Generator For Energy Harvesting Research Articles

Portable Multi-Layer Capsule-Shaped Triboelectric Generator for Human Motion Energy Harvesting.

This paper introduces a novel portable multi-layer capsule-shaped triboelectric generator (CP-TEG), aimed at optimizing the performance of triboelectric generator technology in terms of miniaturization, modularity, and efficient energy collection. The CP-TEG utilizes a unique multi-layer, stacked structure and an elliptical cylindrical design to increase the effective frictional area and enhance power generation efficiency. Its portable design allows for flexible application in various environments and scenarios. Experimental results demonstrate that the CP-TEG can maintain stable and efficient electrical output under various motion amplitudes and frequencies, and it shows good adaptability to the direction of motion excitation. With a motion amplitude of 7 cm and a frequency of 1.94 Hz, the CP-TEG can charge a 220 μF capacitor to 1.3 V within 100 s. The power generation unit's output voltage and current are more than three times higher than that of traditional single-layer contact-separation mode triboelectric devices. Particularly, its performance in harvesting energy from human motion underscores its effectiveness as a renewable energy solution for wearable devices. Through its innovative structural design and optimized working mechanism, the CP-TEG demonstrates excellent energy collection efficiency and application potential, offering new options for sustainable energy solutions and development.

3D-printed Bi2Te3-based Thermoelectric Generators for Energy Harvesting and Temperature Response.

Thermoelectric generators (TEGs) are environmentally friendly energy harvesting technologies that hold great promise in the field of self-powered electronics and sensing. However, the current development of thermoelectric (TE) devices has largely lagged behind the development of thermoelectric materials, especially in the preparation of thermoelectric components with customizable shapes and excellent properties, which largely limits their practical applications. These issues can be effectively addressed by using 3D printing technology. Here, we print multiple p-type thermoelectric legs (pins) consecutively with this simple technique, and the printed TEGs have excellent thermal potential (288 μV K-1 at room temperature) and excellent temperature response properties, which exhibited an output voltage of 127.94 mV at a temperature difference (ΔT) of 40 K. The 3D-printed thermoelectric generator enables the collection of thermal energy. In addition, the device has excellent temperature sensing characteristics, and this temperature signal to electrical signal conversion is very rapid, which enables temperature sensing alarms in a wide temperature domain. Combining these features, an energy harvesting and electrical alarm concept for home-scale applications is proposed, which is expected to provide a diverse research idea for the application of next-generation thermoelectric devices.

Jellyfish-inspired bistable piezoelectric-triboelectric hybrid generator for low-frequency vibration energy harvesting

In pursuit of enhancing the output power of energy harvesters, this paper introduces a novel jellyfish-inspired bistable piezoelectric-triboelectric hybrid generator (JIB-PTHG) with low potential energy barrier characteristics and low-frequency, broadband energy harvesting capabilities. The JIB-PTHG comprises two flexible beams, and two rigid links, connected via a spring. Utilizing the harmonic balance method and Runge-Kutta fourth-order algorithm, a comprehensive analysis of the mechanical properties of the low-barrier bistable structure is conducted. Static equilibrium bifurcation and dynamic response analysis are performed. Subsequently, an electromechanical coupling model incorporating piezoelectricity and triboelectricity is developed to theoretically predict the output voltage of the two modules, revealing a positive correlation between displacement and output voltage. Experiment validation demonstrated that adjusting the length of the rigid links can effectively increase the deformation of the piezoelectric beam and the relative displacement of the triboelectric layers, thus improving the generator's output performance. Specifically, the TENG module exhibited exceptional energy harvesting performance within the frequency range of 3.5–6.5 Hz, achieving a voltage of 1050 V, a power of 1.84 mW, and the ability to illuminate 70 LED lights under an excitation amplitude of 17.5 mm and a frequency of 5.5 Hz. The PEG module, displayed high output performance within the frequency range of 4-7 Hz, reaching a voltage of 6.2 Vs and a power of 12.8 μW at an excitation frequency of 7 Hz and an amplitude of 17.5 mm. Both theoretical and experimental findings indicate that the JIB-PTHG has achieved improved output power within the frequency range of 3.5–6.5 Hz. Furthermore, the JIB-PTHG has the potential to harness bridge vibration energy and convert it into useful electrical energy for powering wireless sensor nodes in bridge health monitoring systems.

