Power Harvesting Research Articles

2D Ordered Mesoporous Lamellar Hetero-Nanochannels with Asymmetric Wettability for Controllable Ion Transport.

Heterogeneous membranes play a crucial role in osmotic energy conversion by effectively reducing concentration polarization. However, most heterogeneous membranes mitigate concentration polarization through an asymmetric charge distribution, resulting in compromised ion selectivity. Herein, hetero-nanochannels with asymmetric wettability composed of 2D mesoporous carbon and graphene oxide are constructed. The asymmetric wettability of the membrane endows it with the ability to suppress the concentration polarization without degrading the ion selectivity, as well as achieving a diode-like ion transport feature. As a result, enhanced osmotic energy harvesting is achieved with a power density of 6.41Wm-2 . This represents a substantial enhancement of 102.80-137.85% when compared to homogeneous 2D membranes, surpassing the performance of the majority of reported 2D membranes. Importantly, the membrane can be further used for high-performance ionic power harvesting by regulating ion transport, exceeding previously reported data by 89.1%.

Evaluation of a comprehensive power management system with maximum power point tracking algorithm for multiple microbial fuel cell energy harvesting

This study presents a comprehensive power management system (PMS) capable of tracking the maximum power point (MPP) and harvesting the energy from up to five microbial fuel cells (MFCs). The harvested energy from the MFCs was used to power the electronics, and in cases where this power was insufficient, alternative backup power options can be used. The voltage can be increased up to 3.3 V, and a hysteresis-based control approach was utilised to regulate the output voltage. The MPP of each MFC was determined using a variable step size incremental conductance algorithm that controls the duty cycle of the synchronous boost converters. No additional electronic components are necessary for the operation of the N and P-channel MOSFETs. The efficiency of the PMS relies on the target output voltage and the power output characteristics of the MFCs. Efficiencies of up to 87 % were achieved by combining the outputs of each MFC boost converter. To save energy, some electronic components are disabled when not in use, and the maximum power consumption of the PCB is below 5.8 mW at an output voltage of 3.3 V. The PMS is applied to simulated and real tubular MFCs under various operating conditions.

ELIXIR: An Expedient Connection Paradigm for Self-Powered IoT Devices

IoT devices usually work under power-constrained scenarios like outdoor environmental monitoring. Considering the cost and sustainability, in the long run, energy-harvesting technology is preferable for powering IoT devices. Since harvesting power is intrinsically weak and transient, the connection between IoT devices not only cannot be maintained constantly but is also extremely difficult to be established. In order to communicate, those devices should have a synchronized timeline so that both transmitter and receiver can start connection simultaneously. Yet due to the transient nature of ambient energy, volatile time data can be easily tampered with by the unstable power supply or corrupted completely by frequent power outages. As a result, unsynchronized IoT devices require significant efforts in time and energy to reconnect and communicate, which further escalates the performance degradation of the edge network. To adapt to ubiquitous self-powered scenarios on the IoT edge, we propose ELIXIR, an expedient connection paradigm, to synchronize swiftly and autonomously in a joint effort for self-powered IoT devices. The lightweight and highly efficient natures enable ELIXIR to be integrated into low-power IoT devices easily and efficiently. The experimental results show that the proposed ELIXIR can avoid a connection loop and help speed up the connection 2.83X and 1.84X faster than baseline methods.

Finite element analysis and computational fluid dynamic study of hybrid composite‐based offshore wind turbines

AbstractOffshore wind turbines are utilized for wind power harvesting through wind farms installed in bodies of water, normally at sea. The blades of the wind turbine resist the airflow and rotate and generate useful mechanical energy. Most of these wind blades are made of synthetic glass and carbon fibers. Synthetic fiber has higher mechanical strength but is non‐biodegradable in nature. The hybrid synthetic and natural composite materials overcome the non‐biodegradable issues to a certain extent and exhibit higher mechanical strength. In this prelude, the present work utilizes sisal, jute and rubber with epoxy‐based hybrid material used for wind blade manufacturing. The hybrid composite materials used in the present work have the volume fraction of synthetic fibers, natural fibers, and resin as 40 %, and 30 %, respectively. CATIA modelling software package is utilized to design the three‐dimensional model of the wind blade and is imported into the ANSYS Workbench. The structural, harmonic, and modal analyses are carried out, and the performance of the wind blades made of different hybrid composite materials is compared. Further, the computational fluid dynamic study is carried out to visualize the proposed composite offshore wind turbine's flow distribution. The results revealed that the proposed hybrid glass/jute/epoxy composite material yields better results and is more suited for offshore wind blade manufacturing.

