Renewable Energy Source - CiteSeerX

©2010 International Journal of Computer Applications (0975 - 8887) Volume 1 – No. 17

Renewable Energy Source Indrajit Mandal Lecturer in CSE Dept SRSIT, Bangalore

P.Santosh Kumar Patra Asst.Professor in ISE Dept SaIT, Bangalore

Abstract: Human kinetic energy can be transferred in a number of ways. Human energy is most commonly used to propel bicycles, but can also be used to generate electricity and power hand-crank tools. The articles on this page are about human kinetic energy and its many uses. Gravitational force acts on everybody that is present on earth, whether it’s stationary or moving. Here we are trying to utilize that force which is acting on everybody that is moving on earth, may be moving vehicles or walking human beings. When this force is associated with displacement, it gets converted to energy (mechanical). This mechanical energy is being converted to electrical energy. This paper illustrates the generation of energy from non-conventional source (Piezoelectric materials) of energy & reduces the use & dependency on fossil fuels. Normally a busy traffic is a source of tension and irritation for all of us. This idea gives us the opportunity to generate energy from busy city traffic. Index Terms:Human kinetic gravitational force, mechanical piezoelectricity, busy city traffic.

energy, energy,

1. INTRODUCTION. Using intelligent materials to harvest energy from ambient vibrations has been of great interest over the past few years. Due to the relatively low power output of piezoelectric materials, energy storage devices are used to accumulate harvested energy for intermittent use. Technology is continuously becoming smaller and smaller. With these advancements, sensors and other electronics can be used in the most remote locations and transmit information wirelessly. However, although the devices are smaller, they still require power sources such as

batteries, which can degrade and would have to be replaced. One possible solution is to use an energy harvesting device containing a piezoceramic to harvest energy from the environment of the sensor. A great deal of research has repeatedly demonstrated that piezoelectric energy harvesters hold the promise of providing an alternative power source that can enhance or replace conventional batteries and power wireless devices. Also, ambient vibrations have been the focus as a source due to the amount of energy available in them. By using energy harvesting devices to extract energy from their environments, the sensors that they power can be self-reliant and maintenance time and cost can be reduced. To maximize the amount of energy harvested from the source, generally a resonant mode of the harvester should match one of the dominant frequencies of the source. Due to inconsistencies in the fabrication of the harvester or variations in the source, frequency matching can be difficult to achieve. By being able to tune the device during fabrication or in real time during operation, a means to meet this criterion during operation of the device can be provided.

2. ORIGIN OF IDEA. I got the idea by an incident that happened to me accidentally. Therefore, it‟s a case of serendipity. One day, I was cooking in my kitchen. And I was about to light my gas stove using my gas lighter. As soon as I pressed my gas lighter, unexpectedly I got an electric shock from it. I was surprised at this that how I could get electric shock because I knew that there was no source (battery or petrol or diesel) of electricity in that lighter. This incident made me to think about the

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lighter. Then I noticed that the spark produced is the cause of that shock. I thought that I am applying pressure and in lieu of that spark is produced. I continued thinking like this-If there is electric spark, there is electrical energy- if this energy can be harvested on a large scale and the problem of energy crisis can be solved to some extent– then my mind suddenly clicked and if it could be used for practical purpose – therefore the dependency on coal and petroleum could be reduced to a greater extent – then I decided to work on this idea. Then out of my curiosity, I just opened the gas lighter to see what the source of spark is. To my surprise, I found that there was a mechanical arrangement of spring with a hammer to hit a block of mass. I thought it was surely a piezoelectric material as I expected because only piezoelectric materials can convert applied pressure into electrical energy. Moreover, it‟s a non-conventional source of energy which doesn‟t create Pollution. It requires only initial cost of implementation and maintenance cost. Then the biggest question was how to implement this idea because we cannot expect that we sit on a sofa during our leisure time and relax by stretching legs and constantly keep on pressing an device like that of an gas lighter to generate energy. This is not at all the conventional way of generating power. But still the question remains i.e. where to get the source of huge amount of pressure? Then my mind was attracted towards the gravitational force of the earth which acts on each and every body whether it is moving or stationary. The picture of Bangalore city traffic came to my mind wherein at some city junctions, the density of vehicles or people walking may be several lakhs per day. Thus, my mind relaxed thinking that there lies the solution of the problem.

be utilized for generating power, which is wasted. This project describes the utilization of pressure that is created at the surface of road due to the weight of vehicles or humans.

