Efficient Energy Harvesting Research Articles

Effect of wing morphing on stability and energy harvesting in albatross dynamic soaring

Dynamic soaring, which harvests energy from the wind, can enhance Unmanned Aerial Vehicles’ (UAVs’) range and endurance. However, energy harvesting efficiency issues hinder UAV applications, which can be addressed by wing morphing. Therefore, this study investigates the influence of albatross wing morphing during dynamic soaring. By constructing a parametric model, the shape of the albatross wing can be modeled and achieve morphing based on joints. From the video data, this paper summarizes the typical wing morphing patterns of the albatross and notices that changes primarily occur during the leeward descent phase. This paper first analyzes the aerodynamic performance of different wing morphing patterns and finds that the drag coefficient can be reduced by 7.75% with a suitable morphing pattern. This paper also explores the drag coefficient reduction mechanism and finds that downwash airflow decreases by 30.32% after wingtip anhedral. Interestingly, the lift-to-drag ratio shows minimal variation under different morphing patterns, within 2%. From the stability perspective, this study finds that the neutral point position changes after morphing. The maximum longitudinal static margin change is 4.9%, enhancing longitudinal stability by increasing the restorative moment arm. The lateral neutral point is 4.87% closer to the center of gravity, decreasing the roll and yaw moments. It can be observed that wingtip anhedral significantly increases the stability of the albatross. Moreover, a flight simulation is carried out to study the morphing influence on trajectory and energy harvesting. The results show that maximum energy gained is improved by 47.99%, and endurance is increased by 13.05%. The results also indicate that the effects of wing morphing are global rather than limited to the phase of morphing occurrence. Finally, based on the results, this paper proposes wing morphing regularity about the wingtip for UAVs. Wingtip bends downward can significantly increase the UAVs’ stability and reduce drag, but the overall trajectory needs to be reconsidered after introducing wing morphing.

Unveiling the potential of bifacial photovoltaics in harvesting indoor light energy: A comprehensive review

Bifacial photovoltaics (BPVs) have received tremendous attention as a potential contender for efficient and cost-effective light energy harvesting. Recently, advancements in BPV technologies have broadened their scope, allowing them to harness artificial indoor light energy efficiently from both top and bottom sides. This innovative approach has demonstrated its effectiveness in energy harvesting through a single-cell design. Among various available PV technologies, thin-film perovskite photovoltaics (PPVs) exhibit exceptional promise for indoor applications in low-light environments. They offer high-power conversion efficiency and ease of design, making them a superior choice when compared to other emerging indoor PV technologies such as kesterite and dye-sensitized PVs. To improve the performance of the indoor BPVs, it is necessary to further review several characteristics relating to their materials, architecture, processing, and indoor characterizations. Additionally, a comprehensive understanding of charge-transfer mechanisms, the variability in indoor lighting sources, the development of standardized indoor simulators, assessment of materials toxicity, and considerations of scalability are essential elements that must be addressed to advance this technology. In summary, this review examines recent developments, emerging trends, challenges, and provide suggestions for the further advancement of i-BPVs, also highlighting their potential as reliable and sustainable indoor energy-harvesting solution.

Nonlinear vibration energy harvesting via parametric excitation: Snap-through with time-varying potential wells

This study introduces a novel method to improve snap-through transitions in a parametrically excited cantilever-based energy harvester featuring repulsive magnetic coupling. The aim is to enhance the efficiency of a piezoelectric energy harvester while broadening its operational frequency range. The design incorporates an oscillating substructure that magnetically interacts with the beam, promoting easier transitions. Additionally, this setup capitalizes on the resonant energy of the substructure to optimize energy capture. This study addresses a previously unexplored limitation in the directly excited counterpart by optimizing the use of substructure’s resonant energy to significantly improve the energy harvesting device’s efficiency. We present a theoretical model based on the Hamilton principle, which is solved numerically. Comprehensive experimental studies are conducted to validate the theoretical results, showing a strong correlation between the experimental outcomes and theoretical predictions. The findings indicate that an oscillating substructure with a tailored natural frequency close to twice that of the parametrically excited piezoelectric beam can induce time-varying potential wells to facilitate snap-through transitions. Despite the damping coefficient of the piezoelectric beam being three times higher than that of its simple beam counterpart, periodic perturbations still effectively expand its instability region. This enlarged instability region, resulting from such perturbations, not only exhibits broadband characteristics but also facilitates efficient energy harvesting at lower excitation levels.

