Electrical Output Research Articles

Multifunctional Triboelectric Metamaterials with Unidirectional Charge Transfer Channels for Linear Mechanical Motion Energy Harvesting

AbstractConventional triboelectric generators (TEGs) have been developed to mainly harvest the energy of linear mechanical motions and convert it usually into oscillating or pulsive, but not sustainable, electrical outputs. In this study, unidirectional charge transfer mechanisms are introduced to develop a triboelectric mechanical metamaterial (TMM) with sustainable electrical outputs. Density functional theory and experimental analyses demonstrate three minimum necessary components of TMMs fabricated by only two triboelectric materials (i.e., copper and PTFE) to generate sustainable electrical outputs. Under a wide range of compression‐tension strain of ±50%, the maximum open‐circuit voltage, short‐circuit current, and volumetric power density are 3860 V, 8 µA, and 365.3 kW m−3, respectively. Different from most conventional cellular solids, the mechanical energy dissipation of the TMMs increases quadratically with the unit cell number. High volumetric electromechanical efficiency is achieved when the unit cell is miniaturized. In addition to energy harvesting and mechanical energy dissipation, TMMs can sense the displacement by counting the number of distinctive peaks in the short‐circuit charge transfer or reaction force versus time curves. The extreme electromechanical functionalities of the TMMs facilitate their applications in intelligent suspension systems, miniaturized green power sources, and self‐sensing energy harvesters.

An enhanced broadband piezoelectric energy harvester via elastic amplification structure for multidirectional vibration

Abstract Vibration energy harvesting using a piezoelectric mechanism has significant potential for powering wireless sensors. However, most current vibration energy harvesters face limitations such as bidirectionality, narrow bandwidth, and high operating frequencies. To address these issues, we propose an enhanced broadband piezoelectric energy harvester utilizing an elastic amplification structure for multidirectional vibration (EB-PVEH). By utilizing the multidirectional rotation capacity of the excitation block and the amplified foundation excitation provided by springs, the EB-PVEH effectively captures broadband vibrations in 2D space under low-frequency excitation. Additionally, its design features long-term durability, as the piezoelectric beams are smoothly excited by the pendulum-induced motion of the block without a tip mass. The practical feasibility and the impact of structural parameters on the output behavior of EB-PVEH were investigated through theoretical analysis and experimental testing. The results revealed that the introduction of springs dynamically amplified the harnessed electrical power output. Moreover, EB-PVEH could harvest the multidirectional vibration, and it exhibited different power-generating characteristics in various directions. Furthermore, the resonance frequency could be efficiently tuned by adjusting the flexible arm length and proof mass, with different optimal arm lengths identified for each vibration direction to maximize working bandwidth. The harvester achieved an optimal output power of 3.98 mW. Practical applications, such as charging a capacitor by driving an e-bike or a bike, demonstrate the potential of the proposed harvester to provide power for micro-electrical devices.

Hydrovoltaic-Photoelectric Coupling Strategy Triggered a Robust Output Signal for High-Performance Self-Powered Electrochemical Sensing.

Hydrovoltaic self-powered electrochemical sensors hold significant potential for constructing wearable, portable, and real-time detection devices, but the low output signal due to the slow phase transition rate of water molecules and the intricate nature of integration limits their applications. In this work, a hydrovoltaic-photovoltaic coupling effect-enhanced self-powered electrochemical sensor was prepared by combining zinc oxide (ZnO) nanowire arrays with cerium-organometallic framework (Ce-MOF) materials, which greatly improved the electrical output of self-powered electrochemical systems and provided a new detection strategy for an efficient self-powered electrochemical sensing system. The heterojunction constructed by ZnO arrays and Ce-MOF could generate a built-in electric field under the action of light irradiation and promote the separation of the photocarriers. Moreover, the number of charged particles in the film further boosted the water evaporation effect. Notably, the optimal ZnO/Ce-MOF-based self-powered electrochemical device by hydrovoltaic-photoelectric coupling strategy displayed an outstanding output signal, which was 11-fold that of a pure hydrovoltaic-based device. As a proof of concept, the self-powered electrochemical sensing platform was explored for sensitive detection of lincomycin via electrostatic adsorption for the binding of an aptamer. The self-powered sensor showed superior performances, including a wide linear range from 1 fM to 1 nM with a detection limit of 0.2 fM, good stability, and satisfactory recoveries for the determination of lincomycin in real samples, holding great promise in environmental monitoring and food analysis. This study provides a promising avenue to boost the energy conversion efficiency with a high output signal for constructing sensitive self-powered biosensors.

