Hybrid Harvester Research Articles

Investigation of a hybrid piezo-electromagnetic energy harvester

Abstract A hybrid energy harvester combining piezoelectric and electromagnetic transduction mechanisms is designed to scavenge vibration energy. The system comprises of a cantilever beam, a piezoelectric harvester and a magnetic mass hung through a spring at the free end. The beam with piezoelectric harvests electrical energy due to the strain induced in the piezoelectric patch. The hung mass oscillates in and out a solenoid to harvest energy due to electromagnetic induction. The system can generate power from any vertically oscillating vibrating host structure. This paper studies the power harvested from the hybrid harvester under harmonic excitation using experimental and analytical evaluations. Comparisons are made with the standalone piezoelectric and electromagnetic harvester under the same excitation environment. The study shows that the present hybrid harvester can harvest energy at a broad range of frequencies. Furthermore few parametric studies are carried out for understanding the device performance. Finally, the efficiency of the proposed hybrid energy harvester is compared with the existing hybrid energy harvester.

A human locomotion driven hybrid energy harvester for wrist wearable applications

In this work, a human locomotion driven hybrid energy generator has been proposed and experimentally validated for scavenging significant biomechanical energy from natural motion of arm swinging, to be used for wrist-wearable smart device applications. A proposed hybrid electromagnetic (EM) and triboelectric (TE) generator can deliver much higher output power than that of the individual harvesting device unit due to the combinational operation of EM and TE mechanisms under the same applied mechanical movements. A novel curved structural design based energy harvester is proposed from the comparative analysis of human hand swinging motion with double pendulum motion, which helps to enhance the output performance and design it fit to wear on wrist. The swinging of human arm during walking and running initiates a freely movable magnetic metal ball to oscillate inside the curved structure through both EM and TE part. The EM part consists of two coils wrapped around the curved body, one at each end and micro-structured Polydimethylsiloxane (PDMS) film is attached on the inner wall of curved body along with copper electrode for TE part. A prototype of the hybrid harvester has been fabricated and tested. The EM and TE devices are capable of delivering maximum 84.37mW peak power at 49.2Ω matching load resistance and 1.86μW peak power at 10MΩ load resistance respectively which are considerably higher than the trending state-of-the-art devices.

Performance analysis of hybrid vibrational energy harvesters with experimental verification

In the present work, performance indices for a hybrid energy harvester (HEH) that is composed of piezoelectric and electrodynamic or electromagnetic mechanisms of energy conversion are analyzed. Performance of a HEH is defined in terms of Q-normalized power factor and efficiency of conversion. They are observed to acutely depend on coupling strength or figures of merit in both piezoelectric and electrodynamic domains. The influence of figures of merit on the Q-normalized power factor, and the limits of conversion efficiency are explored. Based on the studies, a suitable range for figures of merit that would maximize both Q-normalized power factor and conversion efficiency in hybrid harvesters is proposed. The proposed idea is verified experimentally for the appropriate values of figures of merit and efficiencies by fabricating and testing four experimental models of the HEHs.

Heterogeneous 3-D ICs as a platform for hybrid energy harvesting in IoT systems

Three-dimensional integrated circuits are a natural platform for IoT systems. IoT systems exhibit a small footprint, integrate disparate technologies, and require long term sustainability (extremely low power or self-powered). A hybrid energy harvesting system within a three-dimensional integrated circuit is proposed in this paper. The harvesting system exploits different types of energy available from the ambient (electromagnetic, solar, thermal, and kinetic). Integration of the hybrid harvesting system onto a three-dimensional platform ensures that each type of harvested energy can be individually collected. Both static and dynamic evaluations of a hybrid energy harvesting system are provided. For an example IoT system, the static power requirements are approximately 85% of the power delivered to the load. In the dynamic evaluation, a range of activity factors characterizing the load and different storage capacitors are considered. The power requirements of a typical IoT system are shown to be satisfied by a hybrid energy harvesting system within a 3-D platform.

Analysis and experiment of magneto-mechanically coupled harvesters

Abstract Current trend in energy harvesting research is to increase the operating bandwidth of energy harvesters. Multiple harvesters, nonlinear harvesters and hybrid harvesters are suggested to address the issue. In this paper, a system consisting of two electromagnetic harvesters with magnetic and mechanical couplings subjected to harmonic support excitations is proposed. Two pendulums with close resonating frequencies are used to generate power over a broad range of frequencies. The pendulums behave nonlinearly under the influence of magnetic interaction. This nonlinear motion harvests power at broader bandwidth. A mathematical model of the proposed harvester is established. Experiments are performed to validate the theoretical results. It has been observed that the nonlinear responses due to both magnet and mechanical couplings improve individual harvester performance. This is advantageous over harvesters that have magnetically coupling only. Additionally, the dynamics of harvesting system is numerically studied where large amplitude chaotic motion, quasi-periodic oscillations and periodic motions are observed and reported.