3. BANGALORE CITY TRAFFIC SURVEY. Jams in Bangalore are now almost order of the day. You take any important road and most likely you will be caught in Traffic jams in Bangalore. And in the heat of the situation, allegations that fly refer to what the government is doing regarding Bangalore traffic. But leave alone the government, it would take nobody less than god to smoothen traffic here mostly because of the way people drive on Bangalore roads. What any government can do if people do not have basic traffic sense and are hell bent on breaking every rule which may be present. If someone who has travelled on Bangalore roads for few days and witnessed Bangalore traffic, I am sure they can understand what I mean. As an important part of the project I have conducted a Statistical surveys to collect quantitative information at different parts of the Bangalore city. Surveys of human populations walking at railway stations, bus stands and other junctions. Surveys of density of number of vehicles at different city junctions and locations are conducted. I have even enquired about the number of vehicles at junctions from the Bangalore traffic police. For the implementation of the project, the statistical survey holds an important place. I have considered the timing of the Bangalore traffic between 8:00 am and 9:00 pm i.e. a total of 13 hours in a day. The statistical survey is summarized in the table 1 &2 below:

Statistical Survey of vehicles: of city traffic junctions:

Some pictures

Normally, a truck or bus or car is measured in magnitude of several tones. The ample pressure beneath the tyre of vehicles can

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PLACES

1. 2.

snap1

3. 4. 5. 6. 7.

Majestic Bus stand Bangalore central Railway station Shivajinagar Bus Stand S.P. Market Commercial Street K.R. Market Tirupati (A.P)

NUMBER OF PEDESTRIANS(in lakhs) 13 – 15 10 – 12 6–8 8 - 10 8 – 10 15 – 17 20 – 22

Table 2

snap2

As we can see from the statistics that the number of vehicles and pedestrians is in the figure of lakhs. Therefore, we can use these junctions for our purpose.

4. TOTAL DESIGN PROCESS. It is planned to execute the whole project in 4 steps: snap3

1. Theoretical /Mathematical model 2. Prototype model.

PLACES

1.

Corporation Circle 2. Bel Circle 3. M.G. Road 4. S.P. Road 5. Mekri Circle 6. Hosur Road 7. Mysore Road 8. Hebbal-Yehlanka Road 9. Airport Road 10. Avenue Road

NUMBER OF VEHICLES PER DAY(in lakhs/day)

8 – 10 7–8 7–9 8 – 10 10 – 11 9 – 10 9 – 10 10 -11 10 – 12 12 – 13

Table 1 Statistical Survey of pedestrians: Some pictures of pedestrians at bus stands and others:

3. Pilot model. 4. Actual/working model.

4.1. Theoretical /Mathematical model The theoretical model has been designed and described in all respects. The design details, methodology of working, circuit details with necessary diagrams are worked out. The overview of the energy harvesting concept with piezoelectricity.

4.2. Prototype model The prototype or practical model is designed using 4 piezos crystals. These piezos are placed in a wooden panel in such a way that all the piezos (units) are at the same height. Then a platform is placed on top of these units using a spring system such that when the platform is pressed, all the units must get pressed simultaneously and there should be only vertical movement of the platform. This setup was used to charge a rechargeable battery by continuously pressing the platform manually. It is found that

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the battery was getting charged continuously via an electronic circuit which is indicated by multimeter. Hence, the prototype model is successful and encouraged for going onto the next model i.e., pilot model.

is derived as the output the model is averaged as 0.480Watts of power. Efficiency of prototype model= output power / input power = (0.48/1.1) x 100 %

Some snapshots of prototype model:

=43.63 %

4.3.Pilot model. This model is designed in the laboratory for checking various features like the material strength, panel‟s strength to bear maximum load, compute replacement time of components, type of material needed etc. For doing this it requires the following components:

Snap4

A ramming machine which can press the piezo -panel repeatedly with an adjusted frequency. Around 200 piezo crystals are required. Iron angle frames, fillers are required for making the panel.