Bionic dragonfly staggered flapping hydrofoils triboelectric-electromagnetic hybrid generator for low-speed water flow energy harvesting

Water flow energy harvesting with triboelectric nanogenerators (TENGs) is in the spotlight. However, existing front-end energy harvesting structures have drawbacks, such as traditional turbines requiring higher flow speed to start-up, and devices based on vortex-induced vibration exhibiting a lock-in phenomenon, which severely limits the performance of the TENGs in low-speed water environments. Here, a bionic dragonfly flapping hydrofoils-driven triboelectric-electromagnetic hybrid generator (BDFH-TEHG) is reported. The dragonfly-wing-like staggered tandem hydrofoil configuration enables the BDFH-TEHG continuous energy harvesting in the entire time domain. Meanwhile, the power generation part and front-end structure parameters are optimized to enhance the electrical output of the harvester. As a result, the BDFH-TEHG exhibits a low starting flow speed, and efficient power generation at different flow speeds. At the flow speed of 0.21 m/s, the triboelectric nanogenerator (TENG) and electromagnetic generator (EMG) achieve peak powers of 4.19 mW and 8.01 mW, respectively. Furthermore, the BDFH-TEHG can power the wireless water quality sensor and provide early warning successfully for agricultural activities. This work provides a valid method for low-speed water flow energy harvesting, toward practical applications of water environment monitoring in smart agriculture.

High-Entropy Ceramics Enhanced Droplet Electricity Generator for Energy Harvesting and Bacterial Detection.

The droplet electricity generator (DEG) is a solid-liquid triboelectric nanogenerator with transistor-inspired bulk effect, which is regarded as an effective strategy for raindrop energy harvesting. However, further enhancement of DEG output voltage is necessary to enable its widespread applications. Here, high-entropy ceramics are integrated into the design of DEG intermediate layer for the first time, achieving a high output voltage of 525 V. High-entropy ceramics have colossal dielectric constant, which can help to reduce the triboelectric charge decay for DEG. Furthermore, the effect of factors on DEG output performance when employing high-entropy ceramics as the intermediate layer is extensively analyzed, and the underlying mechanisms and mathematical models are explored. Finally, the enhanced output voltage of DEG not only facilitates faster energy harvesting but also develops a novel method for rapid bacterial detection. This work successfully integrates high-entropy ceramics into DEG design, significantly enhances the output voltage, and offers a novel direction for DEG development.

A novel mathematical optimization method to obtain the maximum-power electrical configuration of thermoelectric generators for energy harvesting

Waste thermal energy recovery with thermoelectric generators has been widely studied as a method to make systems that produce hot exhaust gases, such as aircrafts, ground vehicles and factories, more sustainable. In this type of applications, the mismatch in hot and cold side temperatures of thermoelectric modules (TEMs) creates a mismatch in the electrical output. For each situation, there is a certain electrical interconnection between the modules that gives the maximum global power output. Three optimization models to find what is the best way of connecting the TEMs without a trial-and-error process, as usually done in previous literature, based on mathematical programming are proposed: single branch of series-connected TEMs, multiple parallel-connected branches of series-connected TEMs, and multiple groups of independent series-connected TEMs. The main novel contributions of this paper are: (i) a mathematical optimization approach that provides how to connect the thermoelectric modules one by one, (ii) the application of the above-mentioned method in a common case study: an automotive thermoelectric generator, (iii) information about how the optimal connection between modules changes if the heat source changes its operation (iv) a method for selecting a fixed optimal connection even when the heat source operation changes, e.g. different operation modes in a thermal engine, based on introducing weighting parameters in the optimization mathematical model. The optimization approach followed here is novel and has not been applied before to thermoelectric generators.