Design and evaluation of a piezoelectric-electromagnetic energy harvester with a lever structure

This paper proposes a piezoelectric-electromagnetic energy harvester with a lever structure. The prototype combines electro-magnetic energy harvester (EMH) and piezoelectric energy harvester (PEH) organically, which improves the efficiency of energy harvesting. Combining Faraday’s law of electromagnetism with a spring-mass damped system, a physical model is developed and dynamic curves are predicted at different speeds. The output voltage and power of PEH and EMH are compared theoretically and experimentally, EMH performs better at lower loads and PEH is more dominant when the load resistance is high. Experiments have demonstrated that the coupling effect of EMH and PEH is relatively weak. Consequently, it is advisable to utilise the respective advantages of these two concepts by separating them. When the number of rotor contacts is 3, and the magnet diameter and number are 20 mm and 8 respectively, the prototype output is optimal. When the external load is 2KΩ, EMH reaches a maximum power of 5.06mW, whereas PEH output reaches a maximum of 1.04mW when the external load is 10KΩ. A series of experimental tests demonstrate that the prototype is capable of simultaneously providing power to two devices.

High-performance osmotic energy harvesting enabled by the synergism of space and surface charge in two-dimensional nanofluidic membranes

As promising prospects for renewable power harvesting, two-dimensional (2D) nanochannels for osmotic energy capture in a reverse electrodialysis arrangement have garnered significant attention. However, existing 2D nanochannel membranes have shown limited power generation capabilities due to challenges in balancing ion flux and selectivity. Here, we construct montmorillonite (MMT)/TEMPO-mediated oxidation cellulose nanofibers (TOCNFs) nanocomposite membranes for enhanced ion transmembrane transport. The intercalation of TOCNFs not only enlarges the interlayer distance, but also provides abundant space charge inside the nanochannels. Benefiting from the strong ion selectivity and high ion flux, the composite membrane achieves a remarkable power output of ∼16.57 W/m2 in the gradient of artificial seawater and river water, exceeding that of the state-of-the-art heterogeneous membrane-based osmotic energy conversion systems. Both experimental and theoretical findings confirm that the synergism of space and surface charge plays a crucial role in promoting osmotic energy conversion. This research contributes valuable insights into the optimization of 2D membranes for efficient clean energy harvesting purposes.

Ferroelectric Material in Triboelectric Nanogenerator.

Ferroelectric materials, with their spontaneous electric polarization, are renewing research enthusiasm for their deployment in high-performance micro/nano energy harvesting devices such as triboelectric nanogenerators (TENGs). Here, the introduction of ferroelectric materials into the triboelectric interface not only significantly enhances the energy harvesting efficiency, but also drives TENGs into the era of intelligence and integration. The primary objective of the following paper is to tackle the newest innovations in TENGs based on ferroelectric materials. For this purpose, we begin with discussing the fundamental idea and then introduce the current progress with TENGs that are built on the base of ferroelectric materials. Various strategies, such as surface engineering, either in the micro or nano scale, are discussed, along with the environmental factors. Although our focus is on the enhancement of energy harvesting efficiency and output power density by utilizing ferroelectric materials, we also highlight their incorporation in self-powered electronics and sensing systems, where we analyze the most favorable and currently accessible options in attaining device intelligence and multifunctionality. Finally, we present a detailed outlook on TENGs that are based on ferroelectric materials.

High-Coupled Magnetic-Levitation Hybrid Nanogenerator with Frequency Multiplication Effect for Wireless Water Level Alarm.

