4.energy harvesting

S.Y.B.Sc. Sem.I Physics Skill Enhancement Course I
Energy Harvesting
1 Dr. Mrs. Pritee Raotole , MGSM’s, ASC, College, Chopda
UNIT – 4
Energy Harvesting
Syllabus:
a. W i n d E n e r g y h a r v e s t i n g : Fundamentals of Wind energy, Wind
Turbines and different
electrical machines in wind turbines, Power electronic interfaces, and grid interconnection
topologies ( 0 3
L , 0 6 M )
b. P i e z o e l e c t r i c E n e r g y h a r v e s t i n g : Introduction, Physics
and characteristics of piezoelectric effect, materials and mathematical description of
piezoelectricity, Piezoelectric parameters and modeling piezoelectric generators, Piezoelectric
energy harvesting applications, Human power
( 0 4
L , 0 8 M )
c. E l e c t r o m a g n e t i c E n e r g y H a r v e s t i n g : Linear
generators, physics mathematical models, recent applications,
( 0 2 L , 0 4 M )
d. Carbon captured technologies, cell, batteries, power consumption ( 0 1
L , 0 2 M )
e. Environmental issues and sustainability of renewable energy sources. ( 0 1
L , 0 2 M )
a. WIND ENERGY HARVESTING
4.1.a FUNDAMENTAL OF WIND ENERGY
Wind is caused by the uneven heating of the atmosphere by the sun, variations in the earth's
surface, and rotation of the earth. Mountains, bodies of water, and vegetation all influence
wind flow patterns. Wind turbines convert the energy in wind to electricity by rotating
propeller-like blades around a rotor. The rotor turns the drive shaft, which turns an electric
generator. Three key factors affect the amount of energy a turbine can harness from the
wind: wind speed, air density, and swept area.
Equation for Wind Power
 Wind speed

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The amount of energy in the wind varies with the cube of the wind speed, in other
words, if the wind speed doubles, there is eight times more energy in the wind (
). Small changes in wind speed have a large impact on the
amount of power available in the wind.
 Density of the air
The more dense the air, the more energy received by the turbine. Air density varies
with elevation and temperature. Air is less dense at higher elevations than at sea
level, and warm air is less dense than cold air. All else being equal, turbines will
produce more power at lower elevations and in locations with cooler average
temperatures.
 Swept area of the turbine
The larger the swept area (the size of the area through which the rotor spins), the
more power the turbine can capture from the wind. Since swept area is ,
where r = radius of the rotor, a small increase in blade length results in a larger
increase in the power available to the turbine[
Wind is moving air and is caused by differences in air pressure within our atmosphere. As
the sun strikes the earth, it heats the soil near the surface. In turn, the soil warms the air
lying above it. Warm air is less dense than cool air and, like a hot-air balloon, rises. Cool
air flows in to take its place and becomes heated. The rising warm air eventually cools and
falls back to earth, completing the convection cycle. This cycle is repeated over and over
again, rotating like the crankshaft in a car, as long as the solar engine driving it is in the
sky. The atmosphere is a huge, solar-fired engine that transfers heat from one part of the
globe to another. The large-scale convection currents, set in motion by the sun's rays, carry
heat from lower latitudes to northern climates. The flows of air that rush across the surface
of the earth in response to this global circulation are called wind. This wind resource is
renewable and inexhaustible, as long as sunlight reaches the earth.
The direction of the wind is expressed as the direction from which the wind is blowing. For
example, easterly winds blow from east to west, while westerly winds blow from west to

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east. Figure below explains how air currents are formed from moving land mass to water
and other way.
Fig. 4.1a air currents are formed from moving land mass to water
During the day, the air above the land heats up more quickly than the air over water. The
warm air over the land expands and rises, and the heavier, cooler air rushes in to take its
place, creating winds. At night, the winds are reversed because the air cools more rapidly
over land than over water. This wind flow is called as local wind.
4.2.a WIND TURBINE AND DIFFERENT ELECTRICAL MACHINES
IN WIND TURBINES:-
Wind turbines
A wind turbine, or alternatively referred to as a wind energy converter, is a device
that converts the wind's kinetic energy into electrical energy.
Wind turbines are manufactured in a wide range of vertical and horizontal axis. The
smallest turbines are used for applications such as battery charging for auxiliary power for
boats or caravans or to power traffic warning signs. Larger turbines can be used for making
contributions to a domestic power supply while selling unused power back to the utility

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supplier via the electrical grid. Arrays of large turbines, known as wind farms, are
becoming an increasingly important source of intermittent renewable energy and are used
by many countries as part of a strategy to reduce their reliance on fossil fuels.
Wind Turbine Components are nacelle, rotor blades, hub, low speed shaft, gearbox, high
speed shaft with its mechanical brake, electrical generator, yaw mechanism, electronic
controller, hydraulics system, cooling unit, tower, anemometer and wind vane.
The nacelle contains the key components of the wind turbine, including the gearbox, and
the electrical generator. Service personnel may enter the nacelle from the tower of the
turbine. To the left of the nacelle we have the wind turbine rotor, i.e. the rotor blades and
the hub. The rotor blades capture the wind and transfer its power to the rotor hub. On a
modern 1000 kW wind turbine each rotor blade measures about 27 metres (80 ft.) in length
and is designed much like a wing of an aeroplane. The hub of the rotor is attached to the
low speed shaft of the wind turbine. The low speed shaft of the wind turbine connects the
rotor hub to the gearbox. On a modern 1000 kW wind turbine the rotor rotates relatively
slowly, about 19 to 30 revolutions per minute (RPM). The shaft contains pipes for the
hydraulics system to enable the aerodynamic brakes to operate. The gearbox has the low
speed shaft to the left. It makes the high speed shaft to the right turn approximately 50
times faster than the low speed shaft. The high speed shaft rotates with approximately.
1,500 revolutions per minute (RPM) and drives the electrical generator. It is equipped with
an emergency mechanical disc brake. The mechanical brake is used in case of failure of
the aerodynamic brake, or when the turbine is being serviced. The electrical generatoris
usually a so-called induction generator or asynchronous generator. On a modern wind
turbine the maximum electric power is usually between 600 and 3000 kilowatts (kW). The
yaw mechanism uses electrical motors to turn the nacelle with the rotor against the wind.
The yaw mechanism is operated by the electronic controller which senses the wind
direction using the wind vane. The picture shows the turbine yawing. Normally, the turbine
will yaw only a few degrees at a time, when the wind changes its direction. The electronic
controller contains a computer which continuously monitors the condition of the wind
turbine and controls the yaw mechanism. In case of any malfunction, (e.g. overheating of

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the gearbox or the generator), it automatically stops the wind turbine and calls the turbine
operator's computer via a telephone modem link. The hydraulics system is used to reset the
aerodynamic brakes of the wind turbine. The cooling unit contains an electric fan which is
used to cool the electrical generator. In addition, it contains an oil cooling unit which is
used to cool the oil in the gearbox. Some turbines have water-cooled generators.
The tower of the wind turbine carries the nacelle and the rotor. Generally, it is an advantage
to have a high tower, since wind speeds increase farther away from the ground. A typical
modern 1000 kW turbine will have a tower of 50 to 80 metres (150 to 240 ft.) (the height of
a 17-27 story building). Towers may be either tubular towers (such as the one in the
picture) or lattice towers. Tubular towers are safer for the personnel that have to maintain
the turbines, as they may use an inside ladder to get to the top of the turbine. The advantage
of lattice towers is primarily that they are cheaper. The anemometer and the wind wane are
used to measure the speed and the direction of the wind. The electronic signals from the
anemometer are used by the wind turbine's electronic controller to start the wind turbine
when the wind speed reaches approximately 5 metres per second (10 knots). The computers
stops the wind turbine automatically if the wind speed exceeds 25 metres per second (50
knots) in order to protect the turbine and its surroundings. The wind vane signals are used
by the wind turbine's electronic controller to turn the wind turbine against the wind, using
the yaw mechanism.