Piezoelectric and Pyroelectric Properties of Organic MDABCO-NH4Cl3 Perovskite for Flexible Energy Harvesting

This study describes the synthesis and characterization of the lead-free organic ferroelectric perovskite N-methyl-N’-diazabicyclo [2.2.2]octonium)-ammonium trichloride (MDABCO-NH4Cl3). The electrospinning technique was employed to obtain nanofibers embedded with this perovskite in a PVC polymer for hybrid fiber production. The dielectric, piezoelectric, and pyroelectric properties of these fibers were carefully examined. Based on measurements of the dielectric permittivity temperature and frequency dependence, together with the pyroelectric results, a transition from a high temperature paraelectric to a ferroelectric phase that persisted at room temperature was found to occur at 438 K. The measured pyroelectric coefficient yielded values as high as 290 μC K−1 m−2, which is in between the values reported for MDABCO-NH4I3 and the semiorganic ferroelectric triglycine sulfate (TGS). The hybrid nanofibers exhibited good morphological characteristics and demonstrated very good piezoelectric properties. Specifically, a piezoelectric coefficient of 42 pC/N was obtained when applying a periodical force of 3 N and a piezoelectric voltage coefficient of geff = 0.65 V mN−1. The performance of these fibers is on par with that of materials discussed in the existing literature for the fabrication of nano energy-harvesting generators. Importantly, the perovskite nanocrystals within the fibers are protected from degradation by the surrounding polymer, making them a promising environmentally friendly platform for flexible mechanical energy harvesting.

Design, modelling and experimental verification of a tunable electromagnetic generator for multi-directional vibration energy harvesting

Design, modelling and experimental verification of a tunable electromagnetic generator for multi-directional vibration energy harvesting

Design and 3-D Printing of a Hiking Shoe Sole Embedded With a Thermoelectric Generator for Energy Harvesting

Design and 3-D Printing of a Hiking Shoe Sole Embedded With a Thermoelectric Generator for Energy Harvesting

Self-powered system by a suspension structure-based triboelectric-electromagnetic-piezoelectric hybrid generator for unifying wind energy and vibration harvesting with vibration attenuation function

The large-scale deployment of the floor-mounted wind energy nanogenerator with wind cup structure in the Internet of Things provides a promising solution for the continuous and reliable power supply of distributed sensor systems. However, some wind energy harvesting scenarios have high requirements for placement and fixation of device, thereby the suspension structure-based wind energy harvester is considered to be a potential solution in the suspension scenarios. In this paper, a suspension structure-based triboelectric-electromagnetic-piezoelectric hybrid generator (SS-TEPG) with the innovative strategy appropriately integrates suspension and damping structure for jointly achieving high efficiency wind and vibration energy harvesting with vibration attenuation function, consisting of a wind-driven triboelectric-electromagnetic hybrid generator (WD-TEHG), a vibration-driven piezoelectric energy generator and damper (VD-PEGD), and a spring-based energy dissipation structure. After the structural optimization, the vibration energy harvester delivered the instantaneous load power from 1.9 to 8.2 mW on varied vibration frequencies ranging from 8.3 to 31.2 Hz, the TENG and EMG modules of wind energy harvester delivered the instantaneous load power from 0.6 to 2.1 mW and 0.9 to 73.1 mW on varied wind speeds ranging from 2.9 to 16.2 m s−1, respectively, with a significant electrical energy output. The integrated damping structure by the combination of the vibration energy harvester and spring-based energy dissipation structure achieved a significant breakthrough in vibration attenuation of the self-powered device in the suspension scenarios. Moreover, a self-powered system equipped with a traditional hybridized power management (T-HPM) was demonstrated to co-manage three electrical outputs. A LTC 3588-based hybridized power management (L-HPM) with undervoltage lock function was further proposed to effectively co-manage three electrical outputs and provide the standardized typical output for the Bluetooth sensor, which achieved 94% reduction in power consumption compared with the traditional power management. Finally, it is verified that the self-powered system by a hybrid generator equipped with a LTC 3588-based hybridized power management has the characteristics of fast start-up process, short undervoltage charge accumulation process and high energy conversion efficiency, indicating the large-scale application prospects of unifying the energy harvesting in terms of natural wind and harmful vibration.

