JOURNAL OF TELECOMMUNICATIONS, VOLUME 4, ISSUE 2, SEPTEMBER 2010 19

THE FUTURE ASPECTS OF WIRELESS ELECTRICITY TRANSMISSION Md. Imran Hossain, Mohammad Shahidul Islam

Abstract- This paper refers to that electricity transmission without using wire. To implement this concept, Medium is very essential because electricity means flow of electron from one place to another. In the case of transmission there are some parameters which have to consider such as transmitter, receiver, medium or channel. So when we will be gone to think about wireless electricity transmission we have to consider these terms. Process of transmission, occurring noise during transmission has discussed in this paper. Actually, Wireless electricity is not available in the world now. If it is implemented, real world will change dynamically, but there are many problems behind it. To develop this think, System will be more costly than wired transmission and also biological impact is a major fact. Why can’t electricity be wireless? Here some reasons are showed. However, if all obstacles are overcome, will the electricity transmission be wireless? Yes, it is possible. We want to show that how it can be implemented? So potentially, it is possible but there are probably many challenges ahead. Today, it is still not viable but we never can tell, technology has always done the impossible. Index Terms: Flow of electricity, Wired electricity transmission, Wireless electricity transmission ——————————  ——————————

1 INTRODUCTION

T

he electrons near the nucleus are held tight to the atom. We can push some of these electrons out of their shells. We can move them. Moving electrons are called electricity. In the case of electricity transmission, this generating electricity has to transmit from power grid to consumers using power lines. Electricity is transmitted by wire which is commonly formed by drawing the metal through a hole in a die or draw plate. [1] If electrical transmission would wireless what will happen? How would be the everyday scenario of the world? Answer is shown in below. Modern world is much easier than past due to the development of technology. Wireless Technology is one of them. Internet, cell phone and cordless technology have changed everyday scenery of the world. In the same way wireless electricity will change the modern world. It is an important technology than wired electricity transmission. It may implement within short and long distance. But short distance is more efficient than long distance. The amount of loss will be more for longer distance of wireless electricity transmission.

2. Electron and Electricity To establish the wireless electricity we have to analyze ————————————————

F.A. Author is with the Department of Electronics and Telecommunication Engineering, Daffodil International University, Dhaka, Bangladesh. S.B. Author Jr. is also with the the Department of Electronics and Telecommunication Engineering, Daffodil International University, Dhaka, Bangladesh.

about the electron and electricity. Also it is essential to know how electron produces electricity then we could be able to perform research about wireless power transmission. So let us see that flow of Electron and this flow of electron produce electricity. This produced electricity transferred from one place to another through wire. By the time the electron was discovered the idea of electricity flowing from positive (+) to negative (-) (conventional current) was firmly established.[2] Luckily it is not a problem to think of electricity in this way because positive charge flowing forwards is equivalent to negative charge flowing backwards. [3] So this electron has to transmit through air for forming wireless electricity.

3. Wired Electricity Transmission All At first we will discuss about the wired electricity transmission. Figure.1 shows the transmission of electricity from power plant to customer. Electricity is produced in the power plant and it transferred to the step-up transformer (69000 volts to 765000 volts) then it travels long distance through wire. Again a step-down transformer is used to decrease power then it is transferred through primary distribution (4000 volts to 46000 volts) and we use this electricity (120 volts to 240 volts). Electricity moves through the wires very fast. In just one second, electricity can travel around the world seven times.

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Fig.1. Transmission of Electricity from power plant to customer The power plant makes electricity. The electricity flows through transmission lines held up by power towers. The transmission lines carry large amounts of electricity (69000 volts – 756000 volts) to electric poles in cities and towns. Distribution lines carry small amounts of electricity (about 4000 volts to 46000 volts) from the electric poles to houses and businesses. [4] In Wired electricity transmission, power is transmitted through the two ways i.e. Overhead Transmission Underground Transmission Electricity is transmitted at high voltages (110 kV or above) to reduce the energy lost in long distance transmission. Power is usually transmitted through overhead power lines. [5] Underground power transmission has a significantly higher cost and greater operational limitations but is sometimes used in urban areas or sensitive locations.