Recent Patent for Walking Device of Corn Harvester

Background: Corn harvesting is an important part of the entire corn production process. Corn harvester power, turning radius and dehulling device will directly affect harvest efficiency and the quality of harvested corn. Obtaining better performance peeling device with strong power and minimum turning radius is the research direction in this field. Objective: This paper summarizes the patents of the walking system of corn harvesters at home and abroad in recent years, and introduces the characteristics and development of knapsack harvesters, trailed harvesters and self-propelled harvesters, such as power, turning radius and artificial intelligence. summarize its development trend, and provide reference for the development of various aspects of crop harvester. Methods: This paper reviewed the research status of the corn harvester walking system in recent years, and discussed the structure types and applications of various harvester walking systems. Results: By summarizing the patents of the walking system of the corn harvester, this paper obtains the current patent application status, analyzes the main problems in its development, and discusses the problems existing in the walking system of the harvester and the future research direction. Conclusion: The running device of the existing harvester needs to be further improved in terms of reliability, power system, turning radius, etc. The patent of the walking device of the harvester is yet to be developed. With the application of GPS, sensing and detection, information processing, automatic control and other technologies in the field of harvesting, the mechanized corn harvesting is gradually developing towards intelligence and automation.

Bracelet +: Harvesting Leaked RF Energy in VLC with Body Antenna

Recent studies show that the transmitters of Visible Light Communication (VLC) - a promising technology for future 6G networks - not only emit visible light signals but also leak RF signals during transmissions. In this work, we aim to harvest energy from these leaked RF signals. We observe that surrounding objects could help harvest significantly more energy. Based on this observation, we design Bracelet+, which involves the human body as part of the antenna to increase the harvested energy. We prototype our antenna as a bracelet that achieves both high harvested power and convenience for wearing. Bracelet+ improves the average harvested energy by 10x more, achieving micro-watt power harvesting and having potential to power up ultra-low-power sensors such as temperature and glucose sensors.

Simultaneously transmitting and reflecting reconfigurable intelligent surfaces (STAR-RIS) with energy harvesting and adaptive power

Simultaneously transmitting and reflecting reconfigurable intelligent surfaces (STAR-RIS) with energy harvesting and adaptive power

Ultra-Stable ITO-Free Organic Solar Cells and Modules Processed from Non-Halogenated Solvents under Indoor Illumination.

Organic Photovoltaics (OPV) is a very promising technology to harvest artificial illumination and power smart devices of the Internet of Things (IoT). Efficiencies as high as 30.2% have been reported for OPVs under warm white light-emitting diode (LED) light. This is due to the narrow spectrum of indoor light, which leads to an optimal bandgap of ≈1.9eV. Under full sunlight, OPV devices often suffer from poor stability compared to the established inorganic PV technologies such as crystalline silicon. This study focuses on a potentially very cost-effective Indium Tin Oxide (ITO) free cell stack with absorber materials processed from non-halogenated solvents. These organic solar cells and modules with efficiencies up to 21% can already achieve remarkable stabilities under typical indoor illumination. Aging under 50,000lux LED lighting leads to very little degradation after more than 11000h. This light dose corresponds to more than 110years under 500lux. For modules encapsulated with a flexible barrier, extrapolated lifetimes of more than 41years are achieved. This shows that OPV is mature for the specific application under indoor illumination. Due to the large number of potential organic semiconducting materials, further efficiency increase can be expected.

Assessment of past and future potential of ocean wave power in the Gulf of Guinea

ABSTRACT This study investigated the historical and future wave power potential in the Gulf of Guinea (GoG) with the aim of identifying high-density wave energy locations for potential exploitation. To estimate wave power density (WPD) for three time periods (past: 1979–2005, mid-century: 2026–2050, and end-century: 2081–2100), we utilized significant wave height and mean wave period obtained from eight General Circulation Models. Using an ensemble of these WAVEWATCH III simulated datasets, we calculated WPD and assessed overall and seasonal trends, projecting changes under Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios. Results revealed higher potential WPD in the western GoG, particularly near the coast, with increased values offshore. Spatially, WPD change rates varied widely (−0.021 to 0.039 kW/m per year), suggesting both positive and negative trends, though generally low. Projections indicated a potential increase from 0.5 to 1.0 kW/m by the end of the century. The estimated potential power for harvesting exceeded 14,000 MW, with offshore regions showing better wave converter performance. This study concludes that GoG's wave energy is a promising renewable resource, offering a potential solution to future power needs and contributing to regional greenhouse gas emission mitigation.

