is expected to generate 252 MWh annually, achieving self-sufficiency and Self-Consumption Ratios of around 60%. Without export, the performance ratio (PR) is reduced to 51% due to significant curtailment, resulting in a negative Net Present Value (NPV) of −$33,687.5 and a Levelized Cost of Electricity (LCOE) of $0.0682/kWh. Enabling export raises the PR to 85.62%, improving the NPV to $27,965.42, the Internal Rate of Return (IRR) to 8.07%, and the LCOE to $0.0405/kWh. A 200 kWh BESS, sized based on surplus energy and nighttime demand, increases self-consumption and self-sufficiency to 75% and 73%, respectively. However, the LCOE rises to $0.0841/kWh, limiting economic viability under current tariff structures. The results reveal a structural mismatch between prosumer-level economics and system-level benefits, underscoring a need for improved compensation and targeted policy support in Bhutan and similar hydropower-dependent systems. Full article

Anaerobic digesters operating under neotropical conditions face significant technological constraints. High humidity, intense solar radiation, and pronounced diurnal temperature variations increase conductive, convective, and radiative heat losses. These factors reduce internal thermal stability and directly affect methane production rates and overall energy efficiency. As a result, thermal instability becomes a recurrent operational bottleneck in biogas plants without active temperature control. This review examines the thermal and dynamic behavior of anaerobic reactors from a process-engineering perspective. It integrates energy balances, heat-transfer mechanisms, and computational fluid dynamics (CFD) modeling. The combined effects of temperature gradients, hydrodynamic mixing patterns, and structural material properties are analyzed to determine their influence on thermal homogeneity, microbial stability, and methane yield consistency under mesophilic conditions. Technological strategies to mitigate thermal losses are evaluated. These include passive insulation using low-conductivity materials, geometry optimization supported by numerical modeling, and thermal recirculation schemes, as these factors govern temperature distribution and process resilience. Current limitations are also discussed, particularly the frequent decoupling between ADM1-based kinetic models and transient heat-transfer analysis. This separation restricts predictive capability under real-scale diurnal temperature oscillations. The development and validation of coupled hydrodynamic–thermal–biokinetic models under fluctuating neotropical boundary conditions are proposed as critical steps. Such integrated approaches can enhance operational stability, ensure consistent methane production, and improve energy self-sufficiency in organic waste valorization systems. Full article

The decarbonization of the residential sector is a critical component of the European Green Deal, particularly in transition economies like Poland. This study proposes a comprehensive techno-economic optimization of a deeply retrofitted single-family house aiming for net-zero energy building (NZEB) status. The research specifically focuses on the Polish coastal climate zone, characterized by distinct humidity, wind, and temperature profiles compared to inland regions, which significantly influence the efficiency of air-to-water heat pumps (ASHP). Based on a real-world energy audit, the study simulates the synergy between a deep thermal envelope upgrade and a hybrid system comprising an ASHP, photovoltaics (PV), and battery energy storage (BES). This paper presents a detailed economic analysis of such hybrid systems under the new Polish ‘net-billing’ prosumer mechanism. The study evaluates the impact of electricity tariff structures (flat-rate G11 vs. time-of-use G12w) on the investment’s profitability. By calculating key performance indicators—including the levelized cost of energy (LCOE), net present value (NPV), and self-sufficiency ratio (SSR)—the research assesses various system configurations. The initial evaluation indicates that while deep retrofitting significantly reduces heating demand, integrating battery storage plays a critical role in enhancing economic returns under the net-billing framework. The analysis demonstrates that the optimized hybrid system (9.0 kWp PV + 10 kWh BESS) achieves an average annual self-sufficiency ratio (SSR) of 49.8% and reduces the non-renewable primary energy (EP) indicator to 0.0 kWh/(m²·year). Economically, the investment yields a positive NPV of €3194, an IRR of 5.25%, and a LCOE of €0.184/kWh, which is 34% lower than projected grid prices. Furthermore, switching to a time-of-use tariff (G12w) generates an additional 11% (€139) in annual savings. These quantitative findings provide actionable guidelines for policymakers and investors, confirming the financial viability and environmental benefit (annual reduction of 6.12 MgCO₂) of NZEB standards in coastal areas. Full article