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Fig. 4.2a horizontal and vertical wind turbine
4.3.a POWER ELECTRONIC INTERFACES AND GRID
INTERCONNECTION TOPOLOGIES
As the power range of the turbines increases those control parameters become more
important and it is necessary to introduce power electronics as an interface between the
wind turbine and the grid. The power electronics is changing the basic characteristic of the
wind turbine from being an energy source to be an active power source. The electrical
technology used in wind turbine is not new. It has been discussed for several years but now
the price pr. produced kWh is so low, that solutions with power electronics are very
attractive.
The use of wind power generation is increasingly being pursued as a supplement and an
alternative to large conventional central power stations. The specification of the power
electronics interface is subject to requirements related not only to the renewable energy
source itself but also to its effects on power system operation, especially where the
intermittent energy source constitutes a significant part of the total system capacity.
Power electronic interfaces can allow for the control of reactive power at the source of
generation. Most inverters for DG units are self-commutated and can provide an AC
voltage of arbitrary amplitude and phase. This feature allows DG systems to produce power
at any PF. If the DG system is allowed to supply reactive power, this can be extremely
useful. The current IEEE1547 standard states that a DG system should not regulate voltage
at the point of common coupling, although a utility may allow this operation.
Electric utilities and end users of electric power are becoming increasingly
concerned about meeting the growing energy demand. Seventy five percent of total global
energy demand is supplied by the burning of fossil fuels. But increasing air pollution,
global warming concerns, diminishing fossil fuels and their increasing cost have made it
necessary to look towards renewable sources as a future energy solution. Since the past
decade, there has been an enormous interest in many countries on renewable energy for
power generation. The market liberaliza- tion and government's incentives have further
accelerated the renewable energy sector growth. The wind energy is the alternative energy

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sources. Previously, they were used to supply local loads in remote areas, outside the
national grid. Later, they have become some of main sources. The utility is concerned due
to the high penetra- tion level of intermittent Wind energy system in distribution systems
as it may pose a threat to network in terms of stability, voltage regulation and power-quality
(PQ) issues at PCC. Direct-driven permanent magnet synchronous generator (PMSG) is
widely used in wind-power generating system The power converter is a key part of the sys-
tem for the electrical energy fed into the power grid. With the increasing of power capacity
and high demand for power quality, the study of topology of high power converters based
on multi-level converter is attracting more and more attention. The non-linear load current
harmonics may result in voltage harmonics and can create a serious PQ problem in the
power system network. Active power filters (APF) are extensively used to compensate the
load current harmonics and load unbalance at distribution level. This results in an
additional hardware cost. However, in this paper control method incorporated the features
of APF, conventional inverter interfacing WECS with the grid, without any additional
hardware cost and intelligence controller for boost converter.
System Description- The proposed WECS is composed of a direct-drive 3φ PMG
that has its output fed into a 3φ diode rectifier. The output of the generator-end rectifier is
fed into a Artificial neural network controlled dc–dc converter, which supplies the
hysteresis current controlled 3φ VS grid-side inverter. The grid-side inverter supplies its
out- puts to a 400-V 50-Hz grid through a Transformer. The voltage source inverter is a key

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Fig. 4.3a Schematic of wind energy conversion system
element of a WECS system as it interfaces the wind energy source to the grid and delivers
the generated power. The variable speed wind turbines generate power at variable ac vol-
tage. Thus, the power generated from this needs power conditioning (i.e., dc/dc or ac/dc)
before connecting on dc-link. Figure 1 shows General Scheme of the wind energy
conversion system.
b. PIEZOELECTRIC ENERGY HARVESTING
4.4.b INTRODUCTION
Kinetic energy can be converted into electrical energy by means of the piezoelectric effect:
Piezo elements convert the kinetic energy from vibrations or shocks into electrical energy.
The term "energy harvesting" refers to the generation of energy from sources such as
ambient temperature, vibration or air flow. Kinetic energy can be converted into
electrical energy by means of the piezoelectric effect. Mechanically deforming a piezo
crystal with tension or pressure generates electrical charges that can be measured as voltage on
the electrodes of the piezo element.
Piezoelectric generators (energy harvesters) offer a robust and reliable solution by
converting normally wasted vibration energy in the environment to usable electrical energy.
They are ideal in applications that need to charge a battery, super capacitor, or directly
power remote sensor systems.
4.5.b PHYSICS AND CHARACTERISTICS OF PIEZOELECTRIC
EFFECT:
Piezoelectricity, appearance of positive electric charge on one side of certain non-
conducting crystals and negative charge on the opposite side when the crystals are
subjected to mechanical pressure. This effect is exploited in a variety of practical devices
such as microphones, phonograph pickups, and wave filters in telephone-communications
systems.
Certain crystals are called piezoelectric when they exhibit a relationship between
mechanical strain (tension or compression) and voltage across their surfaces. ... On the

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other hand, when subjected to an external voltage, the crystal will expand or contract
accordingly.
i. Piezoelectricity, which literally means ―electricity generated from pressure‖ is
found naturally in many monocrystalline materials, such as quartz, tourmaline,
topaz and Rochelle salt.
ii. Piezoelectric materials are materials that produce a voltage when stress is applied.
Since, this effect also applies in the reverse manner; a voltage across the sample will
produce stress within the sample.
iii. The word ―piezo‖ is a Greek word which means ―to press‖. Therefore,
piezoelectricity means electricity generated from pressure - a very logical name.
Suitably designed structures made from these materials can therefore be made that
bend, expand or contract when a voltage is applied.
iv. This effect was found to be due to the electrical dipoles of the material
spontaneously aligning in the electrical field.
v. Due to the internal stiffness of the material, piezoelectric elements were also found
to generate relatively large forces when their natural expansion was constrained.
vi. Thus piezoelectric materials can also be used as sensors to measure structural
motion by directly attaching them to the structure.
vii. Most contemporary applications of piezoelectricity use polycrystalline ceramics
instead of naturally occurring piezoelectric crystals.
viii. The ceramic materials afford a number of advantages; they are hard, dense and can
be manufactured to almost any shape or size.
ix. polycrystalline ceramic materials, such as lead zirconate titanate (PZT), can be
processed to exhibit significant piezoelectric properties. PZT ceramics are relatively
easy to produce, and exhibit strong coupling between mechanical and electrical
domains.
x. high value of the dielectric constant
xi. presence of spontaneous polarization in some zones (domains)