How technical change has boosted fish aggregation device productivity in the Indian Ocean tuna fishery

Excess harvesting power can threaten the long-term sustainability of fisheries. Indicators of excess harvesting capacity must include input–output-based estimates of economic production efficiency. The increasing use of drifting Fish-Aggregating-Devices (DFADs) has boosted fishing productivity in high-seas tuna fisheries, perhaps beyond the biological capacity of the stocks, and is an object of global debate. We carried out a Data Envelopment Analysis (DEA) of relative changes in production efficiencies of the French purse-seine fleet targeting tropical tuna in the western Indian Ocean using two fishing strategies: (1) on floating objects (FOB) and (2) free swimming schools (FSC) using tuna catch and effort data spanning 1992–2019. We show that FOB fishing evolved dramatically through time with an estimated change of 3.6%yr−1 (8.0%yr−1 2007–2019), in contrast to 2.1%yr−1 for FSC. While the efficiency level in combining and using inputs has barely changed for FOB fishing, it means that all the growth in productivity comes from technical change for this strategy. The dynamics is different for the FSC with a mixture of innovation and higher efficiency. Immediate plans to improve input-based management in this region are needed to prevent further risks of overfishing to yellowfin (Thunnus albacares) and skipjack (Katsuwonus pelamis) tunas.

Ultrahigh Thermoelectric Performance of ZnO-CdO Thin Films

Zinc oxide (ZnO) is emerging as a promising n-type thermoelectric material (TE) for power harvesting due to its high melting point and large Seebeck coefficient. However, the TE performance of ZnO is limited by high thermal conductivity and low carrier mobility. Adding or doping a divalent element such as cadmium oxide (CdO) can lower the thermal conductivity and enhance the carrier concentration of ZnO. In this paper, the thermoelectric transport properties of ZnO-CdO nanocrystalline thin films are investigated by varying the Zn/Cd ratio at temperatures ranging from room temperature (RT) to 423 K. The electrical conductivity, carrier concentration and mobility of ZnO were enhanced by increasing the Cd concentration. The maximum power factor of 2.75 × 10−4 W m−1 K−2 was obtained at 423 K for the Zn/Cd = 1:3 sample. The thermal conductivity was dominated by lattice thermal conductivity in which Umklapp scattering occurs between anharmonic phonons. The thermal conductivity of ZnO decreased significantly with increasing Cd concentration. The highest estimated figure of merit (ZT) of 0.59 was found at 413 K for the Zn/Cd = 1:3 sample, which is 223 times greater than for ZnO, indicating that the film is efficient in energy generation.

Graphene-based biomimetic array film for simultaneous fog water harvesting and wind power generation

Due to geographical restrictions, water and electricity shortages have always been crucial problems in remote areas. Among the numerous potential solutions, the fog harvesting technique using a film has been recognized as one of the effective methods for water collection in dry regions. In this study, researchers drew inspiration from desert beetles in nature to fabricate a biomimetic chitosan hydrophilic array coated on a hydrophobic PVDF/graphene (PG) film that is capable of efficient fog water harvesting, reaching an efficiency of up to 0.63 LMH. Graphene and an ionic liquid (IL) were used to synergistically induce the self-assembly of PVDF crystalline phases into a piezoelectric β-phase, and the resulting optimized PG/IL1.5 wt% film could have a voltage output of up to 13 V (±6.5 V). Upon conducting an integrated assessment of water and electricity extraction from the film, and the results indicated a water collection efficiency of 0.74 LMH and a power generation of 99.2 mW/m2 at a fog wind speed of 4 m/s. Based on the aforementioned research findings, we have demonstrated that a single film utilizing fog and wind as driving forces can achieve simultaneous water and electricity production, providing new research directions for the development of next-generation functional films in the future.

