Efficient Energy Harvesting Research Articles

Towards Ultrahigh Osmotic Energy Harvesting By Covalent-Organic Framework Based Ionic Diode Membranes

The chemical energy stored between seawater and river water, the so-called osmotic energy (or blue energy), can be harvested by an ion-selective membrane. However, previously reported membranes suffer from insufficient ion selectivity and inferior transmembrane ionic flux (low conductance), thus impeding practical application. For example, the output osmotic power density reported by most of existing ion selective membranes is typically below the commercial benchmark (5 W/m2). Taking the inspiration from electrocytes in electric eel, which consist of a large number of sub-nanoscale rectified ion channels that allow unidirectional ion transport with amplified flux, we engineered a sub-2 nm-scale covalent-organic framework (COF)-based ionic diode membrane (IDM) for highly efficient osmotic energy harvesting (Fig. 1). We show that the proposed IDM can rectify ionic current even in high salt concentration, which was supported by our simulations based on the Poisson-Nernst-Planck model. We also probe application of this membrane in harvesting energy from salinity gradients. Notably, in addition to ultrahigh ion selectivity, these sub-2 nm-scale ionic diode membranes can achieve an unprecedented power density, higher than the commercial benchmark bandgap. Impressively, the exploited IDM can produce an ultrahigh power density as high as 27.8 W/m2 by mixing artificial salt-lake water and river water, outperforming all the state-of-the-art ion selective membranes under the same testing condition. Our work would open up new avenues of using pinhole-free COF membranes towards next-generation highly selective and ultrahigh-performance sustainable energy harvesting.

CCC2023_possibilities of obtaining energy from aerodynamic phenomena occurring in selected housing estates in Warsaw, Poland

The study uses wind tunnel experiments to explore the potential for harnessing wind energy from aerodynamic phenomena in selected housing estates in Warsaw, Poland. Aimed at addressing the challenges posed by the European ‘Fit for 55’ resolution, our research focuses on the energy recovery capabilities of large-panel technology buildings established in the latter half of the twentieth century. We aim to provide a roadmap for integrating wind energy solutions into urban planning and design by analyzing the aerodynamic effects within urban environments. Our methodology includes qualitative assessments of wind patterns around residential neighbourhoods and their impact on potential wind energy utilization. Results indicate that specific urban configurations can significantly enhance the efficiency of wind energy harvesting, offering a promising avenue for sustainable urban development. This study contributes to the growing field of renewable energy research by highlighting the untapped potential of urban wind resources and proposing design considerations for future architectural projects.

Concentrated near-field thermophotonics for efficient solar energy harvesting: Model development, system analysis, and performance optimization

In recent years, research on near-field thermophotonic systems has predominantly focused on waste heat recovery and electroluminescence cooling, while studies on near-field thermophotonic converters for solar energy harvesting have not been reported. We propose a near-field solar thermophotonic converter (NF-STC) that harnesses the full solar spectrum to generate electricity. Considering fluctuational electrodynamics and nonradiative recombination losses, we developed a self-consistent model to theoretically evaluate the performance of the NF-STC system from far-field to near-field regimes under two scenarios: varying LED temperature and fixed LED temperature. In the case of variable LED temperature, we identify that increasing the solar concentration, decreasing the thickness of the semiconductor material to mitigate the effect of non-radiative recombination, narrowing the vacuum gap spacing, and implementing gold back reflector for photon recycling can significantly bolster the performance of the system. Specifically, when the gap spacing is 10 nm, and the solar concentration factor is 400, we show that the total electrical power density and overall conversion efficiency can reach 8892 mW cm−2 and 22.2%, respectively. Conversely, in the fixed LED temperature scenario, the performance characteristics diverge from those observed in the variable temperature case. The system exhibits superior performance at higher LED temperatures and smaller gap spacing. This work deepens the understanding of thermophotonic converters’ application in solar energy harvesting by considering the interplay of various physical phenomena. It presents a promising pathway for efficient solar thermal power conversion.