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xii. presence of hysteresis loop in polarization-electric field and strain-electric field
curves
xiii. dielectric constant increases with increase of temperature
xiv. ferroelectric properties disappear above a special point in dielectric constant -
temperature curve (Curie point)
4.6.b MATERIALS AND MATHEMATICAL DESCRIPTION OF
PIEZOELECTRICITY
4.6.1b Materials
Many materials, both natural and synthetic, exhibit piezoelectricity
 Some Naturally occurring crystals such as Quartz, Berlinite (AlPO4), a
rare phosphate mineral that is structurally identical to quartz, Sucrose (table
sugar), Rochelle salt ,Topaz, Tourmaline-group minerals, Lead
titanate (PbTiO3).
 Bone-Dry bone exhibits some piezoelectric properties.
 Biological materials exhibiting piezoelectric properties include-Tendon, Silk,
Wood due to piezoelectric texture, Enamel, Dentin, DNA.
 Synthetic crystals such as Langasite (La3Ga5SiO14), a quartz-analogous crystal,
Gallium orthophosphate (GaPO4), a quartz-analogous crystal, Lithium
niobate (LiNbO3), Lithium tantalate (LiTaO3)
 Synthetic ceramics- Ceramics with randomly oriented grains must be ferroelectric to
exhibit piezoelectricity. Barium titanate (BaTiO3)—Barium titanate was the first
piezoelectric ceramic discovered., Lead zirconate
titanate (Pb[ZrxTi1−x]O3 Potassium niobate (KNbO3), Sodium tungstate (Na2WO3),
Ba2NaNb5O5, Pb2KNb5O15, Zinc oxide (ZnO)–Wurtzite structure.
 More recently, there is growing concern regarding the toxicity in lead-containing
devices so development of lead-free piezoelectric materials.
4.6.2b Mathematical description
Linear piezoelectricity is the combined effect of

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The linear electrical behavior of the material:
D= € E
where D is the electric charge density displacement (electric
displacement), ε is permittivity (free-body dielectric constant), E is electric field
strength, and
Hooke's Law for linear elastic materials:
where S is strain, s is compliance under short-circuit conditions, T is stress, and
These may be combined into so-called coupled equations, of which the strain-charge
form
In matrix form,
{S}= [sE
] {T}+ [dt
] {E}
{D}= [d] {T}+ [€t
] {E}
where [d] is the matrix for the direct piezoelectric effect and [dt
] is the matrix for the
converse piezoelectric effect. The superscript E indicates a zero, or constant, electric field;
the superscript T indicates a zero, or constant, stress field; and the superscript t stands
for transposition of a matrix.
Notice that the third order tensor ∂ maps vectors into symmetric matrices. There are no
non-trivial rotation-invariant tensors that have this property, which is why there are no
isotropic piezoelectric materials.

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The strain-charge for a material of the 4mm (C4v) crystal class (such as a poled
piezoelectric ceramic such as tetragonal PZT or BaTiO3) as well as the 6mm crystal class
may also be written as (ANSI IEEE 176):
where the first equation represents the relationship for the converse piezoelectric effect and
the latter for the direct piezoelectric effect.
Although the above equations are the most used form in literature, some comments about
the notation are necessary. Generally, D and E are vectors, that is, Cartesian tensors of rank
1; and permittivity ε is a Cartesian tensor of rank 2. Strain and stress are, in principle, also
rank-2 tensors. But conventionally, because strain and stress are all symmetric tensors, the
subscript of strain and stress can be relabeled in the following fashion: 11 → 1; 22 → 2;
33 → 3; 23 → 4; 13 → 5; 12 → 6. (Different conventions may be used by different authors
in literature. For example, some use 12 → 4; 23 → 5; 31 → 6 instead.) That is
why S and T appear to have the "vector form" of six components. Consequently, s appears

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to be a 6-by-6 matrix instead of a rank-3 tensor. Such a relabeled notation is often
called Voigt notation. Whether the shear strain components S4, S5, S6 are tensor components
or engineering strains is another question. In the equation above, they must be engineering
strains for the 6,6 coefficient of the compliance matrix to be written as shown, i.e.,
2(sE
11 − sE
12). Engineering shear strains are double the value of the corresponding tensor
shear, such as S6 = 2S12 and so on. This also means that s66 = 1/G12, where G12is the shear
modulus.
In total, there are four piezoelectric coefficients, dij, eij, gij, and hij defined as follows:
( ) ( )
( ) ( )
( ) ( )
( ) ( )
where the first set of four terms corresponds to the direct piezoelectric effect and the second
set of four terms corresponds to the converse piezoelectric effect, and the reason why the
direct piezoelectric tensor is equal to the transpose of the converse piezoelectric tensor
originated from the Maxwell Relations in Thermodynamics. For those piezoelectric crystals
for which the polarization is of the crystal-field induced type, a formalism has been worked
out that allows for the calculation of piezoelectrical coefficients dij from electrostatic lattice
constants or higher-order Madelung constants.
4.7.b PIEZOELECTRIC PARAMETERS AND MODELING
PIEZOELECTRIC GENERATORS
The energy stored in a capacitor is given by the equation: = 1 /2 𝑉2
𝐶 For our circuit,
C = 220 µF. When the multimeter shows 10 volts across the capacitor, the amount of
energy stored is

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= 1/ 2 (10 𝑉)2
(220 𝜇𝐹)= 𝟎. 𝟎𝟏𝟏 𝒋𝒐𝒖𝒍𝒆𝒔
If a single tap on the piezoelectric element increases the voltage from 2 V to 2.05 V, the
amount of energy generated for each tap is
= 1/ 2 (2.052
−22
)(220 𝜇𝐹) = 𝟎. 𝟎𝟎𝟎𝟎𝟐𝟐 𝒋𝒐𝒖𝒍𝒆𝒔/𝒕𝒂p
A typical cell phone battery stores ~18,000 joules of energy. If we replaced our
capacitor with a cell phone battery to charge, how long would it take to fully charge it?
You would have to press this piezoelectric element almost 1 billion times just to charge
your cell phone! If you tapped the piezo element 3 times every second, it would take
8.66 years to fully charge your cell phone.
How Can We Make A Practical Piezoelectric Generator?
Two obvious ways to improve our piezoelectric generator: 1. Use a more efficient
piezoelectric material 2. Place the piezoelectric element where it will get pressed very
rapidly If we have a piezoelectric material that can increase the voltage across our
capacitor from 2 V to 12 V with a single tap, the amount of energy generated is now
0.0154 joules/tap, 700 times greater than before. It would now only take 1,200,000 taps
to charge the cell phone, which could be done in 4.6 days!
The second choice is to place the piezoelectric element where it experiences MANY
more deformations. This has been done by placing the elements under sidewalks and
roads—places where surface movement vibrations tap the element 10,000 times per
second. If our piezoelectric element could be pressed 10,000 times/second, it would
take 22.8 hours to charge. Finally, if we combined both improvements, the phone
battery could be charged in as little as 2 minutes!
In piezoelectric materials basic principle is charge displacement in non symmetric
crystal lattice obtained via mechanical deformation of piezoelectric material.
Mechanical energy mechanical deformation charge displacement
electrical energy
Types of mechanical energy used - corresponding parameter