4. WIRELESS ELECTRICITY TRANSMISSION Wireless energy transfer or wireless power transmission is the process that takes place in any system where electrical energy is transmitted from a power source to an electrical load without interconnecting wires. Wireless transmission is useful in cases where instantaneous or continuous energy transfer is needed but interconnecting wires are inconvenient, hazardous, or impossible. Wireless energy transfer is different from wireless transmission of information, such as radio, where the signal-to-noise ratio or the percentage of power received becomes critical only if it is too low to recover the signal successfully. With wireless energy transfer, efficiency is the most important parameter. The most common form of wireless power transmission is carried out using induction, followed by electrodynamic induction. Other present-day technologies for wireless power include those based upon microwaves and lasers.[6] [7]

Fig.2. Working of wireless power Figure.2 shows the working diagram over short distance wireless power transmission:

 Power from mains to antenna, which is made of copper  Antenna resonates at a frequency of about 10MHz, Producing electromagnetic waves  ―Tails‖ of energy from antenna ―tunnel‖ up to 2m (6.5 ft)  Electricity picked up by laptops antenna, which must also be resonating at 10MHz. Energy used to re-charge device.  Energy not transferred to laptop re-absorbed by source antenna. People/ other objects not affected as not resonating at 10MHz The working principle behind wireless power transmission is electromagnetic induction. [8] Let's look at it. Wireless Electricity, these words are simpler said than done. The concept behind this fascinating term is a little complex. However, if you want to understand it, try and picture what I state in the next few lines. Consider two self resonating copper coils of same resonating frequency with a diameter 20 inches each. One copper wire is connected to the power source (Wireless Electricity transmitter), while the other copper wire is connected to the device (Wireless Electricity Receiver). The electric power from the power source causes the copper coil connected to it to start oscillating at a particular (MHz) frequency. Subsequently, the space around the copper coil gets filled with non-magnetic radiations. This generated magnetic field further transfers the power to the other copper coil connected to the receiver. Since this coil is also of the same frequency, it starts oscillating at the same frequency as the first coil. This is known as 'coupled resonance' and is the principle behind Wireless Electricity. [9] We need a power source and a transmitting antenna, and also a receiving antenna to which we can connect the thing to be powered (the electrical load, or just the load). The power source will deliver a high power signal to the antenna. This will create an electrostatic field around the antenna that changes as the signal to it changes. This will create electromagnetic waves that will travel out from the antenna and through the air. [10] The receiving antenna will be in the path of these waves, and the waves will pass by it and "sweep" it with their moving electromagnetic fields. This will induce a signal in the receiving antenna proportional to the energy that the antenna captures. This signal will cause current flow that will power the load.

4.1. WIRELESS ELECTRICITY TRANSMISSION OVER SHORT DISTANCE

Number Figure.4 shows the wireless electricity transmission over the short distance. It may be appeared inside the house from source which is placed in the ceiling. Actually, wireless electricity is commercializing technology which can be developed that sends power through the air, to run devices like laptops, DVD players, Cell phones, and other common electric devices. All electronic devices of our home such as electric bulb, fan, TV, refrigerator, laptop, cell phone charging etc can be activated by using wireless electricity. To build this technology a wireless electricity source is set up besides the house. AC power,

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circuit and wireless electricity source is used to form this transmitter. Here Circuit converts AC power to a higher frequency (about 10MHz) and feeds to a wireless electricity source; the current inside the source induces an oscillating magnetic field. Wireless Electricity device has to power and it is tuned electronically to the same frequency as the source. This process is called resonant magnetic coupling power which is received from source. The energy of the oscillating magnetic field induces an electrical current in the wireless electricity devices and it lighting bulb, power generates to laptops, cell phones, iPods etc. The source can be installed in ceiling and electronic devices can be placed anywhere in the room.

sion it is examined that the systems are only 45% to 50% efficient. They have to be twice as efficient to compete with the traditional chemical batteries. Though short distance wireless electricity will be implemented in near future but long distance transmission is the dream that can be true one day. Wireless electricity transmission, if successful will definitely change the way we live. Imagine cell phones, laptops, digital camera's getting self charged! At the same time it will be able to come up with the commercial system soon.