In the context of increasing energy demand and the global transition toward sustainable solutions, the integration of renewable energy sources into power systems is becoming a necessity. Data centers, as major energy consumers, are particularly impacted by this shift. Photovoltaic (PV) panels represent a promising alternative to conventional electricity sources due to their low environmental impact. However, their intermittent nature leads to instability in power supply, requiring efficient energy storage solutions to ensure reliability and self-sufficiency. Among the various storage technologies available, hydrogen stands out as a viable energy carrier due to its high energy density, long-term storage capability, and minimal environmental footprint. To address these challenges, a hybrid energy storage system combining hydrogen production, battery storage, and grid connection is designed in this study to enhance energy autonomy while maintaining cost efficiency. The system relies on a combination of an electrolyzer, hydrogen storage tanks, a fuel cell, and a battery to ensure a continuous and stable energy supply. A simulation-based optimization approach is conducted using Python to determine the optimal configuration of these components. The results show that a self-sufficiency rate of 95% is achieved, with a levelized cost of electricity (LCOE) of 0.47 US$/kWh, demonstrating the feasibility of the proposed system. The environmental impact is also assessed, revealing a significant reduction in carbon emissions, with 8.97 tons of CO₂ saved over the system’s 15-year lifespan, compared to the 10 tons emitted by a conventional grid-powered system over the same period. Furthermore, a detailed analysis of energy flow within the system highlights the role of each storage component in balancing supply and demand. The hybrid design leverages the advantages of both hydrogen and battery storage, where the battery is primarily used to compensate for short-term fluctuations, while hydrogen ensures long-term energy storage. The impact of different electrolyzer and fuel cell sizes on system performance is also evaluated, leading to an optimal configuration with an electrolyzer of 5 kW, a hydrogen storage capacity of 200 L at 350 bars, a fuel cell of 2 kW, and a battery of 50 kWh. Full article

Aiming at the problems of high energy consumption and insufficient utilization potential of clean energy in expressway service areas in severe cold and arid desert areas, this paper takes the Xinjiang Kelameili Service Area as the research object to explore the optimal configuration scheme and comprehensive benefits of a photovoltaic system in this specific scenario, providing a technical reference for the energy transformation of transportation buildings in desert areas. The field research method was used to collect measured data of energy consumption and photovoltaic operation in the service area in 2022–2024. The photovoltaic simulation model was constructed using PVsyst 7.3.1 software. The inclination and azimuth parameters were optimized by the control variable method, and the energy savings, carbon emission reductions and economic benefits of the system were calculated by the whole life cycle analysis method. The study found that the total power consumption of the service area in 2024 was 3.661 million kWh, and the actual annual power generation of the existing photovoltaic system was 438 million Wh, accounting for only 12% of the total power consumption. After optimization, the optimal inclination angle of the photovoltaic panel was determined to be 14°, and the azimuth angle was 89°/−89°. Additionally, the maximum annual power generation of the system reached 579 MWh. Throughout the whole life cycle of the photovoltaic system, it is expected to save 1692 tons of standard coal, reduce CO₂ emissions by about 10,311.98 tons, reduce carbon revenue by about 524,800 yuan, and reduce comprehensive income by about 8,097,000 yuan. The static investment recovery period is about 22 years. Reasonable optimization of photovoltaic system configuration can effectively improve the self-sufficiency rate of clean energy in desert expressway service areas. The research results have reference significance for photovoltaic applications in service areas in similar alpine arid areas. Full article