A flexural-beam-type wide-frequency piezoelectric energy harvester for vertical shaft lifting system vibration monitoring

Abstract The coal mine lifting system may experience serious safety accidents due to severe problems with the bucket guides and rolling guide shoes. A piezoelectric energy harvesting (PEH) device for vibration sensor monitoring of shaft lifting system is proposed for the first time to monitor health of shaft lifting system. However, there are differences in the vibration frequencies, the working conditions are complex, leading to issues such as low energy recovery efficiency of the PEH and difficulty in achieving self-powered. To enhance PEH adaptability and reliability, a specifically designed flexural-beam-type wide-frequency piezoelectric energy harvester(FBT-WF-PEH) and a method of achieving real-time vibration monitoring through auxiliary power supply have been proposed. The results indicate when the excited frequency is 17Hz, the highest external output voltage is 11.2V, and under an external load of 17.5kΩ, the maximum output power is 7.168mW, demonstrating a good performance in terms of output power, and energy harvest bandwidth. The captive power supply test verified the PEH can utilize the vibration environment to achieve auxiliary power supply for monitoring systems under working conditions, which is of great significance for conducting research on health monitoring systems for lifting equipment. On the other hand, the new structure proposed in this study matches the operating frequency in the shaft lifting system, and the energy harvest efficiency is higher.

Geothermo-mechanical energy conversion using shape memory alloy heat engine

The shift towards renewable energy sources like geothermal energy has become desirable due to the recurrent energy crisis and global warming challenges influenced by fossil fuels. Geothermo-mechanical energy conversion using shape memory alloy (SMA) heat engines presents a novel and sustainable approach for harnessing geothermal energy. Shape memory alloys, known for their ability to undergo reversible phase transformations driven by temperature changes, are ideal for thermal-to-mechanical energy conversion. This paper explores the design and performance of an SMA heat engine that utilizes geothermal heat sources to drive mechanical work. The engine operates by cycling between the high-temperature geothermal environment and a cooler sink, exploiting the shape memory effect to generate mechanical motion. By integrating geothermal energy and SMA technology, this system offers a potential solution for renewable energy generation, with applications in remote or off-grid locations. The paper also investigates output power and the thermodynamic efficiency. A model is formulated and the engine behavior is simulated. A series of experiments are conducted for engine output power and efficiency. The model is compared to the experimental data for validation. The engine developed a maximum power of 3.5, 8.5, and 11.5 watts at 60, 80, and 90 °C respectively. The proposed SMA-based geothermo-mechanical energy conversion system offers a promising solution for efficient, reliable, and scalable geothermal energy harvesting. This research contributes to the development of innovative, efficient geothermal energy conversion technologies, supporting global renewable energy goals and reducing greenhouse gas emissions. This innovative energy conversion mechanism could play a key role in the future of sustainable power generation.

An ultralow-frequency high-efficiency rotational energy harvester with bistability principle and magnetic plucking mechanism

In this paper, we propose an energy harvester that overcomes the bottleneck problem under ultralow-frequency rotational motion. The harvester consists of bistable dual piezoelectric energy harvesters (BD-PEH) with the magnetic plucking mechanism. The driving magnet is introduced to provide the magnetic plucking to BD-PEH. Therefore, the BD-PEH can operate at high-frequency vibrations across the potential well under ultralow-frequency rotation, which enhances energy harvesting efficiency. A numerical model of the harvester is developed, and the model results are in agreement with the experimental results. The effect of the depth of the potential well on the performance of the harvester is analyzed. The deeper the potential well, the higher the energy output, but it will reduce the bandwidth of the harvester. The experimental results show that the highest average power output is 0.81 mW at 1.2 Hz. In conclusion, the energy harvester proposed in this paper can generate enough energy to drive low-power electronic devices under ultralow-frequency rotational motion.

MPPT Solar Controller: A Theoretical Design and Prototype Development

This paper discusses the theoretical design and ongoing prototype development of a Maximum Power Point Tracking (MPPT) solar controller system aimed at efficient energy harvesting and smart load management. The system is designed to optimize energy extraction from a solar panel using MPPT algorithms, with smart load management for real-time power distribution. The controller incorporates cloud-based monitoring, AI optimization, and a user-friendly interface. The system is expected to deliver robust, efficient, and safe operation under varying environmental conditions

Enhanced RF Energy Harvesting System Utilizing Piezoelectric Transformer.