4.4. Actual/working model

Snap5

Snap6

Efficiency of prototype model. As I have calculated the different parameters and calculations are done based on the data of experiments. The power that we are supplying with our hand is 1.1Watts of power. The calculated amount of power that

After performing the necessary tests in the laboratory, the right materials are chosen and the panel is manufactured with optimum design and dimension so that the wear and tear is minimized and maximum energy can be obtained. Then the panel is to be laid at the level of road or floor at busy railway station or at busy traffic in the city so that it does not create any kind of inconvenience to the vehicles or pedestrians. It has to be maintained time to time for better performance. Piezoelectric energy harvesting circuits have two schemes: one-stage and twostage energy harvesting. A one-stage energy harvesting scheme includes a conventional diode bridge rectifier and an energy storage device. In recent years, two-stage energy harvesting circuits have been explored. Energy storage devices such as rechargeable batteries and supercapacitors have different cell voltages. Moreover, the storage cells can be connected in series to increase the voltage range. The storage device voltage is an important factor that influences the energy harvesting efficiency.

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Some snapshots of actual working model:

protected from rain and dust. 5. Each panel is kept just 3-5 mm above the road level, so that it does not create any kind of inconvenience to vehicles. 6. Each panel is designed in such a way that it will resist Wear and tear due to passing of vehicles over it.

Snap 7

MOVABLE PART CAPSULE

UNIT

Fig1

MOVABLE PART

Snap 8

SINGLE UNIT Fig 2 Snap 9

Efficiency of working model: When a normal weighted human walks on the panel , he exerts 8Watts of power on the panel. And the averaged output of the working model is 3.8Watts. Therefore the efficiency is around 47.5%.

CAPSULE

PIEZOELECTRIC PANEL Fig 3

Fig.4

5. Design 1. A panel consists of many sub-panels called capsules.(fig3) 2. Each capsule consists of piezoelectric crystals units depending upon the requirements.(fig 1) BUSY ROAD

3. When vehicles or human pass over these panels(fig 4), energy is generated and it‟s stored into a battery for future use.

PANEL

STREET LAMP

4. Each panel is designed in such a way that it is

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6.TECHNICAL OVERVIEW Piezoelectric materials exhibit the unique property known as the piezoelectric effect. When these materials are subjected to a compressive or tensile stress, an electric field is generated across the material, creating a voltage gradient and a subsequent current flow. This effect stems from the asymmetric nature of their unit cell when a stress is applied. As seen in Figure , the unit cell contains a small positively charges particle in the center. When a stress is applied this particle becomes shifted in one direction which creates a charge distribution, and subsequent electric field. These materials come in several different forms. The most common crystals:

to produce a small amount of electrical energy, however it was very small and of little use. It was not until the LiTiBa ceramic was discovered that the piezoelectric performance was increased and able to be used in a practical manner in electromechanical devices. A point group describes a material‟s lattice structure. There are 20 point groups which lack a center of symmetry. This means that the material develops a dielectric polarization when subjected to a stress and is known as the piezoelectric effect. The piezoelectric effect is the reason piezoelectric materials can be used as both sensors and actuators. The direct piezoelectric effect describes the material‟s ability to produce a voltage when mechanically strained and is utilized in sensor applications. Common sensor applications taking advantage of this are found in accelerometers and in pickups for acoustic guitars. The converse piezoelectric effect is a material‟s ability to transform an applied voltage into mechanical strain energy. This is commonly used in actuator applications such as creating ultrasonic waves used in

medical imaging devices

Fig.5 Lead Zirconate Titanate unit cell The brothers Pierre and Jacques Curie first demonstrated the piezoelectric effect in 1880. Piezo originates from the Greek word meaning „to press‟ and electric refers to energy or voltage. The Curie‟s showed that certain materials exhibited electrical polarization when a mechanical stress was applied. In 1881, Lippmann mathematically proved that applying a voltage to a piezoelectric material induces strain in the material. The Curie brothers immediately obtained quantitative proof of this effect. In their experiments, Quartz and Rochelle salt were able

