Energy Harvesting and Energy Efficiency

In this millennium, the methodologies to harvest existing dissipated powers not only supply input energy to our sophisticated devices, but also contribute the current technological researches and developments. Single harvester generator or harvesting single power source may remain insufficient for the energy feed into the systems like electronic devices, biosensors, human, structural and machine health monitoring, and wireless sensor nodes. To overcome this problem, hybridization of energy harvesters (EHs) takes place to increase the limited energy generation of stand-alone EHs. In this chapter, piezoelectric and electromagnetic generators are compared and classic as well as novel hybrid energy harvester (HEH) designs are reviewed by considering fixed-frequency; broadband including linear, nonlinear and tunable HEHs; multimode; and multisource powered configurations. This review covers two-, three-, four-multi source powered HEHs in micro-, meso- and large-scales. Overall comparisons of classic and novel HEHs are tabulated and discussed in detail in order to guide potential researchers. In the scope of this chapter review, it is seen that HEHs generate greater power outputs than its single harvester components. The most promising power and energy generations are 315 mW by four-source powered novel HEH in meso-scale, 215 μW by tunable broadband classic HEH in microscale and 440 kW h/day by partially three-source powered HEH in large scale. This chapter indicates that HEHs not only increase the output powers and power densities, but also enables endless configurations to maximize harnessing existing power sources.

Continually growing integration levels and miniaturization in electronics has led to the enrichment of features to enable a variety of new applications with simultaneous reduction in system power consumption. The start of the 21st century is hallmarked by the emergence of small information engines (microsystems) as part of “internet of things” thrust to provide the intelligence behind the building blocks of the increasingly automated, digitized, and connected eco-system around residential, industrial, health, education, transportation, communication, and other sectors of our civilization. These engines require small amount of power to work in an embedded environment where frequent access for maintenance, and power delivery or battery refurbishment is not desirable. The focus of this chapter is batteryless operation, which is at the center-stage of microscale harvesting research efforts to enable such applications. Energy and power budgeting, and system design concerns are reviewed for batteryless operation, and system examples are provided. First part of Sect. 3.1 discusses demand for micro-scale information technologies. Section 3.1.3 provides typical power and energy budgets for sensor nodes. The motivations for batteryless operation are examined in Sect. 3.1.4. Power generation is provided as a recent power management thrust in such systems in Sect. 3.1.5. System design issues for realizing batteryless information technologies are covered in Sect. 3.2 with the review of energy harvesting techniques such as small-scale solar irradiation, environmental vibration, thermal differences, and ambient radio-frequency electromagnetic waves. Finally, the last part of the section briefly discusses upcoming trends and further efforts in enabling batteryless information technologies at a disruptive level.

In the first part of the research, we present the design of a vibration-based energy harvesting system. Robotic flexible arm having variable cross-section is investigated to overcome serious problems, e.g. insufficient bandwidth and model inaccuracies. Most of the energy harvesting systems are linear with unimodal characteristics. On the other hand, real vibrations can be modeled as random, multi-modal and time varying systems. Hence, unimodal linear systems can give highly unsatisfactory results under certain circumstances. However, non-linear systems can have multi-modal character with increased performance in real and practical situations. In this work, tapered links are preferred with nonlinear coupling setup to provide sufficient bandwidth and output power requirements for modern applications. Thus, the proposed scheme has been proven by simulated and experimental results successfully. In the second part of the research, we present design and experimental results of an electromagnetic harvester, energy source of which is single-phase household AC power with a nominal voltage of 220 V and a frequency of 50 Hz. In this case, energy harvesting is based on the induced electromotive force (EMF) as a result of the periodic variations of the magnetic field around the AC power cord. In this part, we also discuss basic principles of a wireless sensor network design powered by electromagnetically harvested energy obtained from household alternating current.

