Showing papers on "Energy harvesting published in 2013"
TL;DR: This work demonstrated the practicability of using NG to harvest large-scale mechanical energy, such as footsteps, rolling wheels, wind power, and ocean waves, by constructing a triboelectric nanogenerator with ultrahigh electric output.
Abstract: This article describes a simple, cost-effective, and scalable approach to fabricate a triboelectric nanogenerator (NG) with ultrahigh electric output. Triggered by commonly available ambient mechanical energy such as human footfalls, a NG with size smaller than a human palm can generate maximum short-circuit current of 2 mA, delivering instantaneous power output of 1.2 W to external load. The power output corresponds to an area power density of 313 W/m2 and a volume power density of 54 268 W/m3 at an open-circuit voltage of ∼1200 V. An energy conversion efficiency of 14.9% has been achieved. The power was capable of instantaneously lighting up as many as 600 multicolor commercial LED bulbs. The record high power output for the NG is attributed to optimized structure, proper materials selection and nanoscale surface modification. This work demonstrated the practicability of using NG to harvest large-scale mechanical energy, such as footsteps, rolling wheels, wind power, and ocean waves.
967 citations
TL;DR: In this article, a city-wide RF spectral survey was undertaken from outside all of the 270 London Underground stations at street level, and four harvesters (comprising antenna, impedance-matching network, rectifier, maximum power point tracking interface, and storage element) were designed to cover four frequency bands from the largest RF contributors within the ultrahigh frequency (0.3-3 GHz) part of the frequency spectrum.
Abstract: RF harvesting circuits have been demonstrated for more than 50 years, but only a few have been able to harvest energy from freely available ambient (i.e., non-dedicated) RF sources. In this paper, our objectives were to realize harvester operation at typical ambient RF power levels found within urban and semi-urban environments. To explore the potential for ambient RF energy harvesting, a city-wide RF spectral survey was undertaken from outside all of the 270 London Underground stations at street level. Using the results from this survey, four harvesters (comprising antenna, impedance-matching network, rectifier, maximum power point tracking interface, and storage element) were designed to cover four frequency bands from the largest RF contributors (DTV, GSM900, GSM1800, and 3G) within the ultrahigh frequency (0.3-3 GHz) part of the frequency spectrum. Prototypes were designed and fabricated for each band. The overall end-to-end efficiency of the prototypes using realistic input RF power sources is measured; with our first GSM900 prototype giving an efficiency of 40%. Approximately half of the London Underground stations were found to be suitable locations for harvesting ambient RF energy using our four prototypes. Furthermore, multiband array architectures were designed and fabricated to provide a broader freedom of operation. Finally, an output dc power density comparison was made between all the ambient RF energy harvesters, as well as alternative energy harvesting technologies, and for the first time, it is shown that ambient RF harvesting can be competitive with the other technologies.
778 citations
IMEC1
TL;DR: The feasibility of harvesting is discussed, leading to the conclusion that RF energy transport is preferred for powering small sized sensors by radio-frequency energy harvesting or transport.
Abstract: This paper presents an overview of principles and requirements for powering wireless sensors by radio-frequency (RF) energy harvesting or transport. The feasibility of harvesting is discussed, leading to the conclusion that RF energy transport is preferred for powering small sized sensors. These sensors are foreseen in future Smart Buildings. Transmitting in the ISM frequency bands, respecting the transmit power limits ensures that the International Commission on Non-Ionizing Radiation Protection (ICNIRP) exposure limits are not exceeded. With the transmit side limitations being explored, the propagation channel is next discussed, leading to the observation that a better than free-space attenuation may be achieved in indoors line-of-sight environments. Then, the components of the rectifying antenna (rectenna) are being discussed: rectifier, dc-dc boost converter, and antenna. The power efficiencies of all these rectenna subcomponents are being analyzed and finally some examples are shown. To make RF energy transport a feasible powering technology for low-power sensors, a number of precautions need to be taken. The propagation channel characteristics need to be taken into account by creating an appropriate transmit antenna radiation pattern. All subcomponents of the rectenna need to be impedance matched, and the power transfer efficiencies of the rectifier and the boost converter need to be optimized.
629 citations
TL;DR: Simulation results illustrate that the proposed iterative resource allocation algorithms approach the optimal solution within a small number of iterations and unveil the trade-off between energy efficiency, system capacity, and wireless power transfer.
