device generating elecricity by footstep using peizoelectic material
1. 1
DEVICE GENERATING ELECRICITY BY FOOTSTEP USING
PEIZOELECRIC MATERIALS SYNOPSIS
Man has needed and used energy at an increasing rate for his sustenance and well-being ever since
he came on the earth a few million years ago. Due to this a lot of energy sources have been
exhausted and wasted. So, non-conventional energy is very essential at the time to world. Walking
is the most common activity in day to day life. Method such as burning of coal, wood, diesel
(generators) etc. is continuously depleting our natural resources such as fossil fuels, which is the
demand for power has exceed the supply due to the rising population. [4]
Energy is the ability to do work. While energy surrounds us in all aspects of life, the ability to
harness it and use it for constructive ends as economically as possible is the challenge before
mankind. Alternative energy refers to energy sources, which are not based on the burning of fossil
fuels or the splitting of atoms. The renewed interest in this field of study comes from the
undesirable effects of pollution (as witnessed today) both from burning fossil fuels and from
nuclear waste by products. Fortunately there are many means of harnessing energy, which have
less damaging impacts on our environment.
The alternatives are,
1. Solar
2. Wind Power
3. Tides
4. Hydroelectric
In addition to these we have developed a new methodology of generating power using human
energy and the name of this alternative is a foot step power generation. [5] We are generating
electrical power as non-conventional method by simply walking or running on the foot step. Non-conventional
energy system is very essential at this time to our nation. Non-conventional energy
using foot step is converting mechanical energy into the electrical energy. [2]
The main aim of this project is to develop much cleaner cost effective way of power generation
method, which in turns helps to bring down the global warming as well as reduce the power
shortages. In this project the conversion of the force energy in to electrical energy by using
electromagnetic induction. In this project the force energy is converted into electrical energy.
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This project uses piezoelectric sensor. A.C. ripples neutralizer, unidirectional current controller
And 12v,1.3 Amp lead acid dc rechargeable battery and an inverter is used to drive AC/DC loads
“An average person weighing 60 kg , will generate only 0.1 watt in the single second required to
take two steps across the tile”, said Yoshiaki Takuya, a planner with sound power crop. “But when
they are converging a Large area of floor space and thousands of people are stepping or jumping
on tem , then we can generate significant amounts of power .” stored in capacitors ,the power can
be channeled to energy-hungry parts of the station ,he said, including the electrical lighting system
and ticket gates. [1]
The average human takes 3,000-5,000 steps a day. Seems like a lot, but most health experts would
tell you to average 10,000 a day. Each step produces only enough electricity to keep a LED-powered
street lamp lit for 30 seconds. So this is the very innovative thought in a commercial way
for reduce the cost of power used in daily life. The purpose of this analysis is to analyze various
methods of foot step power generation such as foot using foot step electricity converter device,
using pavagen slabs (recycled rubber), using liquid droplets and metal electrode embedded in shoe
sole, using piezoelectric material. [2]
Human-powered transport has been existence since time immemorial in the form of walking
running and swimming however modern technology has led to machines to enhance the use of
human power in more efficient manner. In this context, pedal power is an excellent source of
energy and has been in use since the nineteenth century making use of most powerful muscles of
body. Ninety five percent of exertion put into pedal power is used to generate electricity to power
small electronic appliances. [3]
Proposal for the utilization of waste energy of foot power with human locomotion is very much
relevant and important for highly populated countries like India and china were the roads railway
stations, bus stands, temples, etc. are all overcrowded and millions of people move around the
clock.