RF energy harvesting converts ambient signals into electrical power, providing a sustainable energy source. This study demonstrates the use of a piezoelectric transformer for efficient RF energy harvesting. In this work, a piezoelectric transformer (PT) is employed as a high-gain, efficient inverting amplifier to enhance RF wireless energy harvesting. The PT, composed of lead zirconate titanate (PZT), is placed after the receiving loop antenna, with its output connected to an AC-to-DC converter circuit. Maximum harvested power was observed at the PT's resonance frequency of 50 kHz, with an optimal load of 40 kΩ. The system, comprising the antenna, transformer, and rectifier circuit, continues to resonate at 50 kHz, as confirmed by input impedance measurements, demonstrating stable and effective performance. The overall system efficiency was characterized to be 88%.

Evaluating the efficacy of lead-free piezoelectric materials in microcantilever based vibration energy harvesters

Abstract The piezoelectric materials have been extensively utilized in various applications, such as sensors, actuators, and energy harvesters. This study evaluates the performance of six lead-free piezoelectric materials- aluminium nitride (AlN), barium titanate (BaTiO3), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), polyvinylidene fluoride (PVDF), and zinc oxide (ZnO) in MEMS-based piezoelectric vibration energy harvesters (PVEHs) using cantilever configurations. Finite element analysis via COMSOL Multiphysics was employed to assess the deflection, voltage, and power outputs of these materials at their resonance frequencies, both with and without proof masses. The results indicate that BaTiO3 and PVDF cantilevers exhibited the highest voltage outputs, reaching 207.14 mV and 202.07 mV, respectively, with AlN also showing comparable performance at 184.72 mV. ZnO-based cantilevers demonstrated the highest power output of 1.35 nW without proof masses and 190.5 nW with proof masses, indicating its potential for high-power applications. The addition of proof masses generally reduced resonant frequencies but enhanced power outputs, like for ZnO. This comprehensive analysis underscores the critical impact of material selection and structural modifications on the efficiency of PVEHs, with BaTiO3, PVDF, and ZnO emerging as the most promising candidates for optimizing energy harvesting devices. This research lays a foundation for further advancements in piezoelectric MEMS technology, aiming for more efficient energy harvesting solutions.

Insights from Theoretical Modeling of Cesium-Formamidinium-Based Mixed-Halide Perovskite Solar Cells for Outdoor and Indoor Applications.

This study presents an in-depth computational analysis of hybrid organic-inorganic lead halide perovskite solar cells (PSCs) with a composition of Cs0.17FA0.83Pb(Br0.4I0.6)3 (FA: formamidinium) material under cool and warm light-emitting diodes (LEDs). We propose a novel design of an inverted (p-i-n) PSC to compare the power conversion efficiencies (PCEs) of opaque and semitransparent models under the AM1.5G spectrum and indoor LED lighting. The Shockley-Queisser (SQ) limits were estimated for LEDs with color temperatures of 3000 and 6000 K, revealing significant differences in PCE compared to standard solar radiation. The optical and electrical properties of the perovskite devices were simulated by using the transfer-matrix method and one-dimensional drift-diffusion model. We report a PCE of 15.8% for opaque devices under the AM1.5G spectrum, while the semitransparent devices exhibit PCEs of 12.07% and 10.17% for front and rear illumination, respectively. Under indoor conditions with cool LED lighting, the opaque devices demonstrate a significantly higher PCE of 28.38% and an impressive photovoltage of 1.17 V, surpassing the semitransparent devices, which show efficiencies of approximately 19.5% (front illumination) and 18.3% (rear illumination). While the interface between the hole transport layer and perovskite has a major impact on the device performance of opaque solar cells, the perovskite/electron transport layer junction plays a more critical role in the performance of semitransparent solar cells. The power densities for opaque devices reached up to 106.25 μW/cm2 under cool LED and 97.1 μW/cm2 with warm LED illumination. For semitransparent devices, the power densities exceeded 60.71 μW/cm2 on front-side illumination and 73.66 μW/cm2 on rear illumination under cool LEDs. These results emphasize the significant potential of hybrid PSCs for efficient energy harvesting under various lighting conditions, making them promising candidates for powering low-energy-consumption electronics in indoor environments.