Abstract: This paper considers orthogonal frequency division multiple access (OFDMA) systems with simultaneous wireless information and power transfer. We study the resource allocation algorithm design for maximization of the energy efficiency of data transmission (bits/Joule delivered to the receivers). In particular, we focus on power splitting hybrid receivers which are able to split the received signals into two power streams for concurrent information decoding and energy harvesting. Two scenarios are investigated considering different power splitting abilities of the receivers. In the first scenario, we assume receivers which can split the received power into a continuous set of power streams with arbitrary power splitting ratios. In the second scenario, we examine receivers which can split the received power only into a discrete set of power streams with fixed power splitting ratios. For both scenarios, we formulate the corresponding algorithm design as a non-convex optimization problem which takes into account the circuit power consumption, the minimum data rate requirements of delay constrained services, the minimum required system data rate, and the minimum amount of power that has to be delivered to the receivers. By exploiting fractional programming and dual decomposition, suboptimal iterative resource allocation algorithms are developed to solve the non-convex problems. Simulation results illustrate that the proposed iterative resource allocation algorithms approach the optimal solution within a small number of iterations and unveil the trade-off between energy efficiency, system capacity, and wireless power transfer: (1) wireless power transfer enhances the system energy efficiency by harvesting energy in the radio frequency, especially in the interference limited regime; (2) the presence of multiple receivers is beneficial for the system capacity, but not necessarily for the system energy efficiency.
536 citations
TL;DR: This SoC is designed so the integration and interaction of circuit blocks accomplish an integrated, flexible, and reconfigurable wireless BSN SoC capable of autonomous power management and operation from harvested power, thus prolonging the node lifetime indefinitely.
Abstract: This paper presents an ultra-low power batteryless energy harvesting body sensor node (BSN) SoC fabricated in a commercial 130 nm CMOS technology capable of acquiring, processing, and transmitting electrocardiogram (ECG), electromyogram (EMG), and electroencephalogram (EEG) data. This SoC utilizes recent advances in energy harvesting, dynamic power management, low voltage boost circuits, bio-signal front-ends, subthreshold processing, and RF transmitter circuit topologies. The SoC is designed so the integration and interaction of circuit blocks accomplish an integrated, flexible, and reconfigurable wireless BSN SoC capable of autonomous power management and operation from harvested power, thus prolonging the node lifetime indefinitely. The chip performs ECG heart rate extraction and atrial fibrillation detection while only consuming 19 μW, running solely on harvested energy. This chip is the first wireless BSN powered solely from a thermoelectric harvester and/or RF power and has lower power, lower minimum supply voltage (30 mV), and more complete system integration than previously reported wireless BSN SoCs.
311 citations
TL;DR: In this paper, a magnetically coupled nonlinear piezoelectric energy harvester was investigated by altering the angular orientation of its external magnets for enhanced broadband frequency response.
Abstract: We investigate a magnetically coupled nonlinear piezoelectric energy harvester by altering the angular orientation of its external magnets for enhanced broadband frequency response. Electromechanical equations describing the nonlinear dynamic behavior include an experimentally identified polynomial for the transverse magnetic force that depends on magnet angle. Up- and down-sweep harmonic excitation tests are performed at constant acceleration over the range of 0–25 Hz. Very good agreement is observed between the numerical and experimental open-circuit voltage output frequency response curves. The nonlinear energy harvester proposed in this work can cover the broad low-frequency range of 4–22 Hz by changing the magnet orientation.
310 citations
TL;DR: The concept of energy cooperation is introduced, where a user wirelessly transmits a portion of its energy to another energy harvesting user, which enables shaping and optimization of the energy arrivals at the energy-receiving node, and improves the overall system performance, despite the loss incurred in energy transfer.
Abstract: In energy harvesting communications, users transmit messages using energy harvested from nature during the course of communication. With an optimum transmit policy, the performance of the system depends only on the energy arrival profiles. In this paper, we introduce the concept of energy cooperation, where a user wirelessly transmits a portion of its energy to another energy harvesting user. This enables shaping and optimization of the energy arrivals at the energy-receiving node, and improves the overall system performance, despite the loss incurred in energy transfer. We consider several basic multi-user network structures with energy harvesting and wireless energy transfer capabilities: relay channel, two-way channel and multiple access channel. We determine energy management policies that maximize the system throughput within a given duration using a Lagrangian formulation and the resulting KKT optimality conditions. We develop a two-dimensional directional water-filling algorithm which optimally controls the flow of harvested energy in two dimensions: in time (from past to future) and among users (from energy-transferring to energy-receiving) and show that a generalized version of this algorithm achieves the boundary of the capacity region of the two-way channel.