An Experimentally Validated Lumped Circuit Model for Piezoelectric and Electrodynamic Hybrid Harvesters

Energy harvesters transform the ambient energy into usable electrical form that can be potentially used by sensors and other low-power devices. In this paper, modeling of a hybrid energy harvester that is composed of piezoelectric and electrodynamic mechanisms of energy conversion is presented and the predictions from the model are corroborated by experimental results from two hybrid harvesters designed and fabricated for the purpose. A method of representing a hybrid energy harvester using lumped circuit elements is proposed. The optimal electrical loads are then determined with relative ease from the equivalent circuit of the harvester. A magnetic circuit that provides maximum electromechanical coupling in the electrodynamic domain is designed. Moreover, a curved piezoelectric beam is analyzed for a compact arrangement of both domains in a single harvester. Two hybrid energy harvesters having the same electrodynamic domain, one with curved piezoelectric beam and the other with a straight piezoelectric beam, are fabricated and evaluated for their performance in comparison with that estimated from the proposed model. Experimental models generating 1.7 mW from 0.5 $\text{g}_{n}$ input acceleration have been realized with at least 50% of conversion efficiency.

Performance Characterization of Spatially Random Energy Harvesting Underlay D2D Networks With Transmit Power Control

In underlay device-to-device (D2D) networks, the transmitter nodes can harvest energy from downlink cellular (primary) transmissions to solely power the D2D links, which enhances the overall spectral and energy efficiencies. How will the energy harvest and D2D link performance be affected by spatial randomness, temporal correlations, transmit power control, and channel uncertainties? To investigate these issues, we analyze the energy harvesting process of a random (typical) D2D transmitter node, say $\mathcal D_{t}$ , which needs a sufficient harvest to meet the requirements for receiver sensitivity and channel inversion. This system model consists of: 1) three independent homogeneous Poisson point processes; 2) log-distance path loss and Rayleigh fading; and 3) path loss inversion transmit power control. We derive the ambient radio frequency energy at $\mathcal D_{t}$ , and model the harvest as a Gamma random variable. We propose four schemes: 1) single slot harvesting; 2) multislot harvesting; 3) $\mathcal {N}$ slot harvesting; and 4) hybrid harvesting. We develop a Markov chain model for success probability of these schemes, and derive the D2D coverage. We find that a high density of primary transmitters is unfavorable to multislot harvesting for increased D2D link distances. Moreover, hybrid harvesting always outperforms single and $\mathcal {N}$ slot harvesting, and outperforms multislot harvesting except for very high path-loss conditions.

High performance human-induced vibration driven hybrid energy harvester for powering portable electronics

In this work, we demonstrated theoretically and experimentally the use of a dual Halbach magnet array and combined with a magnetically floated electromagnetic–triboelectric energy harvester to convert the mechanical energy of human induced motion into electrical energy. To achieve very high generated powers, the proposed hybrid energy harvester included a Halbach magnet array, nanostructured polytetrafluoroethylene (PTFE), Al nano–grass, and magnetic springs. A prototype of the hybrid energy harvester was fabricated and tested, with either a vibration exciter or human induced motion. Under a vibration exciter test, the fabricated hybrid energy harvester delivered a high output current of 3.74mA and a power of 10.07mW, corresponding to a volume power density of 344W/m3 under a loading resistance of 710Ω at 4.5Hz resonant frequency and 0.6g acceleration. In addition, the hybrid harvester was able to generate output powers of 5.8mW, 2.6mW, and 3.4mW from human induced vibration of handshaking, walking, and slow running, respectively. The fabricated hybrid electromagnetic–triboelectric harvester exhibits a much higher power density than recently reported in similar works. This work takes a significant step toward hybrid energy harvesting from human induced motion and its potential applications in powered portable electronics.