Joint optimization of trajectory and resource allocation in cellular-connected multi-UAV MEC networks

Unmanned aerial vehicles (UAVs)-based mobile edge computing (MEC) has been introduced as a promising model for enhanced edge communications in the future of integrated air-sky-earth and sea communications. However, in UAV-assisted mobile edge computing systems, the energy consumption problem of UAVs during computational offloading becomes a serious challenge. Due to UAVs constrained energy and processing capabilities, the majority of current research does not adequately take into the task of offloading UAVs as end users and the energy consumption problem. Considering this, this paper proposes a novel cellular-connected multi-UAV MEC network in which the UAV can offload its computational tasks to a ground-based station (GBS) and the UAV can harvest energy from the GBS. Total UAV energy consumption is minimized by jointly optimizing the UAV-GBS association, UAV transmit power, UAV trajectory, and energy harvesting time. The formulated energy consumption minimization problem is a difficult non-convex optimization problem. To solve this issue, the optimization problem is first broken down into three sub-optimization problems and resolved using successive convex optimization techniques. Then a joint block coordinate descent (BCD) based resource allocation and UAV trajectory algorithm is proposed to solve the overall optimization problem. Finally, the effectiveness of the suggested scheme is verified by simulation. The simulation results demonstrate that the suggested strategy is more efficient and performs better.

Trans‐oceanic subsurface photovoltaic performance

AbstractUtilization of marine photovoltaic energy is primarily focused on surface harvesting with limited photovoltaic cell implementations in submarine environments. Potential applications include marine wildlife telemetry devices, autonomous underwater vehicles, or remote sensing assets. In these applications, understanding the power at depth is critical, but there has yet to be a long‐term study of cell performance in a realistic marine environment that spans time, geographic location, and depth. In this paper, we present photovoltaic assessments carried out by devices mounted to adult female northern elephant seals (Mirounga angustirostris) during their spring migrations in the Pacific Ocean with deployment times between 76 and 107 days. Encompassing a large geographic area between Santa Cruz, California, and the Aleutian Islands of Alaska during their migrations, elephant seal behavior allows for repeated depth profiles each day, making them an ideal host for subsurface power assessments. This paper presents the first longitudinal study of photovoltaic cell performance in the marine environment that spans location, time, and depth. This work discusses the calibration, data time alignment, and power calculations of these oceanic deployments. Deployment results, including power results and energy predictions from the data record, are presented up to 22 m in depth. We highlight how the recorded power data of these cells compares to previously published results and how depth impacts subsurface power and energy harvesting.

Impedance-Matching-Based Maximum Power Tracking for Magnetic Field Energy Harvesters Using Active Rectifiers

Increasing the power harvested from magnetic field energy harvesters (MFEHs) without expanding their volumes is crucial. Conventional methods for improving power harvest, e.g., flux-shaping capacitor and transfer window alignment techniques, are not applicable under varying primary current and load conditions. To address this vital problem, this paper presents a control strategy of MFEHs based on impedance matching theory, which considers the nonlinear characteristic of magnetic energy sources and can track the maximum power under varying current and load conditions based on an active rectifier. A calculation formula is derived to determine the optimal initial operating point of the active rectifier circuit, which aims to adjust the equivalent impedance to achieve maximum power tracking. An experimental prototype is constructed to verify the effectiveness of the proposed method. It is found that the proposed method enhances the harvested power under different current and load conditions, particularly in deep saturation conditions. Experimental results show that the proposed MFEH can harvest an average power of 2.51W on an 800Ω load from a 50Hz 80A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RMS</sub> power line, which is increased by 136.8% compared with the conventional MFEH with a passive rectifier.

Deep Learning Framework for Two-Way MISO Wireless-Powered Interference Channels

In this paper, we present a realistic and novel protocol for two-way communication in multiple-input-single-output (MISO) wireless-powered interference channels, namely, a simultaneous wireless information and power transfer (SWIPT) then wireless information transfer (WIT) protocol. In the protocol considered, transmitters first perform SWIPT in a forward link (FL) and receivers and then execute WIT using the harvested energy in a backward link (BL). Given that the operation of SWIPT in the FL affects the performance of WIT in the BL, our aim is to find a resource allocation strategy that maximizes the sum spectral efficiency (SE) of the FL and BL, which requires the joint optimization of the transmit beamforming vector, transmit power, and energy harvesting (EH) ratio in the FL and the receive beamforming vector in the BL. To deal with the non-convexity of the optimization problem, a deep learning (DL) framework is devised, in which the optimal resource allocation strategy is approximated by a well-designed deep neural network (DNN) model consisting of six independent DNN modules where the sigmoid and softmax functions are jointly utilized to properly model each control parameter. Furthermore, a two-stage training method is proposed where the DNN model is initialized using suboptimal solutions that are found using a low complexity algorithm in a supervised manner before it is fine-tuned using the main training based on unsupervised learning. Through intensive simulations performed in various environments, we confirm that the proposed method improves the training performance of the DNN model while reducing the training overhead. As a result, the proposed DL-based resource allocation achieves a near-optimal performance in terms of the sum SE with a low computation time.