Hybrid nanogenerators (HNGs) represent a promising avenue for water energy harvesting, yet their commercial viability faces hurdles such as limited power output, poor coupling, and constrained operational lifespans. Here, a highly coupled triboelectric-electromagnetic magnetic-levitation hybrid nanogenerator (ML-HNG) is introduced that shows great potential for water energy harvesting. The ML-HNG fulfills the challenges of high power output, strong coupling, and long operational lifespans. During the contact-separation process of the triboelectric nanogenerator (TENG), the changing magnetic flux in the electromagnetic generator's coils generates a potential difference between the coils and Cu electrodes. The unique design of the ML-HNG employs a shared coil electrode configuration, which enhances the coupling without adding extra volume. This integration allows the ML-HNG to achieve multi-frequency vibrations and multiple output cycles per external longitudinal movement, a phenomenon known as the frequency multiplication effect. With an average power density of 1.69W m-3 in water, the ML-HNG provides continuous power for a thermo-hygrometer and can quickly drive a wireless water level alarm system within a minute. This groundbreaking hybrid nanogenerator design holds significant promise for the efficient and consistent harvesting of low-frequency ocean wave energy, marking a substantial advancement in blue energy technology.

Elastic Self-Recovering Hybrid Nanogenerator for Water Wave Energy Harvesting and Marine Environmental Monitoring.

To achieve large-scale development of triboelectric nanogenerators (TENGs) for water wave energy harvesting and powering the colossal sensors widely distributed in the ocean, facile and scalable TENGs with high output are urgently required. Here, an elastic self-recovering hybrid nanogenerator (ES-HNG) is proposed for water wave energy harvesting and marine environmental monitoring. The elastic skeletal support of the ES-HNG is manufactured using three-dimensional (3D) printing technology, which is more conducive to the large-scale integration of the ES-HNG. Moreover, the combination of a TENG and an electromagnetic generator (EMG) optimizes the utilization of device space, leading to enhanced energy harvesting efficiency. Experimental results demonstrate that the TENG achieves a peak power output of 42.68 mW, and the EMG reaches a peak power output of 4.40 mW. Furthermore, various marine environment monitoring sensors, such as a self-powered wireless meteorological monitoring system, a wireless alarm system, and a water quality monitoring pen, have been successfully powered by the sophisticated ES-HNG. This work introduces an ES-HNG for water wave energy harvesting, which demonstrates potential in marine environment monitoring and offers a new solution for the sustainable development of the marine internet of things.

Microstrip Passive Components for Energy Harvesting and 5G Applications

This review paper provides a comprehensive overview of microstrip passive components for energy harvesting and 5G applications. The paper covers the structure, fabrication and performance of various microstrip passive components such as filters, couplers, diplexers and triplexers. The size and performance of several 5G and energy harvester microstrip passive devices are compared and discussed. The review highlights the importance of these components in enabling efficient energy harvesting and high-speed communication in 5G networks. Additionally, the paper discusses the latest advancements in microstrip technology and identifies key research challenges and future directions in this field. Overall, this review serves as a valuable resource for researchers and engineers working on microstrip passive components for energy harvesting and 5G applications.

Multifunctional biopolymer poly (lactic acid)-based triboelectric nanogenerator via controlled construction of secondary electron path

Seeking sustainable energy solutions for bioelectronic devices, high-performance, multifunctional biopolymer-based triboelectric nanogenerators (TENGs) are proving to be essential for biomedical applications. This study presents an innovative fabrication method for establishing secondary electron transport paths, resulting in biopolymer-based nanocomposites (poly (lactic acid) (PLA)/carbon nanotube (CNT)@expanded graphite (EG)) with inherent electron pathways. By integrating conductive biopolymer nanocomposites with polytetrafluoroethylene (PTFE) films, we developed a contact-separation mode TENG (CS-TENG) that demonstrates outstanding energy-harvesting efficiency. The CS-TENG displays an impressive charge density of 280 μC/m2, accompanied by an open circuit voltage (Voc) of 100.5 V and short circuit current density (Isc) values of 47.25 mA/m2. Moreover, the essential conductive network guarantees the CS-TENG’s stability across different humidity levels and serves as a moisture barrier. In addition to energy harvesting, the fabricated biopolymer nanocomposite films exhibit effective electromagnetic interference (EMI) shielding and Joule heating capabilities, rendering the CS-TENG suitable for use in diverse application scenarios. Our results emphasize the crucial role of conductive network architecture in creating high-performance biopolymer PLA-based TENGs. The innovative fabrication method and our CS-TENG's capabilities reveal the significant potential of biopolymer-based composites to transform energy harvesting, thermal management, and EMI shielding in bioelectronics.