288 citations
TL;DR: The enhanced performance and the flexibility of the PMN-PT nanowire-based nanocomposite make it a promising building block for energy harvesting and self-powered sensing applications.
Abstract: Piezoelectric nanocomposites represent a unique class of materials that synergize the advantageous features of polymers and piezoelectric nanostructures and have attracted extensive attention for the applications of energy harvesting and self-powered sensing recently Currently, most of the piezoelectric nanocomposites were synthesized using piezoelectric nanostructures with relatively low piezoelectric constants, resulting in lower output currents and lower output voltages Here, we report a synthesis of piezoelectric (1 - x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) nanowire-based nanocomposite with significantly improved performances for energy harvesting and self-powered sensing With the high piezoelectric constant (d33) and the unique hierarchical structure of the PMN-PT nanowires, the PMN-PT nanowire-based nanocomposite demonstrated an output voltage up to 78 V and an output current up to 229 μA (current density of 458 μA/cm(2)); this output voltage is more than double that of other reported piezoelectric nanocomposites, and the output current is at least 6 times greater The PMN-PT nanowire-based nanocomposite also showed a linear relationship of output voltage versus strain with a high sensitivity The enhanced performance and the flexibility of the PMN-PT nanowire-based nanocomposite make it a promising building block for energy harvesting and self-powered sensing applications
282 citations
TL;DR: In this paper, the authors considered the design of a wireless communication device relying exclusively on energy harvesting and proposed a save-then-transmit (ST) protocol, in which a fraction of time ρ (dubbed the save-ratio) is devoted exclusively to energy harvesting, with the remaining fraction 1-ρ used for data transmission.
Abstract: In this paper, the design of a wireless communication device relying exclusively on energy harvesting is considered. Due to the inability of rechargeable energy sources to charge and discharge at the same time, a constraint we term the energy half-duplex constraint, two rechargeable energy storage devices (ESDs) are assumed so that at any given time, there is always one ESD being recharged. The energy harvesting rate is assumed to be a random variable that is constant over the time interval of interest. A save-then-transmit (ST) protocol is introduced, in which a fraction of time ρ (dubbed the save-ratio) is devoted exclusively to energy harvesting, with the remaining fraction 1-ρ used for data transmission. The ratio of the energy obtainable from an ESD to the energy harvested is termed the energy storage efficiency, η. We address the practical case of the secondary ESD being a battery with η <; 1, and the main ESD being a super-capacitor with η = 1. Important properties of the optimal save-ratio that minimizes outage probability are derived, from which useful design guidelines are drawn. In addition, we compare the outage performance of random power supply to that of constant power supply over the Rayleigh fading channel. The diversity order with random power is shown to be the same as that of constant power, but the performance gap can be large. Finally, we extend the proposed ST protocol to wireless networks with multiple transmitters. It is shown that the system-level outage performance is critically dependent on the number of transmitters and the optimal save-ratio for single-channel outage minimization.
264 citations
TL;DR: A review of the state-of-the-art on the large-scale vibration energy harvesting, ranging from 1 W to 100 kW or more, can be found in this paper.
Abstract: Nowadays, harvesting energy from vibration is one of the most promising technologies. However, the majority of current researches obtain 10 µW to 100 mW power, which has only limited applications in self-powered wireless sensors and low-power electronics. In fact, the vibrations in some situations can be very large, for example, the vibrations of tall buildings, long bridges, vehicle systems, railroads, ocean waves, and even human motions. With the global concern on energy and environmental issues, energy harvesting from large-scale vibrations is more attractive and becomes a research frontier. This article is to provide a timely and comprehensive review of the state-of-the-art on the large-scale vibration energy harvesting, ranging from 1 W to 100 kW or more. Subtopics include energy assessment from large vibrations, piezoelectric materials and electromagnetic transducers, motion transmission and magnification mechanisms, power electronics, and vibration control. The relevant applications discussed in th...