UJI EKSPERIMEN PENGARUH JUMLAH SUDU DAN DEBIT TERHADAP DAYA DAN EFISIENSI TURBIN AIR TIPE VORTEX

<p class="StyleAuthorBold"><em>The electrification ratio in Indonesia is currently still 87%. This means that there are still 8.5 million residents or the equivalent of 2500 villages that have not received electricity. Indonesia has a lot of potential for renewable energy such as water energy. 7 GW capacity from renewable energy, 66% of which comes from hydropower. The manufacture of pico-hydro scale power plants can be a cheap alternative. Pico-hydro can be applied to irrigation canals so that it can produce small-scale electrical energy. One type of water turbine that can be utilized is a vortex type water turbine. The study used experimental methods. The independent variables are variations in the number of blades 2, 4, and 6 and the distance between the blades and the outlet is 1 cm. The dependent variable of the research is the power and efficiency produced by the vortex water turbine. The data analysis technique in this study used quantitative descriptive analysis techniques. The basin used is a conical basin type with the upper diameter is 40 cm, the lower/oulet diameter is 6.5 cm, and the height is 32 cm. The water discharge in this test has 7 variations, that is 1,12 l/s, 1,26 l/s, 1,54 l/s, 1,68 l/s, 1,82 l/s, 1,96 l/s, and 2,11 l/s. This test produced the highest electrical output power of 9.66 Watts, at a total of 2 blades, the discharge is 1,86 l/s. At the number of blades 6 at a discharge of 1.96 l / d is the highest efficiency value of 6.3%.</em></p>

Forecasting Wind–Photovoltaic Energy Production and Income with Traditional and ML Techniques

Hybrid production plants harness diverse climatic sources for electricity generation, playing a crucial role in the transition to renewable energies. This study aims to forecast the profitability of a combined wind–photovoltaic energy system. Here, we develop a model that integrates predicted spot prices and electricity output forecasts, incorporating relevant climatic variables to enhance accuracy. The jointly modeled climatic variables and the spot price constitute one of the innovative aspects of this work. Regarding practical application, we considered a hypothetical wind–photovoltaic plant located in Italy and used the relevant climate series to determine the quantity of energy produced. We forecast the quantity of energy as well as income through machine learning techniques and more traditional statistical and econometric models. We evaluate the results by splitting the dataset into estimation windows and test windows, and using a backtesting technique. In particular, we found evidence that ML regression techniques outperform results obtained with traditional econometric models. Regarding the models used to achieve this goal, the objective is not to propose original models but to verify the effectiveness of the most recent machine learning models for this important application, and to compare them with more classic linear regression techniques.

Biodegradable and Implantable Triboelectric Nanogenerator Improved by β-Lactoglobulin Fibrils-Assisted Flexible PVA Porous Film.