7.EXISTING TECHNOLOGIES There are several companies and research institutes throughout the world who are focusing on finding useful applications for piezoelectric energy sources. Several years ago a project was done at MIT entitled, “Energy Scavenging with Shoe-Mounted Piezoelectrics.” 1 In this project the researchers lined the bottom of a shoe with piezoelectric transducers and saw what kind of power they got out of it. .

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Another company that is looking into using piezoelectric sources to power networks of wireless sensors is MicroStrain Inc. These companies setup an experiment where piezoelectric transducers were attached to the support beams in a structure. As the structure was constantly under strain, the voltage created by the Piezoelectrics was stored up in a capacitor.

Work (w) = Force (F) X Displacement (D) This work is done on piezo panels which are laid down at the level of road at busy city traffic, which get converted into electrical energy. This energy is stored into a battery through an electronic circuit. This store energy is used for various purposes. The block diagram of the

A German based company called EnOcean already has a commercially available product. The slogan for this company is “no batteries and no wires.” They create products that use piezoelectric transducers to power RF transmitters. One particular product is a light switch that requires no wiring at all. Behind the actual switch is a piezoelectric transducer. Two other companies, Ferro Solutions Inc. and Continuum Control Corp., make small ambient energy harvesting sources. Ferro Solutions makes a product called the Energy Harvester. This little device about the size of two AA batteries contains an electromagnetic generator inside. This small energy source could be used in place of batteries or as a means to recharge batteries. The device supplies about 1 to 10 mW of power and the company is looking to license this technology to wireless sensor companies. At the MIT Media Lab, researchers in the Responsive Environments Group created a piezoelectric floor called the “Magic Carpet.” 2 This floor contained a grid of piezoelectric cables spaced 4” apart. The goal of this project was to create a floor that could track the movements of the person walking across it.

8. METHODOLOGY OF WORKING. Throughout the globe, people are working on piezo crystals. Piezo crystals have different applications like transducers, actuators, generators etc. Here I am concentrating on harvesting energy from piezo crystals. I am trying to utilize the gravitational force (F) that acts on everybody around us. When this force is subjected to a small displacement (D), then work done is given by:

electronic circuit is given below: The major obstacle in designing your own piezoelectric circuit is finding a way to maximize the power output. The major components involved in this circuit would be an AC/DC rectifier, a filter capacitor, and a DC-DC converter. The AC/DC rectifier converts the AC signal from the piezo-source into DC current. The filter capacitor smoothes electrical flow and the DC-DC converter is what allows the battery to store the energy. Most of the power conversion comes into play in the DC-DC converter.

9.SIMULATION RESULTS . The circuit used a piezoelectric transducer as the voltage source which then fed into an op amp. The purpose of the circuit was to provide a voltage gain of 100. Our simulation results proved that the op amp did in fact multiply the voltage from the piezo-transducer by a factor of 100. Unfortunately, in the program we could not find an actual piezo-transducer so we had to model it with an ideal voltage source with an estimated equivalent Thevenin resistance. I considered this project a success on the grounds that it proved that piezo-transducers can in fact act as voltage sources. It also showed that the voltage provided by the transducer can be multiplied by several orders of magnitude

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using certain circuits. This circuit essentially failed to answer the real question of what kind of maximum power one can get out of the piezotransducer.

10.DISCUSSIONS AND CONCLUSION. I have designed prototype model for the project and I am successful in charging a cell, so this idea can be extended on a large scale and surely it‟s going to work for harvesting energy from busy traffic. The summary as follows: 1. On hitting the material, a very high D.C. voltage is obtained. 2. The voltage is of the order of thousand VOLTs.