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LITERATURE REVIEW
2.1. Methodology of shoe power generators
The most common methodology of shoe power generators include
2.1.1. Foot step electric converter device (Mechanical method)
2.1.2. Footstep electricity generation using pavegen
2.1.3. Footwear embedded harvesters
2.1.4. Piezoelectric shoe
2.1.1. Foot step electric device-This device, if embedded in the footpath, can convert foot impact
energy into electrical form. The downward movement of the plate results in rotation of the shaft
of an electrical alternator fitted in the device, to produce electrical energy electricity generated
from these devices can be used for street lights. This is a mechanical arrangement so efficiency is
not so good and wear tear problem is there, the weight is less then 50kg then this device will not
work.[4]
2.1.2. Footstep electricity generation using pavegen- The recycled rubber "PaveGen" paving
slabs harvest kinetic energy from the impact of people stepping on them and instantly deliver tiny
bursts of electricity to nearby appliances. The slabs can also store energy for up to three days in an
on-board battery, according to its creator. Paving slabs that convert energy from people's footsteps
into electricity are set to help power Europe's largest urban mall, at the 2012 London Olympics
site. It’s limited due to cost of installation and complex structure.[4]
2.1.3. Footwear embedded harvesters- This works as follows: droplets of liquid are placed
between electrodes coated in dielectric film. Both droplets and electrodes are connected to an
external electrical circuit. External movement causes the interface between the droplets and the
electrodes to decrease which releases an electrical charge which flows back into the electrical
circuit, generating an electrical current. Limited due to maintenance cost is high and life time of
droplets.[4]
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2.1.4. Piezo electric shoe- The piezoelectric effect a material’s capacity to convert mechanica l
energy into electrical energy, and the inverse is observable in a wide array of crystalline substances
that have asymmetric unit cells. When an external force mechanically strains a piezoelectr ic
element, these polarized unit cells shift and align in a regular pattern in the crystal lattice. The
discrete dipole effects accumulate, developing an electrostatic potential between opposing faces
of the element. Relationships between the force applied and the subsequent response of a
piezoelectric element depend on three factors: the structure’s dimensions and geometry, the
material’s piezoelectric properties, and the mechanical or electrical excitation vector. The output
is not stable always and weight of the shoe is not normal.
Free play energy company (USA) as released a human electricity generator for commercial sale in
which power is generated by pushing up and down with foot on a step –action treadle.A similar,
newly released portable energy source is a foot –powered device that allows individuals to pump
out power at a 40-watt clip to charge its own internal battery, which is capable of providing a
powerful jolt to car batteries and AC and DC devices. [1]
2.2 Research elaborations
2.2.1.Study of piezo materials
Piezoelectric ceramics belong to the group of ferroelectric materials. Ferroelectric materials are
crystals which are polar without an electric field being applied. The piezoelectric effect is common
in piezo ceramics like PbTiO3, PbZrO3, PVDF and PZT. The main component of the project is
the piezoelectric material. The proper choice of the piezo material is of prime importance. For this,
an analysis on the two most commonly available piezoelectric material - PZT and PVDF, to
determine the most suitable material was done. The criterion for selection was better output voltage
for various pressures applied. In order to understand the output corresponding to the various forces
applied, the V-I characteristics of each material namely, PZT and PVDF were plotted. For this the
Piezo transducer material under test is placed on a Piezo force sensor. Voltmeters are connected
across both of them for measuring voltages and an ammeter is connected to measure the current.
As varying forces are applied on the Piezo material, different voltage readings corresponding to
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the force is displayed. For each such voltage reading across the force sensor, various voltage and
current readings of the Piezo test material are noted.[5]
Fig 1: V-I graph of PVDF material
Fig 2: V-I graph of PZT
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The voltage from PZT is around 2 V where as that of PVDF is around 0.4V.We can thus conclude
that better output is obtained from the PZT than the PVDF.
2.2.2. Study of connections
Next to determine the kind of connection that gives appreciable voltage and current necessary,
three PZT are connected in series.
Fig .3: PZT in series connection
A force sensor and voltmeter is connected to this series combination. As varying forces are applied
on this connection, corresponding voltages are noted. Also the voltage generated across the series
connection and the current is measured. Similarly the connections are done for parallel and series-parallel
connections are done and the graphs are as in figures 3.