New model for structural optimisation of airborne wind energy systems with rotary transmission

Rotary Airborne Wind Energy Systems (RAWES) are networks of wings that act as flying wind turbines. The power extracted from the wind can be transmitted to ground-based generators through open tensegrity structures. In recent years, there have been different approaches to the topology of the Tensile Rotary Power Transmission (TRPT) and prototype designs are often driven by trial-and-error. This paper proposes a steady-state model with numerical optimisation to accelerate the development and prototyping of AWES by supporting the evaluation of new design concepts.The coupled steady state model uses aerodynamics and structural dynamics to analyse the AWES performance. A novelty is, that the model includes both cross-wind pressure drag and axial friction drag acting on the tethers and frames in the tensegrity structure. Validation of the model has been achieved using data from field measurements of two prototypes.In conclusion, using the proposed optimisation, RAWES with TRPT can be designed to maximise power density, coefficients of performance or power harvesting factor. While RAWES will not be able to outperform conventional wind turbines, they have the potential advantages in niche applications due to reduced costs and simplified logistics resulting from reduced material usage.

Optimum PV reconfiguration approach based on SOA for improving the harvest power under PS situations

Optimum PV reconfiguration approach based on SOA for improving the harvest power under PS situations

A wireless, battery-free device enables oxygen generation and immune protection of therapeutic xenotransplants in vivo

The immune isolation of cells within devices has the potential to enable long-term protein replacement and functional cures for a range of diseases, without requiring immune suppressive therapy. However, a lack of vasculature and the formation of fibrotic capsules around cell immune-isolating devices limits oxygen availability, leading to hypoxia and cell death in vivo. This is particularly problematic for pancreatic islet cells that have high O2 requirements. Here, we combine bioelectronics with encapsulated cell therapies to develop the first wireless, battery-free oxygen-generating immune-isolating device (O2-Macrodevice) for the oxygenation and immune isolation of cells in vivo. The system relies on electrochemical water splitting based on a water-vapor reactant feed, sustained by wireless power harvesting based on a flexible resonant inductive coupling circuit. As such, the device does not require pumping, refilling, or ports for recharging and does not generate potentially toxic side products. Through systematic in vitro studies with primary cell lines and cell lines engineered to secrete protein, we demonstrate device performance in preventing hypoxia in ambient oxygen concentrations as low as 0.5%. Importantly, this device has shown the potential to enable subcutaneous (SC) survival of encapsulated islet cells, in vivo in awake, freely moving, immune-competent animals. Islet transplantation in Type I Diabetes represents an important application space, and 1-mo studies in immune-competent animals with SC implants show that the O2-Macrodevice allows for survival and function of islets at high densities (~1,000 islets/cm2) in vivo without immune suppression and induces normoglycemia in diabetic animals.

Electrical power harvesting enhancement of PV module by a novel hemispherical configuration

The energy generation demand from environmentally friendly sources is increasing rapidly nowadays. One of the most essential renewable energy systems in this regard is the photovoltaic (PV) module. However, this technology accompanies several limitations, including the ground footprint and tilt angle sensitivity. In this study, the PV module shape has been modified to enhance the productivity of the PV system. The proposed PV module with a hemispherical shape is established to reduce the land cost and provide a perpendicular PV area exposure to the sun all day to harvest sunlight and generate more power without any supporting system. Besides, the proposed hemispherical shape has advantages in aesthetic terms of the PV system to enhance the flat black shape of this technology. The current paper also attempted to develop a new design of a curved PV hemispherical shape that needed less land footprint than the traditional flat shape by 19%. The experimental results showed that the tilted 45° hemispherical PV module generated more power than the conventional tilted PV module by 5%–6% per day in summer. Besides, the power line behaviour was more likely to be as the power generated from the traditional PV module with a tracking system.