Efficient Energy Harvesting Research Articles

From Triboelectric Nanogenerator to Hybrid Energy Harvesters: A Review on the Integration Strategy toward High Efficiency and Multifunctionality.

The rapid development of smart devices and electronic products puts forward higher requirements for power supply components. As a promising solution, hybrid energy harvesters that are based on a triboelectric nanogenerator (HEHTNG) show advantages of both high energy harvesting efficiency and multifunctionality. Aiming to systematically elaborate the latest research progress of a HEHTNG, this review starts by introducing its working principle with a focus on the combination of triboelectric nanogenerators with various other energy harvesters, such as piezoelectric nanogenerators, thermoelectric/pyroelectric nanogenerators, solar cells, and electromagnetic nanogenerators. While the performance improvement and integration strategies of HEHTNG toward environmental energy harvesting are emphasized, the latest applications of HEHTNGs as multifunctional sensors in human health detection are also illustrated. Finally, we discuss the main challenges and prospects of HEHTNGs, hoping that this work can provide a clear direction for the future development of intelligent energy harvesting systems for the Internet of Things.

A novel multisource energy harvester with enhanced thermal conductivity for efficient energy harvesting and superior EMI shielding

With the rapid growth of industries, renewable energy sources like wind and solar have emerged as prominent alternatives. However, their inherent intermittency demands the development of efficient energy harvester technologies. Conventional energy harvesters are limited to capturing a single energy type, resulting in compromised storage capabilities. Moreover, the detrimental effects of electromagnetic interference (EMI) on equipment necessitate immediate attention. To address these challenges, we present the development of a novel phase change composite, CMW@PEG, which possesses remarkable enhancements in thermal conductivity (1.26 W/m∙K), electrical conductivity (71.9 S/cm), and UV absorption capacity (close to 1). Notably, this composite exhibits an outstanding EMI shielding capability of 49.36 dB, safeguarding equipment operations effectively. Furthermore, it showcases impressive solar-thermal (87.9 %) and electric-thermal (93.3 %) conversion efficiencies. The unique properties of CMW@PEG offer a pioneering strategy for harnessing and utilizing renewable energy efficiently and hold tremendous promise in advancing the sustainable energy landscape.

Self-powered system for environment and aeolian vibration monitoring in the high-voltage transmission system by multi-directional wind-driven triboelectric nanogenerator

The concentration of abundant wind energy on the high-voltage transmission tower with the feature of high height not only provides a promising solution for powering distributed sensors in smart grid, but also enables a potential feasibility for the real-time sensing of the multi-directional wind to evaluate the transmission line aeolian vibration induced by wind excitation. In this paper, the comprehensive strategy appropriately hybridizes the ingenious integration of a rotating-type TENG for efficient wind energy harvesting and a flapping-type TENG for multi-directional wind vector sensing to establish the self-powered multi-directional wind-driven triboelectric nanogenerator (SMW-TENG). The basic D-TENG and F-TENG in terms of structural parameters and response characteristics are systematically optimized to realize an efficient energy harvesting with the peak power of 3.9 mW, a smooth output in the wind speed of 3.7–16.3 m s−1 and sensitive response to eight-direction wind speed ranging from 2.6 to 13.5 m s−1. Hybrid power supply strategy based on collaborative working of UD-TENG as a standby power and LD-TENG as a main power is innovatively proposed to prolong the continues power supply of a Bluetooth temperature and humidity sensor by 70% and 126.7% compared to the single module, respectively. Importantly, the F-TENG equipped with an eight-channel signal acquisition and processing is developed to achieve the multi-directional wind vector information in response to the aeolian vibration. Furthermore, a self-powered ambient weather and multichannel wind vector sensing system based on the SMW-TENG, a hybrid power supply circuit, an eight-channel signal acquisition circuit and a Bluetooth module is developed to comprehensively realize the real-time monitoring of temperature, humidity, wind speed and direction. The abnormal wire vibration alarm can be realized through monitoring the wind direction angle on the transmission line cross-section, thereby exhibiting a great potential for developing self-powered sensing in the field of smart grids.

Sustainable Porous Scaffolds with Retained Lignin as An Effective Light-absorbing Material for Efficient Photothermal Energy Conversion.

