As a new generation of wireless chargers goes on sale, scientists, who for decades have dreamed of a better way, believe we are about to tip into a tangle-free future in which our devices and electricity itself are finally unleashed.
The technology behind the following scenario already exists: You drive home in your electric car, which has been charged through the road outside work, and park it in your garage, which is also equipped with an underfloor power source. You sit down and fire up the flat-screen wireless television hanging on the wall while you check your emails on your cable-free laptop. Both devices are powered via the wireless unit in the ceiling, which also started juicing up the phone in your pocket as soon as you walked in the door.
PowerPad, made by the British gadget firm, Gear4, goes on sale next month and is among a new wave of devices sweeping us towards this unplugged utopia.
A protective sleeve slips over an iPhone, slotting into its connecter socket. When the encased phone is placed on a mains-connected pad on, say, a desk or bedside table, electricity makes the jump. American outfits PowerMat and WildCharge make similar devices. Meanwhile, the Palm Pre smartphone has its own "Touchstone" charger and Dell's Latitude Z is the first wireless laptop.
"Wireless electricity is something we used to talk about years ago almost as a bit of a joke when we made predictions about the future," says Michael Brook, editor of the gadget magazine, T3. "To a lot of people it sounds insane that you could even do it like some kind of witchcraft but we're seeing a lot of interest in the first wireless chargers. It's going to take off in a big way."
If not witchcraft, how does it work? Here's the science: Current from the mains is wired into a transmitter coil in the charging mat. This generates an electromagnetic field. A receiver coil in the phone's case takes the power from the magnetic field and converts it back into electricity that charges the device. By separating those coils, induction charging takes the 150-year-old principle used in the transformers found in most electric devices and splits it in half. No more tripping over laptop leads and their power bricks or diving under your desk to plug in your charger just put your gadget on the mat and induction takes care of the rest.
But wireless induction, which, in a less-sophisticated form has charged electric toothbrush chargers and some medical implants for years, isn't perfect. Advances mean it's now viable for more demanding devices, but in the case of the PowerPad, it requires a case that adds bulk to what is already a hefty handset. Another drawback is the lack of compatibility a phone with a PowerPad case will not charge on a PowerMat.
A growing group of electronics firms want to deal with the problem. The Wireless Power Consortium (WPC) includes Gear4 and the mobile phone giants, Nokia, Samsung and RIM, makers of the Blackberry. "These companies think there won't be a mass market for wireless charging unless there is a standard," says Menno Treffers, chairman of the consortium's steering group and a director at Philips.
Learning their lesson from the hopeless incompatibility of wired chargers, supporters of WPC's Qi ("chi") standard will put universal coils in devices that will work without cumbersome cases. They'll also be compatible with any charging mat, whether it's on your desk or recessed in a table at Starbucks. Treffers expects the first Qi-compatible devices to hit shelves next year.
But there remains a major flaw in charging mats their need for proximity. Separation of even a millimetre renders most mats useless. Take your laptop to your bedroom to watch a DVD and you'll need a second mat or a cable. For a truly wireless scenario, electricity must make a giant leap.
Marin Soljacic is a Croatia-born physics professor at Massachusetts Institute of Technology (MIT). In 2002, he got annoyed when his wife's mobile phone woke him up with beeping when its battery ran low. "Not only did I have to wake up to plug it in but had to find the charger in the dark," he says. "I thought, power is everywhere sockets all over the house yet it isn't close enough."
Soljacic was sure there must be a way to bridge the gap. He wanted his wife's phone to charge while it was still in her handbag. Two years ago, after months of equation crunching and computer modelling, Soljacic literally had a light bulb moment when he flicked the switch of a 60-watt lamp. No big deal except that the electricity powering the light was travelling two metres through thin air.
Soljacic and his team at MIT have since formed a company called WiTricity. Last July, its chief executive, Eric Giler, came to Oxford to demonstrate a wireless television. In front of an amazed audience at a technology conference, he powered up a giant plasma screen TV that had no cables. Electricity sprung from a sleek unit on the floor to a receiver mounted on the back of the screen. Last month, Giler traveled to Japan to show off a wirelessly charged electric car. "Every time I show people they're blown away," Giler says. "When you see it up close it does appear almost magical."
Soljacic's magic takes the split-transformer model that powers charging mats and adds a key ingredient to make electricity fly. It's called resonance, the phenomenon that means a singer who matches the acoustic frequency of a wine glass can shatter it.
Soljacic knew that two resonant objects of the same resonant frequency tend to exchange energy efficiently imagine a tuning fork causing a nearby fork with the same frequency to chime sympathetically. His breakthrough was to work out a way to use resonance in magnetic form to transfer not sound but electricity. He explains: "By coupling the magnetic field that surrounds a resonant coil to another coil resonating at the same frequency, we can make the electricity hop from one to the other."
WiTricity's strongly coupled magnetic resonance means cars, TVs, free-standing lamps, and computers anything that requires electricity can be powered or charged from a central source in the ceiling or under the floor. And it's all totally safe. "The fields that we are generating in are about the same as the earth's magnetic field," Giler says. "We live in a magnetic field."
Giler and his team are in talks with big-name electronics manufacturers, including many of those who are putting their names to the Qi standard for charging mats. Giler says proximity charging is "first-generation stuff; by the end of next year you'll start seeing devices with WiTricity components built in".
If he is right, homes and offices could soon be fully wireless.
"It's a fundamental breakthrough in science and a game changer for the industry," he says. "Cut the cords and the world's going to change."
Wireless electricity appears cutting-edge but one man had dreams of a world without cables more than 100 years ago. Nikola Tesla, a pioneering American physicist, saw wireless energy as the only way to make electricity thrive. He couldn't imagine a future in which we would be mad enough to bind the globe with miles of copper and steel.
In 1901, work started on Tesla's Whardenclyffe communications tower on Long Island, New York. His plan: to transmit electricity like radio waves across entire continents.
In1908, he wrote: "It will be possible for a businessman in New York to dictate instructions, and have them instantly appear in type at his office in London... An instrument not bigger than a watch will enable its bearer to hear anywhere... music or song [or] the speech of a political leader... delivered in some other place, however distant." But Tesla, whose name lives on in the electric car manufacturer, Tesla Motors, lost his investors before he could prove his vision was more than science fiction.
J.P Morgan was concerned that wireless electricity could not be metered, while John Jacob Astor went down with the Titanic. His tower left to ruin, Tesla died, poor and frustrated, in 1943.