Extreme condition-tolerant stretchable flexible supercapacitor and triboelectric nanogenerator based on carrageenan-enhanced gel for energy storage, energy collection and self-powered sensing

As flexible electronics devices for energy storage, mechanical energy collection and self-powered sensing, stretchable flexible supercapacitor and triboelectric nanogenerator (TENG) have attracted extensive attention. However, it is difficult to satisfy the requirements of high safety and resistance to extreme conditions. Dual roles of mechanical and electrical enhancement of inorganic salt are put forward, and a carrageenan (CG) enhanced poly (N-hydroxyethyl acrylamide)/CG/lithium chloride/glycerol (PCLG) conductive gel is prepared by designing hydrogen bonding self-crosslinking and chain entanglement. A high concentration and rapid deposition strategy is proposed to prepare a PCLG gel-based stretchable flexible all-in-one supercapacitor for energy storage, and a single electrode PCLG gel-based TENG is designed for mechanical energy collection, self-powered strain and tactile sensing. The supercapacitor has high capacitance, excellent cycling stability. The TENG possesses efficient energy harvesting with high and stable output voltage and power density, and sensitive and stable self-powered strain and tactile sensing without external power supply. Even under extreme conditions such as low temperatures, self-healing after damage, prolonged placement, deformation, post-deformation, multiple continuous work, pinprick and burning, the supercapacitor and TENG still have excellent properties. Therefore, we provide novel ideas to design flexible supercapacitor and TENG used under extreme conditions for future wearable electronics.

Versatile hybrid transparent triboelectric nanogenerator-solar cell device enables efficient energy harvesting and personal handwriting recognition

The continuous energy supply for wearable electronic devices, including health monitoring sensors and human-machine interface devices, poses a significant challenge to their development. Renewable energy sources, such as nanogenerators and solar cells, offer promising solutions to this challenge. In this study, we explore the potential of a versatile device based on a smart hybrid triboelectric nanogenerator (SH TENG) and photovoltaic (PV) cell for efficient energy harvesting and personal handwriting recognition. A transparent, self-cleaning, UV-protective, bidirectional, non-rigid, lightweight, ultra-durable, eco-friendly, and uniform composite of epoxy resin/ZnO/Ag nanowires-based sandwich-like TENG can produce a power density of 2.3 W m−2. Integrating SH TENG with PV led to improved energy harvesting and increased the charging voltage of the capacitor by up to 5 times. Moreover, this material is a multifunctional sensor capable of detecting temperature, humidity, pressure, handwriting content, and the writer. These features make it an intriguing candidate for e-skin applications. By employing a generalized deep neural network (DNN) model, our device can accurately recognize handwritten letters, numbers, and personal identification with a high level of precision, achieving an accuracy of 97 %. This device can function as an intelligent touch screen with dual-purpose energy production and detection, paving the way for developing highly efficient and sustainable wearable electronic devices.

Three-dimensional triboelectric nanogenerator manufacturing using water transfer printing

Triboelectric nanogenerators (TENGs) have been widely studied due to their efficient energy harvesting capabilities and fast electrical response signals. In this study, a processing method based on water transfer printing (WTP) is developed for preparing TENG devices with three-dimensional (3D) structures. With this method, electrodes and ink layers can be integrated onto a variety of 3D objects to form a one-piece structure, which offers advantages including application to 3D surfaces, abrasion resistance, handling ease, adaptability, and decorativeness. The process istaken to prepare a 5 × 5 cm2 single-electrode TENG (IF-TENG), with FEP serving as the negative triboelectric layer and ink serving as the positive triboelectric layer. The TENG’s open-circuit voltage and short-circuit current are 184 V and 1.53 μA, respectively. Additionally, a door handle TENG (DH-TENG) device has been built for practical application demonstrations. The DH-TENG device is used in wireless alarm systems that prevent children from accidentally ingesting medication. It is also used in self-powered guidance systems that illuminate LED arrow lights to help the elderly or children at night. Seamless integration of 3D surface TENG devices using WTP is expected to have applications in smart home systems, smart transportation and security, wearable electronics, and energy harvesting.