This chapter focuses on the nonlinear problems in the piezoelectric harvester systems under the magnetic field. In this manner, the chapter initially mentions an introductory section on the studies of piezoelectric harvester dynamics. After the introductory section, the basic properties of the piezoelectric systems and their energy harvester applications will be presented. Since the harvesters have a complicated structure under the magnetic field, the electromagnetic design, modeling and algebraic studies of a novel harvester study will be pointed out. After the presentation of a theoretical outline on the harvester systems, the experimental setups will be explained in detail. Thus, a complete picture of the problem will be produced in order to sustain a comparable study on the theory and experiment. The main dynamic quantities such as displacement and velocity of the vibrating piezoelectric layer as function of the system parameters will be explored. According to results, the effect of periodic magnetic flux can give varieties of responses from regular dynamics to chaotic one. Phase space constructions, Poincare sections and FFTs are evaluated depending on the parameter sets including the excitation frequency f, amplitude Uc of electromagnet and the distance d. It is proven that the periodic magnetic flux can exert high frequency velocity fluctuations nearby the minimal and maximal values of the velocity, whereas the situation differs for the position. Therefore it will be pointed out that the magnetic field mostly governs the velocity by yielding complicated vibrations. According to the detailed analyses, the FFTs prove the high frequency responses in addition to the main frequency. When f differs from the natural frequency of the system f ₀, the responses become chaotic. It is proven that lower and higher frequency fluctuations in displacement and velocity, which are different from f ₀ decrease the electrical power harvested by the piezoelectric pendulum. Indeed, it is remarkable to get a relation between the rms values of displacement/velocity and the harvested power according to the measurements. Thus this relation can be used to estimate the power output in harvester systems. The piezoelectric harvester generates much energy when f is closed to f ₀ and the distance to the magnetic device should be closer in order to decrease the nonlinearities in displacement and velocity. The pendulum-like harvesters as the most preferable ones can be applied to many devices or units as a power source. The maximal power for these magnetically-excited structures can be estimated by the system parameters. At the end of the chapter, the recent techniques of maximal power point tracking (MPPT) and proposed controller units are explained for the piezoelectric harvester systems in order to optimize the harvested power.

The energy harvesting is known as the conversion process of ambient energy into usable electrical energy. The energy of the renewable and green Energy Sources (ES) is free and available without territorial restrictions. In this chapter the possibility to use the Extremum Seeking Control schemes for harvesting the solar energy via a Photovoltaic Hybrid Power Source is presented. The new ESC schemes based on a band-pass filter instead of the series combination of high-pass and low-pass filters are analyzed in order to evaluate their performance. The performance indicators used are the search speed and the tracking accuracy. The simulations performed highlight the advantages of the Extremum Seeking Control schemes based on a band-pass filter in comparison with the classical Extremum Seeking Control schemes. A Maximum Power Point tracking technique based on a modified Extremum Seeking Control slightly improves the energy efficiency of the Photovoltaic Hybrid Power Source. The advanced Extremum Seeking Control scheme reduces the power ripple, so the energy efficiency of the Photovoltaic Hybrid Power Source increases as well. The analysis of the dither persistence in the Extremum Seeking Control loop scheme shows the relations between the search speed and the derivatives of the Photovoltaic power. The ratio of these search speeds is also used as the performance indicator. Finally, the dynamical operation of the Photovoltaic Hybrid Power Source under variable irradiance profile is shown.

Due to both reduction and insufficient of fossil fuel to supply current growing energy needs, investigation and employing of renewable resources has been accelerated. Besides, using fossil fuel affected the environment negatively. Therefore, renewable energy resources in the most studies are solar, wind and geothermal. In this study, electrical energy production methods from solar energy have been examined, a fixed and a two axis tracking system have been designed. Both systems are compared each other regarding to several factors by performing annual measurements. Energy consumption of the system is minimized by employing actuator motor in two axis solar tracking system. According to the efficiency of two-axis tracking system, the annual average has been calculated as 31.67% more. This efficiency has been calculated as 70% in winter, 11% in summer. As a result of these measurements several graphics of a year empirically daily, monthly and annual data have been contributed to the literature for Diyarbakir, one of the prominent cities of Southern east, having the most solar energy of Turkey. In the first section, literature review will be indicated. In the second section, solar angles, photovoltaic panels and systems, sample designs and solar tracking systems are examined. In the third section, photovoltaic two-axis solar tracking system and qualifications, work and advantages of fixed system which we designed are stated. In following section, obtained results will be given and in last section, financial analysis of fixed and tracking photovoltaic systems has been performed. Also, recommendations for increasing their efficiency have been noted.

