Imagine a world devoid of bulky batteries, free from the labyrinth of electric wires! However, the ever-so ubiquitous nature of batteries and wires in our day-to-day lives makes the previous statement sound more like some piece of science fiction. But what we perceive as science fiction today may become reality tomorrow! With this zeal to make the impossible, possible, scientists at the MIT Physics Research Laboratory, after a series of diligent experiments, were able to light a 60W light bulb from a power source more than two meters away; there was no physical connection between the source and the appliance! Welcome, to what the MIT team refers to as “WiTricity” (as in wireless electricity).
Baffled? Perplexed?! That was my reaction too! It is worth noting that almost trillions of dollars are invested in infrastructure to get electricity from its place of production to its final destination; 40 billion disposable batteries are manufactured every year! With incessant environmental issues relating to battery disposal being raised as well as high infrastructural costs, this sure comes as a huge relief to engineers and environmentalists alike!
But you may reason that, in today’s technologically cognizant society where wires are viewed as nothing more than an inevitable menace, wireless power transmission does seem like a very “obvious” solution! So why didn’t anyone think of it earlier?! Well, yes! More than 100 years ago, one man, way ahead of his time, dared to think differently; beyond the indoctrinated beliefs of those times.
An aficionado of electrical engineering, wireless power transmission, in essence, was his brainchild! Nikola Tesla who literally electrified the world through his numerous uncredited inventions, mainly in the field of AC power and AC operated devices, is now primarily remembered for his visionary ideas in the field of wireless electricity. He did work on his ideas and come up with the concept of Tesla coils which stepped up standard voltage of 120V to more than 500,000 volts.
However, even visionaries need money, and his work stalled due to lack of funding and also because of FBI intervention over safety issues. Also, with an idea as bold as sending out electrical pulses wirelessly, various other social issues cropped up as well. In Nikola Tesla’s words then, “The world was not prepared for it. It was too far ahead of its time. But the same laws will prevail in the end and make it a triumphal success.”
Carrying forward his legacy the WiTricity project is ambitious and sceptical at the same time. Such wireless power transmission utilizes the concept of “magnetic coupled resonance”. Don’t get bowled over by that phrase! Think of power transformers which are used to step-up or step-down voltage levels. Internally, they have two coils, one primary and one secondary.
The two coils, by virtue of the differing number of turns, are able to regulate the voltage levels. Between the two coils there exists a miniscule gap (of the order of millimetres) and energy is transferred as a result of the magnetic flux between one coil connecting with the other (without any actual physical contact); or in other words, these two coils are magnetically coupled, right? So, wireless power transmission extends this concept of magnetic coupling to coils separated by much larger distances than in a transformer.
So where does the word “resonance” figure in the picture? As most of you may know, resonance is the phenomenon where the external frequency equals the natural frequency of the object. At resonance, the resonating body absorbs maximum energy so you may have noticed (more likely, heard!) of a big, fat (not a necessary condition!) opera singer shattering glass when she sings a note of the same frequency as the natural frequency of glass. So what it means is that one copper coil is connected to the electric power source and is made to oscillate at a particular (MHz) frequency. This generates a magnetic field which transfers power to the receiving copper coil.
Since this receiver coil is kept at the same frequency, it resonates and thus absorbs maximum electrical energy transmitted, enabling effective power transmission! So if you have followed me so far (which I doubt, since the above paragraph does sound a “little” bit convoluted even to me!), a natural query would be “why do we need resonant coupling” and not just “simple coupling” (like in normal transformers) without any of this ‘frequency business’?!
Well, that is where the magic of the resonant coupling comes in! For large inter-coil distances, the usual non-resonant magnetic induction would be almost 1 million times less efficient in this particular system! Phew, THAT was a lot of explanation for the three “not-so-innocent” looking words “magnetic coupled resonance”!
Will the WiTricity project lead to wide-scale commercial application? Or will it just fizzle out in its infancy? Will it convincingly address safety issues, as it claims? Is it really so powerful as to make electrical wires redundant? Well, every ambitious project naturally receives a critical (read, cynical) response initially! However, the WiTricity Project can definitely be viewed as a humble beginning to a new scientific era where our entire perception of power and electricity is going to be revolutionized. This project is truly a quintessence of a feat so subtle and so profound, it could change the world!
I’ll end with Nikola Tesla’s words,
“Let the future tell the truth and evaluate each one according to his work and accomplishments. The present is theirs; the future for which I really worked is mine.”