Harnessing the mechanical and magnetic energy with PMN-PT/Ni-Mn-In-based flexible piezoelectric nanogenerator

Multifunctional piezoelectric nanogenerators (PENG) hold significant potential in developing smart sensing technologies for the military, healthcare, and industrial sectors. Here, we present the efficient energy harvesting from mechanical and magnetic stimuli in 0.67Pb (Mg1/3Nb2/3)O3-0.33PbTiO3 (PMN-PT) / Ni50Mn35In15 (Ni-Mn-In)-based PENG fabricated on a flexible nickel substrate using the DC/RF magnetron sputtering technique. The performance of the device has been assessed by imparting forces in the range of 0.12–0.61 N using various weights, finger tapping, bending, and magnetic fields. The device generates the maximum open circuit voltage (Voc) of 9.3 V and 6 V with 0.61 N of force and finger tapping, respectively. The corresponding short circuit current (Isc) has been obtained as 1.33 µA (0.61 N) and 0.9 µA (finger tapping). The device shows a maximum Voc of 10.6 V and Isc of 1.51 µA at the bending angle of 120°. Furthermore, the Voc and Isc have increased from 0 mV and 0 nA to 240 mV and 35 nA under the presence of 0 Oe to 500 Oe of DC magnetic field, respectively. The fabricated device exhibited a power density of 2.7 µW/cm2 with a high mechanical stability of 2500 cycles. Additionally, LEDs of green, red, yellow, and white color have been illuminated. The receptiveness of the fabricated PENG towards mechanical and magnetic stimuli highlights its potential in areas such as tactile sensing, wearable electronics, human-machine interfaces, and biomedical devices.

UAVs Revolutionizing Efficiency: Integrating DRL and Random Walrus for Enhanced Energy and Spectral Resource Management

The improvement of energy efficiency and spectral efficiency in networks is achieved by seamlessly integrating energy harvesting, cognitive radio technologies, and Non-Orthogonal Multiple Access (NOMA) techniques. These complementary strategies optimize resource usage and address challenges related to energy consumption. Additionally, the adaptability and versatility of Unmanned Aerial Vehicles (UAVs) offer innovative solutions for enhancing coverage performance, thereby improving connectivity, efficiency, and reliability. We introduce a novel approach called the Deep Reinforcement Learning-Random Walrus (DRL-RW) algorithm, which combines Deep Reinforcement Learning (DRL) with the Random Walrus optimization (RWO) technique for efficient spectrum resource allocation and energy harvesting management in dynamic environments. The DRL-RW algorithm enables UAVs to learn optimal spectrum-sharing strategies and energy harvesting policies, while the RWO enhances the algorithm's adaptability and speed in exploring diverse solutions. Simulation results demonstrate the effectiveness of the DRL-RW algorithm, showing significant improvements in several performance metrics, including reduced energy consumption, enhanced computation time, improved convergence, increased signal-to-noise ratio, higher throughput, extended network lifetime, and increased harvested energy. These findings underscore the efficacy of the DRL-RW approach in addressing challenges associated with energy management in cognitive radio networks. The integration of UAVs, NOMA networks, and this novel algorithm represents a promising direction for developing energy-efficient communication systems.

A single‐inductor self‐powered SECE interface circuit for dynamic load multi‐PZTs energy harvesting

AbstractThere is always considerable inconsistency between the input energy and the amount of the energy required for the load in piezoelectric transducers (PZTs) energy harvesting interface circuits that often degrades the harvesting performance of most of them. Multiple piezoelectric transducers (multi‐PZTs) vibration scavenging may address this issue by enhancing input power and, consequently, environmental adaptability and reliability. The proposed interface circuit may extract energy from a PZT array regardless of each PZT amplitude, frequency, or phase, even under dynamic or heavy load circumstances. The circuit is thoroughly simulated by LTSpice software and evaluated by post‐simulation calculations and discussions. The simulation findings demonstrate that the proposed self‐powered (SP) SECE‐based multi‐PZT EH interface circuit, named MI‐SP‐SECE, can extract a peak power of 12.8 µW from three PZTs in the provided actual scenario at a dynamic load regime with a simulated excitation of 1.5 g and 50 Hz. The proposed circuit's energy integration and harvesting efficiencies are 75% and 85%, respectively. It can achieve a power enhancement of 2.8× relative to a multi‐input full‐bridge rectifier. In addition, the proposed circuit is scalable effectively because it requires just one inductor component.