TL;DR: Using an Alfoil of thickness ≈18 μm as a substrate and electrode, a piezoelectric nanogenerator that is super-flexible in responding to the wavy motion of a very light wind is fabricated using ZnO nanowire arrays as discussed by the authors.
Abstract: Using an Al-foil of thickness ≈18 μm as a substrate and electrode, a piezoelectric nanogenerator (NG) that is super-flexible in responding to the wavy motion of a very light wind is fabricated using ZnO nanowire arrays. The NG is used to harvest the energy from a waving flag, demonstrating its high flexibility and excellent conformability to be integrated into fabric. The NG is applied to detect the wrinkling of a human face, showing its capability to serve as an active deformation sensor that needs no extra power supply. This strategy may provide a highly promising platform as energy harvesting devices and self-powered sensors for practical use wherever movement is available.
TL;DR: This paper presents the design of a cost effective, hybrid energy harvesting circuit combining a solar cell and a rectenna capable to harvest ambient electromagnetic energy.
Abstract: This paper presents the design of a cost effective, hybrid energy harvesting circuit combining a solar cell and a rectenna capable to harvest ambient electromagnetic energy. Electromagnetic analysis is used to model and optimize the designed circuits in order to allow the antenna and solar cell to share the same area leading to a compact structure. Nonlinear harmonic balance optimization is used to maximize the RF-to-DC conversion efficiency of the rectenna circuitry in the presence of the solar cell and both wideband and multiband topologies are presented. Furthermore, a low cost and flexible polyethylene terephthalate PET substrate and a flexible amorphous silicon solar cell are chosen, providing for both a low cost and conformal structure. A prototype able to generate a maximum DC power of 56 mW when the solar cell is illuminated with 100 mW/cm2 solar irradiance, and a dual band rectenna demonstrating an efficiency of 15% around 850 MHz and 1850 MHz when illuminated by a microwave signal of available power is presented.
TL;DR: In this article, an innovative design of regenerative shock absorbers is proposed, with the advantage of significantly improving the energy harvesting efficiency and reducing the impact forces caused by oscillation.
Abstract: Energy-harvesting shock absorbers are able to recover the energy otherwise dissipated in the suspension vibration while simultaneously suppressing the vibration induced by road roughness. They can work as a controllable damper as well as an energy generator. An innovative design of regenerative shock absorbers is proposed in this paper, with the advantage of significantly improving the energy harvesting efficiency and reducing the impact forces caused by oscillation. The key component is a unique motion mechanism, which we called ?mechanical motion rectifier (MMR)?, to convert the oscillatory vibration into unidirectional rotation of the generator. An implementation of a MMR-based harvester with high compactness is introduced and prototyped. A dynamic model is created to analyze the general properties of the motion rectifier by making an analogy between mechanical systems and electrical circuits. The model is capable of analyzing electrical and mechanical components at the same time. Both simulation and experiments are carried out to verify the modeling and the advantages. The prototype achieved over 60% efficiency at high frequency, much better than conventional regenerative shock absorbers in oscillatory motion. Furthermore, road tests are done to demonstrate the feasibility of the MMR shock absorber, in which more than 15 Watts of electricity is harvested while driving at 15?mph on a smooth paved road. The MMR-based design can also be used for other applications of vibration energy harvesting, such as from tall buildings or long bridges.
TL;DR: In this paper, a device for electromagnetic field energy harvesting that employs a plurality of electrically small resonators such as split-ring resonators that provide significantly enhanced energy harvesting or energy collection efficiency while occupying smaller footprint is presented.
Abstract: Antennas developed for electromagnetic field energy harvesting, typically referred to as rectennas, provide an alternative electromagnetic field energy harvesting means to photovoltaic cells if designed for operation in the visible frequency spectrum. Rectennas also provide energy harvesting ability or power transfer mechanism at microwave, millimeter and terahertz frequencies. However, the power harvesting efficiency of available rectennas is low because rectennas employ traditional antennas whose dimensions is typically proportional or close to the wavelength of operation. This invention provides a device for electromagnetic field energy harvesting that employs a plurality of electrically-small resonators such as split-ring resonators that provide significantly enhanced energy harvesting or energy collection efficiency while occupying smaller footprint. The invention is applicable to electromagnetic energy harvesting and to wireless power transfer.
TL;DR: Energy harvesting from ambient vibrations using piezoelectric effect is a promising alternative solution for powering small electronics such as wireless sensors as mentioned in this paper, however, it is not suitable for wireless sensor networks.