Triboelectric nanogenerators (TENGs) are highly promising as implantable, degradable energy sources and self-powered sensors. However, the degradable triboelectric materials are often limited in terms of contact electrification and mechanical properties. Here, a bio-macromolecule-assisted toughening strategy for PVA aerogel-based triboelectric materials is proposed. By introducing β-lactoglobulin fibrils (BF) into the PVA aerogel network, the material's mechanical properties while preserving its swelling resistance is significantly enhanced. Compared to pure PVA porous film, the BF-PVA porous film exhibits an eightfold increase in fracture strength (from 1.92 to 15.48J) and a fourfold increase in flexibility (from 10.956 to 39.36MPa). Additionally, the electrical output of BF-PVA in triboelectric performance tests increased nearly fivefold (from 45 to 203V). Leveraging these enhanced properties, a biodegradable TENG (bi-TENG) for implantable muscle activity sensing is developed, achieving real-time monitoring of neuromuscular processes. This innovation holds significant potential for advancing implantable medical devices and promoting new applications in bio-integrated electronics.

Photogalvanics of the lactic acid reductant - Carmoisine A photosensitizer-CAPB surfactant electrolyte: An optimization, stability and illumination window size effect

The photogalvanic cells presented in this research work are energy devices having dual role of simultaneous solar power generation and storage. The study of photogalvanics of the Lactic acid reductant-Carmoisine A photosensitizer- Cocamidopropyl betaine (CAPB) surfactant-NaOH alkali has been done under artificial illumination for exploring a most suitable combination of photosensitizer, reductant and surfactant for further enhancing the solar harvesting efficiency. This combination of chemicals (Lactic acid-Carmoisine A-CAPB-NaOH) has shown remarkable improvement in the cell performance. The optimum conditions for cell have also been investigated for optimal cell performance. The electrical output of the cell has been found to depend on the cumulative effect of all cell fabrication variables. The observed power is of the order 1012.70 μW with efficiency 28.84 %. The electrical out-put of the photo-galvanic cells is found almost independent of the size of the illumination window. The initial power generated from the cell was ∼309.0 µW (taken as 100 %), and power at the end of 6th day was ∼0.0009 %. This long term study of the cell in post-illuminated dark conditions shows capacity of the cell to store and release the power over long period of time. Therefore, the Lactic acid reductant-Carmoisine A photosensitizer -CAPB surfactant combination is a good alternative for use in the fabrication of highly efficient photogalvanic cells.

Performance Enhancement of Thermoelectric Generator‐Radiative Cooling System With Thermal and Electrical Energy Storage

ABSTRACTA thermoelectric generator (TEG) converts thermal energy into electrical energy when temperature gradients are created across its two surfaces. Integrating the TEG with a phase change material (PCM) and radiative cooling (RC) can increase the temperature gradient across its two surfaces. In this study, a two‐layer RC paint has been developed and applied to the cold side of a TEG, and its performance was compared with TEG‐white paint and TEG‐no paint. The RC lowers the temperature of the cold side by 3.5°C and 4.7°C compared to TEGs with white paint and no paint, respectively. Integrating PCM with TEG–RC ensured a high electrical output, enabling continuous power for a typical weather sensor. The PCM–TEG–RC generated 2.7and 0.61 mW during summer and winter days in Istanbul, and nighttime outputs of 0.302 W and 0.395 mW, respectively. Despite similar costs, the electrical performance of TEG–RC was nearly double that of the TEG‐white paint. It has also been determined that a storage capacitor with a value of 0.5 F can provide 24‐h power backup to the typical weather sensor.

Multi-Criteria Optimization of the Paper Production Process Using Numerical Taxonomy Methods: A Necessary Condition for Predicting Heat and Electricity Output in a Combined Heat and Power (CHP) System

The subject of this study is the optimization of the paper production process in one of Poland’s leading paper mills. In addition to its primary objective of paper production, the company generates heat and electricity for internal consumption and external clients, including the local municipality. Surplus energy may be sold on the power exchange; however, this requires forecasting the quantity of energy to be sold 24 h in advance, which introduces an element of uncertainty. Production stoppages, often caused by random events such as paper breakage, force a power decrease in the CHP system, further complicating energy forecasting. To minimize the occurrence of such events, numerical taxonomy methods were employed to determine the optimal screen speed (Vs) and winding speed (Vn) for two paper machines, based on the type and weight of the paper produced. This analysis utilized detailed daily data collected by the company over the period 2015–2020. The findings contribute to minimizing the occurrence of paper roll tearing, thereby reducing the risk of inaccurate forecasts of the energy and heat produced by the CHP system. Furthermore, the methodology employed in this study may be effectively applied to other optimization problems in industrial processes.

