How tesla electricity can create wireless power | The Economist

the inventor Nikola Tesla dreamt of wireless power among his work in the realm of electricity he built a coil later named the Tesla coil which could illuminate lamps from across a room and throw the occasional bolt of lightning at the nearest conductor Tesla coils remained popular today though often for their ability to put on a fantastic lightning show Nikola Tesla believed in wireless power with such an enthusiasm that with the financing of JP Morgan he constructed a giant apparatus the Wardenclyffe tower at his lab in Shoreham Long Island in 1901 this was before the world was wired way back then when people were thinking about electricity and how people might use it I don't think it ever occurred to them that people would string wires all over the country the early on people were thinking about transferring power wirelessly the idea to send wireless power around the globe we love electricity so much human beings love it so much that we've been willing to put in wired power everywhere I'm sure if you go back to Tesla's time he wanted to do things wirelessly and experimented with it because he thought who would be crazy enough to put in the trillions of dollars of infrastructure that we've put in more than a century after Tesla's Tower were still tethered to the wall why tricity a start-up in Watertown Massachusetts is one of several companies hoping to revive Tesla's dream and it's doing so by developing a business in wireless power transfer there's power everywhere in the world except that last few feet from the wall to the center of the room that is the last part to go wireless and once that last part goes wireless this projector can receive its power from a source that's almost a meter below here's how it works run an electric current through a coil of copper wire and the coil will produce a short-range magnetic field place a second coil within this field and an electric current will flow through it the magnetic field has transferred electrical power from one coil to the other this principle is called induction and it has been understood for more than a century induction is what charges a wireless electric toothbrush for example and it works well over extremely short distances hold the coils apart and the power transfer ceases it turns out that the trick to longer distance power transfer is the same principle an opera singer uses to shatter a wine glass from across the room it's called resonance for the opera singer when the frequency of the sound wave matches the unique resonant frequency of a glass the acoustic energy is converted to kinetic energy at the highest possible efficiency the energy then builds inside the glass until it shatters the coils that why tricity uses to transfer power wirelessly are magnetic resonators first a rapidly oscillating electric current is applied to a coil at its specific resonant frequency this creates a magnetic field in the region around the coil tune a second coil to the same resonant frequency as the source and it will couple resonating anywhere within that region and converting the oscillating magnetic field into an electrical current within the second coil this response is called highly coupled magnetic resonance and it hasn't been done before by attaching the second coil to a device such as the battery of an electric car or a mobile phone this current can be made to do useful work the source can be either of centimeters or meters away from the device being powered and can deliver power through walls or around metal obstacles the power can even be distributed across multiple devices at once so by a simple trick of physics power is transferred wirelessly Nikola Tesla would be proud you could put these resonators in walls and floors and ceilings and would allow you to power virtually anything in your house you could place it under the counters imagine you could just go home and you if you carry a purse you throw your purse onto the counter and you don't even have to think about taking your phone or your camera or your PDA out of your purse it just charges because the surface underneath your counter is energized by tricity is developing a system not a specific product and as a result they have many different platforms on display at once in white Rissa t's demonstration rooms a flat-screen television is powered using a resonator hidden in its base laptops with their batteries removed and replaced by resonators flicker on and flash lights glow when placed next to a source concealed behind a bulletin board the system can even be extended beyond the range of a single source using passive resonators like this one by this method many cabinet lights are lit well beyond the expected range of the single source below maybe no surprise you get the light to come on even inside the cabinet way up in the cabinet you can almost think of it as though the energy is held by the structure itself we're not sending electricity through the air and it doesn't radiate out into space it's when's another kind of a copper coil or wire coil comes in the vicinity of that field that it can sense it and then capture it and turn that magnetic field into a into a current so safety is definitely one of the issues that people think about and ask us about so one of the things that makes it very safe is the fact that we're using the magnetic field to transfer the power humans look almost like free space to a magnetic field in addition to that you know we have a lot of you know electronic devices that we use every day and so there are well-established standards for what the fields around those devices can look like and all the technology that we develop will conform to those same kind of standards the intensity the magnetic fields we're using by the way are about the same intensity as that of the earth most people don't think of it but the earth is it we're in a magnetic field right now the applications of wireless power in a wired world are endless and rethinking infrastructure may be decades away a simple first step could be removing costly batteries from things as mundane as computer accessories and instead placing a small wireless resonator in the computer itself tackling waste by centimeters at first at the end of the day if you can find something that is convenient for people and saves energy that's the killer app wireless power has in fact been available for decades just waiting for a clever user to snatch it out of the air it exists in radio and television signals and is available 24 hours a day Josh Smith and Al Anson sample of Intel labs in Seattle Washington are pointing their devices at television antennas and powering small but useful gadgets solely off of the energy that carries TV programs well there's energy all around us TV signals which you normally think of as just information also have a little bit of energy content one of their projects is named warp and it stands for wireless ambient radio power according to them we are just entering the boom years of energy harvesting we're receiving energy from the TV towers that are for coal is out that way they're putting out a megawatt of power this TV antenna picks up the radio signal through this coax cable here little rectifying circuit turns the radio signal it's a regular DC voltage just like a battery would put out and right now it's powering this kitchen thermometer so as we turn this away from the TV tower at a certain point it's going to lose power now it's off because it's not facing the TV tower we bring it back pops pops back on as soon as it's got enough so here's the TV tower transmitting tower here we're up here near the University of Washington these circles show the amount of power you'd expect to be able to get as a function of distance so kind of anywhere in the city of Seattle you'd expect to be able to get up to you know 100 microwatts compared to solar course Solar is a really good energy harvesting source but it's only available for 12 hours a day TV towers have been broadcasting about the same amount of energy or power for you know decades but what's changed recently is that the power requirements of the smallest devices have gotten low enough that you can actually power them off of a TV tower now Josh Smith says wireless ambient radio power harvesting might yield a milliwatts or so to a device that's not very much it would require twenty milliwatts to keep a mobile phone in standby mode but it might be enough to perform some useful low-power functions does it sound like much but you know that's actually a lot for four sensors you know you may not be able to make a cell phone call but maybe you can press you know a 911 that does nothing but sends this you know one very small but very important data packet I think many consumer electronic devices will start to have a little kind of reptilian brain that you know perhaps never powers down and perhaps that is being powered off of ambient RF signals you know there's the annoying flashing VCR clock I don't know if people have VCRs anymore but so that may be another solution to the problem but no reason why digital clocks in the future should ever run out of energy I think if you wait a few years it'll actually get really practical and I don't see why you wouldn't see it all over the place amazing to think of it some of and the potential for us to actually harvested thank you City this is arguably not the most useful thing ever but I think the potential is really there makes it very nikola tesla's tower was torn down in 1916 mr. Morgan his financier was uninterested in broadcasting electricity that people could so easily harvest for free instead we strung wires and built meters Tesla knew that wireless power transfer was possible but he never saw his dream realized it seems that soon enough we will The Economist

