Search Results (2,284)

Sodium-ion batteries (SIBs) have emerged as a highly promising candidate for large-scale energy storage and low-temperature (LT) applications, featuring abundant raw materials, low cost and working mechanisms analogous to lithium-ion batteries (LIBs). Although the ionic radius of Na⁺ is slightly larger than that of Li⁺, their smaller Stokes radius and lower desolvation energy barrier endow SIBs with unique thermodynamic advantages in LT environments. However, under extremely LT conditions, issues such as a sharp increase in electrolyte viscosity, sluggish desolvation kinetics, lattice distortion and detrimental phase transitions in electrode materials, as well as instability at the electrode–electrolyte interface, collectively constrain the LT electrochemical performance of SIBs. Most existing literature merely conduct fragmented and decoupled summaries focusing on a single component (electrolyte, cathode or anode), lacking systematic elucidation of the multi-factor coupled degradation mechanism under LT conditions and holistic evaluation of multi-dimensional modification strategies. To fill this research gap, this work systematically elaborates the intrinsic LT degradation mechanism of SIBs driven by multi-physical-field coupling. From four core perspectives, including electrolyte engineering, cathode modification, anode structural construction and precise interface regulation, we comprehensively summarize mainstream technical systems for LT performance enhancement at the current stage, and thoroughly analyze the working principle, technical merits and inherent limitations of various modification approaches. Finally, the future development directions of SIBs are prospected on the basis of previous research, aiming to provide systematic and scientific theoretical guidance for in-depth mechanism exploration and industrial technological upgrading of wide-temperature-range, high-performance SIBs. Full article

Approximately 5–33% of the dates growing in Saudi Arabia are downgraded to low-quality fruit that either goes to waste or is used to make animal feed, which is considered a potential feedstock abundant in sugar. By a thorough comparative study, this study evaluated the up-cycling of low-quality Saudi dates (Wannana, Shagra, Sabbaka, Barhi, Saqai, Khalas and Sukkari) as fermentation substrates for xanthan gum production by Xanthomonas campestris. Pure glucose, pure sucrose, and a commercial standard were used as a baseline. The sole carbon source was date juice (≈12.5–17 °Brix) in a batch aerobic fermentation conducted at the standard conditions of temperature (30 °C), speed 180 rpm, and time (120 h). The xanthan gum was quantified and tested for its properties like functional groups (FTIR), color, thermal behavior (TGA and DSC), and rheology in the form of both steady- and dynamic-shear rheology. Xanthan gum was produced in the range 5.60–7.77 g L⁻¹ by the date-based substrates with Barhi (7.77 g L⁻¹) and Saqai (7.58 g L⁻¹) surpassing those of the glucose (6.68 g L⁻¹) and sucrose (6.23 g L⁻¹) controls. FTIR spectra of date-derived gums were almost identical to that of the commercial standard, indicating that their functional groups and the primary structure were very similar. In addition, the date-derived powders were darker and yellower (L* 61.09, 71.00; whiteness index 54.92, 63.34) than the commercial gum (L* 84.71; whiteness index 78.19). This is likely attributed to the presence of residue date pigmentation and products of Maillard and caramelization. Thermogravimetric analyses revealed that the breakdown of materials occurred in two stages, of which the char residue of the date-derived gums was much higher for those degraded at 500 °C (48.93, 54.05%) versus that of the commercial reference (33.49%), which is to be interpreted as a better ability of the former to resist thermal degradation. All solutions acted as pseudoplastic, shear-thinning liquids (flow behavior index n < 1); the consistency coefficient (K) rose with concentration and fell with temperature. The activation energy varied between 9.98 kJ mol⁻¹ (commercial) and 29.39 kJ mol⁻¹ (Saqai). Overall, low-quality Saudi dates can be considered a technically and economically viable, sustainable, and low-cost carbon substrate suitable for upcycling to produce xanthan gum, which is safe for use as a food additive. Full article