The solar energy have become a challenging area among other renewable energy sources (RESs) since the photovoltaic (PV) systems have the advantages of not causing pollution, having low maintenance, and long-lasting operation life. Besides these advantages, a PV system has several drawbacks such as considerably higher installation cost comparing some other RESs, and limited efficiency ranges between 9–18%. The feasibility analyses have a great role in order to determine the most appropriate plant site before installation. On the other hand, the operating analyses and improvements based on maximum power point tracking (MPPT) are quite important to increase the harvested total energy. The intermittent characteristic and perturbing power curve of a PV module is one of the most important defects that should be tackled to increase the generation efficiency. The power-voltage (P-V) and current-voltage (I-V) curves are main efficiency indicators of a PV system that exhibit nonlinear characteristics in its natural structure. Furthermore, the generated maximum power with a PV panel depends on two main quantities of temperature and irradiation. However, it is possible to increase the generated power up to maximum rates by MPPT algorithms. This chapter introduces most widely used algorithms respecting to their implementation and utilization properties. The indirect, direct, and computational methods are presented considering their advantages and disadvantages. The conventional and novel algorithms are explained with flowcharts and analytical details in order to provide clear comparison. The artificial methods are expressed in the last section where fuzzy logic, artificial intelligence, and optimization-based approaches are discussed.

Solar energy is one of the most important energy, which is environmentally friendly such as clean, inexhaustible and free, among the renewable energy sources. Studies on solar photovoltaic (PV) energy generation system were promoted in last two decades. The main application of PV systems are in stand-alone (water pumping, lighting, electrical vehicle, etc.), hybrid and grid-connected (PV power plants) configuration. Stand-alone PV power generation system is considered as good alternative for places that are far from conventional power generation/transmission/distribution system. PV generation systems have two big problems; PV conversion efficiency is very low and PV electricity generation is effected from changing of weather condition. PV output varies periodically in a year and in a day, and is not stable due to environmental condition. Accordingly, in order to increase PV output and PV efficiency, it is crucial to analyze PV output considering solar radiation, temperature, wind speed, shadow, etc. Maximum power point trackers (MPPTs) are employed for extracting power from photovoltaic (PV) panels. MPPTs enforce the solar modules to operate at maximum power point (MPP) under the fluctuations of ambient conditions. Therefore, they take a vital role for increasing of PV system efficiency. In this part, the case studies of MPPT system, which includes stand-alone and hybrid PV systems, will be briefly reviewed, followed by discussion of the MPPT modeling, design, etc. Several stand-alone and hybrid MPPT application will be presented. Latest developments in MPPT methods will be summarized. Finally some of the present challenges facing the MPPT techniques will be explored.

Photovoltaic modules have nonlinear current-voltage (I-V) characteristics. Thus, output power of the photovoltaic module varies with module specification and its operation point. It means that, the photovoltaic system generates maximum power at a single operation point for an environmental condition such as the irradiation level and angle, ambient temperature level etc. In addition, energy conversion efficiency varies with load level and operation point of the photovoltaic system. Since these parameters are variable, operation point of the photovoltaic system should be controlled to get maximum output power and maximum energy conversion efficiency. This action is called as maximum power point tracking. The maximum power point tracking action is usually performed with a power electronics converter. A number of maximum power point tracking methods have been introduced to obtain fast response, especially in rapidly-changing atmospheric conditions, low oscillation and higher energy conversion efficiency values. However, most of these methods are effective for uniform solar irradiation conditions. If the solar irradiation is non-uniform, the power-voltage (P-V) curve of the photovoltaic module or array has multiple peak points: Several local maximum power points and one global maximum point. In this case, traditional maximum power point tracking methods determine the nearest peak power point, which may be a local maximum point. Thus, some improved maximum power point tracking methods have been proposed to determine the global maximum power point of the photovoltaic system even under partial shading conditions. A discussion on different maximum power point tracking methods for the solution of these problems will be given and the most powerful techniques in the literature will be outlined.