A Hybrid Electromagnetic–Triboelectric Energy Harvester Using a Dual Halbach Magnet Array Powered by Human‐Body‐Induced Motion

AbstractA highly miniaturized hybridization of electromagnetic–triboelectric energy harvesters with different mechanisms in one harvester is proposed using a Halbach magnet array from human‐body‐induced motion, and it is theoretically and experimentally validated. In particular, the proposed dual Halbach array allows the concentrated magnetic flux lines to interact with the same coil in a manner that produces maximum flux linkage. To obtain much higher power generation at low‐amplitude and low‐frequency vibrations, the proposed harvester is comprised of a Halbach magnet array, sandpaper‐based microstructure polydimethylsiloxane (PDMS), a triboelectric, and magnetic springs. A prototype of the hybrid energy harvester is fabricated and tested, both using a vibration exciter test, and by manual handshaking. Under vibration exciter test, the fabricated hybrid harvester prototype delivers a high output current and power of 4.5 mA and 12.51 mW, respectively, corresponding to a volume power density of 411 W m−3 under a loading resistance of 617 Ω at 6.5 Hz resonant frequency and 0.5g acceleration. The hybrid prototype is also capable of delivering output current and power of 3.55 mA and 7.35 mW, respectively, if driven by handshaking vibration. The fabricated hybridized harvester exhibits much higher power density than similar recently reported works.

A triple hybrid micropower generator with simultaneous multi-mode energy harvesting

This study presents a triple hybrid energy harvesting system that combines harvested power from thermoelectric (TE), vibration-based electromagnetic (EM) and piezoelectric (PZT) harvesters into a single DC supply. A power management circuit is designed and implemented in 180 nm standard CMOS technology based on the distinct requirements of each harvester, and is terminated with a Schottky diode to avoid reverse current flow. The system topology hence supports simultaneous power generation and delivery from low and high frequency vibrations as well as temperature differences in the environment. The ultra-low DC voltage harvested from TE generator is boosted with a cross-coupled charge-pump driven by an LC oscillator with fully-integrated center-tapped differential inductors. The EM harvester output was rectified with a self-powered and low drop-out AC/DC doubler circuit. The PZT interface electronics benefits from peak-to-peak cycle of the harvested voltage through a negative voltage converter followed by synchronous power extraction and DC-to-DC conversion through internal switches, and an external inductor. The hybrid system was tested with a wearable in-house EM energy harvester placed wrist of a jogger, a commercial low volume PZT harvester, and DC supply as the TE generator output. The system generates more than 1.2 V output for load resistances higher than 50 kΩ, which corresponds to 24 μW to power wearable sensors. Simultaneous multi-mode operation achieves higher voltage and power compared to stand-alone harvesting circuits, and generates up to 110 μW of output power. This is the first hybrid harvester circuit that simultaneously extracts energy from three independent sources, and delivers a single DC output.

Optimizing Joint Data and Power Transfer in Energy Harvesting Multiuser Wireless Networks

Energy harvesting emerges as a potential solution for prolonging the lifetime of the energy-constrained mobile wireless devices. In this paper, we focus on Radio Frequency (RF) energy harvesting for multiuser multicarrier mobile wireless networks. Specifically, we propose joint data and energy transfer optimization frameworks for powering mobile wireless devices through RF energy harvesting. We introduce a power utility that captures the power consumption cost at the base station (BS) and the used power from the users' batteries, and determine optimal power resource allocations that meet data rate requirements of downlink and uplink communications. Two types of harvesting capabilities are considered at each user: harvesting only from dedicated RF signals and hybrid harvesting from both dedicated and ambient RF signals. The developed frameworks increase the end users' battery lifetime at the cost of a slight increase in the BS power consumption. Several evaluation studies are conducted in order to validate our proposed frameworks.

The effects of maize ( Zea mays L.) hybrid and harvest date on above- and belowground biomass dynamics, forage yield and quality – A trade-off for carbon inputs?