It can be seen from the graph that the voltage from a series connection is good but the current
obtained is poor, whereas the current from a parallel connection is good but the voltage is poor.
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But this problem is rectified in a series- parallel connection where a good voltage as well as current
can be obtained.[5]
Fig.4: V-I graph of parallel and series combination
2.2.3. Hardware implementation
In the hardware set up a tile made from piezo material is made. The voltage generated across a
piezo tile is supplied to a battery for it to recharge and supply the dc loads. Voltage generated is
also given to an inverter, from where it is supplied to all the ac loads. A LCD is interfaced to the
tile using a PIC microcontroller to display the voltage generated across the piezo tile.
2.2.4.Maximum theoretical voltage generated
When a force is applied on piezo material, a charge is generated across it. Thus, it can be assumed
to be an ideal capacitor. Thus, all equations governing capacitors can be applied to it. In this
project, on one tile, we connect 3 piezo in series.10 such series connections are connected in
parallel. Thus when 3 piezoelectric discs are connected in series, its equivalent capacitance
becomesHence, the net voltage generated in series connection is the sum of individual voltages
generated across each piezoelectric disc. Output voltage from 1 piezo disc is 13V.Thus the
maximum voltage that can be generated across the piezo tile is around 39V.
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2.2.5. Analysis done on the piezo tile
People whose weight varied from 40kg to 75 kg were made to walk on the piezo tile to test the
voltage generating capacity of the Piezo tile. The relation between the weight of the person and
power generated is plotted in figure 8. From the graph it can be seen that, maximum voltage is
generated when maximum weight/force is applied. Thus, maximum voltage of 40V is generated
across the tile when a weight of 75 Kg is applied on the tile.[5]
Fig 5: Weight V/s power graph of piezo tile
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PROPOSED WORK
There are Connections to make the model which we will done in future project work.
Unidirectional current
controller
Rechargeable
battery
A.C. ripple
neutralizer
D.C. load
LCD Display
Voltage sampler
Power Micro controller
Supply unit
ADC
Fig.6: Connections in the model
Piezoelectric
Material Sheet
Invertor
Load
The working of the model is as follows
1. The piezoelectric material converts the pressure applied to it into electrical energy.
2. The source of pressure can be either from the weight of the moving vehicles or from the weight
of the people walking over it.
3. The output of the piezoelectric material is not a steady one. So a bridge circuit is used to convert
this variable voltage into a linear one.
3. Again an AC ripple filter is used to filter out any further fluctuations in the output. The output
dc voltage is then stored in a rechargeable battery.
4. As the power output from a single piezo-film was extremely low, combination of few Piezo
films was in vestigated.
5.Two possible connections were tested - parallel and series connections. The parallel connection
did not show significant increase in the voltage output.
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6. With series connection, additional piezo-film results in increased of voltage output but not in
linear proportion. So here a combination of both parallel and series connection is employed for
producing 40V voltage output with high current density.
7. From battery provisions are provided to connect dc load. An inverter is connected to battery to
provide provision to connect AC load.
8. The voltage produced across the tile can be seen in a LCD. For this purpose microcontroller
PIC16F873A is used.
9. The microcontroller uses a crystal oscillator for its operation. The output of the microcontroller
is then given to the LCD which then displays the voltage levels.
Fig 7: Schematic representation of the working model
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REFERENCES
1. www.BEProjectreport.com
2.KiranBoby, Aleena Paul K, Anumol.C.V, Josnie Ann Thomas, Nimisha K., International Journal
of Engineering and Innovative Technology (IJEIT) Volume 3, Issue 10, April 2014
3. International Journal of Scientific and Research Publications, Volume 3, Issue 3, March 2013
4. www.ijesrt.com
5.Alla Chandra Sekhar, B MuraliKishore ,TJogiRaju, International Journal of Scientific and
Research Publications, Volume 4, Issue 6, June 2014