Based on the experiences of five solar cars designed and manufactured in 11 years, participations in establishments of solar charging stations and local solar power plant projects, this chapter involves modeling energy harvesting and storing parts of solar cars, differences between maximum power point tracker topologies in implementations, the structures of brushless direct current motors (BLDCMs) and batteries as loads and the similarities of brushless direct current motors; briefly, solar energy harvesting for electro mobility. Light weight is one of the keys for efficiency in electro mobility. This enforces implementations of new technologies in manufacturing light weight electric vehicles. The end of the first section of this chapter is about using polymer composites in manufacturing process of solar cars. On the other hand, if energy harvesting should be separated from the vehicle, modular on or off-grid solar charging stations might be an efficient solution and an implementation of this type of energy harvesting is presented in the second section of this chapter. The last section in this chapter is about hybrid off-grid systems which also includes smart solutions. Implementations of this chapter are manufacturing process chassis and body of a solar car using polymer composites, a model of an off-grid PV charging station for electric vehicles (EVs) in a campus area, electrical units of a solar car for World Solar Challenge.

Energy harvesting is known as the conversion process of ambient energy into usable electrical energy, including the available and free energy of the renewable and green energy sources. This chapter analyzes the possibility to use the Extremum Seeking Control schemes for harvesting the hydrogen energy via a Fuel Cell Hybrid Power Source. The new Extremum Seeking Control schemes proposed here are based on a band-pass filter with the frequencies’ band larger than that of the series combination of high-pass and low-pass filters used in the classical Extremum Seeking Control scheme. The mathematical modeling of the Extremum Seeking Control scheme that is applied to nonlinear dynamic plant shows the close relations between the search speed, the derivatives of the unknown input-to-output map, and the cut-off frequencies of the band-pass filter. The simulation results are compared with the results of classical Extremum Seeking Control schemes. The ratio of these search speeds is used as the performance indicator, besides the tracking accuracy evaluated for each control scheme. A Maximum Power Point tracking technique is proposed for the Fuel Cell stack based on a modified Extremum Seeking Control that slightly improves the performance. A higher value of the searching speed is obtained for the same tracking accuracy. The search speed will increase proportionally with the product of both control parameters (the closed loop gain and the dither gain), so it is practically limited for safe reasons. An advanced Extremum Seeking Control scheme is proposed here to further reduce the power ripple and obtain the imposed performance related to the search speed and tracking accuracy. Finally, the dynamical operation of the Fuel Cell stack under constant and variable load is shown.

The chapter deals with a single DC bus hybrid configuration of a power source required for an automotive application. Such system architecture is the best choice for interconnecting multiple energy sources in order to meet the load profile in the most efficient way. This work analyzes a new PEM Fuel Cell stack-Hybrid Power Source (PEMFCs-HPS) topology consisting of a 5 kW PEMFC stack (primary source of power) and a bank of ultracapacitors (130 F, 56 V, 57 Wh) (auxiliary power source) to fulfill the high energy and high power requirements of the vehicle applications, wherein the power demand is impulsive rather than constant. This topology uses three programmable unidirectional DC/DC converters which connects the PEMFCs, the UC and the programmable electronic load. The energy management strategy (EMS) for different power sources has great effect in decreasing the fuel consumption, increasing the performance and the lifetime of the fuel cells. The proposed EMS is based on the FC efficiency map and on the state of charge of the UC. The EMS is used to split the power between the PEMFCs and the UC in the hybrid arrangement to fulfil the power requirement, which depends on the operating conditions considering the optimum power of PEMFCs and UC. An algorithm the EMS is able to achieve the steady-state PEMFCs operating with minimum hydrogen consumption and the UC state of charge (SoC) maintaining at values higher than 20%. The system ability to efficiently follow the load variations under that EMS is also presented. The consumption of hydrogen was reduced by 11.8% in comparison with the system without UC. The experimental data acquisition system is monitored and controlled using the NI Labview® software with the NI Compact-RIO hardware.