AI‐Enhanced Gait Analysis Insole with Self‐Powered Triboelectric Sensors for Flatfoot Condition Detection

AbstractFlatfoot is an orthopedic malformation where the inner foot arch flattens during motion, potentially leading to chronic musculoskeletal issues. Monitoring foot conditions is essential, as existing screening methods often need more objectivity and cost‐effectiveness. This research develops an insole‐based screening device using self‐powered triboelectric nanogenerators (TENGs) as tactile sensors and Arduino hardware setup. TENG converts mechanical energy into electrical energy, offering simple fabrication, cost‐effectiveness, longevity, and high‐output power benefits. The device records the electrical output generated by foot movements via Arduino and sends data via Bluetooth to the processing tool. Machine learning algorithms employing the Random Forest Classifier process the data to detect flatfoot conditions accurately after training sessions. For data collection, 100 participants are asked to march and walk for the same duration and distance, ensuring consistent output. Analysis reveals that the insoles' middle sensors produce higher electricity levels in individuals with flatfoot, showing a uniform pressure distribution across the foot and contact in the arch area. In contrast, individuals with normal feet exert more pressure on the toe and heel foot areas. The system achieves an overall accuracy of 82%, demonstrating the insole's potential as a commercial flatfoot detection device.

Bimodal Droplet-Based Electricity Generation Through Semi Cassini Oval Dynamic Morphology Control.

Droplet-based electricity generator (DEG) is the promising energy harvesting technology applicable in versatile scenarios. Despite numerous optimizations in DEG's materials and structures, few has paid attention to the droplet dynamics and morphology control. Here the droplet's spread-retraction dynamics and the resultant semi Cassini oval (SCO) morphology are reported, characterized by convex at both ends and concave in the middle. The lifted top electrode (LTE) is designed to respond to the dynamic SCO morphology in two steps: 1) LTE first contacts the leading edge of the spreading droplet, generating a negative voltage peak; 2) LTE second contacts the trailing edge of the retracting droplet, generating a positive voltage peak. In this way, bimodal electrical output is obtained, which exhibits 25% increase in peak-to-peak voltage and 33% increase in average power compared to the traditional DEG with only one voltage peak. These results prove that incorporating the droplet dynamics and morphology control into DEG design uplifts the energy harvesting limit from individual droplet. The proposed LTE-DEG inspires alternative route for DEG power enhancement by maximizing energy utilization of individual droplet from the perspective of droplet dynamic morphology design.

Contribution of transient heat transfer to overpressure protection in a passive Boiling Water Reactor

The BWRX-300 reactor is a small modular reactor with 300 MW nominal electric power output. As the abbreviation indicates, the reactor is a boiling type reactor using water as the coolant. The main operating principle of the reactor model is the use of natural circulation of the coolant for both steady-state operation and emergency cooling of the reactor. Isolation Condenser Systems (ICS) have been used in early BWRs and were reintroduced in the 1990s to implement passive safety.Modern technologies enable effective simulation of objects of various complexity. In this study, the thermal-hydraulic system code TRACE v.5 is used to simulate BWRX-300 reactor plant operation. The software enables calculation of a system consisting of the reactor pressure vessel and ICS in both steady-state and transient operation.The ICS is an emergency cooling system borrowed from the previous generation of GE Hitachi BWRs, the ESBWRs, and it consists of a vertical tube bundle heat exchanger immersed in a water tank. Although this system design remains unchanged, its purpose is different. The BWRX-300 design completely eliminates safety and relief valves. This is why the ICS must perform both overpressure protection and long term heat dissipation functions.Three reactor plant operation states were simulated: normal operation with nominal parameters; reactor isolation; and the transient process into the cooling down mode by reactor shutdown and ICS activation. The results demonstrate that the ICS is capable to mitigate overpressure transients. Upon ICS startup, its metallic structures absorb heat well in excess of its nominal steady-state rating. Initial thermal inertia of the system is important for overpressure mitigation in transients.