Organic phase change materials (PCMs) are promising to utilize thermal energy from solar radiation for photothermal energy conversion. However, the issues of poor photo absorption and liquid leakage greatly restrict their practical application. Herein, a sustainable porous scaffold comprising periodate oxidized wood (POW) as the supporting material and in situ retains lignin as the light-absorber dopant are demonstrated. The π-π stacking ability of lignin molecules endows the retained lignin with efficient photonic energy harvesting characteristics for fast thermal conductivity to reach a higher maximal energy storage volume. The inherently porous structure of the POW scaffold enables excellent shape-stability, which bypasses the liquid leakage problem. The resulting POW/PCM composites exhibit superior comprehensive performance, including enhanced light absorption capacity, high photothermal conversion efficiency (≈86.7%), and high latent heat of 151 J g-1 . Furthermore, the POW/PCM composites also possess the ability to maintain a relatively constant indoor temperature when fixed atop the model house roof, showing great potential for their practical applications in the thermal regulation of intelligent buildings. This work not only paves a new way to obtain sustainable and effective porous scaffolds for sufficient photothermal energy conversion but also provides more possibilities for their practical application in the future.

Figure-of-Merits (FOM) for Direct Current TENG (Triboelectric Nanogenerator): Structural vs Dimensionless

This review paper provides a detailed overview of figure-of-merits (FOM) of Direct Current triboelectric nanogenerators (DC-TENGs). TENG represent a potentially ground-breaking technology for extracting mechanical energy from the environment. The FOM is a critical parameter that determines the efficiency of the energy conversion. This paper discusses the various working modes of DC-TENGs and also the research done to maximize output charge density. The review looks at recent different FOMs that could be formulated to improve the analysis of the performance and efficiency of TENGs more accurately. Finally, the paper concludes with a comparison between two different types of FOMs namely structural FOMs and dimensionless FOMs. It provides a valuable resource for researchers working in the field of TENGs and it sheds light on the key factors that influence the FOM of DC-TENGs. This enables the development of more efficient energy harvesting devices.

Enhanced multi-band acoustic energy harvesting using double defect modes of Helmholtz resonant metamaterial

Acoustic metamaterials (AMs) based on phononic crystals have been widely employed for acoustic energy harvesting, for their capacity to amplify incident sound waves and transfer them to piezoelectric devices. By substituting a resonator unit with a piezoelectric material having distinct characteristics, the periodicity of the AM is locally disrupted, resulting in the generation of defect bands within the band gap. At the frequencies corresponding to these defect bands, the AM exhibits the phenomenon of local resonance, which concentrates the incident acoustic energy at the defect sites and significantly enhances the output power of the piezoelectric devices. Conventional AMs primarily consist of elastic resonators, which can be regarded as spring-mass systems. The elastic resonances of these resonators lead to local resonance in the AM and are utilized for single-band acoustoelectric conversion. In contrast, Helmholtz resonators (HRs), in addition to demonstrating mechanical resonance, generate acoustic resonance at specific frequencies. By combining AM with HRs, the resulting Helmholtz AM (HAM) achieves energy localization effects within two defect bands, thereby increasing the output power and broadening the operational frequency range of the AM. This study aims to investigate the energy localization in HAM with multiple point defects within the two defect bands through numerical simulations and experimental analysis. Multiple HRs are intentionally removed from the HAM to introduce these multi-point defects. The interaction of elastic waves localized within these defects further enhances the energy harvesting efficiency of the HAM. Comparing the voltage frequency response functions, it is observed that, in both the first and second band gaps, the output voltage of the three double-defect HAM structures surpasses that of the single-defect HAM. As the distance between the two defects decreases, the energy harvesting at the defect modes intensifies due to a stronger coupling effect.

A Review of Cognitive Hybrid Radio Frequency/Visible Light Communication Systems for Wireless Sensor Networks.

The development and growth of Wireless Sensor Networks (WSNs) is significantly propelled by advances in Radio Frequency (RF) and Visible Light Communication (VLC) technologies. This paper endeavors to present a comprehensive review of the state-of-the-art in cognitive hybrid RF-VLC systems for WSNs, emphasizing the critical task of seamlessly integrating Cognitive Radio Sensor Networks (CRSNs) and VLC technologies. The central challenge addressed is the intricate landscape of this integration, characterized by notable trade-offs between performance and complexity, which escalate with the addition of more devices and increased data rates. This scenario necessitates the development of advanced cognitive radio strategies, potentially facilitated by Machine Learning (ML) and Deep Learning (DL) approaches, albeit introducing new complexities such as the necessity for pre-training with extensive datasets. The review scrutinizes the fundamental aspects of CRSNs and VLC, spotlighting key areas like Energy Efficient Resource Allocation, Industrial Scenarios, and Energy Harvesting, and explores the synergistic amalgamation of these technologies as a promising pathway for enhanced spectrum utilization and network performance. By delving into the integration of cognitive radio technology with visible light, this study furnishes valuable insights into the potential for innovative applications in wireless communication, presenting a balanced overview of the current advancements and prospective avenues in the field of cognitive hybrid RF/VLC systems.