14. The voltage produced is a spike voltage i.e. discrete in nature. 15. From “MAXIMUM POWER TRANSMISSION THEOREM”, we know that there is a maximum power transfer from source to load if there is proper impedance matching of source and load. 16. The problem of fatigue of natural crystals is solved by adding some other compounds to the synthetic crystals. So the synthetic crystals have more life span. 17. Since the upper part of model is just 3mm to 5mm above the road level so its not going to create any kind of inconvenience to the vehicles as aerodynamically the vehicle will balance and it has got shock absorbers and the passengers will not even fell that they have pressed a panel under the tyres.

3. It lasts for a fraction of second. 4. Its waveform is in the form of discontinuous spikes. 4. It is pulsated DC voltage produced. 5. Readings (average): Minimum voltage: 80-120 volts. Maximum voltage: 500-1500 volts.

18. This model is dust proof, water proof, temperature proof and stress proof. For example suddenly a truck of 30tonns passes over the panels, care has been taken in the design part that it wont break the panel. 19. The direct load of the human or vehicle is not applied on the piezo crystals directly therefore the crystals are safe and protected by heavy loads.

6. Current is of order of micro amperes.

11. APPLICATIONS.

7. Power in the range of watts. 8. Since the voltage is very high, heavy duty wires have to be used. 9. The voltage produced depends on the pressure created and the kind of piezo material used. 10. Internal impedance of the material is very high in the order of mega ohms. 11. Increasing or decreasing pressure on a piezoelectric material causes electrical current to flow. 12. Electrical current flows opposite directions depending on whether pressure is increasing or decreasing. 13. Parallel connections between the piezo crystals help to reduce the source impedance.

Here are some proposed applications 1. Self Powered street lamps. 2. Self powered traffic signals. 3. Domestic use. 4. Industrial uses. 5. Avoid disasters. Can we avoid disasters using this technology? Yes, we can avoid disaster by this technology. Mostly, the traffic signals are run by electricity on the roads. Things go smoothly when the power is available. But, it is not true always. In the situation where the power is cutoff for a moment, the traffic is set on chaos as there is no

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light. It can even lead to human life casualties in the More research can be done in this field worst case. Therefore, this problem can be solved with for better efficiency of the system. Better this technology. We can have self powered traffic signalsproduction of the synthetic piezos can be which is powered by the piezoenergy. manufactured. We can avoid disasters or accidents that take place in the absence of 12.ADVANTAGES OF PROJECT. electricity in the city traffic. We can save so many lives by avoiding accidents. The advantages are listed below 1. 2. 3. 4. 5.

It‟s a non-conventional source of energy. It does not create pollution. It requires only initial cost of implementation and maintenance. Maintenance is easy. Works on simple mechanism.

13. LIMITATION OF THE PROJECT.

Comparison of energy scavenging Energy source

Power Density for 10 years

Solar(outdoor)

15,000 microWatts/cm3

Solar(indoor)

6 microWatts/cm3

Vibrations(piezoelectric)

250 microWatts/cm3

Vibrations(electrostatic)

50microWatts/cm3

1. This idea is only applicable to busy traffic and pedestrians as the amount of energy produced is a function of frequency of piezo-crystals being pressed and not the load.

Acoustic noise

0.003microWatts/cm3(75 dB)

2. Due to wear and tear, the units are required to be replaced from time to time.

Hydrocarbon Fuel(micro heat engine)

33microWatts/cm3

Fuel cells(methanol)

28 microWatts/cm3

14.FUTURE SCOPE & COMMERCIALIZATION. There is a bright future of this model. The existing sources of fossil fuels are going to last for another hundred years or so. Normally we know that busy city traffic is a source of tension and irritation for all of us, but using this idea we get the opportunity of utilizing the energy that is dissipated at the feet and under the tyre of vehicles due to their weight. As we are very much aware of the fact that the cost of fossil fuels that includes coal, petrol, diesel and others are increasing at rapid rate in the market. Therefore, its time for us to think in a different direction. The piezo energy can mark a turning point in the history of nonconventional energy use. The comparison of energy shows that piezo energy holds an important place in the hierarchy of renewable source of energy.