Nanomaterials (NMs) have shown broad application potential in wastewater deep treatment, but the actual application is constrained by some issues such as nanoparticle (NP) aggregation and poor recyclability. Different from previous comprehensive reviews, this article systematically synthesizes data from over 100 peer-reviewed studies (2012 to 2026) to review the preparation methods, purification mechanisms, and removal efficiencies for various pollutants, and the technical and economic feasibility of NMs, with an emphasis on carrier-assisted immobilization and NM–microbial aggregate interactions. To start with, the methods of preparation were roughly distinguished into two categories which were “top-down” and “bottom-up” methods. The advantages, disadvantages, and utilities of the physical, chemical, and eco-friendly methods of biosynthesis were investigated while paying particular attention to the function of the loading technique in preventing NP aggregation and improving recyclability. By using the technique of loading in the carrier, the growth of NPs could be restricted up to 2–50 nm. Secondly, seven basic mechanisms that underlie the process of removing pollutants by using NPs were explained: adsorption, catalytic degradation, ion exchange, surface complexation, antibacterial action, redox transformation, and waste recycling. Particular focus was placed on understanding the interactions between NMs, microbial aggregates, and extracellular polymeric substances in wastewater treatment systems. Extracellular polymeric substances (EPS) could capture >90% NMs and mitigate their toxicity. Once again, the removal efficiency and main influencing factors associated with different types of NMs, for the treatment of heavy metals, dyes, antibiotics, and pathogenic microorganisms were summarized. Removal efficiencies of the pollutants ranged from 70% to over 99%, but these values were strongly influenced by pH and matrix and often decreased substantially in real wastewater. The existing literature was used to classify the experimental substrates (single-solute systems, multi-solute synthetic systems, municipal wastewater, industrial wastewater, secondary effluent). The performance of NMs in different categories was compared, revealing the huge performance gap between ideal laboratory conditions and practical applications. Lastly, the economic viability of the methods based on the use of NMs for purifying water was assessed taking into consideration various factors such as raw materials’ prices, energy costs of the process of making materials, recyclability of the materials, and the possibility of introducing the use of NMs on a larger scale. Unlike existing reviews, this article aims to provide a quantitative mechanistic framework bridging the rational design, safe application, and engineering promotion of NMs in deep wastewater treatment. Full article

High-capacity long-distance HVDC is indispensable for the centralized integration of deep-sea offshore wind farms and sandy-region renewable energy bases. Hybrid flexible HVDC, which adopts voltage-source converters at the sending end and current-source converters at the receiving end, meets the technical needs and potentially offers better economic efficiency in terms of converter station capital cost. However, technical challenges remain, including passive sending-end charging and start-up, joint grid formation of multiple converters, commutation failure immunity at the receiving end, and minimum continuous current maintenance. This paper proposes a hybrid flexible HVDC system scheme along with its control strategy. The scheme employs modular multilevel converters (MMCs) at the sending end and hybrid commutated converters (HCCs) at the receiving end, and a small-capacity uncontrolled diode rectifier (UDR) is configured in parallel with the HCCs. Operating characteristics of the three types of converters are analyzed, and the overall system operating strategy is presented. Electromagnetic transient simulation results show that the UDR provides a system charging circuit and can automatically supply continuous current when renewable generation power fluctuates; for bipolar HVDC or hierarchical HVDC, virtual synchronous generator control of the MMCs enables the joint grid formation and realizes the power balance between multiple converters; for faults in the receiving grid, the HCCs are able to actively turn off the valves at risk of commutation failure, ensuring a smooth ride-through. Full article

This study presents a techno-economic assessment of utility-scale photovoltaic (PV) installations integrated with Battery Energy Storage Systems (BESSs) in the context of Poland’s energy transition. Three technical configurations are analyzed: a standalone 100 MW PV plant, a standalone 100 MW/500 MWh BESS facility, and a hybrid PV-BESS system. Economic performance is evaluated using Net Present Value (NPV), Internal Rate of Return (IRR), and Levelized Cost of Electricity/Storage (LCOE/LCOS) metrics. Under base-case market conditions, the standalone PV plant remains highly profitable (NPV = €57.2 million, IRR = 15.7%), while standalone storage is economically unviable (NPV = −€102.8 million). The hybrid PV-BESS system also yields a negative NPV (−€46.5 million) in the base case; however, optimization identifies key profitability thresholds. Break-even (NPV = 0, IRR = 6%) is achieved when capacity market revenues increase by 15% above the base rate and annual system service revenues exceed €3.57 million. The results indicate that the long-term viability of hybrid renewable systems in Central Europe is highly sensitive to market dynamics and regulatory support. Increasing the Battery Inverter Ratio (BIR) and Inverter Loading Ratio (ILR) enhances grid stability and energy output, but remains economically favourable only if declining technology costs offset the decreasing marginal market value of PV generation. Full article