Abstract: Energy harvesting from ambient vibrations using piezoelectric effect is a promising alternative solution for powering small electronics such as wireless sensors. A conventional piezoelectric energy...
TL;DR: In this article, a large-area and highly efficient NCG device using a bar-coating technique with inherently excellent piezoelectric PZT particles was demonstrated to significantly increase electric output performance.
Abstract: 25 ] provides a new concept and simple fabrication approach for low-cost self-powered energy systems. However, there are still the unresolved issues with fl exible piezoelectric nanogenerators, such as insuffi cient output performance and size limitations before they can be commercialized for oper-ating sensor network systems. Here, we demonstrate a large-area and highly effi cient NCG device using a bar-coating technique with inherently excellent piezoelectric PZT particles to signifi cantly increase electric output performance. Due to the exceptional piezoelectric per-formance compared to other piezoelectric materials, PZT-based piezoelectric devices have been widely commercialized for not only energy harvesting devices
Patent•
12 Nov 2013TL;DR: In this article, the authors describe a sensor device that includes an energy harvesting element, an energy storage element, and a transmitter circuit coupled to the energy storage and configured to transmit a wireless signal when the energy stored in the storage element is sufficient to power a transmission of the wireless signal.
Abstract: Methods, systems and devices for an energy harvesting sensor are disclosed. A sensor device may include an energy harvesting element configured to harvest energy from a source of energy that is to be measured by the sensor device, and an energy storage element configured to store energy generated by the energy harvesting element. The sensor device may further include a transmitter circuit coupled to the energy storage element and configured to transmit a wireless signal when the energy stored in the energy storage element is sufficient to power a transmission of the wireless signal. The time between transmissions by the transmitter may be used by a receiver of those transmissions to calculate a measure of the quantity being used for energy harvesting.
TL;DR: A self-adapting power management unit is proposed for efficient battery voltage down conversion for wide range of battery voltages and load current and adapts itself by monitoring energy harvesting conditions and harvesting sources.
Abstract: A 1.0 mm3 general-purpose sensor node platform with heterogeneous multi-layer structure is proposed. The sensor platform benefits from modularity by allowing the addition/removal of IC layers. A new low power I2C interface is introduced for energy efficient inter-layer communication with compatibility to commercial I2C protocols. A self-adapting power management unit is proposed for efficient battery voltage down conversion for wide range of battery voltages and load current. The power management unit also adapts itself by monitoring energy harvesting conditions and harvesting sources and is capable of harvesting from solar, thermal and microbial fuel cells. An optical wakeup receiver is proposed for sensor node programming and synchronization with 228 pW standby power. The system also includes two processors, timer, temperature sensor, and low-power imager. Standby power of the system is 11 nW.
TL;DR: By integrating the TENG inside a buoy ball, wave energy harvesting at water surface has been demonstrated and used for lighting illumination light, which shows great potential applications in marine science and environmental/infrastructure monitoring.
Abstract: An unstable mechanical structure that can self-balance when perturbed is a superior choice for vibration energy harvesting and vibration detection. In this work, a suspended 3D spiral structure is integrated with a triboelectric nanogenerator (TENG) for energy harvesting and sensor applications. The newly designed vertical contact–separation mode TENG has a wide working bandwidth of 30 Hz in low-frequency range with a maximum output power density of 2.76 W/m2 on a load of 6 MΩ. The position of an in-plane vibration source was identified by placing TENGs at multiple positions as multichannel, self-powered active sensors, and the location of the vibration source was determined with an error less than 6%. The magnitude of the vibration is also measured by the output voltage and current signal of the TENG. By integrating the TENG inside a buoy ball, wave energy harvesting at water surface has been demonstrated and used for lighting illumination light, which shows great potential applications in marine science...
TL;DR: In this paper, an approach to harvesting energy from the electric field around the conductor to supply the wireless sensor nodes was investigated, and a prototype of the power module was realized and tested under high voltage laboratory conditions.