Channel: The Economist

Views: 1,397,800

Rating: 4.8445091 out of 5

Keywords: The Economist, Economist, Economist Films, Economist Videos, Politics, News, short-documentary, tesla wireless electricity, telsa electricity from air, how magnetic fields create wirless power, magnetic fields, wireless electricity, wireless power, tesla, power, air, app, apps, wireliess, infrastructure, electricity, nikola, projector, induction, coils, coil, energy, environment, witricity, current, magnetic, technology, metal, plug, home, physics, resonance

Id: I1IDC8FEIBU

Length: 10min 28sec (628 seconds)

Published: Wed Jun 16 2010

Reddit Comments

[u/vdirequest]

A milliwatt from old broadcast TV towers. I could see uses for that.

[u/badassumption]

Last year Nokia had a prototype phone that could harvest 3-5mW from ambient radio waves, with hopes to increase it to 50mW resulting in a phone that never needed plugged in.

[u/shamecamel]

man, can you even fathom how different consumer electronics would be today if they were and had always been wireless?

lamps, appliances, phones... man.

[u/elganyan]

I'm pretty sure this is the technology behind Wacom pen tablets (the kind used by graphic designers etc. to interface with a computer drawing program). And they've been doing it for a while.

The pens are wireless and battery-less, but contain electronics, buttons, pressure sensitive switches (for the tip pressure when drawing), etc. that are powered when the pen is hovered over the drawing tablet (direct contact with the tablet isn't necessary to activate the pen's functions). It can also then track the exact location of the pen tip with regards to the tablet and display the cursor position appropriately on the screen.

Awesome stuff.