Implementation of Ambient Energy Harvesting from Air for ULP Devices as a Renewable Energy Source

B.R.Shashank#1, G.SharanKumaar*2, K.Kalaiarasi#3,A.Shalini#4 and A.Raagavendra Prabu#5 #Department of Electronics and Communication Engineering

Angel College of Engineering and Technology 1Shashy.br@gmail.com, 2mew2sharan@gmail.com, 3itsmekalai6@gmail.com

Abstract-Energy harvesting techniques are environment friendly energy sources which form a promising alternative to the existing energy sources. These include solar cells, wind power and vibrational energy from magneto-strictive materials. This paper presents a new method,Harvesting energy from ambient air in RF and Microwave regions along with measures to implement it into Low and Ultra low powered applications. The first step into realizing this goal is taken, by designing and implementing this technology into a mobile device, thereby giving it complete mobility even while charging. For other major applications, the possible types of antennas are being discussed.

We use an optimized harvesting circuitry interfaced with the devices, scavenging energy using appropriate antennas.The paper also presents the simulation and experimentation results of steps taken.

I. INTRODUCTION Energy harvesting techniques are emerging as

environment friendly energy sources, which form a promising alternative to existing energy resources. These include energy harvesting from solar power, wind power, vibrational sources and also passive human power. Here another source is introduced from which energy could be harvested – RF/Microwaves in air.

Through the years, technology has given numerous gadgets every day for varied applications, giving the possibility of being wireless and mobile in everything. Though wireless, every device that we hold today is not completely wireless, except for the time when we plug in those devices to power for charging. With Energy harvesting, it is now possible to grant these devices complete mobility.

There is always abundance of energy around us all the times. We are being bombarded with energy waves every second of the day. Radio and Television towers, satellites orbiting the earth, and even the cellular phone antennas are transmitting energy. We harvest these ambient energy and can use it as a source of power. In our case, it can be used to recharge the batteries of mobile devices, giving them the potential to be completely wireless.

The energy around is harvested by using appropriate antennas to grab the energy available in different bands of transmission. They are connected to appropriate circuitry to multiply them and render in usable by all portable mobile devices. The design and implementation of this is discussed in this paper with the results.

II. HARVESTING PRINCIPLE The energy present in the air is grabbed by using a

technique called energy harvesting. Energy harvesting is the idea of gathering transmitted energy and either using it to power a circuit or storing it for later use. The concept needs an efficient antenna along with a circuit capable of converting alternating current (AC) into direct current (DC)[2]. The efficiency of the antenna, as being discussed here, is related to the shape and impedance of the antenna, and the impedance of the circuit. If the two impedances are not matched then there is reflection of the power back into the antenna, meaning that the circuit will be unable to receive the available power. Matching of the impedance means that the impedance of the antenna is the complex conjugate of the impedance of the circuit.

Fig. 1 schematic diagram of energy harvesting system

To experiment this idea into a portable device, it was first decided to do test with a mobile phone and then into complex other devices. The goal is thus to determine if it is possible to capture enough power in a cellular phone in order to charge the battery.

The requirements for the system to be presented are that it be incorporated into a base station and the operating frequency is set. The design of the board and choice of antenna for the stand are the focal point of the experiments that are to be performed. In order to prove the concept, power needs to be supplied to the energy harvesting circuit by an external transmitter. This transmitter will send a signal at the set frequency. Our test system will then receive this signal through the energy harvesting circuit.

III. ENERGY HARVESTING DESIGN AND IMPLEMENTATION

A. Transmitter The most basic transmitter setup consists of a piece of

equipment that generates a signal whose output is then fed into an amplifier that is finally output through a radiating antenna – the air interface. A condition must be met where the antenna operates optimally at the desired frequency

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2011 2nd International Conference on Environmental Science and Development IPCBEE vol.4 (2011) © (2011) IACSIT Press, Singapore

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] Sabate, J. A., Miniaturizatio

] Joseph A. Hharvesting for

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] S. P. Beeby,vibration souSCIENCE AN

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] Radio Shack ] http://www.se0] http://we.hom

VIII. Cstep towards an the cellular ce industry asile we were

overall goal ofo charge the bhe phone usinggoal of being in its stand. charging path

F energy harv

IX. FU

s remain that The first thing

the RF energas efficient, fr

uarter-wave who be much mr to get the pto the level ofmonopole is

al product. Anerhaps there auld be more

be tried. The le the cellular to divulge the

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not completf having the chbattery of a ceg a wireless Rable to chargeCircumventin

h will allow fuesting concep

UTURE WORK need to be st

g to look at is gy.The antennafrom a voltagehip antenna u

more emphasipower transfef the quarter wabout 50% o

nother thing are other ways

power-efficielast thing to t

phone compe circuitry inv

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