Table 3 As we can see that the power density of piezoelectricity is considerably very high, there is no doubt that the harvesting energy using this method can solve many of the energy problems of day-to-day life. The energy produced from different sources can be compared to prove that the cost of energy produced from the piezos can be cheaper. Here is an proposed expenditure for the my idea. SOURCES OF ENERGY 1. Solar Power 2. Piezo Power 3. Fossil Fuel Energy Table 4

COST PER UNIT ( in Rupees/unit) 50 30 5

The solar power is costly because the manufacture of solar panels is hold by a single

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person throughout the globe and moreover it‟s a costly technology as it requires ultra level technology. Therefore, people can think to commercialize this model of generating power from non-conventional source.

3.Dr. Seetharam ( M.Tech and PhD from IIT,Bombay) ,Department of Computer Science and Engineering, Sambhram Institute of Technology,Bangalore-97

15. COMPARISONS WITH RELATED WORK.

REFERENCES

Here is a brief comparison with related works conducted by different technical graduates and scientists at different corner of the world for various reasons. In USA, scientists have tried to generate power by using piezo-crystals slabs under the shoe sole. But they found that the energy produced was practically very meager, which could not be used for any practical purpose. In Japan, piezo-crystals were used at railway station gates. When people would pass through the gates, they have to push the gate and energy was generated which could be used for other purposes. They have found in common that the voltage that could be generated in their experiment is of the order of millivolts. So they had to conclude that the power generated in such experiment is very less and that in turn could not be used in any practical purposes. Here in the experimental setup that is discussed in this paper is different from their experimental setup and therefore the output of the experiment differs considerably. In the experiment that is discussed here the voltage output of the experiment is of the order of thousands of voltage. It is nearly lakh times greater than the existing outputs.

[1] Shenck, Nathan S. and Joseph A. Paradiso. Energy Scavenging with Shoe-Mounted Piezoelectrics. MIT Media Laboratory, Responsive Environments Group. http://www.computer.org/micro/homepage/may_ june/shenck/?SMIDENTITY=NO

ACKNOWLEDGEMENTS

[7] Ottman, Geoffrey K. and Lesieutre, George A. “Optimized Piezoelectric Energy Harvesting Circuit.” Power Electronics. Vol.18, No.2, March 2003.

1.Prof. C.Dharuman, Senior Scientific Officer, Department of Mechanical Engineering, Indian Institute of Science, Bangalore-560097(India). 2.Mr. K.Mallikarjunappa, Joint Director, Diagnostics, Cables & Capacitors Division, Central Power Research Institute,( A Government India Society, Ministry of Power), Bangalore- 560 080, India.

[2] D.L. Churchill, M.J. Hamel, “Strain Energy Harvesting for Wireless Networks.” Microstrain Inc. http://www.microstrain.com/white_strain_ energy_harvesting.htmm Enocean http://www. enocean.com/indexe.html [3] O‟Handley, Kevin. “Energy Harvester: Converts Low-Level Vibrations into Usable Energy.” Ferro Solutions Corp. http://www.ferrosi.com/files/FS_product_sheet_ wint04.pdf [4] Bent, Aaron. “Piezoflex” Continuum Control Corp.http://www.powerofmotion.com/ technology / ipower/characteristics.html [5] Orr, Robert J. “FCE Smart Floor.” Georgia Tech.http://www.cc. gatech.edu/ fce /

smartfloor/ [6] Horowitz, Paul and Winfield Hill, The Art of Electronics. 2nd Edition, Cambridge: Cambridge University Press. 1989. P.1039

[8] The Magic Carpet: Physical Sensing for Immersive Environments J. Paradiso, C. Abler, KY. Hsiao, M. Reynolds, in Proc. of the CHI '97 Conference on Human Factors in Computing Systems, Extended Abstracts, ACM Press, NY, pp. 277-278(1997)

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