This study evaluates integrated shipboard freshwater production and fresh air pretreatment on a 20,000 TEU-class container vessel, addressing its freshwater demand and the inefficient recovery of exhaust waste heat from the main engine. The system integrates rotary dehumidification, seawater condensation, and water purification. A theoretical model was developed to evaluate the system performance, incorporating design, thermodynamic modeling, parameter optimization, and adaptability analyses under various operating conditions. The results indicate that under optimal conditions (seawater at 25 °C, outlet temperature difference of 2 °C), the single-stage system is predicted to produce approximately 1.45 m³ of freshwater per day, meeting 20.7% of the vessel’s freshwater requirement. The auxiliary electrical energy consumption, estimated based on standard engineering correlations, is 1–1.5 kWh/m³, representing a 70–80% reduction compared to conventional reverse osmosis systems (3–6 kWh/m³). The sensitivity coefficient for seawater temperature was −0.334, whereas that for output temperature was −0.167. A two-stage series configuration has the potential to further improve the demand satisfaction rate to 41–61%. Overall, the proposed system enables the cascade utilization of ship waste heat and functional integration of air pretreatment and freshwater production, offering a promising auxiliary engineering solution for energy conservation, emission reduction, and onboard freshwater self-sufficiency in marine applications. Full article

Background: Computed tomography (CT)-guided lung biopsy plays a pivotal role in diagnosing thoracic lesions. However, its diagnostic yield may be compromised in large, necrotic, or heterogeneous tumours due to inadvertent sampling of non-viable tissue. Dual-energy CT (DECT) iodine mapping provides functional imaging by identifying iodine-avid, perfused areas, thereby offering the potential to improve biopsy targeting. Methods: This single-centre retrospective study evaluated the clinical feasibility and diagnostic performance of DECT-guided biopsy. Adult patients with suspected necrotic lung or mediastinal lesions who underwent DECT iodine mapping prior to CT-guided biopsy between April 2021 and December 2022 were evaluated. DECT iodine maps were generated using dual-source CT and used to identify viable tumour regions for targeted biopsy. The primary outcome was diagnostic yield, defined as obtaining a definitive histopathological diagnosis. Secondary outcomes included safety and adequacy of samples for molecular testing. Results: Twenty patients were included. A definitive diagnosis was obtained in 18/20 biopsies (90%). Diagnostic yield was 9/11 (81.8%) for pulmonary lesions and 9/9 (100%) for mediastinal/pleural lesions. Diagnoses included non-small-cell lung cancer (n = 8), Hodgkin lymphoma (n = 4), thymoma (n = 3), and other malignancies (n = 3). Biopsy material was sufficient for additional molecular testing in 13/20 cases (65%). Complications were minor (one pneumothorax not requiring drainage and two self-limited bleeding events). Conclusions: DECT iodine map-guided targeting was feasible in this retrospective cohort and was associated with high diagnostic yield, low complication rates, and frequent acquisition of tissue suitable for molecular analyses. Prospective controlled studies are needed to quantify benefit over conventional CT guidance. Full article

Evaluating energy self-sufficiency in the residential sector is crucial for decarbonization. However, the discrepancy between design-stage estimates and actual measurements (the performance gap) poses a significant challenge. While the primary cause of this gap lies in uncertainties stemming from occupant behavior and weather conditions, no medium-term probabilistic forecasting framework for the energy self-sufficiency rate (ESSR) incorporating these factors has been established. To address this issue, this study proposes a probabilistic forecasting framework that integrates a pre-trained time-series foundation model called Chronos with Monte Carlo simulation. Validation using real data from 39 households demonstrates that the proposed method can achieve prediction accuracy superior to baseline models. Furthermore, the derived probability distributions of ESSR quantify fluctuation risks across households and seasons, highlighting the limitations of conventional uniform evaluation models. Full article