Boosting the Output of Liquid–Solid Triboelectric Nanogenerator by an External Charge‐Pumping Strategy

AbstractIn recent years, liquid–solid triboelectric nanogenerator (LSTENG) has attracted great attention. However, its low average power density and long charging time limit the practical application of this technique. Here, for the first time, a liquid–solid triboelectric nanogenerator combined with external charge‐pumping method (ECP‐LSTENG) is proposed. Compared to traditional LSTENGs, a charge storage capacitor is added in this ECP‐LSTENG to store the output charges from the pumping generator. Then, a charge extraction capacitor is formed by the spreading and shrinking processes of falling droplet, while the charging and discharging process between charge storage and extraction capacitors can generate displacement current output for external circuit. Meanwhile, it is found that a special charged droplets adhesion phenomenon happens at the liquid–solid interface, which seriously hinders the continuous output of ECP‐LSTENG. To overcome this limitation, a special coaxial deceleration commutation component is designed to ensure continuous output of the ECP‐LSTENG. Finally, the peak power density of a droplet (50 µL) reaches 231.8 W m−2, surpassing the highest research record to date by 1.43 times. This ECP‐LSTENG provides a different approach for the future development of large‐scale integrated raindrop generators for efficient raindrop energy harvesting.

An Integrated Charge Excitation Alternative Current Dielectric Elastomer Generator for Joint Motion Energy Harvesting

AbstractJoint movement is a plentiful source of energy in living organisms; however, it is challenging to harvest due to its multidirectional nature, and effective technologies for harnessing this energy are lacking. In this study, a novel approach is presented to harvest joint motion energy by combining an alternating current dielectric elastomer generator (AC‐DEG) with an electret nanogenerator (ENG). The ACENG‐DEG, utilizing ion hydrogel electrodes and ENG, exhibits remarkable stretchability (860%) and efficiently converts mechanical energy into electrical energy through a stretch‐based mechanism. With only 37 cycles, the device reaches a saturation voltage of 1.18 kV and generates an output charge of 1.96 µC per cycle. Notably, the charge output response speed is approximately four times faster than that of traditional AC‐DEGs. The proposed strategy for harvesting human mechanical energy in this study represents a promising pathway for developing high‐performance energy harvesting devices and self‐powered systems.

Giant piezoresponse in nanoporous (Ba,Ca)(Ti,Zr)O3 thin film.

Lattice strain effects on the piezoelectric properties of crystalline ferroelectrics have been extensively studied for decades; however, the strain dependence of the piezoelectric properties at nano-level has yet to be investigated. Herein, a new overview of the super-strain of nanoporous polycrystalline ferroelectrics is reported for the first time using a nanoengineered barium calcium zirconium titanate composition (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 (BCZT). Atomic-level investigations show that the controlled pore wall thickness contributes to highly strained lattice structures that also retain the crystal size at the optimal value (<30 nm), which is the primary contributor to high piezoelectricity. The strain field derived from geometric phase analysis at the atomic level and aberration-corrected high-resolution scanning transmission electron microscopy (STEM) yields of over 30% clearly show theoretical agreement with high piezoelectric properties. The uniqueness of this work is the simplicity of the synthesis; moreover the piezoresponse d 33 becomes giant, at around 7500 pm V-1. This response is an order of magnitude greater than that of lead zirconate titanate (PZT), which is known to be the most successful ferroelectric over the past 50 years. This concept utilizing nanoporous BCZT will be highly useful for a promising high-density electrolyte-free dielectric capacitor and generator for energy harvesting in the future.

Using a stepper motor as a low-power, low-rotation DC generator for renewable energy harvesting

Currently, the need for renewable energy is getting bigger; studying renewable energy generation requires a small-scale or miniature generator with a low rotation that can produce power for lamp loads. The selection of generators is not as appropriate as using DC motors with high rpm, as generators still produce a small voltage (&lt;12V) and a small current. The use of DC motors equipped with gears requires a large torque to rotate the rotor. The solution offered to overcome this problem is the use of stepper motors as a DC generator with low rotation. The stepper motor has a multi-pole coil and permanent magnet that qualify it as a generator. This study uses the nema23 stepper motor as a DC generator. The stepper motor used is a 6-wire stepper motor (two pairs of coils), a half-wave rectifier, and a capacitor to buffer the voltage. The load is a 12VDC lamp. The results obtained indicate that the stepper motor generator can turn on the lights with a manual hand rotation.