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Vibration (in solid bodies)- natural frequencies
Sound (transmitted through air) - frequency spectra or broad band
Impact- Amplitudes
Deformation - Acoustic or mechanical coupling
Rotation – Force and bending movement
Change of position – rotation speed
Design of generator – generator as double or triple layer beam (1-2 piezo layer +
stiffening layer). Double nature generator also the spring of seismic mass of
mechanical oscillator. Stiffening layer required to generate unidirectional stress in piezo
layer. Optimal height of both layers for fitting stress load in piezo layer, both for
generator and actuators.
Fig. 4.4. b piezoelectric generator model
4.8.b APPLICATIONS OF PIEZOELECTRIC ENERGY
HARVESTING
Electricity Generation — Some applications require the harvesting of energy from
pressure changes, vibrations, or mechanical impulses. The harvesting of energy is
possible by using piezoelectric materials to convert deflections or displacements into
electrical energy that can either be used or stored for later use.
Pressure Sensors — In nearly any application requiring the measurement of dynamic
pressure changes, using piezoelectric pressure sensors yields more reliable results than
using conventional electromechanical pressure sensors.

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Engine Knock Sensors — Engine manufacturers are constantly facing challenges
related to the control of engine parameters. Under the wrong circumstances, gasoline
engines are susceptible to an undesirable phenomenon known as detonation.
Sonar Equipment — Depth sounders and sonar equipment rely extensively on
piezoelectric sensors to transmit and receive ultrasonic ―pings‖ in the 50-200kHz range.
Besides having an ideal frequency response for such applications, piezoelectric
transducers have a high power density that enables large amounts of acoustic power to
be transmitted from a small package.
Diesel Fuel Injectors — In the last decade, regulations on emissions from diesel
engines have become increasingly stringent. Additionally, customers continue to
demand quieter engines with improved power and torque curves. In order to meet these
stringent demands for compliance and performance, engine manufacturers have resorted
to using precisely timed and metered injections of fuel during the combustion process.
Fast Response Solenoids — Some processes require quick and precise mechanical
actuation that is difficult, if not impossible, to achieve with electromagnetic solenoids.
While speed may not always be a concern, power consumption or compactness of size
is a top priority. In such cases, piezoelectric actuators are often able to fill the niche as
they provide fast response and low power consumption in small packages, compared to
electromagnetic solenoids.
Optical Adjustment — Some optics need to be adjusted or modulated with a wide
frequency response and with a minimum number of moving parts. Piezoelectric
actuators are often employed in such applications where they provide fast and accurate
control over a long service life.
Ultrasonic Cleaning — Piezoelectric actuators are also used for ultrasonic cleaning
applications. To perform ultrasonic cleaning, objects are immersed in a solvent (water,
alcohol, acetone, etc.). A piezoelectric transducer then agitates the solvent. Many
objects with inaccessible surfaces can be cleaned using this methodology.
Ultrasonic Welding — Many plastics can be joined together using a process known
as ultrasonic welding. This type of process requires ultrasonic waves to be transmitted

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to a focused area where they can cause pieces of plastic to fuse together. Frequently,
piezoelectric actuators are used to accomplish this task.
Piezoelectric Motors — One advantage of using piezoelectric materials is that their
characteristics are precise and predictable. Thus, expansion and contraction of a
piezoelectric actuator can be precisely controlled as long as the supply voltage is
controlled.
Stack Actuators — Multiple piezoelectric elements may be stacked to multiply the
displacement achieved for a given voltage. These types of devices are known as stack
actuators, piezoelectric materials used to design this to get quick response.
Stripe Actuators — Two strips of piezoelectric material may be sandwiched together in
a configuration that is similar to a bimetallic strip. In this configuration, the electric
input causes one strip to expand while the other strip simultaneously contracts, causing a
deflection.
Piezoelectric Relays — Piezoelectric elements may be implemented to actuate
electromechanical relays or switches. For these applications, either stripe actuators or
stack actuators may be used to open and close electrical contacts.
Piezoelectric Printers — Generally speaking, there are two main types of printers that
use piezoelectric actuators:dot matrix and inject printer.
Piezoelectric Speakers — Piezoelectric speakers are featured in virtually every
application that needs to efficiently produce sound from a small electronic gadget.
These types of speakers are usually inexpensive and require little power to produce
relatively large sound volumes. Thus, piezoelectric speakers are often found in devices
such as the following:– Cell phones, Ear buds, – Sound-producing toys, Musical
greeting cards, Musical balloons
Piezoelectric Buzzers — Piezoelectric buzzers are similar to piezoelectric speakers,
but they are usually designed with lower fidelity to produce a louder volume over a
narrower frequency range. Buzzers are used in a seemingly endless array of electronic
devices.

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Piezoelectric Humidifiers — Many cool mist humidifiers use a piezoelectric
transducer to transmit ultrasonic sound energy into a pool of water. The ultrasonic
vibrations cause fine water droplets to break away and atomize from the surface of the
pool where they become entrained in an air stream and enter the desired space.
Electronic Toothbrushes — Linear piezoelectric actuators are implemented to vibrate
the bristles in some electronic toothbrushes.
Instrument Pickups — Many acoustic-electric stringed instruments utilize
piezoelectric pickups to convert acoustic vibrations to electric signals. Typically, a strip
of piezoelectric material is placed between the instrument body and a structure that
supports the strings. For instance, an acoustic-electric guitar usually houses its
piezoelectric strip beneath the bridge and within the saddle. As the strings vibrate, the
strip is agitated to generate an electric signal.
Microphones — Some microphones (such as contact microphones for percussion
instruments) use piezoelectric materials to convert sound vibrations to an electrical
output. These microphones generally possess high output impedances that must be
matched when designing their respective pre-amplifiers.
Microelectronic Mechanical Systems (MEMS) — MEMS devices have become more
commonplace as more integrated capabilities are required in smaller packages, such as
cell phones, tablet computers, etc. The advantage of MEMS devices is that gyroscopes,
accelerometers, and inertial measuring devices can be integrated into chip-sized
packages. In order to accomplish such a feat, piezoelectric actuators and sensors are
often used.
Micro Robotics — In the field of small robotics, small power-efficient mechanical
actuators and sensors are needed. With the use of piezoelectric actuators, building
something as small as a robotic fly that can crawl and fly is technically feasible.
4.9.b HUMAN POWER
Bones are the integral part of human body that shows piezoelectric properties. It means
that when mechanical stress or mechanical excitation is applied to human body, this
mechanical excitation directly affects the bones in body. Due to this excitation bones