REFERENCES [1] [2]

Fig.3. Wireless power transmission for short distance

4.2 Wireless Electricity transmission over long distance The most common form of wireless power transmission is known as near field transference. A different form of wireless electricity can transfer power over long distances. This is known as the far field method and can be used to transfer energy through radio waves, microwaves or lasers. If microwave technology is used to transmit power through air the microwave source consists of a microwave oven magnetron [11] with electronics to control the output power. The output microwave power ranges from 50 W to 200 W at 2.45 GHz.[12] Over long distance it has a problem which is that it is challenging to "direct" and "confine" the transmitted signal to optimize how much of it gets to the receiving antenna. Additionally, distance causes loss, and there will be a lot of loss over longer distances. The more the distance the signal travels, the much more the loss. Wireless power over longer distance is not efficient. Efficiency is the major factor of any system, in the case of this system efficiency is about 45% up to 50%. Loss is more than efficiency. But the system works to a limited degree. For long distance high frequency is required hence it will create biological effect. Traditionally, all power must be transferred from the source to a device that uses the electricity via some sort of transmission line. However, wireless power uses various forms of transference not requiring this line. 5. Conclusion From the above results of wireless electricity transmis-

http//www.wikipedia.com/wireless energy transfer Richard J. Fowler," Electricity Principle and applications", Fifth Edition, chapter-1, page: 7-8 [3] http://www.kpsec.freeuk.com/electron.htm [4] http://www.eere.energy.gov/femp/pdfs/primer.pdf. [5] V.K Mehta and Rohit Mehta," Principle of Power System", Multicolor Illustration Edition, Ch-10, Pages: 228-251 [6] http://www.economist.com/science/tq/displayStory.cfm?stor y_id=13174387. [7] http://www.forbes.com/2009/01/09/ces-wireless-powertech-sciences-cx_tb_0109power.html. [8] David K. Cheng," Field and Waves Electromagnetic", Second Edition, pages: 17, 18, 324 [9] http://www.buzzle.com/articles/witricity-wirelesselectricity.html [10] http://www.witricitypower.com/index.html [11] Sanjeeva Gupta, Dinesh Arora, Satya Bhushan Sarna and Prashant Lankar, "Microwave Engineering", Third Edition, Ch8, Pages: 209-211 [12] James O. McSpadden," Wireless Power Transmission Demonstration" Texas, Space Grant Consortium Md.Imran Hossain received his B.Sc. degree in Computer Science and Engineering from Jahangirnagar University, Savar, Dhaka, Bangladesh in 2004 and M.Sc. degree in Telecommunication Engineering from Blekinge Institute of Technology (BTH), Sweden in 2008. Now he is serving as a Senior Lecturer in the department of Electronics and Telecommunication Engineering at Daffodil International University, Dhaka, Bangladesh. His field of research interest includes wireless and mobile communication, Mobile Ad-hoc Network (MANET). Mohammad Shahidul Islam received his B.Tech. degree in Computer Science and Technology from Indian Institute of Technology-Roorkee, Uttar Pradesh, India in 2002, M.Sc. degree in Computer Science from American World University, London Campus, U.K in 2005 and M.Sc in Mobile Computing and Communication from University of Greenwich, London, U.K in 2008. Now he is serving as a Senior Lecturer in the department of Electronics and Telecommunication Engineering at Daffodil International University, Dhaka, Bangladesh. His field of research interest includes wireless and mobile communication, Satelite Commucation and Computer Networking.