Fabric‐Reinforced Functional Insoles with Superior Durability and Antifracture Properties for Energy Harvesting and AI‐Empowered Motion Monitoring

AbstractFunctional triboelectric insoles hold promise for advancing self‐powered wearable technologies. However, their durability is compromised by continuous compressive forces and friction, leading to surface abrasion and material fracturing. To address these challenges, an innovative fabric‐reinforced structure combined with a dual‐L backrest design is developed that enhances anti‐fracture capabilities and electric outputs while enabling AI‐empowered motion monitoring. Polydimethylsiloxane (PDMS) is used as the negative triboelectric material with a dual‐L backrest design, while insulated copper wire (icuW) serves as the positive triboelectric material with an annular structure design. These components are intricately nested to enable a multilayered friction pairing. The fabric‐reinforced structure demonstrates excellent compressive rebound resilience, withstanding forces of at least 1000 N. The functional insole, featuring a fabric‐reinforced dual‐L backrest structure (FRdL‐insole), efficiently harvests biomechanical energy with a peak power of 8214 µW and maintains highly consistent performance after 10 washing cycles and 60 000 durability tests. It can power portable electronic devices such as digital watches, calculators, hygrometers, and LEDs. Enhanced with machine learning algorithms, the FRdL‐insole processes sensor signals to monitor human movements, accurately identifying seven distinct motions. This positions the insole as a smart, real‐time, self‐powered tool for activity recognition, showcasing its potential in intelligent wearable technology.

Electro–Centrifugal Spinning of Core–Sheath Composite Yarns with Micro/Nano Structures for Self–Powered Sensing

In recent years, triboelectric nanogenerators (TENGs) have garnered extensive attention in the realm of self-powered sensors due to their capability to harness low-frequency mechanical energy. Among these, textile-based triboelectric nanogenerator stands out as a pivotal platform for wearable sensing. Nevertheless, conventional approaches, such as directly coating triboelectric materials on fabrics, often compromise the inherent properties. In this study, we utilized our self-developed electro-centrifugal spinning equipment to continuously fabricate core-sheath yarns with micro/nano structures, resulting in the development of pocket-shaped fabric-based (PF) TENGs. This innovative design preserves the original softness and breathability of the fabric while delivering substantial electrical output owing to its layered structure and extensive specific surface area. PF–TENGs can accurately detect electrical output signals from various motion states. This electro–centrifugal spinning technology offers new research directions and sensing application prospects for self-powered smart textile development.

Lead-free perovskite Cs3Sb2Cl3I6 via additive engineering for enhancing output performance of optoelectronic and triboelectric coupled nanogenerator

Perovskite-based triboelectric nanogenerators (TENGs) are emerging as promising renewable energy devices that achieve optoelectronic and triboelectric coupling on their own to improve electric output. Nevertheless, the coupled electric output is susceptible to low triboelectric and optoelectronic properties due to internal defects of perovskites and limitations in film quality. Hence, in this work, additive engineering was used to introduce poly(ethylene oxide) (PEO) polymer into lead-free perovskite Cs3Sb2Cl3I6 precursor to modulate the crystal growth and passivate the crystal defects and optimize film quality, which can synergistically optimize optoelectronic and triboelectric properties. Under illumination, the open-circuit voltage (VOC) and the short circuit current (ISC) of unmodified Cs3Sb2Cl3I6-based TENG are 116V and 11.4 μA through optoelectronic and triboelectric coupling effects, respectively. In contrast, the VOC and ISC of TENG based on Cs3Sb2Cl3I6 modified by PEO are up to 184V and 19.1 μA, respectively, which increases by 58.62% and 67.54%. The maximum power density can reach 2.13Wm-2. Most importantly, the PEO-modified Cs3Sb2Cl3I6-based TENG exhibits excellent stability, which can maintain 90.9% of its initial triboelectric output within 40 days. This work declares that ligand modification is an effective strategy to improve the electric output of coupled TENG, providing a new perspective for achieving high-performance perovskite-based TENG, and photothermal therapy by monitoring both human motion and environmental light intensity.

