Simulative verification of a novel semi-active broadband energy harvester

This paper presents a semi-active broadband vibrational-energy harvesting system. Based on a non-resonant rotational generator, electronic circuitry was used to overcome the physical start-up restrictions. Due to the functional design it remains an energy harvester suitable for battery-less devices. For the first time a vibrational energy harvester is presented that allows standardization and thus higher volume production. A system layout, simulation, and measurement data will be shown

Micromechanics for energy generation

The emergence and evolution of energy micro-generators during the last two decades has delivered a wealth of energy harvesting powering solutions, with the capability of exploiting a wide range of motion types, from impulse and low frequency irregular human motion, to broadband vibrations and ultrasonic waves. It has also created a wide background of engineering energy microsytems, including fabrication methods, system concepts and optimal functionality. This overview presents a simple description of the main transduction mechanisms employed, namely the piezoelectric, electrostatic, electromagnetic and triboelectric harvesting concepts. A separate discussion of the mechanical structures used as motion translators is presented, including the employment of a proof mass, cantilever beams, the role of resonance, unimorph structures and linear/rotational motion translators. At the mechanical-to-electrical interface, the concepts of impedance matching, pre-biasing and synchronised switching are summarised. The separate treatment of these three components of energy microgenerators allows the selection and combination of different operating concepts, their co-design towards overall system level optimisation, but also towards the generalisation of specific approaches, and the emergence of new functional concepts. Industrial adoption of energy micro-generators as autonomous power sources requires functionality beyond the narrow environmental conditions typically required by the current state-of-art. In this direction, the evolution of broadband electromechanical oscillators and the combination of environmental harvesting with power transfer operating schemes could unlock a widespread use of micro-generation in microsystems such as micro-sensors and micro-actuators

Available Technologies and Commercial Devices to Harvest Energy by Human Trampling in Smart Flooring Systems: a Review

Technological innovation has increased the global demand for electrical power and energy. Accordingly, energy harvesting has become a research area of primary interest for the scientific community and companies because it constitutes a sustainable way to collect energy from various sources. In particular, kinetic energy generated from human walking or vehicle movements on smart energy floors represents a promising research topic. This paper aims to analyze the state-of-art of smart energy harvesting floors to determine the best solution to feed a lighting system and charging columns. In particular, the fundamentals of the main harvesting mechanisms applicable in this field (i.e., piezoelectric, electromagnetic, triboelectric, and relative hybrids) are discussed. Moreover, an overview of scientific works related to energy harvesting floors is presented, focusing on the architectures of the developed tiles, the transduction mechanism, and the output performances. Finally, a survey of the commercial energy harvesting floors proposed by companies and startups is reported. From the carried-out analysis, we concluded that the piezoelectric transduction mechanism represents the optimal solution for designing smart energy floors, given their compactness, high efficiency, and absence of moving parts

Human Powered Energy Harvester based on Autowinder Mechanism: Analysis, Build and Test

Experts estimate that approximately one third of the worldwide population currently owns a smartphone, and subscriptions continue to grow. Compared to mobile devices of the past decade, smartphones provide desktop computer-level processing power in a palm-sized package. However, the high computing power and 24 hours - 7 days a week connectivity results in a shorter battery life, often forcing the user to rely on portable battery packs. Worldwide energy consumption statistics show that the electric power grid depends primarily on fossil fuels. Thus, a renewable power source based on human motion energy harvesting offers a potential solution to power portable communication devices and may help reduce dependence on the power grid. A novel wrist-worn energy-harvester, based on an automatic winding mechanism, was designed, fabricated and experimentally tested. The mechanism frequently employed in wrist and pocket watches dates back to the 18th century, and is one of the oldest examples of mobile human energy harvesting. In this project, the prototype device contains a rotary pendulum connected to a DC generator through a planetary gear train. An electronics module consisting of a rectifier and boost converter filters the generator output, supplying regulated DC output to charge a battery, and/or power an electrical load. An onboard microcontroller broadcasts the voltage, current, and power data wirelessly for data collection during testing. Numerical and experimental validations were conducted for the energy harvester. A mathematical model for human arm swing dynamics was developed based on a triple pendulum system, and the device’s behavior was studied for both walking and running activities. The mechanical energy output from the rotary harvester pendulum was predicted to be 0.42 mJ and 2.06 mJ for simulated walking and running sequences over a period of 5 seconds (without load). A subsequent mathematical model was developed incorporating the electromechanical behavior of the generator and attached electronics module. A simulated running sequence with a representative electrical load yielded 1.72 mJ of electrical energy output over 5 seconds. The prototype was experimentally validated over the same conditions, resulting in an unregulated energy output of 1.39 mJ and a regulated energy output at 5 VDC of 1.16mJ for 5 seconds. Experimental testing successfully demonstrated the harvester’s potential as a mobile energy source for portable consumer electronics. Future steps shall focus on implementing efficient components for increased power output and designing for improved ergonomics