Hybrid Generator for Efficient Vibration Energy Harvesting and Self-Powered Gear Condition Monitoring Applications in Industrial Equipment

Hybrid Generator for Efficient Vibration Energy Harvesting and Self-Powered Gear Condition Monitoring Applications in Industrial Equipment

Energy harvesting from vibration of stay cables using polyvinylidene fluoride materials: Experimental investigations

Piezoelectric energy harvesters (PEHs) have garnered significant attention due to their potential to scavenge ambient vibration energy. However, their application to stay cables presents unique challenges. To evaluate the efficacy of PEHs for cable vibration energy harvesting, this paper conducts field tests on the designed cable polyvinylidene fluoride piezoelectric energy harvester (CPPEH) based on laboratory research. The effects of external load resistance, stay cable parameters, mounting position of the polyvinylidene fluoride (PVDF) piezoelectric film, orientation of the piezoelectric devices, polydimethylsiloxane (PDMS) flexible substrate, and stability of the piezoelectric devices on the energy output performance of CPPEH were studied. Results indicate an optimal resistance of 0.24 MΩ for the CPPEH configuration employing four piezoelectric films connected in parallel. The CPPEH exhibited superior energy performance in the in-plane and vertical installation on the stay cable. Optimal energy harvesting efficiency was achieved with a stay cable length of 91.99 m at an inclination angle of 48.879°. The PDMS flexible substrate enhanced the piezoelectric potential of the CPPEH, while the designed CPPEH demonstrated excellent cyclic stability. This innovative approach introduces a sustainable energy solution for solid bridge cable-stayed structures and offers substantial environmental and economic benefits to bridge infrastructure, offering significant engineering and societal value.

A Synergistically Enhanced Triboelectric-Electromagnetic Hybrid Generator Enabled by Multifunctional Amorphous Alloy for Highly Efficient Self-Powered System.

Triboelectric-electromagnetic hybrid generator (TEHG) has emerged as an effective technology for mechanical energy harvesting. However, the independent operation of triboelectric nanogenerator (TENG) and electromagnetic generator (EMG), along with tribo-materials wear and magnetic field divergence, constrain the device's overall performance. To address these challenges, a synergistically enhanced TEHG (SE-TEHG) is proposed based on the multifunctional amorphous alloy. Following detailed material analyses, Fe72Si8B20 is selected as the synergistic layer for its low surface roughness, high Vickers-hardness, amorphous structure, and high magnetization. Compared to Al, this material not only boosts TENG's output current and current retention rate by 28.75% and 85.24%, but also improves EMG's output power by 51.05%. In constructing a self-powered system with TEHG, a significant impedance discrepancy exists between the energy harvester (with matched impendence of 16 MΩ for TENG and 110 kΩ for EMG) and the application end. Without power management circuits, the demonstrated self-powered variable impedance system achieves an energy utilization efficiency that is 2.98 times greater than the conventional constant impedance system. The integration of multifunctional materials to realize strong-coupling hybrid generators, combined with the customization of variable impedance systems, set a milestone in efficient mechanical energy harvesting and utilization.

Full-duplex cooperative relaying systems for simultaneous wireless information and power transfer with non-orthogonal multiple access

In this research, we propose a system model based on cooperative non-orthogonal multiple access (NOMA) for simultaneous wireless information and power transfer (SWIPT) within a full-duplex (FD) communication framework. We investigate two protocols - time switching protocol (TSR) and power splitting protocol (PSR) - designed to accommodate delay-tolerant-transmission (DTT) as well as delay-limited-transmission (DLT), thereby improving data processing and energy harvesting (EH). We present explicit formulas for pivotal performance measures such as energy efficiency, ergodic rate, throughput, and outage probability. These performance measures are thoroughly evaluated in numerous specifications, encompassing inter-user separation, required spectral efficiency, EH efficiency, time and power splitting ratios in moderate-to-high signal-to-noise ratio scenarios. The results expose improved EH efficiency, hence meliorated transmission reliability. Importantly, NOMA in the proposed system model is proved to be considerably better than traditional orthogonal multiple access.