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produce a current within itself which is a human bone property called as piezoelectric
effect also known piezoelectricity. It is ability of certain materials for generating AC
voltage when it is subjected to mechanical excitation or vibration. Human bones are
made up of piezoelectric material thereby when human comes under mechanical
excitation, AC voltage sets up in whole body due to piezoelectric effect in bones. A
current starts flowing in all parts of body thereby the aim of our research is to determine
the electrical conductivity in human body to establish the maximum voltage of 30-60
volts so that this produced piezoelectric charge could be stored in our designed human
electricity sensor device.
Some equipment uses human power. It may directly use mechanical power from
muscles, or a generator may convert energy generated by the body into electrical power.
Human-powered equipment consists of electrical appliances which can be powered by
electricity generated by human muscle power as an alternative to conventional sources
of electricity such as disposable primary batteries and the electrical grid. Such devices
contain electric generators or an induction system to recharge their batteries. Separate
crank-operated generators are now available to recharge battery-powered portable
electronic devices such as mobile phones. Others, such as mechanically powered
flashlights, have the generator integrated within the device.
An alternative to rechargeable batteries for electricity storage is supercapacitors, now
being used in some devices such as the mechanically powered flashlight shown here.
Devices that store the energy mechanically, rather than electrically, include clockwork
radios with a mainspring, which is wound up by a crank and turns a generator to power
the radio.
An early example of regular use of human-powered electrical equipment is in
early telephone systems; current to ring the remote bell was provided by a subscriber
cranking a handle on the telephone, which turned a small magneto generator. Human-
powered devices are useful as emergency equipment, when natural disaster, war,
or civil disturbance make regular power supplies unavailable. They have also been seen
as economical for use in poor countries, where batteries may be expensive and mains

Energy Harvesting
electricity unreliable or unavailable. They are also an environmentally preferable
alternative to the use of disposable batteries, which are wasteful source of energy and
may introduce heavy metals into the environment. Communication is a common
application for the relatively small amount of electric power that can be generated by a
human turning a generator.
is work or energy that is produced from the human body. It can also refer to
the power (rate of work per time) of a human. Power comes primarily from muscles,
but body heat is also used to do work like warming shelters, food, or other humans.
World records of power performance by humans are of interest to work planners and
work-process engineers. The average level of human power that can be maintained over
a certain duration of time — say over the extent of one minute, or one hour— is
interesting to engineers designing work operations in industry. Human power is
occasionally used to generate, and sometimes to store, electrical energy in batteries for
use in the wilderness.
c. ELECTROMAGNETIC ENERGY HARVESTING
Energy harvesting or energy scavenging is the process of transforming ambient energy into
useful electrical energy. The ambient energy could be the kinetic energy of a moving or
vibrating structure, the radiant energy of sunlight, or the thermal energy of a warm object.
Electomagnetism has been used to generate electricity shortly after Faraday’s fundamental
breakthrough in electromagnetic induction. An electromagnetic vibratory energy harvester
can scavenge energy from a vibratory environment by relying on external vibrations to
move either a conductor or a permanent magnet relative to one another. Such relative
motions create a time-varying magnetic flux which induces a time-varying current in a
closed-loop conductor. Electromagnetic energy harvesters are currently being used to
power wireless sensor nodes and portable devices. They are easy and cheap to design, but
has scalability issues and low energy density because they usually require bulky magnets
and coils
4.10.c LINEAR GENERATOR

Energy Harvesting
Linear generator is similar to any other generator which works on the principle of
electromagnetic induction. while all the generators work in rotatory motion linear generator
work on linear motion that is motion in straight line. when magnet moves in a relation to
electromagnetic coil,this changes the magnetic flux passing through the coil and thus
induces the flow of electric current which can be used to work. Linear generator is used to
convert back forth motion directly to electrical energy. The best example for this will be a
TORCH.
When a magnet moves in relation to an electromagnetic coil, this changes the magnetic flux passing
through the coil, and thus induces the flow of an electric current, which can be used to do work. A
linear alternator is most commonly used to convert back-and-forth motion directly into electrical
energy. This short-cut eliminates the need for a crank or linkagethat would otherwise be required to
convert a reciprocating motion to a rotary motion in order to be compatible with a rotary generator.
The simplest type of linear alternator is the Faraday flashlight. This is a torch (UK)
or flashlight (USA) which contains a coil and a permanent magnet. When the appliance is shaken
back and forth, the magnet oscillates through the coil and induces an electric current. This current is
used to charge a capacitor, thus storing energy for later use. The appliance can then produce light,
usually from a light-emitting diode, until the capacitor is discharged. It can then be re-charged by
further shaking.
Other devices which use linear alternators to generate electricity include the free-piston linear
generator, an internal combustion engine, and the free-piston Stirling engine, an external
combustion engine.
Fig. 4.5.c Free Piston Engine as Linear Generator

Energy Harvesting
Linear electromagnetic energy harvesters operate based on the basic principle of resonance.
In other words, when the excitations frequency of the environmental source matches the
fundamental frequency of the harvester, its sets a solid magnet in motion relative to a
stationary coil which generates a time-varying current in the coil as per Faraday’s law.
Several linear harvesting systems have been proposed to scavenge energy from human
motion by different research groups, in which kinetic energy is harvested via the
electromagnetic induction.
4.11.c RECENT APPLICATIONS
Today electrical generators have widespread use in power generation systems such as fossil
fuels, nuclear power, hydroelectric power, and wind turbines. Summarizing the last century
of development in electromagnetism and electrical generators would be a daunting task.
Inductive energy harvesters can be categorized by how they achieve a relative velocity
between the coil and the magnet.
Linear harvesters feature the magnet moving along a straight line relative to the coil.
Rotational harvesters use magnets mounted on a spinning rotor with stationary coils
mounted around the rotor.
Pendulum harvesters feature the magnet on a pendulum moving relative to a stationary coil.
Beam-based harvesters attach either a magnet or a coil to an elastic beam.
The electromagnetic energy harvester was modeled as a dashpot which exerted a force on
the mass that was directly proportional to the relative velocity between the mass and the
frame. As the rigid frame oscillated, some of the mechanical energy of the moving proof
mass was transferred through the harvester to a load resistor. Williams and Yates concluded
that increasing the natural frequency or the deflection of the proof mass would increase the
power output of the device to the load resistor.
a linear electromagnetic energy harvester for vehicle suspensions. The regenerative shock
absorber captured vibrations caused by road irregularities and vehicle accelerations and
decelerations. The shock absorber was able to generate 16 W to 64 W from a RMS
suspension velocity between 0.25 m/s and 0.5 m/s.