Comparative Study on Efficiency Analysis of Fixed and Dual-Axis Solar Tracking System

Solar energy is a crucial renewable energy source, offering sustainable solutions to address energy demands and combat climate change. Maximizing the efficiency of solar energy harvesting is essential for widespread adoption and integration into the energy landscape. Solar tracking systems play an important role in increasing the efficiency of solar panels by optimizing their orientation towards the sun throughout the day. This research presents a comparative analysis of the efficiency of dual-axis solar tracking systems using Light-Dependent Resistors (LDRs) as input devices. A closed-loop tracking technique is implemented to adjust the position of the solar panels based on real-time sensor feedback. A comparative study between LDRs demonstrates their effectiveness in detecting the sun's position, despite limitations such as susceptibility to ambient light conditions and saturation to light intensity. Through experimental evaluation and data analysis, this study provides valuable insights into the power output and assessment of efficiency variation of dual-axis solar tracking systems offering applications for optimizing solar energy harvesting in practical scenarios.

Engraved complementary toroidal metasurfaces for potential energy harvesting applications in microwave band

In the current study, complementary metasurface units with toroidal geometry were fabricated, using the computer numerical control engraving method. The metasurfaces were engraved in copper-coated, FR-4 plates. The produced metasurfaces were electromagnetically characterized in the microwave regime. Furthermore, they were studied regarding their energy harvesting capability, in the microwave range, where they absorb electromagnetic energy. It was found that toroidal structures harvest energy from the incident microwaves and transform it to electric power, through a simple rectification circuit. Moreover, their energy harvesting efficiency was found to be comparable or even superior to those of others reported so far. Therefore, the hereby obtained experimental results evidently show that engraved toroidal metasurfaces could potentially be used as energy harvesters in the microwave regime.

The Latest Advances in Ink-Based Nanogenerators: From Materials to Applications.

Nanogenerators possess the capability to harvest faint energy from the environment. Among them, thermoelectric (TE), triboelectric, piezoelectric (PE), and moisture-enabled nanogenerators represent promising approaches to micro-nano energy collection. These nanogenerators have seen considerable progress in material optimization and structural design. Printing technology has facilitated the large-scale manufacturing of nanogenerators. Although inks can be compatible with most traditional functional materials, this inevitably leads to a decrease in the electrical performance of the materials, necessitating control over the rheological properties of the inks. Furthermore, printing technology offers increased structural design flexibility. This review provides a comprehensive framework for ink-based nanogenerators, encompassing ink material optimization and device structural design, including improvements in ink performance, control of rheological properties, and efficient energy harvesting structures. Additionally, it highlights ink-based nanogenerators that incorporate textile technology and hybrid energy technologies, reviewing their latest advancements in energy collection and self-powered sensing. The discussion also addresses the main challenges faced and future directions for development.

A novel asymmetric tri-stable piezoelectric vibration energy harvester for low-orbit vibration energy harvesting enhancement

This study introduces an innovative asymmetric tri-stable piezoelectric vibration energy harvester (ATPVEH) augmented with an elastic base (EB), aimed at optimizing energy capture from low-orbit vibrations. This design incorporates a uniquely configured asymmetric tri-stable piezoelectric cantilever beam, positioned within a U-shaped block that is further enhanced by an elastic base. A strategically placed spring (kf)–mass (Mf) system, situated between the U-shaped block and the constrained end of the beam, significantly boosts the vertical displacement of the beam during vibrational events. We developed a dynamic model for the ATPVEH+EB utilizing Lagrange’s equations, exploring the impact of various factors—including the asymmetry of the potential well, the stiffness of the elastic base, the mass of the spring–mass system, and the load resistance—on the system’s nonlinear dynamic responses. Our findings indicate that the ATPVEH+EB facilitates more efficient energy harvesting from low-orbit vibrations, demonstrating dual response peaks across its operational frequency spectrum. Notably, the displacement and output voltage amplitudes of the ATPVEH+EB can be enhanced by increasing mf or decreasing kb, whereas the peak output power transitions toward a lower frequency range as the load resistance escalates. Both theoretical analyses and numerical simulations corroborate the ATPVEH+EB’s superior performance in harvesting energy within low-orbit vibrational environments.

