Are we finally ready to cut the cord?
Wireless electricity is coming closer to practical reality
Nikola Tesla, the SerbianAmerican engineer born 150 years ago, wanted to give the world free electricity. Financed by the banking tycoon JP Morgan, Tesla designed a system for sending electricity through the air, using a series of enormous towers to create a “global wireless power grid”. Newspapers at the time said the project would “run all the earth’s industries”.
However, Tesla’s plan turned out to be more expensive than first thought. Morgan lost interest and Tesla suffered a nervous breakdown. The US Government blew up his 57m test tower in 1917, amid fears it was being used by spies.
Instead, the electrical revolution was wired. But a century after Tesla’s dream died, the idea of wireless power is again gathering steam. Electricity transferred through the air could mean mobile phones that never have to be plugged in, lights that don’t need a connection, and devices from security cameras to thermostats that do not need batteries.
“The power cord is the last cord left in our lives right now,” says Sanjay Gupta, president of the AirFuel alliance, a consortium that is investing in wireless power systems.
Supporters say the technology could make cables and power sockets anachronisms like the dial-up modem.
Today, the wireless charging systems available to the public involve placing a smartphone on a pad. Such “inductive charging” technology involves magnetic coils creating an electrical field, picked up by a sensor in a phone. However, the experience isn’t a big improvement on plugging in a cable, since the charging works at a maximum distance of 2.5cm.
That may just be about to change. Wi-Charge, an Israeli company founded in 2012, has developed a charging system that uses infrared light to beam energy from a ceiling transmitter to a device anywhere in a room. Yuval Boger, its chief marketing officer, says the system can fully charge a phone in three to four hours, compared to around an hour when plugged in.
“Today we have become enslaved to our phones, we worry about how much battery we have. If it can be perpetually charged [it’s different],” he says.
While the system is not on sale today, Boger says that almost every major electronics company has been in touch with Wi-Charge.
Gupta, of the AirFuel Alliance, is pushing a rival technology using radio waves. It transmits power at frequencies traditionally used by mobile networks, radio and TV. The alliance includes Samsung, LG and Huawei, and a handful of products already use the technology, including a hearing aid that can be charged at 4.5m.
The competing technologies both have downsides, however. Infrared charging requires direct line of sight between a transmitter and a device, meaning sofas, walls and pockets would block the signal. Radio frequencies of the type proposed by AirFuel have their own challenges, particularly in how much power can be sent over the air safely.
Professor Grant Covic of the University of Auckland’s electrical, computer and software engineering department, says concerns about radiation and interference with devices such as pacemakers will restrict the energy that can be transferred.
“The limitation will always be safety,” says Covic. “Cellphones are always getting power hungrier and the battery demands are going up. Would the energy you could transfer be sufficient?”
AirFuel admits that smaller and less power-hungry devices such as headphones and wearable devices, not smartphones, are most likely to use its charging technology.
Disagreements over competing standards threaten to hold back the technology, says Dan Bladen of Chargifi, a British start-up. “It’s technically possible but it’s not going to happen any time soon because of the standards. Pretty much all of the companies are working on their own technologies,” he says.
But the one company with the influence to advance the technology might be doing just that. Last year, Apple signed a US$600 million ($891m) deal with Britain’s Dialog Semiconductor to acquire much of its power management technology. Dialog, in turn, has been a major investor in wireless power company Energous.
Apple is notoriously secretive, but patents hint that it is working on overthe-air charging. The wired connection might not have long left.
The power cord is the last cord left in our lives right now.
Sanjay Gupta, the AirFuel alliance