Compact, robust, and regulated-output hybrid generators for magnetic energy harvesting and self-powered sensing applications in power transmission lines

A hybrid magnetic energy harvester is demonstrated for self-powered sensors in transmission lines, showcasing unprecedented power density, compact size, lightweight, waterproofing, resilience to current fluctuations, and environmental robustness.

A fabric-based hydrovoltaic electricity generator with multi-component carbon black for sustainable energy output.

Water evaporation-induced electricity generators are considered a promising green energy-harvesting technology to alleviate the increasingly serious fossil energy crisis. Previous water evaporation-induced electricity generators mainly focused on single component carbon black, limiting the improvements in energy output. At present, there are relatively few studies on multi-component carbon black for improving electricity-generation performance. Herein, inspired by plant transpiration, we designed a fabric-based water evaporation-induced electricity generator (FWEG) based on multi-component carbon black, which can maintain a voltage of 0.65 V for more than 48 h. Through the synergistic effect of multi-component carbon black-enhanced oxygen-containing functional density, the FWEG can generate an enhanced output current of 61.61 μA without any additional energy input. Moreover, we show that the FWEG can be integrated readily to charge commercial capacitors or directly power LED lights and calculators for a long time. This work provides new insights for designing high-performance hydrovoltaic electricity generators for sustainable green energy harvesting.

(Invited) SAE-MEMS Technology for Electrostatic Vibrational Energy Harvesters

Energy harvesting [1] is expected to be a self-powering technology for small wireless sensor nodes in the next generation Internet-of-Things (IoT). In particular, small vibrational energy harvesters (VEHs) based on micro-electro-mechanical systems (MEMS) technology, which are battery-free and can generate electricity even at night or in the dark, are being investigated worldwide for next-generation power sources for small wireless IoT nodes [2,3]. Electrostatic MEMS VEHs, which use semi-permanent charge-holding dielectrics called "electrets," are useful for power generation using environmental vibrations because they have a higher output power density at lower frequencies than other methods [4]. Further miniaturization, higher performance, and higher productivity will be required to use electret-type MEMS VEHs as power sources for compact wireless IoT nodes and other devices. Although the integration of MEMS VEHs with power management circuits enables miniaturization, higher performance, and improved productivity, the monolithic integration of electret-type MEMS VEHs and electronic circuits is an unexplored area in conventional technology. Conventional electrostatic MEMS VEHs involve corona discharge, electron beam irradiation, X-ray irradiation, or high-temperature treatment as electret charge processing, which imposes restrictions on the design and manufacturing of MEMS structures and the integration of MEMS and electronic circuits. Recently, self-assembled electrets (SAEs), which are electrets that do not require any charging process, have been developed using materials for organic electroluminescent devices [5]. The surface charge density of SAEs is equivalent to those of previously reported electrets for VEHs, and thus SAE is expected to improve the performance of VEH and simplify the manufacturing process. However, there have been no reports of MEMS devices using SAEs.Our proposed method is the first technology to form SAEs inside MEMS structures using only a vacuum evaporation process at room temperature, and we have succeeded in actual vibration power generation [6]. This technology can be integrated into existing semiconductor processes because the electret formation requires only room-temperature deposition, making it possible to monolithically integrate electret-type MEMS VEHs and electronic circuits on the same substrate. In addition, since the SAE surface potential is proportional to the film thickness, the amount of electricity generated can be further increased by increasing the thickness of the SAE film. Therefore, this technology is expected to accelerate the miniaturization, performance, and productivity improvement of MEMS environmental vibration power generation devices. Akinaga, “Recent advances and future prospects in energy harvesting technologies,” Jpn. J. Appl. Phys. 59 (2020) 110201.D. Mitcheson, E. M. Yeatman, G. K. Rao, A. S. Holmes, and T. C. Green, “Energy Harvesting from Human and Machine Motion for Wireless Electronic Devices” Proc. IEEE 96 (2008) 1457–1486.Suzuki, “Recent progress in MEMS electret generator for energy harvesting,” IEEJ Trans. Elec. Electron. Eng. 6 (2011) 101-111.Toshiyoshi, S. Ju, H. Honma, C.-H. Ji, and H. Fujita, “MEMS vibrational energy harvesters,” Sci. Technol. Adv. Mater. 20 (2019) 124-143.Tanaka, N. Matsuura, and H. Ishii, “Self-Assembled Electret for Vibration-Based Power Generator,” Sci. Rep. 10 (2020) 6648.Yamane, H. Kayaguchi, K. Kawashima, H. Ishii, and Y. Tanaka, “MEMS post-processed self-assembled electret for vibratory energy harvesters,” Appl. Phys. Lett. 119 (2021) 254102.