Energy Harvesting
linear generators for capturing the energy of ocean waves. These devices consist of a 7
buoy floating on the ocean surface attached by a cable to a sliding rod inside a generator on
the seabed. As a wave passes, the vertical motion of the buoy pulls on a cable and moves
the rod. Magnets mounted on the rod induce a voltage in the coils of the generator.
rotational energy harvesters. Typically these harvesters require a mechanism to convert the
linear motion of a vibrating structure into a rotational motion to drive the device. Rotational
energy harvesters are not limited in displacement like linear harvesters, and this allows for
larger power densities. However rotational generators typically operate at higher
frequencies than linear generators
Pendulum-based induction harvesters allow for rotational motion to be achieved through
linear vibrations.
A pendulum-based harvester design can also produce power when placed on a rotating
structure.
d. CARBON CAPTURED TECHNOLOGY
4.12. d Carbon Captured Technology
Carbon Capture and Storage (CCS) is a technologythat can capture up to 90% of
the carbon dioxide (CO2) emissions produced from the use of fossil fuels in electricity
generation and industrial processes, preventing the carbon dioxide from entering the
atmosphere. The process of trapping carbon dioxide at its emission source, transporting it to
a usually underground storage location, and isolating it there: New carbon
capture technologies provide an additional weapon against global warming. Also
called carbon capture and storage, car. · bon cap.
When a coal, oil or gas plant burns fuel to create electricity, a major by-product is the
greenhouse gas carbon dioxide (CO2).
One approach to keeping carbon emissions under control is the use of carbon capture and
storage (CCS) technologies that use underground rocks as ―storage tanks‖. But how do
these technologies work?

Energy Harvesting
When fossil fuels are burnt they produce a range of different gases including oxygen,
nitrogen and CO2.
CCS focuses on selectively pulling this CO2 out of the gas mixture and preparing it for
underground storage. Three main approaches have been developed to do this – pre-
combustion, post-combustion and oxyfuel combustion.
4.12.1 d Pre-combustion
As the name says, a pre-combustion setup focuses on capturing CO2 before the fuel is
burnt.
First, an air separator strips oxygen from the atmosphere, producing an almost pure stream
of oxygen gas. This is then fed into a unit known as the gasifier, which bakes the coal at
around 700 °C, releasing a mixture of gases including hydrogen, carbon monoxide, CO2
and steam. Collectively this is known as syngas.
By adding water to this syngas in a shift reactor it is converted into hydrogen and CO2.
Separating these two gases produces a stream of hydrogen, which is burnt off, and CO2
which is dehydrated to remove any leftover water and compressed to concentrate the gas
into a liquid form for transport and storage.
To maximise efficiency of the process, the heat produced by burning the hydr ogen is
redirected to convert water to steam and so produce more electricity using conventional
steam turbines.
4.12.2 d Post-combustion
Post-combustion is another technique used to capture CO2. It has the advantage of being
able to be retrofitted to existing power plants.
Fuel is injected into a boiler with air and burnt in the same way you would typically find at
a coal, oil, or gas-fired power plant.
The heat produced inside this boiler is used to convert water to steam that in turn powers a
set or turbines to produce energy.
The by-product of this burn is a mixture of nitrogen, CO2 and water collectively termed
flue gas.

Energy Harvesting
A wide variety of filtration systems can pluck the CO2 from this mixture. Some examples
currently used or being investigated are ultra-porous crystals, ammonia and limestone
membranes that can selectively bind and release CO2, and even populations of algae or
cyanobacteria which feed on the gas to survive.
This filtration pulls the CO2 from the flue gas, which can then be dehydrated and
compressed ready for transport and storage.
4.12.3d Oxyfuel combustion
Oxyfuel combustion systems burn coal using flue gas and pure oxygen, produced with an
air separation unit. From this reaction comes heat, which is used to convert water to steam,
and a mixture of flue gas and water.
This mixture can be used to regulate the temperature of the boiler before being passed
through a CO2 purification unit that first removes other pollutants including sulfur and
nitrogen.
It then compresses the CO2 and separates it from other non-reactive gases including
oxygen and nitrogen to produce a stream of water that has a very high concentration of
CO2.
4.12.4.d Storage
Once the CO2 has been captured from the energy production process it is ready to be
stored.
After transportation by trucks or pipeline, the liquid gas is pumped into porous rock
formations that can be kilometres below the surface.
At these depths, the temperature and pressure keeps the gas in its liquid form where it is
trapped within the geological layer.
Depleted oil fields are often used as storage tanks because a large amount of geological
data is readily available, produced during the prospecting process.
The most important part of selecting a storage site is the presence of an impermeable rock
layer above the porous rock known as ―cap rock‖, which prevents the liquid gas from
escaping.

Energy Harvesting
Fig.4.6.d show different Carbon Capture Technologies
4.13.d CELL
A cell is a single unit device which converts chemical energy into electric energy.
Depending on the types of electrolytes used, a cell is either reserve, wet or dry types. Cell
also includes molten salt type. A cell is usually light and compact as it has a single unit. A
cell supplies power for a shorter period of time. A cell is used mostly for lighter
tasks which requires less energy. It is used inlamps, clocks, lamp, etc. Cells are usually

Energy Harvesting
cheap. An electrical cell is a device that is used to generate electricity, or one that is used
to make chemical reactions possible by applying electricity. Special chemical
reactions which occur inside the electrical cell, result in oxidation and reduction of the
substances inside the cell. This produces electrical energy. Normal batteries work like this.
Some electrical cells produce electricity without using chemical energy. For example, solar
cells produce electricity when they are exposed to sun light.[2]
A plate of zinc and a plate of copper immersed in a dilute solution which
contains acid or salt is an example of the chemical reaction based cell. The solution acts as
an electrolyte(electric conductor). When the two plates are connected to a current meter
with a wire, electric current will pass; this is because oxidation and reduction processes
take place in this chemical reaction turning the zinc plate to a negative electrode and the
copper plate to a positive electrode, and so the electrons flow from zinc to copper.
Cell, in electricity, unit structure used to generate an electrical current by some means other
than the motion of a conductor in a magnetic field. A solar cell, for example, consists of a
semiconductor junction that converts sunlight directly into electricity. A dry cell is a
chemical battery in which no free liquid is present, the electrolyte being soaked up by some
absorbent material such as cardboard. A primary, or voltaic, cell produces electricity by
means of a chemical reaction but is not rechargeable to any great extent. The conventional
dry cell (e.g., flashlight or transistor-radio battery) is a primary cell. A secondary cell, such
as a lead-acid storage battery, is rechargeable, as are some primary cells, such as the
nickel–cadmium cell. A fuel cell produces an electrical current by constantly changing
the chemical energy of a fuel and an oxidizing agent, separately stored and supplied to a
chamber containing electrodes, to electrical energy. Two or more cells connected together
are a battery, although in common usage ―battery‖ is also used to designate a single cell.
4.14.d BATTERIES
A battery is a device consisting of one or more electrochemical cells with external
connections provided to power electrical devices such as flashlights, smartphones,
and electric cars. When a battery is supplying electric power, its positive terminal is
the cathode and its negative terminal is the anode. The terminal marked negative is the