Abstract: For electric power transmission the overhead power line monitoring system plays an important role in operating security for grid operators as well as high supply availability at optimised cost. In this study, an approach to harvesting energy from the electric field around the conductor to supply the wireless sensor nodes was investigated. Special requirements in functionality, reliability and limited accessibility at the power line result in the development of a specific energy management strategy. A prototype of the power module was realised and tested under high voltage laboratory conditions. Then, a field test was carried out under real operating conditions. The test results confirm that the power module can collect enough energy to power the sensor nodes. The contribution in this study presents theoretical considerations of energy availability from the electric field, design of energy management and results from measurements with the prototype in a high voltage laboratory and in field test. The field test results demonstrate that the energy harvester can collect enough energy to power the sensor nodes by 16 mW.
TL;DR: This work characterizes the light energy availability in indoor environments and develops algorithms for calculating time fair energy allocation in systems with deterministic energy inputs, as well as in systems where energy inputs are stochastic.
Abstract: Recent advances in energy harvesting materials and ultra-low-power communications will soon enable the realization of networks composed of energy harvesting devices. These devices will operate using very low ambient energy, such as energy harvested from indoor lights. We focus on characterizing the light energy availability in indoor environments and on developing energy allocation algorithms for energy harvesting devices. First, we present results of our long-term indoor radiant energy measurements, which provide important inputs required for algorithm and system design (e.g., determining the required battery sizes). Then, we focus on algorithm development, which requires nontraditional approaches, since energy harvesting shifts the nature of energy-aware protocols from minimizing energy expenditure to optimizing it. Moreover, in many cases, different energy storage types (rechargeable battery and a capacitor) require different algorithms. We develop algorithms for calculating time fair energy allocation in systems with deterministic energy inputs, as well as in systems where energy inputs are stochastic.
TL;DR: In this paper, the authors used piezoelectric patches attached to the surface of a flexible flag in axial flow to convert the solid deformation into an electric current powering purely resistive output circuits.
Abstract: Self-sustained oscillations resulting from fluid–solid instabilities, such as the flutter of a flexible flag in axial flow, can be used to harvest energy if one is able to convert the solid energy into electricity. Here, this is achieved using piezoelectric patches attached to the surface of the flag, which convert the solid deformation into an electric current powering purely resistive output circuits. Nonlinear numerical simulations in the slender-body limit, based on an explicit description of the coupling between the fluid–solid and electric systems, are used to determine the harvesting efficiency of the system, namely the fraction of the flow kinetic energy flux effectively used to power the output circuit, and its evolution with the system’s parameters. The role of the tuning between the characteristic frequencies of the fluid–solid and electric systems is emphasized, as well as the critical impact of the piezoelectric coupling intensity. High fluid loading, classically associated with destabilization by damping, leads to greater energy harvesting, but with a weaker robustness to flow velocity fluctuations due to the sensitivity of the flapping mode selection. This suggests that a control of this mode selection by a careful design of the output circuit could provide some opportunities to improve the efficiency and robustness of the energy harvesting process.
TL;DR: This review presents the categorization of the current energy harvesting techniques and describes each conversion technique and the advantages and drawbacks are presented, and the suitability is shown for each category.
Abstract: Various energy harvesting systems have been proposed in the last years The use of ambient energy, such as vibration energy, has evoked great interests Most vibration-based converters generate the maximum power only when the generator is excited at its resonance frequency To overcome this limitation, researchers focus on strategies for increasing the working bandwidth of an energy harvester Due to the amount of different approaches for broadband energy harvesting, we suggest a categorization This review presents a classification of the current techniques Every technique has its own benefits and drawbacks and is suitable for different applications This review presents the categorization and describes each conversion technique Typical research approaches are shown to get a better understanding of the energy harvesting techniques The advantages and drawbacks are presented, and the suitability is shown for each category
TL;DR: In this paper, a metamaterial energy harvester (MEH) was proposed to transform the incoming structure-borne wave energy into electrical energy by coupling the metammaterial and electroelastic domains.