Design and Analysis of a Mechanical Driveline with Generator for an Atmospheric Energy Harvester

The advent of renewable energy as a primary power source for microelectronic devices has motivated research within the energy harvesting community over the past decade. Compact, self-contained, portable energy harvesters can be applied to wireless sensor networks, Internet of Things (IoT) smart appliances, and a multitude of standalone equipment; replacing batteries and improving the operational life of such systems. Atmospheric changes influenced by cyclical temporal variations offer an abundance of harvestable thermal energy. However, the low conversion efficiency of a common thermoelectric device does not tend to be practical for microcircuit operations. One solution may lie in a novel electromechanical power transformer integrated with a thermodynamic based phase change material to create a temperature/pressure energy harvester. The performance of the proposed harvester will be investigated using both numerical and experimental techniques to offer insight into its functionality and power generation capabilities. The atmospheric energy harvester consists of a ethyl chloride filled mechanical bellows attached to an end plate and constrained by a stiff spring and four guide rails that allow translational motion. The electromechanical power transformer consists of a compound gear train driven by the bellows end plate, a ratchet-controlled coil spring to store energy, and a DC micro generator. Nonlinear mathematical models have been developed for this multi-domain dynamic system using fundamental engineering principles. The initial analyses predicted 9.6 mW electric power generation over a 24 hour period for ±1°C temperature variations about a nominal 22°C temperature. Transfer functions were identified from the lumped parameter models and the transient behavior of the coupled thermal-electromechanical system has been studied. A prototype experimental system was fabricated and laboratory tested to study the overall performance and validate the mathematical models for the integrated energy harvester system. The experimental results agree with the numerical analyses in behavioral characteristics. Further, the power generation capacity of 30 mW for a representative electrical resistance load and emulated rack input which correspond to 50 cyclic bidirectional temperature variations (~175 hours of field operation) validated the simulation models. This research study provides insight into the challenges of designing an electromechanical power transformer to complement an atmospheric energy harvester system. The mathematical models estimated the behavior and performance of the integrated harvester system and establishes a foundation for future optimization studies. The opportunity to power microelectronic devices in the milliwatt range for burst electric operation or with the use of supercapacitors/batteries enables global remote operation of smart appliances. This system can assist in reducing/eliminating the need for batteries and improving the operational life of a variety of autonomous equipment. Future research areas have been identified to improve the overall system capabilities and implement the harvester device for real-world applications

Power Management Electronics

Accepted versio

WearETE: A scalable wearable e-textile triboelectric energy harvesting system for human motion scavenging

In this paper, we report the design, experimental validation and application of a scalable, wearable e-textile triboelectric energy harvesting (WearETE) system for scavenging energy from activities of daily living. The WearETE system features ultra-low-cost material and manufacturing methods, high accessibility, and high feasibility for powering wearable sensors and electronics. The foam and e-textile are used as the two active tribomaterials for energy harvester design with the consideration of flexibility and wearability. A calibration platform is also developed to quantify the input mechanical power and power efficiency. The performance of the WearETE system for human motion scavenging is validated and calibrated through experiments. The results show that the wearable triboelectric energy harvester can generate over 70 V output voltage which is capable of powering over 52 LEDs simultaneously with a 9 × 9 cm2 area. A larger version is able to lighten 190 LEDs during contact-separation process. The WearETE system can generate a maximum power of 4.8113 mW from hand clapping movements under the frequency of 4 Hz. The average power efficiency can be up to 24.94%. The output power harvested by the WearETE system during slow walking is 7.5248 µW. The results show the possibility of powering wearable electronics during human motion

Advanced Energy Harvesting Technologies

Energy harvesting is the conversion of unused or wasted energy in the ambient environment into useful electrical energy. It can be used to power small electronic systems such as wireless sensors and is beginning to enable the widespread and maintenance-free deployment of Internet of Things (IoT) technology. This Special Issue is a collection of the latest developments in both fundamental research and system-level integration. This Special Issue features two review papers, covering two of the hottest research topics in the area of energy harvesting: 3D-printed energy harvesting and triboelectric nanogenerators (TENGs). These papers provide a comprehensive survey of their respective research area, highlight the advantages of the technologies and point out challenges in future development. They are must-read papers for those who are active in these areas. This Special Issue also includes ten research papers covering a wide range of energy-harvesting techniques, including electromagnetic and piezoelectric wideband vibration, wind, current-carrying conductors, thermoelectric and solar energy harvesting, etc. Not only are the foundations of these novel energy-harvesting techniques investigated, but the numerical models, power-conditioning circuitry and real-world applications of these novel energy harvesting techniques are also presented