Sustainable Energy Harvesting Mechanism with Flow-Induced Vibration

This study investigates the feasibility of utilizing a flow-induced vibration actuator as a potential energy source using piezoelectric energy harvesting. The focus is on exploring the behavior of piezo films configured as cantilever beams subjected to flow-induced vibration, which can be induced with fluid or wind streams. The primary objective is to maximize the harvested energy from the vibrating structure. This paper develops theoretical models to analyze the resonant frequencies and energy-harvesting potential of the piezo films in the context of flow-induced vibration. Experimental validations are conducted to verify the theoretical predictions. The findings indicate that higher operating frequencies in the second mode offer improved energy harvesting efficiency compared with lower modes. With the strategic adjustment of resonant frequencies using attached masses on individual piezo films, the harvestable energy output of a single film can be significantly increased from less than 1 μW to approximately 18 μW. However, the phase differences among individual piezo films can impact frequency measurements, necessitating careful fine-tuning of the physical conditions of individual components. To optimize energy harvesting, this study emphasizes the importance of implementing efficient charging mechanisms. By identifying suitable environmental vibration sources, the required charging duration for a synthesized energy harvesting array can be reduced by 25% as well. Despite certain challenges, such as phase deviations and turbulence, this study demonstrates the promising potential of flow-induced vibration resonators as sustainable energy sources. This work lays the foundation for further advancements in energy harvesting technology, offering environmentally friendly and renewable energy solutions.

Numerical and experimental study of a novel vacuum Photovoltaic/thermal (PV/T) collector for efficient solar energy harvesting

Photovoltaic/thermal (PV/T) technology can generate electricity and heat simultaneously and improve solar energy harvesting efficiency. However, flat-plate PV/T collectors have strong heat loss in cold conditions and the collected heat is low-grade thermal energy, which limits the practical application of the PV/T collectors on a large scale. Herein, the vacuum environment is introduced to the flat-plate PV/T collector, conductive and convective heat loss are blocked, improving the efficiency and operating temperature of the PV/T collector. In this paper, a novel design of the vacuum PV/T collector has been proposed and fabricated, which maintains both the upper and lower space of the absorber in a vacuum state without additional glass cover causing energy loss. Performance comparison between the vacuum PV/T collector and the air–gap PV/T collector has been conducted, demonstrating that the vacuum condition can decrease the heat loss coefficient by 16.08%. In addition, a combined thermal-electrical mathematical model is constructed and validated. The predicted results reveal that the annual thermal energy outputs of the vacuum PV/T collectors without and with ideal low emissivity coating are 124.88% and 346.58% higher than that of the air–gap PV/T collector when the operating temperature is 50 °C. In summary, the vacuum PV/T collector exhibits great potential in improving thermal performance while slightly reducing the output of electrical energy. This work contributes to extending the working time of the PV/T collector and guides the design of the new generation of highly efficient PV/T collectors.

A High-Performance Circularly Polarized and Harmonic Rejection Rectenna for Electromagnetic Energy Harvesting.

This paper presents a novel circularly polarized rectenna designed for efficient electromagnetic energy harvesting at the 2.45 GHz ISM band. A compact antenna structure is designed to achieve high performance in terms of radiation efficiency, axial ratio, directivity, effective area, and harmonic rejection over the entire bandwidth of the ISM frequency band. The optimized rectifier circuit enhances the RF harvested energy efficiency, with an AC-to-DC conversion efficiency ranging from 36% to 70% for low-level input power ranging from -10 dBm to 0 dBm. The stable output of DC power confirms the suitability of this design for various practical applications, including wireless sensor networks, energy harvesting power supplies, medical implants, and environmental monitoring systems. Experimental validation, which includes both the reflection coefficient and radiation patterns of the designed antenna, confirms the accuracy of the simulation. The study found that the proposed energy harvesting system has a high total efficiency ranging from 53% to 63% and is well-suited for low-power energy harvesting (0 dBm) from ambient electromagnetic radiation. The proposed circularly polarized rectenna is a competitive option for efficient electromagnetic energy harvesting, both as a standalone unit and in an array, due to its high performance, feasibility, and versatility in meeting various energy harvesting requirements. This makes it a promising and cost-effective solution for various wireless communication applications, offering great potential for efficient energy harvesting from ambient electromagnetic radiation.