The large-scale integration of variable renewable energy sources (RES) such as solar and wind into transmission networks poses significant challenges to grid stability, operational efficiency, and economic dispatch. Battery Energy Storage Systems (BESS) offer a flexible solution, but their optimal placement remains critical to maximizing technical and economic benefits. This paper presents a multi-index, scenario-based framework for optimal BESS siting in a modified IEEE 118-bus transmission system under high renewable penetration. Six complementary indices are employed: Voltage Deviation Index (VDI), Fast Voltage Stability Index (FVSI), Line Congestion Index (LCI), Bus Congestion Index (BCI), Z-bus Sensitivity Index (ZBSI), and nodal price difference (Δλ). Eight extreme scenarios, combining high/low solar, wind, and hydro generation under peak load, are used to identify vulnerable buses. Five weighting case studies reflect different stakeholder priorities: voltage stability, congestion relief, energy arbitrage, loss reduction, and equal weightage. Results show that the congestion relief case achieves the lowest daily operating cost (approx. $8000 less than the base case) and the highest net economic benefit, while the loss reduction case delivers the greatest reduction in active (34 MW) and reactive (169 MVAr) power losses, compared to the base case. The proposed framework demonstrates that integrating technical and market-based indicators enables more robust and economically attractive BESS placement. This work provides a practical, data-driven planning tool for grid operators and investors aiming to enhance transmission system sustainability under high-RES variability. Full article

Distributed generation (DG) is reshaping distribution networks through bidirectional power flows, operational variability, and dependence on coordinated regulation, pricing, and control. This paper examines how regulatory architecture, grid-code requirements, tariff design, and Distributed Energy Resource Management Systems (DERMS) influence DG integration, emphasizing Honduras. A structured mixed-source review is applied, combining Scopus-based bibliometric analysis of 2438 records (2000–2026) with targeted synthesis of technical, regulatory, tariff-related, and institutional sources. The bibliometric results show sustained growth and a thematic shift from conventional voltage-control studies toward active distribution networks, DER coordination, storage, demand response, tariff reform, and digital energy management. The analytical synthesis shows that effective DG integration requires more than interconnection compliance: it depends on grid-support functions, cost-reflective and equitable tariffs, and operational tools capable of managing voltage deviations, reverse power flow, congestion, protection coordination, and limited visibility. DERMS is an enabling layer for voltage control, active and reactive power management, congestion mitigation, adaptive protection, and predictive operation. For Honduras, current regulatory progress should be complemented by phased modernization focused on observability, smart metering, data infrastructure, local flexibility, and progressive DERMS deployment. The study provides an integrated framework for aligning regulatory, economic, and operational dimensions of DG integration in emerging distribution systems. Full article

Multi-energy virtual power plants (VPPs) aggregate electricity, heating, and natural gas resources to provide flexible regulation services to the external power grid. Their operational flexibility, however, cannot be accurately characterized using equipment capacities or single-period energy balances alone, because district heating and natural gas networks introduce heat transport delays, pipeline thermal storage, pressure dynamics, and linepack effects. This paper proposes an operational flexibility boundary assessment method for electricity–heating–gas VPPs based on a dynamic energy circuit model (ECM). The frequency-domain ECM converts heating-network temperature dynamics and gas-network pressure dynamics into algebraic constraints, which are integrated with electric-network and multi-energy coupling-device constraints. The net exchange power at the point of common coupling (PCC) is used as the external flexibility interface, and the period-wise upper and lower boundaries are determined subject to network and device constraints, terminal-state recovery requirements, and an economic feasibility limit. Case studies on an electricity–heating–gas VPP demonstrate that the dynamic ECM captures the intertemporal regulation capability provided by pipeline thermal storage and gas-network linepack. Compared with the static model, the dynamic ECM exhibits consistently greater downward flexibility and comparable or lower upward flexibility in several periods, thereby correcting the underestimation of electrical absorption capability and the optimistic estimation of power-export capability caused by the static approximation. The economic feasibility constraint further excludes high-cost boundary schedules, yielding a technically feasible and economically acceptable flexibility range. Full article