Abstract There are two major environmental constraints of silage maize (Zea mays L.) production: loss of soil organic carbon (SOC) and nitrogen (N) leaching to groundwater. Winter catch crops (CC) increase carbon inputs and can accumulate residual N, but only if the preceding maize is harvested timely to allow high above- and belowground biomass and N accumulation. To quantify the combined effects of hybrid maize variety and harvest date on forage yield and quality, as well as on root dynamics, root turnover and carbon input, a two-year field experiment (April 2012–October 2013) was conducted in northern Germany. Early maturing Suleyka was harvested at 10 (hd1) and 20 (hd2) September and mid-early Ronaldinio at 30 September (hd3) and 15 October (hd4). Maize hybrids showed no consistent differences of aboveground dry matter (DM) and N accumulation dynamics. Only the very early harvest (hd1) resulted in 11–13% lower DM yields. Sufficiently high DM and starch contents, however, were not achieved at harvest dates prior to hd3 (30 September). Similar to shoot yield, the final accumulated root biomass, carbon (C) and N were not affected by hybrid/harvest date, and on average amounted 2.48 t DM, 1.2 t C and 52.9 kg N ha‐1 in the upper soil depth of 30 cm, which represented between 77 and 75% of the DM, C and N accumulation to 60 cm soil depth. Root turnover during the growing season reached up to 65, 75 and 69% of root DM, N and C. Stubble DM and C left on the field, however, was 31% lower at early harvest (hd1) compared to later harvests, resulting in a trade-off to total C inputs compared to delayed harvest. The quantified C inputs are discussed by two C balance approaches, which indicate that silage maize cultivation is not necessarily associated with SOC degradation, especially if winter catch crops are introduced.

Energy generation in a hybrid harvester under harmonic excitation

A hybrid energy harvester combining piezoelectric and electromagnetic transduction mechanisms is designed to harvest vibration energy. The system comprises of a cantilever beam PZT harvester and a magnetic mass hung through a spring at the free end. The beam with PZT harvests energy using piezoelectric effect while the hanging mass oscillates through a copper coil to harvest electromagnetic energy. This paper studies power harvested from the hybrid harvester under harmonic excitation using experimental and analytical evaluations. Comparisons are made with the standalone piezoelectric and electromagnetic harvesters under similar excitation environment. The study shows that the present hybrid harvester can harvest energy at a broad range of frequencies. Furthermore, a few parametric studies are carried out to understand the device output performance. The bandwidth of the harvester and the power harvested within the bandwidth can be designed based on the stiffness of the system and also by changing the electromechanical coupling coefficient. Studies reported also show that bandwidth of harvester can also be increased by increasing the magnetic mass.

Eclectic Approach to the Donor Area in Baldness Surgery: Use of the Preview Long Hair (PLH) and Hybrid Harvesting Technique (FUE + FUT)

Eclectic Approach to the Donor Area in Baldness Surgery: Use of the Preview Long Hair (PLH) and Hybrid Harvesting Technique (FUE + FUT)

Effects of agronomic factors on yield and quality of whole corn plants and the impact of feeding high concentrations of corn silage in diets containing distillers grains to finishing cattle.

Corn plants were sampled over 2 consecutive years to assess the effects of corn hybrid maturity class, plant population, and harvest time on whole corn plant quality and yield in Nebraska. A finishing experiment evaluated the substitution of corn with corn silage in diets with corn modified distillers grains with solubles (MDGS). The first 2 harvest dates were at the mid- and late-silage harvest times whereas the final harvest was at the grain harvest stage of plant maturity. Whole plant yields increased as harvest time progressed (yr 1 quadratic P < 0.01; yr 2 linear P < 0.01). However, differences in TDN concentration in both years were quite minimal across harvest time, because grain percentage increased but residue NDF in-situ disappearance decreased as harvest time was delayed. In the finishing experiment, as corn silage inclusion increased from 15 to 55% (DM basis) by replacing dry rolled and high moisture corn grain with corn silage in diets containing 40% MDGS, DMI, ADG, and G:F linearly decreased (P ≤ 0.01), with the steers on the 15% corn silage treatment being 1.5%, 5.0%, and 7.7% more efficient than steers on treatments containing 30, 45, and 55% corn silage, respectively. Calculated dietary NEm and NEg decreased linearly as corn silage inclusion increased indicating that net energy values were greater for corn grain than for corn silage. In addition, dressing percentage decreased linearly (P < 0.01) as silage inclusion increased suggesting more fill as silage inclusion increases in diets. Cattle fed greater than 15% corn silage in finishing diets based on corn grain will gain slower and be slightly less efficient and likely require increased days to market at similar carcass fatness and size. When 30% silage was fed with 65% MDGS, DMI, and ADG were decreased (P < 0.01) compared to feeding 30% silage with 40% MDGS suggesting some benefit to including a proportion of corn in the diet. Conversely, when 45% silage was fed with 40% MDGS, ADG, and G:F were greater (P < 0.04) than when 45% silage was fed with just grain implying a greater energy value for MDGS than for corn grain. Substituting corn silage for corn grain in finishing diets decreased ADG and G:F which would increase days to finish to an equal carcass weight; however, in this experiment, increasing corn silage levels with MDGS present reduced carcass fat thickness without significantly decreasing marbling score.

