Is wireless power safe?
As the Wikipedia page on Tesla coils puts it, “large systems can deliver higher energy, potentially lethal, repetitive highvoltage capacitor discharges from their top terminals”. A large coil can generate up to half a million volts, and as any museum tour
Today, consumer applications of wireless power like device charging pads aren’t enough to hurt you, but you wouldn’t want anything as obtrusive, loud or dangerous as a Tesla coil on top of your house, hissing away and throwing electrical arcs all over the yard.
But in a world where the electromagnetic fields generated by mobile phones still concern some people, should we be worried about our houses or workplaces enveloped in a sea of magnetic fields?
So far, wireless energy is a low-power proposition. It’s enough to charge your mobile or iPad over time, but energy intensive applications like games and streaming video will still deplete the battery faster than low-powered wireless energy can charge it. The consumer applications offered by WiTricity, according to CTO Sanjay Gupta, are lower powered than even a mobile, so the magnetic fields aren’t strong enough to be absorbed into the human body.
But powering every device in the living room, office or a whole city building constantly would need a much more powerful signal, and that can become a problem. Even though the effects of electromagnetic fields on human health is a contentious issue, few argue that there are indeed effects.
To Ha Pham N, a PhD and lecturer at the University of Technology, Sydney’s school of electrical, mechanical and mechatronic systems, the answer isn’t stronger magnetic fields, it’s more efficiency in devices to harvest the magnetic fields that generate electricity. “It is actually about design,” he says “In the future, we need technology that requires very low power because our body has a limit. If we exceed that limit then [wireless power] will become dangerous.”
If mobile phones are indeed dangerous (conspiracy theorists wait for the day when years of lobbying records and manufacturer cover-ups are revealed), then the kind of magnetic fields we’ll need to run higher-powered devices wirelessly won’t be as safe as we’d like.
But even then, it’s a matter of successful systems design. “As long as there is no living body in the strong field, it’s okay,” says Dr Pham. “A good product will make sure that the living bodies are kept away from that.
“A good example is wireless vehicle charging — you’re not supposed to lie under your car in the middle of the magnetic field charging it, so when the floor is safe — for example, using sensor technology — it can be a little higher powered.”