Energy poverty is a multidimensional phenomenon resulting from the interaction of different factors. This study investigated energy vulnerability in Seville by integrating a gender perspective with residential building performance. A total of 530 census tracts and 58,819 energy certificates were analyzed to evaluate indicators such as building efficiency ratings (E-F-G), energy burden, and gendered household structures. Unsupervised machine learning algorithms (K-means++) and geographic information systems (GISs) were used to identify patterns and map the obtained results, respectively. The findings revealed three distinct vulnerability profiles. Cluster 3 demonstrates severe vulnerability, linking low building efficiency with high unemployment and significant energy costs. Conversely, Cluster 1 highlights a specific risk among older women living alone, despite higher average income levels. The results conclude that energy poverty is deeply influenced by the intersection of building characteristics and gender roles. This GIS-enabled classification provides a robust framework for prioritizing residential retrofitting interventions, ensuring that mitigation strategies address both technical deficiencies in the building stock and the social realities of gender-driven vulnerability. Full article

Mine leachate and saline industrial wastewater streams are often treated as liabilities to be remediated or disposed of. These flows often contain substantial water and dissolved mineral resources that can be reclaimed. In this work, a waste-heat-assisted falling-film evaporation reactor was developed and assessed for application as a pre-concentration step before water and mineral recovery processes. Two case studies were considered: synthetic saline wastewater containing 80 g/L Na₂SO₄ and 70 g/L NaCl for salt recovery, and iron-rich mine water containing approximately 4000 mg/L Fe²⁺, 95 mg/L Fe³⁺, and 13,000 mg/L acidity as CaCO₃ for downstream pigment and magnetite recovery. Saline water or mine leachate flows down a bank of vertical conduit pipes as a thin film while air flows through the pipe cores. Heat is transferred to the system from industrial waste gas externally. Psychrometric relationships, heat transfer, energy balances, and techno-economic analysis were used to assess the impact of air temperature, conduit diameter, column height, pipe material, and waste-gas temperature on overall reactor performance. Experiments were carried out to confirm expected psychrometric operation and establish appropriate operating temperatures while confirming the impact of conduit geometry on heat-transfer characteristics. A benchmark case of design evaporation rate equal to 100 L/h was chosen for comparison of all tests. Dry air operation was shown to be technically possible but severely limited by the moisture capacity of air; at 26 °C and 101.3 kPa, approximately 205,000 m³/h of air was required. When using industrial waste heat, the operation changed from psychrometric/mass-transfer-limited to heat-transfer-controlled. Using waste gas entering at 144 °C and exiting at 80 °C reduced airflow requirements to approximately 880 m³/h, allowing a much more compact reactor design with approximately 635 (12 mm diameter) conduit pipes. Relative to the 40 °C air benchmark, electrical power was reduced from approximately 24.7 kW to 2.9 kW, and screening-level reactor cost by ~84%. Findings demonstrated that appropriate waste heat enables the application of evaporation if there is sufficient local heat flux. Smaller conduit diameters, sufficient column height, and greater waste-gas inlet temperatures were all beneficial. Choice of material required trade-offs between heat-transfer coefficient, corrosion, and material cost. Full article

The sustainability of buildings and the built environment extends beyond energy and environmental performance to circular resource use, health and safety, digital infrastructure, and stakeholder collaboration. This exploratory integrative literature review examines how these established but insufficiently connected domains reshape business models in the built environment. Since the built environment is a major source of global carbon emissions and waste, a primary research stream concerns the transition toward circular economy principles beyond traditional profit-maximization logics. The literature also highlights the potential of health- and safety-oriented innovations to reduce risks and improve indoor environments. Other studies highlight the potential of digital innovations to improve life-cycle management, resource efficiency, and risk mitigation. However, their widespread adoption faces systemic barriers, including data interoperability and cybersecurity issues, implementation costs, skills shortages, organizational resistance, and regulatory and governance challenges. The literature often emphasizes technical potential while paying less attention to value-capture mechanisms and the allocation of costs, risks, benefits, and responsibilities among the actors involved. Integrating sustainable practices, digital infrastructures, circular-economy principles, and collaborative governance is therefore essential to develop economically viable, organizationally feasible, and ethically responsible business models for the built environment, across the building life cycle and among public and private stakeholders. Full article