Thermal Management Enhancement of Building-Integrated Photovoltaic Systems using Coupled Heat Pipe and Evaporative Porous Clay Cooler

The building-integrated photovoltaic (BIPV) panel systems often lead to a notable decline in PV panels efficiency and lifetime due to their temperature rise because of inadequate cooling. This study investigates the performance of innovative cooling strategy of using a coupled heat pipes and porous clay cooler and compare it with other related three BIPV cooling systems configurations including a conventional BIPV cooling with and without air gap and a pure evaporative porous clay cooling. The aim is to improve the PV panel cooling, ultimately reduce the PV temperature and enhance the overall performance of the BIPV system as well as reducing the building indoor temperature and boosting energy efficiency within the building. The system model, comprising sets of transient equations for the different system configurations, was solved using MATLAB and confirmed with previous experimental findings. The results indicate that comparing with the traditional BIPV system, using BIPV/Clay cooling systems and the hybrid BIPV/Clay-heat pipe cooling systems achieved peak PV temperature reductions of up to 14 °C and 14.7 °C, respectively. Additionally, these cooling methods led to a maximum interior room temperature reduction of approximately 14°C and an average decrease of 8°C. Moreover, the hybrid BIPV/Clay-heat pipe cooling system demonstrates superior performance compared to traditional BIPV system, achieving the highest improvements in PV electrical efficiency, output power, and exergy efficiency, with gains of 7.8%, 6.4%, and 8.4%, respectively. Further, when the hybrid BIPV/Clay-heat pipe cooling system was employed, the clay cooling efficiency and clay exergy efficiency values improved on average by 30.2% and 29.7%, respectively, compared to the BIPV/Clay cooling system in addition to the increase of the lifetime of the PV panels due to isolating it from the contact with the water/water vapor of the clay cooling system. However, this hybrid approach resulted in a rise in electricity production costs from 0.077 $/kWh to roughly 0.138 $/kWh and extended the payback time from 7.38 years to 13.6 years. But, despite its initial economic drawbacks, the hybrid BIPV/Clay-HP cooling system demonstrates considerable effectiveness and long lifetime compared to other cooling configurations.

Bacterial film-based degradable triboelectric nanogenerator for both contact and non-contact sensing

As an emerging environmentally friendly energy conversion device, degradable triboelectric nanogenerators (TENGs) play an important role in self-powered sensing, health care and human–machine interaction. However, traditional degradable materials used in TENGs often suffer from limited material sources and complex preparation processes, restricting large-scale production for widespread applications. Here, we propose a simple and efficient way to prepare degradable TENGs with inactivated bacterial film, taking advantage of wide source, self-proliferation and easy culture properties of bacteria. The prepared bacterial film-based TENG (BF-TENG) has stable electrical output, good durability and fatigue resistance, along with superior capabilities in both contact and non-contact sensing. In contact mode, the BF-TENG can generate a peak voltage of up to 83.3 V, which is employed for accurate Morse code transmission. In non-contact mode, the BF-TENG is capable of effectively perceiving the target polymer at a distance of 150 cm. The non-contact LED control circuit and a sensing array based on BF-TENG further demonstrate its practical potential for gesture recognition and spatial position perception. Furthermore, the fully degradable nature of BF-TENG ensures effortless disposal after use without environmental impact, serving as a promising solution for the new generation of eco-friendly and sustainable sensing devices.