Biomimetic swallowtail V-shaped attachments for enhanced low-speed wind energy harvesting by a galloping piezoelectric energy harvester

Efficient low wind speed energy harvesting is pivotal in expanding the reach of sustainable wind power to regions with limited wind resources. This paper introduces an innovative approach to enhance wind energy harvesting efficiency in low wind speed environments through the development of a biomimetically inspired design featuring V-shaped attachments on a square bluff body. Drawing inspiration from the swallowtail, these attachments are engineered to manipulate airflow, creating an asymmetrical pressure field that significantly improves the vibration amplitude of the harvesting device. The proposed design is tested in wind tunnel experiments, demonstrating a 32 % reduction in cut-in wind speed and a significant increase in power output at the lowest tested wind speed of 1.7 m/s, compared to traditional designs. Computational fluid dynamics simulations further elucidate the mechanism behind the enhanced energy harvesting, highlighting the role of V-shaped attachments in generating stronger and more stable vortex shedding, crucial for efficient energy harvesting. The proposed attachments not only substantially reduce the cut-in wind speed of galloping but also significantly increase the device's power output, demonstrating the potential of this design for expanding the viability of wind energy in regions with limited wind resources.

A triboelectric nanogenerator based on a spiral rotating shaft for efficient marine energy harvesting of the hydrostatic pressure differential

Equipment used in underwater sensing and exploration typically relies on cables or batteries for energy supply, resulting in a limited and inconvenient energy supply and marine environmental pollution that hinder the sustainable development of distributed ocean sensing networks. Here, we design a deep-sea differential-pressure triboelectric nanogenerator (DP-TENG) based on a spiral shaft drive using modified polymer materials to harness the hydrostatic pressure gradient energy at varying ocean depths to power underwater equipment. The spiral shaft structure converts a single compression into multiple rotations of the TENG rotor, achieving efficient conversion of differential pressure energy. The multi-pair electrode design enables the DP-TENG to generate a peak current of 61.7 μA, the instantaneous current density can reach 0.69 μA cm−2, and the output performance can be improved by optimizing the spiral angle of the shaft. The DP-TENG can charge a 33 μF capacitor to 17.5 V within five working cycles. It can also power a digital calculator and light up 116 commercial power light-emitting diodes, demonstrating excellent output capability. With its simple structure, low production cost, and small form factor, the DP-TENG can be seamlessly integrated with underwater vehicles. The results hold broad prospects for underwater blue energy harvesting and are expected to contribute to the development of self-powered equipment toward emerging “smart ocean” and blue economy applications.

High performance triboelectric nanogenerator for wave energy harvesting through the gas-assisted method

Triboelectric nanogenerators (TENGs) have unparalleled performance advantages in the low-frequency range and become an emerging technology for efficient wave energy harvesting. There are various methods to improve the output performance of triboelectric nanogenerators, but the output effect and manufacturing convenience of the TENGs cannot be balanced, which limits their promotion and application in a wider field. Here, a gas-assisted triboelectric nanogenerator (GA-TENG) for harvesting wave energy is reported, which has high performance through a gas-assisted method. The gas-assisted device is mainly composed of two airbags and a flexible substrate to increase the actual contact area between the triboelectric layers, which increases the open-circuit voltage (Voc) and transferred charge (Qsc) by 7.99 and 13.86 times, respectively, compared to the rigid substrate. The power density of GA-TENG can reach 20.4 W/m3 under the wave frequency of 1 Hz. In addition, the applications of GA-TENG are successfully demonstrated, including powering three lamps of 3 W, a wireless temperature and humidity sensor, and a water level monitoring module. This work provides a design scheme for wave energy harvesting and a universal method for TENG to harvest renewable energy efficiently.