This article presents a technical and economic analysis of a photovoltaic system operating in conjunction with a heat pump in a single-family home. The aim of this study was to compare the cost-effectiveness of two prosumer billing systems currently in use in Poland, net metering and net billing, implemented in accordance with the provisions of the Renewable Energy Sources (RES) Act and the Energy Law and to assess the effectiveness of a proprietary algorithm for managing surplus electricity produced by the photovoltaic system. The energy performance of the facility was determined using ArCADia Termo 11.1 software, while energy and economic calculations were performed using Microsoft Excel 365 and a developed heat pump control algorithm. The algorithm is based on an analysis of the building’s energy balance with a 15 min resolution and utilizes data on outdoor temperature, energy production from the PV system, building heat loss, heat pump operating parameters, and energy self-consumption. Its goal was to maximize the use of energy produced for the building’s own needs by appropriately controlling the heat pump and storing surplus energy as heat stored in domestic hot-water tanks. The annual electricity consumption of the analyzed building was 6902.18 kWh, of which 3724.13 kWh was for heating and domestic hot water provided by the heat pump. The algorithm reduced grid energy consumption by approximately 900 kWh per year and achieved a self-consumption level of 12.73 (%). Full article

The present work presents a new synthetic jet piezoelectric pump designed to address the airflow delivery needs arising from the increasing power density of high-performance microelectronics. Traditional miniaturized cooling techniques suffer from low efficiency, bulky size, and high cost, while microfluidic cooling has emerged as a vital chip thermal management method with outstanding miniature heat removal capacity. We systematically designed the vibration mode and pump structure, adopting the sixth-order resonant frequency as the operating frequency. A dual resonant layer with stiffness-guided fixed boundaries was employed to enhance vibration efficiency and energy conversion, together with an optimized flow channel layout and parametric design. Experiments conducted under 35 V square-wave excitation demonstrate that the 20 mm × 20 mm × 2.5 mm pump delivers a flow rate of 1.6 L/min and a back pressure of 2.7 kPa. This work provides a feasible technical route for large-scale airflow delivery applications of synthetic jet piezoelectric pumps, with potential for thermal management in microelectronic devices, while balancing excellent performance and low manufacturing cost. Full article

In offshore wind farm micro-siting, maximizing annual power generation across all wind directions often involves a trade-off among different directional conditions, especially when the primary and secondary wind directions account for most wind energy. To address this issue, this paper proposes a turbine layout strategy combining horizontal and vertical staggering. The objective function maximizes the simplified capital efficiency (power generation per unit capital cost) under the primary and secondary wind directions, for which a layout optimization model is constructed and solved using the Tian Ji’s Horse Racing Algorithm (THRO). A case study on an offshore wind farm validates the proposed approach. Results show that, compared with manual empirical layout and the GA-PSO algorithm, the proposed strategy significantly improves the simplified capital efficiency under the primary and secondary wind directions, while also enhancing overall power generation efficiency across all wind directions. This offers a new technical pathway for offshore wind farm micro-siting. Additionally, the THRO algorithm converges within 30 iterations, outperforming conventional optimization algorithms and demonstrating its effectiveness in solving such optimization problems. Full article

Currently, heating supply in rural areas of China still predominantly relies on conventional coal-fired heating, which suffers from poor thermal insulation performance and severe environmental pollution. To address the issues of energy waste and environmental pollution associated with traditional heating methods in rural China, this study selects a detached rural residential building in Jilin City as the research object. A building thermal load calculation model incorporating phase-change material (PCM) walls and dynamic simulation models for five clean heating coupling systems are developed using TRNSYS software, so as to analyze the influence of PCM placement at different positions within the wall assembly on the building’s thermal load, as well as the technical and economic performance of the five heating systems. The results show that, when PCM is placed on the inner side of the building envelope, the peak heating load is reduced from 15,234.2 W to 11,266.5 W, and the cumulative heating load drops from 33,744.3 kWh to 25,688.9 kWh. Compared with the conventional PV (photovoltaic) system, the PVT (photovoltaic–thermal) system achieves an 11% improvement in power generation efficiency. Among the five clean heating systems, the PVT–ground-source heat pump system exhibits the lowest energy consumption, while the PVT–biomass boiler system records the highest energy consumption. Based on life-cycle cost analysis, the PVT–biomass boiler system delivers the optimal economic performance, with a equivalent annual cost of 9285.48 CNY. Full article