High performance analysis and optimization of metal halide perovskite-based thermoelectric generators for sustainable energy harvesting

Metal halide perovskite-based thermoelectric materials have garnered considerable attention due to their ultralow thermal conductivities and decent electric transport properties, while the research into thermoelectric generators (TEGs) lag much behind the progress of materials. In this paper, a real-sized 3D finite element model of a metal halide perovskite-based TEG is established under iso-thermal and iso-heat flux boundary conditions. Compared with traditional PbTe-based TEGs, perovskite-based TEGs exhibit more promising TE performance with TE conversion efficiency reaching ∼12 % at a 104 W/m2 thermal input power. In addition, the geometric parameters as well as the thermal management parameters under the iso-heat flux boundary condition, are optimized and discussed. The Taguchi optimization combined with the analysis of variance (ANOVA) method is further employed to quantify the contribution and importance of these factors on the output performance of the perovskite-based TEG. The results demonstrate that changing the device geometry and thermal management parameters will affect the temperature distribution between the hot- and cold-side. The thermal input power and the height of the p-n legs are the dominant factors affecting the output power and the TE conversion efficiency of the perovskite-based TEG. Promisingly, the TE conversion efficiency can reach above 20 % (or 65 % of the corresponding ideal Carnot efficiency) for an optimized perovskite-based TEG. This work predicts and verifies the highly promising TE performance of new metal halide perovskite-based TEGs. The principles behind the analyses here provide new strategies for designing and optimizing TEGs for waste-heat harvesting and other sustainable energy conversion applications.

Stretchable Thermoelectric Generators Based on Bulk Bi2Te3 and Liquid Metals

AbstractFlexible energy‐generating electronics have attracted great interest. Generally, such devices can be classified into three categories: energy storage, energy harvesting, and wireless charging. In this work, a flexible thermoelectric generator (TEG) for energy harvesting is fabricated. Bi2Te3 ingots are used as thermoelectric legs. To introduce flexibility, liquid metals and elastomers are utilized as the interconnects and encapsulation, respectively. The as‐fabricated device exhibits an output density of 34.5 µW cm−2 over a temperature difference of 25 °C. The device exhibits promising robustness under mechanical stretching, as the fracture limits reach 100%. The device is tested on the human body, and it delivers an instantaneous output of 75.2 mV. Therefore, the as‐fabricated TEG is suitable for human wearable electronic applications.

Development of Cu2Se/Ag2(S,Se)-Based Monolithic Thermoelectric Generators for Low-Grade Waste Heat Energy Harvesting.

With the ongoing climate and energy crises, thermoelectric conversion has slowly emerged as a clean and reliable alternative energy source for small Internet of Things (IoT) devices. Commercially available thermoelectric generators (TEGs) are typically composed of expensive and toxic Bi2Te3-based thermoelectric materials and require complicated and energy-intensive device assembly processes. As an alternative solution, we have developed a Ag- and Cu-chalcogenide-based monolithic TEG using simple, quick, and low-energy-cost device fabrication processes for low-grade waste heat recovery for energy harvesting. We used ductile Ag2S0.55Se0.45 and overstoichiometric Cu2.075Se, both possessing excellent transport properties around room temperature, with a zT value of ∼0.5 at 300 K. By optimizing the device fabrication process, we were successfully able to assemble the monolithic TEGs without any significant Ag- or Cu-ion migration and obtained a dense and robust device. Strategic optimization of the device structure was able to reduce the electrical contact resistance of the device, which resulted in increased power output. A maximum power density of 0.68 mW/cm2 at a ΔT = 30 K was obtained, which is comparable to a similar Bi2Te3-based monolithic TEG. These results show the potential of chalcogenide-based monolithic TEG as a simple and low-cost alternative to Bi2Te3-based TEGs for energy harvesting applications.