A piezoelectric–electromagnetic hybrid energy harvester inspired by flapping motion of the Diptera insect

Low-frequency vibration is widespread in nature. Vibration energy harvesting is considered to be a reliable and sustainable method to achieve continuous power supply. It is a feasible method to design an energy harvesting system of the bio-inspired mechanical structure to improve the efficiency of energy harvesting. A hybrid energy harvester piezoelectric–electromagnetic that mimics the flapping wing motion of the Diptera insect. The biomimetic energy harvesting device consists of two piezoelectric cantilever beams structure with the mass block installed, which mimics the flapping movement mechanism of the Diptera insect. The intermediate part of this harvester inspired by the insect skeleton and muscle structure of the Diptera insect is composed of magnetic levitation coupled repulsion structure, which is easily affected by vibration and changes greatly, to realize electromagnetic energy harvesting. The ‘click’ mechanism of the Diptera insect is constructed by storing energy in springs to improve the performance of energy harvesting devices. The hybrid energy harvesting device realizes piezoelectric–electromagnetic energy harvesting with multiple energy outputs at one excitation input. A dynamic model of the proposed energy harvester is constructed based on the electromechanical coupling characteristics. The modal analysis and structure optimization of this device is realized by the finite element method (FEM). The FEM simulation and experimental results can verify that under the low-frequency excitation of 3 Hz, the maximum output power of the designed harvester reaches 12.33 mW in the low-frequency environment.

Exploring the Effect of Meteorological Factors on Predicting Hourly Water Levels Based on CEEMDAN and LSTM

The magnitude of tidal energy depends on changes in ocean water levels, and by accurately predicting water level changes, tidal power plants can be effectively helped to plan and optimize the timing of power generation to maximize energy harvesting efficiency. The time-dependent nature of water level changes results in water level data being of the time-series type and is essential for both short- and long-term forecasting. Real-time water level information is essential for studying tidal power, and the National Oceanic and Atmospheric Administration (NOAA) has real-time water level information, making the NOAA data useful for such studies. In this paper, long short-term memory (LSTM) and its variants, stack long short-term memory (StackLSTM) and bi-directional long short-term memory (BiLSTM), are used to predict water levels at three sites and compared with classical machine learning algorithms, e.g., support vector machine (SVM), random forest (RF), extreme gradient boosting (XGBoost), and light gradient boosting machine (LightGBM). This study aims to investigate the effects of wind speed (WS), wind direction (WD), gusts (WG), air temperature (AT), and atmospheric pressure (Baro) on predicting hourly water levels (WL). The results show that the highest coefficient of determination (R2) was obtained at all meteorological factors when used as inputs, except at the La Jolla site. (Burlington station (R2) = 0.721, Kahului station (R2) = 0.852). In the final part of this article, the complete ensemble empirical mode decomposition adaptive noise (CEEMDAN) algorithm was introduced into various models, and the results showed a significant improvement in predicting water levels at each site. Among them, the CEEMDAN-BiLSTM algorithm performed the best, with an average RMSE of 0.0759 mh−1 for the prediction of three sites. This indicates that applying the CEEMDAN algorithm to deep learning has a more stable predictive performance for water level forecasting in different regions.

Coupled dynamic and piezoelectric response of RPEHs embedded in road under traffic load via multiscale finite element models

Road Piezoelectric Energy Harvesting Systems (RPEHs) effectively collect and convert mechanical energy from road surface into electrical energy for intelligent traffic guidance and monitoring. To accurately evaluate the energy harvesting efficiency of RPEHs under traffic loads and road conditions, a multiscale finite element model of traffic load-road-RPEHs is developed. The model encompasses a encapsulated stacked piezoelectric transducer embedded in an large-scale road model. This approach addresses the limitations of previous studies that neglected the effect of RPEHs structure on the dynamic and piezoelectric response. The large-scale model provides the dynamic response of RPEHs for an independent small-scale model of the stacked piezoelectric transducer to enable coupled dynamic and piezoelectric behavior. Furthermore, a piezoelectric output theory considering the loss impedance is formulated. Combining this theory with the open-circuit voltage obtained from the multiscale models, we determine the output voltage and power of RPEHs under various conditions, such as vehicle speeds, axle weights, burial depths. The results demonstrate that the loss impedance undergoes significant changes under different conditions, exerting a substantial impact on the output of RPEHs, which should be considered during analysis. RPEHs positioned closer to the road surface produce higher output but also exhibit increased stress concentration. The pavement modulus is inversely proportional to the piezoelectric output, while the subgrade modulus has a comparatively smaller impact due to the stiffness of RPEHs.