Abstract: Enhancement of structure-borne wave energy harvesting is investigated by exploiting metamaterial-based and metamaterial-inspired electroelastic systems. The concepts of wave focusing, localization, and funneling are leveraged to establish novel metamaterial energy harvester (MEH) configurations. The MEH systems transform the incoming structure-borne wave energy into electrical energy by coupling the metamaterial and electroelastic domains. The energy harvesting component of the work employs piezoelectric transduction due to the high power density and ease of application offered by piezoelectric materials. Therefore, in all MEH configurations studied in this work, the metamaterial system is combined with piezoelectric energy harvesting for enhanced electricity generation from waves propagating in elastic structures. Experiments are conducted to validate the dramatic performance enhancement in MEH systems as compared to using the same volume of piezoelectric patch in the absence of the metamaterial component. It is shown that MEH systems can be used for both broadband and tuned wave energy harvesting. The MEH concepts covered in this paper are (1) wave focusing using a metamaterial-inspired parabolic acoustic mirror (for broadband energy harvesting), (2) energy localization using an imperfection in a 2D lattice structure (for tuned energy harvesting), and (3) wave guiding using an acoustic funnel (for narrow-to-broadband energy harvesting). It is shown that MEH systems can boost the harvested power by more than an order of magnitude. (Some figures may appear in colour only in the online journal)
28 Mar 2013
TL;DR: An ambient RF energy harvesting sensor node with onboard sensing and communication functionality was developed and tested and shown to operate at a distance of 10.4 km from a 1 MW UHF television broadcast transmitter, and over 200 m from a cellular base transceiver station.
Abstract: An ambient RF energy harvesting sensor node with onboard sensing and communication functionality was developed and tested. The minimal RF input power required for sensor node operation was -18 dBm (15.8 μW). Using a 6 dBi receive antenna, the most sensitive RF harvester was shown to operate at a distance of 10.4 km from a 1 MW UHF television broadcast transmitter, and over 200 m from a cellular base transceiver station. A complete ambient RF-powered prototype was constructed which measured temperature and light level and wirelessly transmitted these measurements.
TL;DR: In this paper, privacy in a smart metering system is studied from an information theoretic perspective in the presence of energy harvesting and storage units and it is shown that energy harvesting provides increased privacy by diversifying the energy source, while a storage device can be used to increase both the energy efficiency and the privacy of the user.
Abstract: Smart meters are key elements for the operation of smart grids. By providing near realtime information on the energy consumption of individual users, smart meters increase the efficiency in generation, distribution and storage of energy in a smart grid. The ability of the utility provider to track users' energy consumption inevitably leads to important threats to privacy. In this paper, privacy in a smart metering system is studied from an information theoretic perspective in the presence of energy harvesting and storage units. It is shown that energy harvesting provides increased privacy by diversifying the energy source, while a storage device can be used to increase both the energy efficiency and the privacy of the user. For given input load and energy harvesting rates, it is shown that there exists a trade-off between the information leakage rate, which is used to measure the privacy of the user, and the wasted energy rate, which is a measure of the energy-efficiency. The impact of the energy harvesting rate and the size of the storage device on this trade-off is also studied.
Patent•
14 Mar 2013
TL;DR: In this paper, a harvesting and measurement device is operable in at least a normal operation mode, a demand measurement mode, and a fault measurement mode; the device is able to harvest energy from an associated power line and monitor current and voltage conditions through a lower power circuit.
Abstract: A harvesting and measurement device is operable in at least a normal operation mode, a demand measurement mode, and a fault measurement mode. In the normal operation mode, the device is able to harvest energy from an associated power line and monitor current and voltage conditions through a lower power circuit. In the demand measurement mode, harvesting elements of the circuit are disabled so as not to interfere with accuracy of demand current measurements. In the fault measurement mode, one or more Hall sensors are activated such that high currents can be accurately measured.
04 Mar 2013
TL;DR: This chapter contains sections titled: Introduction Node Platforms Techniques of Energy Harvesting Prediction Models Protocols for EHWSNs and References.
Abstract: This chapter contains sections titled: Introduction Node Platforms Techniques of Energy Harvesting Prediction Models Protocols for EHWSNs References
TL;DR: In this article, a prototype of a cantilever piezoelectric harvester is designed, tested and modelled, and a simple model is proposed for theoretical prediction of the delivered power in terms of traffic intensity.
Abstract: This paper focuses on energy harvesting from traffic-induced vibrations in bridges. Using a pre-stressed concrete highway bridge as a case study, in situ vibration measurements are presented and analysed. From these results, a prototype of a cantilever piezoelectric harvester is designed, tested and modelled. Even though the considered bridge vibrations are characterized by small amplitude and a low frequency (i.e. below 15 Hz), it is shown that mean power of the order of 0.03 mW can be produced, with a controlled voltage between 1.8 and 3.6 V. A simple model is proposed for theoretical prediction of the delivered power in terms of traffic intensity. This model shows good agreement with the experimental results and leads to a simple but effective design rule for piezoelectric harvesters to be used on bridges.