Dr. Weeks’ Comment: Cool stuff, but get your Graham Stetzer meters and measure for electrical pollution!
Transmitting electric power without wires
From the time of Thomas Edison, scientists have been trying to develop a system that would send electric power through the air without wires. Now a
January 6, 2009
Wireless Electricity Is Here (Seriously)
By Paul Hochman
I’m standing next to a Croatian-born American genius in a half-empty office in
Either way, all I can think of is my electrician, Billy Sullivan. Sullivan has 11 tattoos and a voice marinated in Jack Daniels. During my recent home renovation, he roared at me when I got too close to his open electrical panel: “I’m the Juice Man!” he shouted. “Stay the hell away from my juice!”
He was right. Only gods mess with electrons. Only a fool would shoot them into the air. And yet, I’m in a conference room with a scientist who is going to let 120 volts fly out of the wall, on purpose.
“Don’t worry,” says the MIT assistant professor and a 2008 MacArthur genius-grant winner, Marin Soljacic (pronounced SOLE-ya-cheech), who designed the box he’s about to turn on. “You will be okay.”
We both shift our gaze to an unplugged Toshiba television set sitting 5 feet away on a folding table. He’s got to be kidding: There is no power cord attached to it. It’s off. Dark. Silent. “You ready?” he asks.
If Soljacic is correct — if his free-range electrons can power up this untethered TV from across a room — he will have performed a feat of physics so subtle and so profound it could change the world. It could also make him a billionaire. I hold my breath and cover my crotch. Soljacic flips the switch.
Soljacic isn’t the first man to try to power distant electronic devices by sending electrons through the air. He isn’t even the first man from the Balkans to try. Most agree that Serbian inventor Nikola Tesla, who went on to father many of the inventions that define the modern electronic era, was the first to let electrons off their leash, in 1890.
Tesla based his wireless electricity idea on a concept known as electromagnetic induction, which was discovered by Michael Faraday in 1831 and holds that electric current flowing through one wire can induce current to flow in another wire, nearby. To illustrate that principle, Tesla built two huge “World Power” towers that would broadcast current into the American air, to be received remotely by electrical devices around the globe.
Few believed it could work. And to be fair to the doubters, it didn’t, exactly. When Tesla first switched on his 200-foot-tall, 1,000,000-volt
But strap on your rubber boots; Tesla’s dream has come true. After more than 100 years of dashed hopes, several companies are coming to market with technologies that can safely transmit power through the air — a breakthrough that portends the literal and figurative untethering of our electronic age. Until this development, after all, the phrase “mobile electronics” has been a lie: How portable is your laptop if it has to feed every four hours, like an embryo, through a cord? How mobile is your phone if it shuts down after too long away from a plug? And how flexible is your business if your production area can’t shift because you can’t move the ceiling lights?
The world is about to be cured of its attachment disorder.
WIRELESS JUICE: A PRIMER
TECH 1: Inductive Coupling
THE FIRST WIRELESS POWERING SYSTEM to market is an inductive device, much like the one Tesla saw in his dreams, but a lot smaller. It looks like a mouse pad and can send power through the air, over a distance of up to a few inches. A powered coil inside that pad creates a magnetic field, which as Faraday predicted, induces current to flow through a small secondary coil that’s built into any portable device, such as a flashlight, a phone, or a BlackBerry. The electrical current that then flows in that secondary coil charges the device’s onboard rechargeable battery. (That iPhone in your pocket has yet to be outfitted with this tiny coil, but, as we’ll see, a number of companies are about to introduce products that are.)
The practical benefit of this approach is huge. You can drop any number of devices on the charging pad, and they will recharge — wirelessly. No more tangle of power cables or jumble of charging stations. What’s more, because you are invisible to the magnetic fields created by the system, no electricity will flow into you if you stray between device and pad. Nor are there any exposed “hot” metal connections. And the pads are smart: Their built-in coils are driven by integrated circuits, which know if the device sitting on them is authorized to receive power, or if it needs power at all. So you won’t charge your car keys. Or overcharge your flashlight.
The dominant player in this technology for the moment seems to be Michigan-based
TECH 2: Radio-frequency Harvesting
THE INDUCTION SYSTEMS are only the beginning. Some of the most visually arresting examples of wireless electricity are based on what’s known as radio frequency, or RF. While less efficient, they work across distances of up to 85 feet. In these systems, electricity is transformed into radio waves, which are transmitted across a room, then received by so-called power harvesters and translated back into low-voltage direct current. Imagine smoke detectors or clocks that never need their batteries replaced. Sound trivial? Consider: Last November, to save on labor costs, General Motors canceled the regularly scheduled battery replacement in the 562 wall clocks at its
TECH 3: Magnetically Coupled Resonance
Availability: 12-18 months
INVENTED BY MIT’S SOLJACIC (who has dubbed it WiTricity), the technique can power an entire room, assuming the room is filled with enabled devices. Though WiTricity uses two coils — one powered, one not, just like eCoupled’s system — it differs radically in the following way: Soljacic’s coils don’t have to be close to each other to transfer energy. Instead, they depend on so-called magnetic resonance. Like acoustical resonance, which allows an opera singer to break a glass across the room by vibrating it with the correct frequency of her voice’s sound waves, magnetic resonance can launch an energetic response in something far away. In this case, the response is the flow of electricity out of the receiving coil and into the device to which it’s connected. The only caveat is that receiving coil must be properly “tuned” to match the powered coil, in the way that plucking a D string on any tuned piano will set all the D strings to vibrating, but leave all other notes still and silent. (This explains why Soljacic considers the machinery that create these frequencies, and the shape of the coils, top secret.)
Importantly, then, WiTricity doesn’t depend on line-of-sight. A powered coil in your basement could power the rest of the house, wirelessly. Will the cat be okay? “Biological organisms are invisible to, and unaffected by, a magnetic field,” Soljacic says. While I am mulling that statement, he tells me the company will not yet reveal the name of its partners because those partnerships haven’t been formalized, but they include major consumer electronics brands and some
As has been the tradition since Nikola Tesla and Thomas Edison angrily parted ways in 1885, the enormous consumer demand for wireless electricity is begetting intense competition. Last November, a consortium of manufacturers coalesced around
Just as Tesla derided his doubters as “nothing more than microbes of a nasty disease,” some name-calling is inevitable in this increasingly heated battle. WiPower, for example, insists that the eCoupled technology approach has several problems. “Their system is very sensitive to alignment, and I’ve heard there’s a heating issue,” says CEO Ryan Tseng. “Our system is more elegant, much less expensive, and easier for manufacturers to integrate.” Meanwhile, Powercast calls Dave Baarman,
But as I stand, covering myself, in that featureless suburban conference room, such bickering fades to background noise. Because with Tesla’s 100-foot-long lightning bolts and blue grass vivid in my mind, I have a big question: Will Soljacic, the MacArthur Foundation fellow, be able to turn on that Toshiba TV from across the room? Or will I be bathed in a magnetic field so intense my molecules all align to face true north?
After he flips the switch, the little television, 5 feet away, springs to life. Wirelessly. The DVD player inside spins up to a low whine. Colors flicker on the moving screen. And Soljacic’s eyes dance with the reflected light of the image.
Paul Hochman is the gear and tech editor for Today on NBC and host of MSN.com’s GearDaddy.