Imagine not having to hunt for an outlet for your laptop because your café table charges it automatically. Or arriving in a disaster zone and tapping into the ground to provide electricity to an entire neighbourhood within minutes.
That's the future some University of Alberta researchers envision. With a system they've dubbed QWiC power - short for quasi-wireless capacitive - the research team in the Faculty of Engineering has wirelessly powered everything from cellphones and lamps to motors and wheelchairs, simply by sitting them on tinfoil, desks and floors. Most recently, in a discovery published by Cambridge University Press, the team transmitted electricity through the ground, opening up a whole new area of potential.
Real-world applications could be ready in as little as two years and the technology could eventually make electrical outlets and power lines obsolete, says Charles Van Neste, a member of the research team led by Canada Excellence Research Chair Thomas Thundat.
At a lab in the Department of Chemical and Materials Engineering, Van Neste explains how "remote electricity" works using a small robotic crab and an everyday piece of aluminum foil.
Using the robo-crab as an example, here's how it works:
1. Look Ma, No Batteries: A power source clipped to the aluminum foil delivers a low-voltage current to the foil.
2. Ping-Pong Power: A device called a resonator draws electricity from the foil, boosting the current and creating a particular frequency to produce standing waves. The current pings back and forth between the foil and resonator, through the robo-crab.
3. Friction Fuel: The robo-crab (the "load" in electrical terms) interferes with the flow of the current, creating resistance. That resistance, or electrical friction, powers the robo-crab.
The big difference (Or all you really need to know)
If you're not into science and just want the basics, all you need to know is that while typical electrical systems are looped, meaning the electrons that carry the electrical charge travel around a circuit, remote electricity uses something called "standing waves." Standing waves are created by particular frequencies of electricity that cause the electrons to bounce back and forth along a single electrical wire rather than in a loop. This creates some cool advantages.
Van Neste uses the analogy of a paddle ball to explain how a resonator amplifies the current. At the right frequency, a small movement in the paddle (the foil) can make the ball (electrons) move a large distance.
Why It's Exciting
Remote electricity has some big advantages over traditional electrical systems, Van Neste says.
- It's less wasteful. The energy is transmitted only when a "load" is present. (A load is the portion of a circuit, like an appliance or light bulb, that consumes electricity.)
- There's no risk of electrocution. A human body cannot complete a standing wave circuit, as it can with a traditional looped system.
- Energy is transferred at about 95 per cent efficiency, which is better than current wireless technologies.
- Remote electricity doesn't fill the air with electromagnetic fields.
Charging Forward
So what's the big deal? You can already charge cellphones by laying them on the surface of a charging device. The difference, Van Neste says, is that most wireless chargers today use "field coupling." Two transmitters generate a magnetic field between them, and your device must be within the field to access power. QWiC power doesn't generate a magnetic field, so its use is restricted only by the size of the charged surface.
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