A multi-frequency and multi-mode metasurface energy harvester for RF energy harvesting

Metasurface energy harvesters (MEHs) lessen the dependence of wireless communication devices on batteries or other external power sources by capturing untapped electromagnetic energy in the surroundings. In this paper, we propose a multi-frequency and multi-mode microwave metasurface for efficient radio frequency (RF) and microwave energy harvesting. The MEH is comprised of a sub-wavelength resonant ring array, which can harvest RF energy in both Wi-Fi and 5 GHz bands. A feeding network is designed to integrate the TE and TM wave energy collected by the MEH into two separate networks that each gather AC energy and deliver them to the resistive loads. In terms of the simulation’s results, the efficiency of energy harvesting at frequencies of 2.4 GHz, 3.1 GHz, as well as 3.6 GHz is 91.3%, 88.9%, and 73.9%, specifically. We manufactured a 6 × 6 array sample and conducted experiments utilizing a microwave anechoic chamber. The simulation results and results from experiments were approximately identical. The proposed design has potential applications in various fields, such as efficient wireless energy harvesting systems, self-powered devices, which has a significant potential on the environment and the energy sector by reducing carbon emissions and reducing reliance on non-renewable energy sources.

UAV‐assisted multi‐hop D2D relaying for communication in large disaster area

SummaryAn unmanned aerial vehicle (UAV)‐assisted communication is a promising technique for enabling ground users in a non‐functional area (NFA) or disaster area to communicate. All the base stations in the disaster area may be partially or fully damaged due to the natural calamity. Device‐to‐device (D2D) communication can be a viable solution for immediate connection between users in an NFA. We propose a UAV‐assisted multi‐hop D2D communication following a hybrid power‐time switching (PTS) in this paper. Moreover, a D2D user of a cluster can communicate with another D2D user in a different cluster through UAVs. However, D2D users can harvest energy from their respective ad hoc energy stations and forward the information to the nearby D2D user following a hybrid PTS‐based strategy. We propose a time frame for the same and show a node‐based energy harvesting strategy. The expressions of outage probability, throughput, end‐to‐end energy consumption, and energy efficiency are developed for the Rician and Nakagami‐m faded channel. The impact of several network parameters such as energy harvesting factor, energy harvesting efficiency, and fading parameter on the network performance is also indicated.

Analysis on flow-induced vibration of square cylinders with different vibration forms and the flow energy harvesting capacity

This study numerically investigates the flow-induced vibration (FIV) of a single-degree-of-freedom transverse vibration and pivoted rotation of a square cylinder with the Reynolds number (Re) range of 0.7 × 104 to 6 × 104. Different FIV phenomena with Re increasing are reported. In the vortex-induced vibration (VIV) branch, the amplitude and energy harvest efficiency of the transverse vibration are higher than those of the pivoted rotation, and the situation is opposite in the VIV-galloping transition and galloping branches. Checking the wake vortex indicated that the change in the angle of attack caused by the pivoted rotation of the square cylinder was the cause of these phenomena. The most significant feature was that, at the maximum amplitude, a pair of co-rotating vortices (C mode) shed. The transverse vibration had larger vibration amplitudes and lower aerodynamic force and energy harvest efficiency compared with the pivoted rotation in galloping, and the energy harvest efficiency no longer increased with higher Re. The energy harvest efficiency of the pivoted rotation had two outstanding peaks at maximum pivot angles of θmax = 29° and 41.2°, followed by a decreasing trend. For the transverse vibration, the force induced by the vortices cancels each other out so that the energy harvest efficiency almost does not change. For the pivoted rotation, the amplitude, which does not increase, makes it easier for the wake vortex to interact and interfere with the energy harvest procedure.