Ever increasing demand for electricity supply along with higher power quality and reliability, available fossil fuels restrictions and environmental pollutions led to aggregation of clean energy resources (distributed generations) and developing microgrids. Integration of distributed generations such as wind power and solar energy are challenging with various problems such as non-deterministic nature of available wind power and solar energy. On the other hand, power systems are subject to other uncertainties such as load and energy prices in day-ahead (DA) and balancing markets. Hence, intermittence could be highlighted as the main obstacle of distributed generations’ aggregation which cause to imbalance charges set by uncertain market prices and accordingly economic losses. To this end, a comprehensive study should be performed to elaborate aforementioned issues. In this chapter, a stochastic model with the goal of profit maximization and imbalance cost minimization is presented. Unlike previous works, in the proposed model all existent uncertainties related to wind power, solar energy, load, day ahead and imbalance market prices altogether are considered by the means of scenario based investigations. In order to generate probable scenarios, uncertain parameters should be predicted. In this framework, a new method based on neural network theory is proposed for predicting wind speed and solar radiation. Afterwards, pumped-storage plant and demand response program are utilized as two complementary resources to compensate power imbalances. Storage devices are used as flexible resources to exchange power between low consumption—cheap hours and peak hours. Finally, to investigate efficiency of the proposed method two operating modes, namely coordinated and uncoordinated operation of clean energy resources, are assumed and testified on a test microgrid.

This chapter explains a methodology for optimal planning of a micro-combined cooling, heating and power system driven by a solar dish Stirling heat engine. The solar dish concentrator collects the sun radiations and transforms them into thermal energy. The absorber and thermal storage systems are employed to absorb and store the thermal energy collected by a solar dish for continuous energy supplying when the sunlight is insufficient. The solar energy is absorbed and transferred to the working fluid in the hot point of the Stirling engine. The air source heat pump has been proposed to cool and heat the residential buildings in hot and cold weather conditions, respectively. During a hot weather, the air to air heat pump receives heat from the inside air and transfers it into the outside air, and vice versa in a cold climate. The heating energy obtained from air source heat pumps is not generated by a combustion process, rather it is transferred from the inside air to the outside air. Hence, the most promising aspect of the proposed micro-combined cooling, heating and power system is that it can be solar driven and transfer heat from the inside air during summer. Note that the process is reversed in winter times. Due to the increasing rate of carbon dioxide and more attention paid to the greenhouse gas emissions, use of solar energy and air source heat pumps in a micro-trigeneration system, which does not use any fossil fuel such as gasoline or natural gas, not only gives more chances to significant reduction of carbon dioxide, greenhouse gas emissions, and environmental pollution, but also increases the economic saving in fuel consumption. In an air to air heat pump, the electricity energy is only used by indoor/outdoor fans, and a compressor. Hence, the small-scale tri-generation system consumes less electrical energy than the traditional ones. In order to conduct an optimization, the mathematical model and thermodynamic analysis of proposed microsystem have been provided. Several key parameters related to solar dish Stirling heat engine and air to air heat pumps have been selected as the decision variables to minimize the cost of the electricity energy purchased from the main grid.

