Katie Hall’s ideal home doesn't have electrical outlets, but the structure she envisions will be outfitted with the same kinds of appliances found in just about any modern dwelling. The only difference? The electronics—like wide-screen TVs, refrigerators, computers and lights—will all be powered by energy transmitted wirelessly from inside the walls.
It's a vision of the future that's not as far-fetched as it seems, especially when you realize that groundwork for the technology already exists. It was right around the turn of the 20th century that influential inventor and Thomas Edison rival Nikola Tesla attempted to apply his work on alternating currents to build a tower that would beam wireless power to far-off sites like residences and businesses.
Even though plans for that structure were scrapped after investors pulled the plug on funding, a startup named WiTricity, where Hall serves as chief technology officer, hopes to extrapolate from that vision by developing a new technology that may allow us to finally do away with plugs altogether.
So far, the company has used its innovative charging pad to recharge familiar consumer products. For it to work, a television, for instance, or an iPhone have to be equipped with a receiver. For the phone, WiTricity designed a special case, unveiled at this year's Consumer Electronics Show, that syncs up with the charging pad. The case has been shown in tests to supply power at twice the rate of the smartphone's standard 5-watt charger.
To demonstrate how the technology works, the company released a video showing how a user could adhere the charging pad underneath his or her desk, plugged in. After sliding an iPhone into the WiTricity case, the device begins to charge wirelessly through the table. The phone begins to charge when it's placed anywhere within the 7-foot range of the power source, according to the video; multiple devices can also be charged using a single "base charger."
Someday, the company believes, nearly all consumer electronics will come with cordless power capablities, in much the same way most mobile devices today have integrated bluetooth and other wireless connectivity features. WiTricity already has several partnerships with companies who are using the technology to develop new products.
In a way, the WiTricity's "resonant inductive coupling" technogy is similar to what's used in electronic toothbrushes. To generate a magnetic field, alternating electrical currents pass through an iron coil located inside the toothbrush's power source. When this field comes in contact with another coil, built inside the toothbrush, it induces a current to power the device. But this setup, while wireless, is limited by the fact that the magnetic fields are relatively small. Using this method would require household devices to be placed in a precise position and in very close proximity to the power source when they are recharging.
Resonant inductive coupling is much more versatile. With this method, the inductive coil inside the power source has flat, circular metallic plates attached to each end. These “capacitator plates," as they're called, are spaced slightly apart from one another, causing the coil to "resonate" as currents flow through it. The idea is that a magnetic field emitted through resonance can travel longer distances and transfer energy more efficiently than conventional wireless charging so long as another object (in this case a coil in the receiver) resonates at around the same frequency.
In 2007, a team of researchers at MIT demonstrated the potential of such a system in an experiment. They were able to use a resonator, or power source, to turn on a 60-watt light bulb sitting about seven feet away. The results were detailed in the journal Science.
Soon after, the inventor, MIT physics professor Marin Soljačić created WiTricity to further develop and commercialize the technology. His development team, based out of Boston, is looking into ways to improve the range and efficiency of the technology as the components—such as the coil and resonator—are shrunken down to fit into smaller, mobile gadgets. (Larger coils, they've found, generally offer better efficiency over greater distances).
“Our main competitors are basically a wire and an outlet," Hall says. “So to get [the technology] where its efficient enough to be practical, we're working on improvements like integrating sensors that, depending on whether a device is within range, can automatically detect when to turn the field on or off so it won't waste energy.”
While the notion of channeling energy through a kitchen counter, for instance, to run a toaster is sure to raise some eyebrows healthwise, Hall asserts that the system they've created is as safe as other forms of energy transmission, such as WiFi signals coming from a router.
“The energy that extends out from the source isn't actually electricity,” she explains. “We're actually putting into the air a magnetic field that's non-radiative and doesn't affect us.”
Hall says she and her team have optimized the technology to the point where it can convert more than 95 percent of the magnetic field's energy into electricity, enough to re-juice a cell phone more quickly than with a conventional wall charger.
The technology does, however, have its skeptics. Ambient Devices founder David Rose says there's a lot of uncertainty over the long-term adoption of wireless power because it will require the support of the industry's major players.
"It’s going to take all of Toyota to do all of their next generation of electric cars, and Mercedes and Audi and everybody else in order for most people to want one of these in their garage," Rose told WGBH News. "And it’s also going to take a big consumer electronics player like Samsung or Apple and Starbucks and places that people go, in order to have this become widely accepted. That’s a huge uphill battle the company faces for any big system-wide change."
So where will consumers see long-distance wireless in the future? The company has recently licensed its technology to Toyota, which plans to add wireless charging capability to its upcoming line of electric and hybrid vehicles within the next couple of years, according to Hall. WiTricity has also received interest and financial backing from Taiwanese mobile electronics manufacturer Foxconn and chipmaker Intel.
"It'll most likely start out making it's way commercially as a feature that's packaged into the cost of buying a car or device,” Hall says. “But as the technology becomes more ubiquitous, businesses may start installing them [wireless charging] into walls and floor and eventually almost all buildings won't have outlets anymore. I mean, imagine that.”