A new
company called Energous has devised a method of wirelessly transmitting power
over long distances. Its prototype system can beam 10 watts, more than enough
to charge your smartphone or tablet, over a distance of 15 feet — and, rather
importantly, it will track your device if you move around. The company hopes to
commercialize its technology soon, with partner companies showing off the tech
at CES in January 2015. It seems that the first generation of wireless
charging — those awful, short-range
charging plates — may finally be drawing to a close. The dream of
having your smartphone and other mobile devices constantly topped up — while
you sit on the sofa, while you stand in line at the coffee shop — may soon come
to pass.
Usually when
we write about wireless
charging on ExtremeTech we’re referring to magnetic resonance, where
you have two coils of wire (antennas, basically) that are both tuned to a
certain frequency. When you pass electricity through one coil, it induces a
resonant electromagnetic field in the other coil, (fairly) efficiently
transferring energy through the air. This is the method that almost every
upcoming wireless charging technology uses, including WiTricity (an MIT
spin-off that has been trying to bring magnetic resonance wireless charging to
market for a good 5+ years). Not Energous, though.
According
to Technology
Review, Energous appears to use a very different technique, consisting of
“lots of small antennas.” This antenna array sends radio waves to nearby mobile
devices that have announced their presence via Bluetooth. Beyond that, there
are sadly few few details. In the demo video above, you can see that Energous’
Energy Router can send power to two devices. The Router can also “track”
devices as they move around (though there’s no word on how big an area it can
track). From these details, we can infer that some kind of beam forming is
used, to transmit a tight beam of electromagnetic radiation at the target
device. The max range is apparently 15 feet (4.7 meters), with fairly
modest efficiency of 20% (not a huge deal, when you’re talking about
mobile devices with tiny power consumption).
To
receive the wireless power, Energous uses special case that you slip your
smartphone into. Again, no word what’s inside the special case, but presumably
it’s a bunch of antennas/coils. It is these cases that will first come to
market, says Energous, with partners showing off cases and Energy Routers at
CES 2015. Eventually, though, of course, Energous wants to get its technology
built directly into devices — and the company says it’s having receiver and
transmitter chips made at the moment. This is a good sign that, despite the
cases and Energy Router being rather large at the moment, the technology can be
scaled down.
While Energous might not have the industry
support that WiTricity has (its “Rezence” tech is backed by Intel and Qualcomm
among others), it’s exciting to see another technique for wireless power
transfer that doesn’t use magnetic resonance. With magnetic resonance there are
some fairly strict rules (as governed by the laws of classical physics)
that limit its potential for wireless power transfer. An array of beamforming
antennas makes a lot of sense, for wirelessly charging multiple devices as they
move through a 3D space. (If that’s how Energous actually works, anyway; I
could have it completely wrong.)
Who
knows. With Energous (or WiTricity/Rezence if
it actually comes to market in mobile devices) we may soon be living in a world
where your mobile devices can be constantly topped up, whether you’re sitting
on the couch, at your office desk, or standing in line at the coffee shop.
Wireless power transmission could also be the key to powering large sensor
networks (smart homes, smart
cities), without having to attach each device to the grid or provide them
with a bulky battery.
Guys, stay in touch for more...
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