A low-frequency piezoelectric-electromagnetic-triboelectric hybrid broadband vibration energy harvester

In practical applications, vibration-based energy harvesters are usually restricted by their output performance and operating bandwidth. Therefore, improving the performance and increasing the operating bandwidth of vibration energy harvester become to two significant and urgent research focuses in past years. In this paper, a low-frequency piezoelectric-electromagnetic-triboelectric hybrid broadband vibration energy harvester is presented and investigated. It consists of flexible PET picking-up vibration structures which designed to achieve broadband behavior at low acceleration. In the meanwhile, integrate piezoelectric, triboelectric and electromagnetic mechanisms successfully enhanced the electric output of the hybrid energy harvester. As a result, the novel hybrid harvester can scavenge vibration energy at a wide vibration frequency. Under 0.5g acceleration at 20Hz, the novel hybrid harvester obtained maximum output power 41.0μW at a load resistance of 800.1kΩ for one PEH unit, 66.5μW at a load resistance of 343.1Ω for one EMEH unit, and 4.6μW at a load resistance of 1.4MΩ for one TEH unit, and the piezoelectric, electromagnetic and triboelectric EH units can reach 3.5Hz, 10.0Hz, and 18.1Hz operating bandwidth under 0.5g acceleration, respectively.

The Design, Simulation and Testing of V-shape Roof Guide Vane Integrated with an Eco-roof System

Abstract The aim of this study is to present the performance of an innovative wind–solar-rain water hybrid renewable energy generator and harvester roof system. A novel V-shape roof guide vane (VRGV) that located above the vertical axis wind turbine (VAWT) is introduced to guide and increase the wind speed by the venturi effect before it interacts with the rotor blades, hence improve the performance of the wind turbine. 2D CFD simulations was carried out to verify the optimized effect of VRGV out of nine different angles of roof designs and to estimate the increased speed by the VRGV. From the simulations, the optimum inclination arrangement of the V-shape roof guide vane is 25°. The wind speed augmented factor of the VRGV was 44%, from 2.00 m/s to 2.88 m/s. The working concept of the VRGV is to minimize the negative torque zone of a VAWT and to reduce turbulence and rotational speed fluctuation. Besides, the design of the VRGV that blends into the building architecture can be aesthetic as well. An experimental setup has been developed to verify the effect of VRGV using a prototype. Anemometric measurements were used to calculate the power of wind turbine. The system was also designed to provide optimum surface area and orientation for solar power generation. An automatic cooling and cleaning system with a stream of rain water was designed to clean and cool the roof which can improve the electrical efficiency of the solar photovoltaic modules. The ventilation vents of the system allow warm air inside the building to be ventilated out from the building by the pressure difference. The skylighting in the system improve the living comfort level and reduce power consumption of artificial lighting.

Eclectic Approach of the Donor Area in Baldness Surgery- Use of the long hair(PLH) and the hybrid harvesting technique (FUE + FUT): the perfect choice for advanced cases.

Eclectic Approach of the Donor Area in Baldness Surgery- Use of the long hair(PLH) and the hybrid harvesting technique (FUE + FUT): the perfect choice for advanced cases.

The expected economic advantage of a new hybrid harvesting machine

The expected economic advantage of a new hybrid harvesting machine

A novel hybrid energy harvester with increased power density

In this paper, a novel hybrid energy harvester is investigated by using a rotational generator and a surface permanent magnet linear generator (SPMLG). The rotational generator that was developed by Hendijanizzaded [1] can harvest maximum power under the optimum design process with constrain on the relative displacement of the mass. The aim of adding the SPMLG is to increase electrical damping that will affect the displacement of the moving mass. This idea is different than the existing hybrid systems in which energy is harvested from two different sources, such as sunlight and sound or heat and light to increase power extracted. The interactions between different electromechanical parameters can be taken advantages of to improve the power harvesting of the device. By adding SPMLGs to a rotational generator, electrical damping of the system will be increased while the mechanical parameters of the system, for example, the resonant frequency, the spring stiffness and the seismic mass are unchanged. The system model of the rotational and the hybrid harvesters will be established and numerically simulated. Also, the power extraction between the original rotational generator and the hybrid harvester under the same conditions will be compared to confirm the viability of the method. Obviously, the trade-off for this power increase is the additional weight of the SPMLGs that must be considered in the calculations of the power density which is outside the scope of this paper.