Energy Harvesting
source of electrons that will flow through an external electric circuit to the positive
terminal. When a battery is connected to an external electric load, a redox reaction converts
high-energy reactants to lower-energy products, and the free-energy difference is delivered
to the external circuit as electrical energy. Historically the term "battery" specifically
referred to a device composed of multiple cells, however the usage has evolved to include
devices composed of a single cell.
Primary (single-use or "disposable") batteries are used once and discarded;
the electrode materials are irreversibly changed during discharge. Common examples are
the alkaline battery used for flashlights and a multitude of portable electronic
devices. Secondary (rechargeable) batteries can be discharged and recharged multiple times
using an applied electric current; the original composition of the electrodes can be restored
by reverse current. Examples include the lead-acid batteries used in vehicles and lithium-
ion batteries used for portable electronics such as laptops and smartphones.
Batteries come in many shapes and sizes, from miniature cells used to power hearing
aids and wristwatches to small, thin cells used in smartphones, to large lead acid
batteries or lithium-ion batteries in vehicles, and at the largest extreme, huge battery banks
the size of rooms that provide standby or emergency power for telephone exchanges and
computer data centers.
A battery usually consists of group of cells. A battery is either a primary battery or a
secondary battery meaning it is rechargeable or non-chargeable. Battery normally consists
of several cells thus giving it a bigger size and is bulky. A battery can supply power long
durations. A battery is mostly used for heavy duty tasks. It is used in inverters, automobiles,
inverter, etc. Batteries are much costlier.
4.15.d POWER CONSUMPTION
Power consumption refers to the electrical energy per unit time, supplied to operate
something, such as a home appliance. Power consumption is usually measured in units of
watts (W) or kilowatts (kW). The energy used by equipment is always more than
the energy really needed.

Energy Harvesting
Electric energy is most often measured either in joules (J), or in watt hours (W·h)
representing a constant power over a period of time.
1 W·s = 1 J
1 W·h = 3600 W·s = 3600 J
Electric and electronic devices consume electric energy to generate desired output
(i.e., light, heat, motion, etc.). During operation, some part of the energy—
depending on the electrical efficiency—is consumed in unintended output, such as
waste heat.
Electricity has been generated in power stations since 1882.[2]
The invention of the
steam turbine in 1883 to drive the electric generator started a strong increase of
world electricity consumption.
In 2008, the world total of electricity production was 20.279 petawatt-hours (PWh).
This number corresponds to an average power of 2.31 TW continuously during the
year. The total energy needed to produce this power is roughly a factor 2 to 3
higher because a power plant's efficiency of generating electricity is roughly 30–
50%. The generated power is thus in the order of 5 TW. This is approximately a
third of the total energy consumption of 15 TW (see world energy consumption).
In 2005, the primary energy used to generate electricity was 41.60 Quadrillion BTU
[12, 192 TWh] (Coal 21.01 quads [6,157 TWh], Natural Gas 6.69 quads [1,960
TWh], Petroleum 1.32 quads [387 TWh], Nuclear electric power 8.13 quads [2,383
TWh], Renewable energy 4.23 quads [1,240 TWh] respectively). The gross
generation of electricity in that year was 14.50 Quads [4,250 TWh]; the difference,
27.10 Quads [7,942 TWh], was conversion losses. Among all electricity, 4.84
Quads [1,418 TWh] was used in residential area, 4.32 Quads [1,266 TWh] used in
commercial, 3.47 Quads [1,017 TWh] used in industrial and 0.03 Quads [8.79
TWh] used in transportation.
1 Quad = 1 Quadrillion BTU = 1 x 1015
BTU = 293 TWh

Energy Harvesting
16,816 TWh (83%) of electric energy was consumed by final users. The difference
of 3,464 TWh (17%) was consumed in the process of generating power and lost in
transmission to end users.
A sensitivity analysis on an adaptive neuro-fuzzy network model for electric
demand estimation shows that employment is the most critical factor influencing
electrical consumption. The study used six parameters as input data, employment,
GDP, dwelling, population, HDD and CDD, with electricity demand as output
variable.
e. ENVIRONMENTAL ISSUES
4.15.e BENEFITS OF RENEWALE ENERGY SOURCES
1. Less global warming
most renewable energy sources produce little to no global warming emissions. Even when
including ―life cycle‖ emissions of clean energy (ie, the emissions from each stage of a
technology’s life—manufacturing, installation, operation, decommissioning), the global
warming emissions associated with renewable energy are minima
2. Improved public health
Wind, solar, and hydroelectric systems generate electricity with no associated air pollution
emissions. Geothermal and biomass systems emit some air pollutants, though total air
emissions are generally much lower than those of coal- and natural gas-fired power plants.
3. Inexhaustible energy
Strong winds, sunny skies, abundant plant matter, heat from the earth, and fast-moving
water can each provide a vast and constantly replenished supply of energy.
4. Jobs and other economic benefits
Compared with fossil fuel technologies, which are typically mechanized and capital
intensive, the renewable energy industry is more labor intensive. Solar panels need humans
to install them; wind farms need technicians for maintenance.

Energy Harvesting
This means that, on average, more jobs are created for each unit of electricity generated
from renewable sources than from fossil fuels.
5. Stable energy prices
Renewable energy is providing affordable electricity across the country right now, and can
help stabilize energy prices in the future.
6. Stable energy prices
4.16.e ENVIRONMENTAL ISSUES AND SUSTAINABILITY OF
RENEWABLE ENERGY SOURCES
Modular systems are composed of numerous individual wind turbines or solar arrays.
Even if some of the equipment in the system is damaged, the rest can typically continue to
operate.
Harnessing power from the wind is one of the cleanest and most sustainable ways to
generate electricity as it produces no toxic pollution or global warming emissions. Wind is
also abundant, inexhaustible, and affordable, which makes it a viable and large-scale
alternative to fossil fuels.
Despite its vast potential, there are a variety of environmental impacts associated with
wind power generation that should be recognized and mitigated.
4.16.1.e Land Use
The land use impact of wind power facilities varies substantially depending on the site:
wind turbines placed in flat areas typically use more land than those located in hilly areas.
However, wind turbines do not occupy all of this land; they must be spaced approximately
5 to 10 rotor diameters apart (a rotor diameter is the diameter of the wind turbine blades).
Thus, the turbines themselves and the surrounding infrastructure (including roads and
transmission lines) occupy a small portion of the total area of a wind facility. Offshore
wind facilities require larger amounts of space because the turbines and blades are bigger
than their land-based counterparts. Depending on their location, such offshore installations
may compete with a variety of other ocean activities, such as fishing, recreational
activities, sand and gravel extraction, oil and gas extraction, navigation, and aquaculture.
Employing best practices in planning and siting can help minimize potential land use