This chapter presents wired and wireless communication systems in smart homes and smart buildings by considering the recent developments seen in applications. In order to provide further knowledge for readers, the basic principles of the smart homes and energy efficient buildings are firstly introduced. Then, the nearly zero-energy buildings and renewable energy integration in buildings issues are comprehensively explained by taking into account existing applications. In addition, advanced metering infrastructure that is a vital component of the smart home systems is expressed in detail. Afterwards, the potential candidates of communication systems for smart buildings that have an important role to realize nearly zero-energy buildings are discussed by comparing each method and application types thoroughly. These communication systems are classified as wired and wireless communication systems to examine more detailed and the communication systems are compared according to several considerable parameters such as used spectrum, modulation types, bit rates, supported network topologies, media access control (MAC) schemes, carrier types, and application areas. Moreover, several applications of examined communication systems are presented both for outdoor and indoor scenarios.

Space agencies all over the world are interested today in very small satellites because of their advantages compared to heavier satellites. This chapter starts with the general characteristics, Earth orbits, eclipses and current missions of very small satellites. It continues with a brief summary of the component parts of the electrical power system: the array of solar cells, batteries for space applications, 3 power architectures and 19 maximum power point tracker’s algorithms. Authors’ attention is mainly focused on designing, simulation and practical demonstration of a prototype with a flexible hybrid proposed architecture of the power conditioning unit for very small satellites, whose component blocks are the battery charge unit (BCU) including the dc–dc converter, the digital controller, the BCU sensors circuitry and the BCU prototype) and the battery charge/discharge monitor unit (BCDMU) including the microcontroller, the BCDMU sensors circuitry, the battery switch, the battery heater and the telemetry system.

The need for high power density has been the trend of the power conversion industry for many years. The key to obtain a high power density is to increase system’s efficiency. In the case of space applications, there is the same need for high power density but with the very important note that the reliability of the system must not be compromised. In order to increase system’s efficiency while maintaining reliability, the latest soft switching converter topologies, high power density packaging, improved heat extraction and planar magnetics are used. Other key parameters are: the digital loop control and the digital energy management through microcontrollers, and digital signal controllers.

Determining the optimal battery model for a specific application is a complex process that must take into account several factors: the type of application, the accuracy required, the degree of complexity, etc. This chapter introduces a new method for determining the optimal model and has its starting point in analyzing the discharge profile, and employs a multi-criteria analysis for processing the experimental data. The method presented is validated experimentally for a LiFePO₄ battery subjected to discharge after an Urban Dynamometer Driving Schedule (UDDS) cycle.

The energy management problem is essential in optimal planning and operation of water distribution systems. This problem involves establishing the operation schedule for all water hydrophore stations from the system. One of the available policies for improving energy efficiency is related to the decrease of electricity consumption. This supposes two important aspects: the upgrading of the water distribution system and use of software packages order to ease the decision making process. Two approaches based on clustering and decision trees are proposed for electrical energy consumption forecasting in the water distribution systems. The comparative studies were realized using a database of 85 urban water hydrophore stations belonging to a Romanian water distribution company. Based on these results, it can be considered that the new proposed approaches have the ability to constitute an IT infrastructure which can be actively used for improving energy efficiency in water distribution systems.

The following chapter provides an overview about available knowledge, references and investigations on the active and passive flow control devices, initially developed for aeronautic industry that are currently being investigated and introduced on wind turbines. The main goal pursued with the introduction of these devices is to delay the boundary layer separation and enhance/suppress turbulences. The aim is to achieve a lift enhancement, drag reduction or flow-induced noise reduction among other parameters. However, achieving these goals present some issues, because the improvement of one of these parameters may suppose an undesired effect in another. For this reason it is necessary to study in detail each one of these devices, their operating concept, applications and their main advantages and drawbacks. Depending on the flow control nature, devices can be classified as actives or passives. Passive techniques allow to improve the performance of the wind turbines without external energy expenditure whereas active techniques require external energy for their activation. There are a lot of devices and in this chapter there have been compiled some of the most important ones, both passives devices (Vortex Generators, Microtabs, Spoilers, Fences, Serrated trailing edge) and actives devices (Trailing edge flaps, Air Jet Vortex Generators, Synthetic Jets).