Address wind farm layout problems by an adaptive moth-flame optimization algorithm

As a clean renewable energy source, wind energy has been widely used to generate electricity in wind farms. Plenty of turbines work together to form a wind farm to increase electricity output. However, this produces an inevitable wake effect, which affects the efficiency of turbines in capturing wind energy, further leading to a decrease in the power generated by wind farms. To minimize the wake effect, optimizing the turbines layout in wind farms is necessary. Therefore, an adaptive Moth-Flame Optimization algorithm with enhanced Exploration and Exploitation capabilities (MFOEE) is proposed. The refinements of the algorithm include: i) defining a selection probability to utilize diverse information of moths; ii) an enhanced exploitation strategy by pushing moths towards the best flame; iii) developing an enhanced exploration strategy, in which three moths exchange information and two inferior moths fly to the superior moth. To validate the performance of MFOEE, four scenarios are set up using grid-based simulations of actual wind farm conditions. The experimental findings demonstrate that MFOEE can offer the most optimal scheme among the four scenarios, which indicates that MFOEE proves highly effective in addressing wind farm layout optimization challenges.

Технико-экономические показатели энергокомплекса при использовании ветроэнергетических установок для покрытия собственных нужд ТЭЦ

In accordance with the Russia Energy Strategy until 2035, within the framework of the implementation of energy-saving technologies in the power-generating sector, it is planned to use hybrid energy, which is one of the ways of transition from conventional generation to generation with a high share of renewable energy sources. However, to implement such complexes, it is necessary to conduct research that considers the natural and climatic characteristics of the region, its resource capabilities, as well as the mutual influence of conventional and renewable energy sources in the structure of generating equipment capacities. The wind potential at the construction site has been analyzed to assess the feasibility of incorporating wind turbines. Based on the technical characteristics of wind turbines and meteorological conditions, the model of wind turbines to be installed has been selected. Technical and economic indicators of the energy complex operation, providing for the use of wind power plants to partially cover the house load of CHPs have been obtained. The indicators are determined on an annual, monthly basis using the physical method of attributing the total fuel costs for heat and electricity output in case of their combined production. Operation of wind power plants as a part of the energy complex with CHP in winter has a positive effect on the process of thermal efficiency of combined heat and power generation, and in summer, on the contrary, leads to deterioration of the efficiency indicators. Relatively small fuel savings per year when using wind power plants as a part of the energy complex with CHP does not allow to consider the project cost-effective. The obtained results should be considered when making system-wide decisions on the development of renewable energy sources in parallel operation with fossil fuel power plants.

A self-regulated wind energy harvester with automatic mode transition strategy enabled by wind-induced centrifugal force

Abstract Natural wind energy distributes over a wide speed range, but conventional wind turbines with high electrical damping can only work under relatively high wind speeds, whereas breeze harvesters with low electrical damping suffer from limited electric outputs despite their low start-up wind speeds. To solve this dilemma, we report herein an automatic mode transition (AMT) strategy for rotary wind energy harvesters (WEHs) to realize self-regulation of electrical damping according to ambient wind speeds. The superior performance achieved with the AMT strategy has been demonstrated through an AMT-WEH comprising a low-damping as well as a high-damping power generation units. Theoretical analysis and experimental tests reveal that the AMT-WEH not only can work in low-damping single-unit mode to harvest weak wind (≥ 2.6 m/s), but also can switch spontaneously to high-damping dual-unit mode to efficiently capture strong wind. As connected with matched electrical loads, the AMT-WEH can switch to dual-unit mode and generate high average power of 188.2 mW under 8.2 m/s wind, which is more than 11.5-fold increase as compared with that (16.3 mW) of a conventional WEH without the AMT design. This study demonstrates a distinctive AMT strategy for WEHs to effectively exploit wide-speed-range wind energy toward self-contained sensors and electronics.