Self-powered human movement measurement with a unidirectional ratchet driven wearable energy harvester

A large amount of energy is generated during human movement which is mostly not effectively utilized. To collect human movement energy and utilize it rationally, a wearable piezoelectric-electromagnetic energy harvester (WPEEH) driven by a unidirectional ratchet is proposed, which adopts the principle of up-conversion to convert mechanical energy into electrical energy. The electromagnetic power generator unit is used to obtain energy to power the sensing circuit, while piezoelectric generator unit can be used for both energy generation and self-powered sensing. A spring push rod and a ratchet structure are used to convert the swinging of the human limb into the unidirectional rotation of the device to enhance its energy harvesting efficiency. The theoretical model of the WPEEH is established, and the experimental test platform is built. The results show that the WPEEH is able to generate a maximum power of 17.2 mW at an oscillation frequency of 1.5 Hz. In the actual wearable test, the proposed energy harvester is able to supply the harvested energy to the low-power electronic devices through capacitors, and it enables to light up 42 LEDs as well as to drive the digital thermo-hygrometer to work continuously and stably. Apart from having excellent properties of a high output power and low drive frequency, the proposed energy harvester also exhibits a high energy density (7.1 × 10–5 W/cm3). What’s more, the speed of human movement can be predicted and calculated for different individuals by testing the results of the swing frequency with a maximum error of 2.71 %. The investigation proves that the proposed WPEEH can measure human movement and has great potential in the field of power supply for low-power electronic devices.

High-efficient, polarization-insensitive, wide-angle, compact metamaterial energy harvester for S-band and C-band applications

This article proposes a polarization-insensitive compact Metamaterial (MM) energy harvester that can be used seamlessly in the S-band and C-band frequencies. It is important to focus on the limitations of many current designs of harvesters, which need to be overcome. The existing devices are large and often operate in a single frequency band, while their Energy Harvesting (EH) efficiency is low. The proposed harvester solves these problems using smart technology, using a rectangle strip with two gaps, each containing 50 Ω resistors for efficient energy collecting. Also, four hexagonal ring resonators are embedded into the cross-dumbbell configuration, connecting them with strip lines. Smaller rectangular rings surround these hexagonal rings, each with gaps labelled g1–g4. Despite its sophisticated design, the size of this harvester is (10 × 10) mm2 only. This harvester operates at frequencies of 3.5 GHz and 5.5 GHz, demonstrating remarkable absorption responses across varying polarizations and incident angles in both transverse electric (TE) and transverse magnetic (TM) modes. The simulation results indicated impressive energy harvesting efficiencies of 97% at 3.5 GHz and 98% at 5.5 GHz. In addition, experiments in an anechoic chamber with a 3 × 3 array (30 × 30) mm2 were used to confirm the efficiencies empirically. The simulated and measured results showed a strong correlation, confirming the reliability of the proposed design. The proposed MM harvester is distinguished by its high efficiency, polarization-insensitive behaviour, and compactness, making it very promising for many applications in EH.

Neuron-Inspired Flexible Phase Change Materials for Ambient Energy Harvesting and Respiration Monitoring.

The global energy crisis and climate change pose unprecedented challenges. Wearable devices with personal thermoregulation and energy harvesting hold great promise for achieving energy savings and human thermal comfort. Here, inspired by neurons, a novel phase change material (PCM) is reported for efficient energy harvesting and respiratory monitoring via a self-assembly strategy. The use of gum arabic (GA) enabled the encapsulation of polyethylene glycol (PEG) and the targeted distribution of carboxylated multi-walled carbon nanotubes (cMWCNTs) simultaneously in poly (ethylene vinyl acetate) (EVA) matrix. The material exhibits an outstanding toughness value of 14.88MJ m-3 and high elongation at a break of 565.67%, exhibiting remarkable flexibility. The material with sufficient melting enthalpy (71.11 J g-1) demonstrates high photothermal conversion efficiency (95.27%) under 808nm laser irradiation (105mW cm-2). In addition, due to the synergistic effect of GA and PEG, especially the formation of microdome structures on the surface, the material demonstrates ultrasensitive humidity responsiveness for respiratory monitoring with high precision, excellent repeatability, and fast response/recovery time (50.4/50.5ms). Notably, it shows great potential for moisture-electric generators (MEGs) with the function of non-contact sensing. This material opens the path toward next-generation wearable devices in energy conversion and health monitoring.