Novel Source-Storage Coordination Strategy Adaptive to Impulsive Generation Characteristic Suitable for Isolated Island Microgrid Scheduling

Wave energy generator (WEG) is a new renewable energy source with prominent advantages and disadvantages. Theoretically, it can move around the sea to harvest wave energy better and will not take up valuable land resources. Normally, WEG collects tiny wave energy continuously and generates electricity intermittently on the minute time-scale to enhance energy harvesting efficiency. Thus, the output of WEG shows prominent impulsive characteristics, which needs to be compensated by the battery energy storage system (BESS) and therefore brings about significant battery life losses. For the purpose of stable and economic operation of the weak power grid connected by WEG, a flexible control method enabling a quantifiable tradeoff between its energy harvesting efficiency and impulsive characteristics is proposed. Then, a novel source-storage coordination strategy and the corresponding energy exchange model of WEG with several optimizable control parameters is formulated to depict the energy flow within the microgrid. Subsequently, an optimization algorithm is proposed to schedule the WEG’s mobile route and optimizable control parameters simultaneously. Simulation results show that the proposed source-storage strategy and the energy management scheme can balance WEG’s energy harvesting and impulsive impact, and utilize its mobility to improve the isolated island microgrid’s operation economy and power quality.

Computational fluid dynamics-based PDMS-graphene triboelectric nanogenerator ‘PG-TENG’ blue energy harvester

Developing cost-effective and efficient energy harvesting technologies is critical with the rising demand for clean and sustainable energy. In this research paper we presents a CFD-based study on a PDMS-Graphene Triboelectric Nanogenerator (PG-TENG) for blue energy harvesting. Our study focuses on the vertical (contact-separation) mode of the PG-TENG and investigates the effect of TENG’s varying size on its electrical output performance. To optimize the properties and performance of the PG-TENG system, we used COMSOL Multiphysics for mathematical-modeling and simulations. The outcomes show that the varying size of the PG-TENG significantly impacts its electrical output capabilities, with larger PG-TENGs exhibiting higher current and voltage outputs. Moreover, we compared our outcomes to other studies on graphene-based TENGs and highlighted the advantages of our PG-TENG in terms of durability, performance, and mechanical stability. Our research contributes to the field of blue energy generation by providing insights into the design and optimization of PG-TENGs for low-cost, effective, and efficient energy harvester devices.

Enhancing Electrical Generation Efficiency through Parametrical Excitation and Slapping Force in Nonlinear Elastic Beams for Vibration Energy Harvesting.

This study aims to enhance conventional vibration energy harvesting systems (VEHs) by repositioning the piezoelectric patch (PZT) in the middle of a fixed-fixed elastic steel sheet instead of the root, as is commonly the case. The system is subjected to an axial simple harmonic force at one end to induce transversal vibration and deformation. To further improve power conversion, a baffle is strategically installed at the point of maximum deflection, introducing a slapping force to augment electrical energy harvesting. Employing the theory of nonlinear beams, the equation of motion for this nonlinear elastic beam is derived, and the method of multiple scales (MOMS) is used to analyze the phenomenon of parametric excitation. This study demonstrates through experiments and theoretical analysis that the second mode yields better power generation benefits than the first mode. Additionally, the voltage generation benefits of the enhanced system with the added baffle (slapping force) surpass those of traditional VEH systems. Overall, the proposed model proves feasible and holds promising potential for efficient vibration energy harvesting applications in various industrial sectors.

Wave-heat-electricity conversion: Design and analysis of an electromagnetic energy conversion device

An innovative electromagnetic energy harvester was developed using a compact four-ring single-resistor unit cell. To achieve efficient conversion of electromagnetic waves into electricity, we integrated the high-performance Bi2Te3 thermoelectric material onto the load resistor. Remarkably, this unit cell exhibits exceptional energy harvesting capabilities at a frequency of 5.8 GHz while maintaining polarization insensitivity. Through comprehensive analysis, we evaluated the energy harvesting efficiencies, power loss distribution, and current density distribution. Additionally, we investigated the impact of incident power on the unit cell's temperature and energy conversion efficiencies. To enhance energy concentration on the load, we ingeniously designed an “L-shaped” metal through-hole structure within the four-ring single-resistor unit cell. Our results demonstrate that the four-ring single-resistor unit cell achieves an impressive harvesting efficiency of 94.5% at 5.8 GHz, with a thermal conversion efficiency of 43.3 °C/W, an electrical conversion efficiency of 0.23 mV/°C, and an electrical response rate of 9.4 mV/W. Notably, when subjected to a power input of 7 W, the unit cell produces an output voltage of 65.9 mV, and its theoretical maximum output power reaches 180 mW.