Due to the increasingly severe energy crisis and extreme climate conditions in recent years, the development and use of alternative clean energy sources have become increasingly important. This study evaluates the energy performance of applying residential solid oxide fuel cells (SOFCs) in a typical passive-designed residential village house in Xi’an. Furthermore, the study integrates photovoltaic (PV) systems and storage batteries with a solid oxide fuel cell co-generation system (SOFC-CGS) to enhance its overall energy performance. The results show that when the SOFC-CGS operates independently, it can provide stable electricity. However, due to its limited capacity, it only meets 43% of the total energy demand and cannot fully satisfy the heating requirements. In this energy supply scenario, the SOFC-CGS heating efficiency reaches 25%, the power generation efficiency reaches 42%, and the overall efficiency reaches 67%. After integrating the PV battery system with the SOFC-CGS, the addition of photovoltaic and battery systems boosts the energy self-sufficiency rate by 32 percent, reaching 75%. In other words, this clean energy combination can cover 75% of the household’s traditional energy consumption. In addition, the heating efficiency increases by 2 percentage points to 27%, the power generation efficiency rises by 4 percent to 46%, and the overall system efficiency improves by 6 percent to reach 73%. Furthermore, the utilization rate of the photovoltaic battery system also rises from 25% to 73%: an increase of 48 percent. Therefore, according to the analysis results, integrating PV and storage batteries with the SOFC-CGS proves to be a profitable and efficient solution for application in passive-designed village houses in Xi’an. Full article

China’s rural areas possess abundant renewable energy resources, but lack sufficient energy storage facilities. Hydrogen energy storage has been considered a potential green solution. This study, for the first time, constructed a planning model for a rural electric–hydrogen microgrid incorporating hydrogen and electricity storage, and conducted comprehensive technical and economic analysis under different time periods and combinations of technological elements. The levelized cost of electricity (LCOE) was employed as a key indicator, K-means clustering was employed to obtain typical source–load curves, and the curtailment/self-balancing rate was combined for evaluation. Off-grid energy storage schemes, grid-connected/off-grid modes, and hydrogen production methods were compared to determine the optimal solution. The simulation results show the following: in 2025, off-grid mode with alkaline water electrolyzer (AWE) hydrogen production, hydrogen–battery hybrid storage was the most cost effective (LCOE 0.2824 ¥/kWh) due to hydrogen sales profits and battery flexibility, while fuel cells were unfeasible. Grid-connected mode reduced LCOE by 0.008 ¥/kWh vs. off-grid. Currently, AWE’s LCOE is 0.0172 ¥/kWh lower than proton exchange membrane (PEM), but PEM may have a 0.0004 ¥/kWh lower LCOE by 2030, becoming preferred. The results are potential for cost effectiveness, aiding rural energy transition. Full article

This paper presents an optimal-design methodology for small-scale Integrated Energy Systems (IESs) that couple electricity and heat in distributed networks. A hybrid reliability assessment integrates probabilistic state enumeration with scenario-based simulation. Mathematically, the design is cast as a stochastic, reliability-driven ranking: time-sequential Monte Carlo (MC) produces estimators of Loss of Load Probability (LOLP), Expected Energy Not Supplied (EENS), and Self-Sufficiency Rate (SSR), which are normalized and combined into a Composite Reliability Index (CRI) that orders candidate siting/sizing options. The case study is the D-campus microgrid with Photovoltaic (PV), Combined Heat and Power (CHP), Fuel Cell (FC), Battery Energy Storage Systems (BESSs), and Heat Energy Storage Systems (HESSs; also termed TESs), across multiple siting and sizing scenarios. Results show consistent reductions in LOLP and EENS and increases in SSR as distributed energy resource capacity increases and resources are placed near critical nodes, with the strongest gains observed in the best-performing configurations. The CRI also reveals trade-offs across intermediate scenarios. The operational concept of the campus Energy Management System (EMS), including full operating modes and scheduling logic, is developed to maintain a design focus on reliability-driven decision making. Probability-based formulations, reliability metrics, and the sequential MC setup underpin the proposed ranking framework. The proposed method supports Distributed Energy Resource (DER) sizing and siting decisions for reliable, autonomy-oriented IESs. Full article