Energy Harvesting
impacts of offshore and land-based wind projects. Depending on their location, larger
utility-scale solar facilities can raise concerns about land degradation and habitat
loss. Hydrothermal plants are sited on geological ―hot spots," which tend to have higher
levels of earthquake risk. There is evidence that hydrothermal plants can lead to an even
greater earthquake frequency
4.16.2.e Wildlife and Habitat
The impact of wind turbines on wildlife, most notably on birds and bats, has been widely
document and studied. A recent National Wind Coordinating Committee (NWCC) review
of peer-reviewed research found evidence of bird and bat deaths from collisions with wind
turbines and due to changes in air pressure caused by the spinning turbines, as well as from
habitat disruption.
4.16.3.e Public Health and Community
Sound and visual impact are the two main public health and community concerns
associated with operating wind turbines. Most of the sound generated by wind turbines is
aerodynamic, caused by the movement of turbine blades through the air. There is also
mechanical sound generated by the turbine itself. Overall sound levels depend on turbine
design and wind speed.
Some people living close to wind facilities have complained about sound and vibration
issues
4.16.4.e Water Use
Concentrating solar thermal plants (CSP), like all thermal electric plants, require water for
cooling. Water use depends on the plant design, plant location, and the type of cooling
system. Water use at a biomass plant ranges between 20,000 and 50,000 gallons per
megawatt-hour. This water is released back into the source at a higher temperature,
disrupting the local ecosystem. The nutrient runoff from energy crops can also harm local
water resources as well. And growing energy crops in areas with low seasonal rainfall puts
stress on the local water supply.
Most geothermal plants re-inject water into the reservoir after it has been used to prevent
contamination and land subsidence (see Land Use below). In most cases, however, not all

Energy Harvesting
water removed from the reservoir is re-injected because some is lost as steam. In order to
maintain a constant volume of water in the reservoir, outside water must be used. The
amount of water needed depends on the size of the plant and the technology used;
however, because reservoir water is ―dirty," it is often not necessary to use clean water for
this purpose.
4.16.5.e Hazardous Materials
The PV cell manufacturing process includes a number of hazardous materials, most of
which are used to clean and purify the semiconductor surface. These chemicals, similar to
those used in the general semiconductor industry, include hydrochloric acid, sulfuric acid,
nitric acid, hydrogen fluoride, 1,1,1-trichloroethane, and acetone. The amount and type of
chemicals used depends on the type of cell, the amount of cleaning that is needed, and the
size of silicon wafer . Workers also face risks associated with inhaling silicon dust. Thus,
PV manufactures must follow U.S. laws to ensure that workers are not harmed by exposure
to these chemicals and that manufacturing waste products are disposed of properly.
4.16.6.e Noise Pollution – The constant noise from wave capture devices especially in
rough conditions may have an impact on whales and dolphins that use echo location to
hunt.
Recreational Activities – Offshore and nearshore devices could have an effect on some
forms of recreational swimming and of water sports around the floating devices.
Navigational Hazards – Possible navigational hazards to shipping as their low profile could
result in them being difficult to detect visually or by a ships radar. Also, water quality may
be affected due to potential oil spills from increased boat traffic in the area for maintenance
and repair.
Marine Eco-system – Marine mammals may be vulnerable to the floating structures or they
may act as barriers to marine movement and migration affecting the fauna and flora on the
seabed.

Energy Harvesting
4.16.7.e Air Emissions
Despite being a relatively clean alternative to more harmful fossil fuels, biomass still
generates harmful toxins that can be released into the atmosphere as it's combusted.
Emissions vary greatly depending on the feedstock of the plant
Transporting waste from forestry and industry to a biomass plant also carries a significant
carbon footprint from the petroleum used by transportation. This release of greenhouse
gases may be a secondary environmental impact from biomass energy generation,.
In geothermal open-loop systems emit hydrogen sulfide, carbon dioxide, ammonia,
methane, and boron. Once in the atmosphere, hydrogen sulfide changes into sulfur dioxide
(SO2). This contributes to the formation of small acidic particulates that can be absorbed
by the bloodstream and cause heart and lung disease . Sulfur dioxide also causes acid rain,
which damages crops, forests, and soils, and acidifies lakes and streams. However, SO2
emissions from geothermal plants are approximately 30 times lower per megawatt-hour
than from coal plants, which is the nation’s largest SO2 source.
4.17.e RENEWABLE ENERGY SOURCES AND SUSTAINABILITY
Renewable energy sources replenish themselves naturally without being depleted in the
earth; they include bioenergy, hydropower, geothermal energy, solar energy, wind energy
and ocean (tide and wave) energy. Tester defines sustainable energy as, ―a dynamic
harmony between the equitable availability of energy-intensive goods and services to all
people and preservation of the earth for future generations‖.The world’s growing energy
need, alongside increasing population led to the continual use of fossil fuel-based energy
sources (Coal, Oil and Gas) which became problematic by creating several challenges such
as: depletion of fossil fuel reserves, greenhouse gas emissions and other environmental
concerns, geopolitical and military conflicts, and the continual fuel price fluctuations.
These problems will create unsustainable situations which will eventually result in
potentially irreversible threat to human societies (UNFCC, 2015).
Notwithstanding, renewable energy sources are the most outstanding alternative and the
only solution to the growing challenges (Tiwari & Mishra, 2011). In 2012, renewable

Energy Harvesting
energy sources supplied 22% of the total world energy generation (U.S. Energy
Information Administration, which was not possible a decade ago.
Reliable energy supply is essential in all economies for heating, lighting, industrial
equipment, transport, etc. (International Energy Agency, 2014International Energy
Agency. (2014). Renewable energy supplies reduce the emission of greenhouse gases
significantly if replaced with fossil fuels. Since renewable energy supplies are obtained
naturally from ongoing flows of energy in our surroundings, it should be sustainable. For
renewable energy to be sustainable, it must be limitless and provide non-harmful delivery
of environmental goods and services. For instance, a sustainable biofuel should not
increase the net CO₂ emissions, should not unfavourably affect food security, nor threaten
biodiversity (Twidell & Weir (2015). In spite of the outstanding advantages of renewable
energy sources, certain shortcoming exists such as: the discontinuity of generation due to
seasonal variations as most renewable energy resources are climate-dependent, that is why
its exploitation requires complex design, planning and control optimization methods.
Fortunately, the continuous technological advances in computer hardware and software are
permitting scientific researchers to handle these optimization difficulties using
computational resources applicable to the renewable and sustainable energy field

Energy Harvesting
Questions
Questions for (02) Marks
1. Define the cell
2. State what is wind energy harvesting in short
3. What the concept of Electromagnetic Energy Harvesting
4. What is battery?
1. Write note on Fundamentals of Wind energy
2. What is the concept of Power electronic interfaces and grid
interconnection topologies.
3. Write short note on Piezoelectric Energy harvesting
4. State and explain Physics and characteristics of piezoelectric effect
5. Enlist Piezoelectric energy harvesting applications
6. State the recent application of Electromagnetic Energy Harvesting
7. Write note on cell and batteries
8. Write note on sustainability of renewable energy sources
1. Explain wind turbines in detail
2. Write brief note on materials and mathematical description of piezoelectricity
3. Explain in detail Piezoelectric parameters and modeling piezoelectric generators
4. Explain the linear generators in detail
5. Write broad note on Carbon captured technologies
6. Describe Environmental issues of renewable energy sources
************

Energy Harvesting
b.: Introduction,
, ,
,
, Human power
( 0 4 L , 0 8 M )
c. n g : Linear generators, physics mathematical models,
, ( 0 2 L , 0 4 M )
d., cell, batteries, power consumption ( 0 1 L , 0 2 M )
e.

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