Wireless Energy Transfer

This chapter proposes an overview of microwave energy harvesting with focuses on the design of high efficiency low power rectifying circuits. A background survey of RF energy harvesting techniques is presented first. Then, the performances of conventional rectifier topologies are analyzed and discussed. A review of the most efficient rectenna designs, from the state of the art, is also presented. Design considerations for low power rectifier operations are detailed and new high efficient rectifying circuits are designed and evaluated in both GSM and ISM bands under low power constraints.

A Theory of Thermoelectric Energy Harvesting Systems

This chapter presents a study of thermoelectric energy harvesting with nano-sized thermopiles (nTE) in a planar 65 nm silicon CMOS process. These devices generated power from a 5C temperature difference at a density comparable to commercially available thermoelectric generators, following a metric used in the research literature (Hudak, 2008). By analyzing these devices as a thermoelectric harvesting system, the authors explore the impact of additional performance metrics such as heat source/sink thermal impedance, available heat flow density, and voltage stacking, providing a more comprehensive set of criteria for evaluating the suitability of a thermal harvesting technology. The authors use their thermoelectric system theory to consider the prospects for several thermoelectric energy harvesting applications.

Energy Harvesting and Energy Conversion Devices Using Thermoelectric Materials

The authors propose in this chapter an original, self-sustainable, power supply system for wireless monitoring applications that is powered from an energy harvesting device based on thermoelectric generators (TEGs). The energy harvesting system's purpose is to gather the waste heat from low temperature sources (<90°C), convert it to electrical energy and store it into rechargeable batteries. The energy harvesting system must be able to power a so-called condition monitoring system (CMS) that is used for the monitoring of heat dissipation equipment. The setup used for measurements (including mechanical details) and the experiments are described along with all the essential results of the research. The electronic system design is emphasized and various options are discussed.

Energy Harvesting Aspects of Irregular Vibrating Forces Acting on Piezoelectric Devices

After a brief introduction of piezoelectric materials, this chapter focuses on the characterization of vibrating freestanding piezoelectric AlN devices forced by different external forces acting simultaneously. The analyzed vibrating forces are applied mainly to piezoelectric freestanding structures stimulated by irregular vibration phenomena. Particular kinds of theoretical noise signals are commented. The goal of the chapter is to analyze the effect of the noise in order to model the chaotic vibrating system and to predict the output current signals. Moreover, the author also shows a possible alternative way to detect different vibrating force directions in the three dimensional space by means of curved piezoelectric layouts.

Optical Nano-Antennas for Energy Harvesting

The solar energy is able to supply humanity energy for almost another 1 billion years. Optical nano-antennas (ONAs) are an attractive technology for high efficiency, and low-cost solar cells. These devices can be classified to semiconductor nano-wires and metallic nano-antenna. Extensive studies have been carried out on ONAs to investigate their ability to harvest solar energy. Inspired by these studies, the scope of the chapter is to highlight the latest designs of the two main types of ONAs. The metallic nano-antennas are discussed based on the following points: plasmon, modeling, and performance of antenna designs using different configurations and materials. Moreover, the semiconductor nano-wires are studied thoroughly in terms of photonic crystals, antenna design with different patterns, nano-wire forms and materials. Also, the applications of ONAs and their fabrication aspects such as diode challenges are presented in detail. Finally, three novel designs of ONAs are presented and numerically simulated to maximize the harvesting efficiency.

Earth Long-Wave Infrared Emission, New Ways to Harvest Energy

This chapter summarizes the physical properties of THz antennas, provides a summary of some of the most important recent developments in the field of energy harvesting of Earth long-wave infrared radiation, discusses the potential applications and identifies the future challenges and opportunities. In particular, a THz antenna is designed in order to transform the thermal energy, provided by the Sun and re-emitted from the Earth, in electricity. The proposed antenna is a square spiral of gold printed on a low cost dielectric substrate. Simulations have been conducted in order to investigate the behavior of the antenna illuminated by a circularly polarized plane wave with an amplitude chosen according to the Stefan-Boltzmann radiation law. Moreover, these THz antennas could be coupled with other components to obtain direct rectification of T radiation. As a consequence, these structures further optimized could be a promising alternative to the conventional photovoltaic solar cells.

Nonlinear Dynamics and Design of Aeroelastic Energy Harvesters

The concept of harvesting energy from flow-induced vibrations has received a great deal of attention in the last few years. This technology would help in the replacement of small batteries that require expensive and time consuming maintenance and development of self-powered electronic devices, such as health monitoring sensors, medical implants, data transmitters, wireless sensors, and cameras. In this chapter, a particular focus is paid to the concept of harvesting energy from aeroelastic instabilities, such as flutter in airfoil sections, vortex-induced vibrations in circular cylinders, and galloping in prismatic structures. Nonlinear electroaeroelastic models for these energy harvesters are derived and validated with experimental measurements. It is shown how linear and nonlinear analyses can be used to breach traditional barriers in the design and performance enhancement of these aeroelastic energy harvesters, characterization of their behaviors, and identification of the contribution of different types of nonlinearities.

Biomechanical Energy Harvesting

Portable electronic systems and wearable sensor networks are offering increasing opportunities in fields like healthcare, medicine, sport, human-machine interfacing and data sharing. The technological research is looking for innovative design solutions able to improve performances and portability of wearable systems. The power supply strategy is crucial to improve lifetime, reduce maintenance, preserve the environment and reduce costs of smart distributed electronic systems applied to the body. The conversion of biomechanical energy of limbs and joints to electricity has the potential to solve much of the actual limitations. The design and building of wearable energy harvesters for wearable applications require different approaches respect to traditional vibratory energy harvesters. This chapter focuses on transduction materials, modeling strategies, experimental setups, and data analysis for the design of biomechanical energy harvesters; a case study based on system integration and miniaturization is also described for applications in the field of human-machines interfacing.

Rainfall Energy Harvester

This chapter provides a detailed study on the harvest of the energy contained in raindrops by means of piezoelectric transducers. The energy harvester has the role of an electric source, able to recharge storage devices of small electronic components, such wireless sensors, by using the vibrational energy released by the drops hitting the transducer, reducing in such a way the chemical waste of conventional batteries. In technical literature, diverse studies agree on the level of suitable generated voltage on the electrodes of a piezoelectric transducer subjected to rainfall, but a complete characterization on the supplied power is still missing. This work, also to limit optimistic forecasts, takes into account the behavior of the transducers in different scenarios: subjected to real and artificial rainfall, standalone or in parallel configuration, in conventional geometries, due to the commercial format or in customized shape, free to move or with an imposed optimal deflection.

Silver Coatings with Protective Transparent Films for Solar Concentrators

The use of solar energy as a renewable source is one of the most promising resources to generate electricity. The viability of concentrating solar power (CSP) systems depends on the development of highly reflective materials that are inexpensive and maintain their optical properties for extended lifetimes under outdoor environments. In this chapter, the implementation of flexible polymer substrates plated with silver by the Dynamic Chemical Plating technique (DCP) is proposed because of its low cost, and easy and rapid deposition, in addition to the high speed at which the deposit is made. However, the deposits made under this technique have certain nanoscale imperfections, which begin to exist certain permeability of substances that can stain the silver over time, so a study of this feature is performed, to help assess their durability.