Wireless electricity is in our near future, so get ready to quit tripping over all your electronic charger wires. An article on CNN today highlights a new company working on wirelessly powered gadgets and took us on a short glimpse into our future. The CNN article discusses the venture that came out of research performed at MIT (they're the engineering arch-nemesis to my Alma mater, Georgia Tech) called WiTricity.
Wireless power is nothing new. In fact, Nikola Tesla had several patents regarding wireless electricity transfer as early as 1900. And looking into the future, Japan has announced serious plans to put solar panels in space and beam the power wirelessly down to earth. Japan isn't talking about just a few Watts. They're talking 1 Giga-watt! That's the equivalent of a coal power plant's output. Let me assure you that you don't want to walk in the way of that beam unless you want to end up wirelessly transmitted to heaven (or hell if you are behind Magniwork).
The basics behind wireless electricity transfer are really pretty straightforward and Popular Science had a great article on the topic (that also covered the company that came out of MIT) in January of 2008, so the CNN article isn't exactly breaking news.
To simplify, wireless electricity transmission is caused by electric current at a specific frequency running through one coil, which causes a magnetic field oscillating at that same frequency to be emitted from the coil. When that magnetic field comes in contact with an identical coil at another location, the 2nd coil resonates at the same frequency as the magnetic wave and a current is induced in the second coil. To see a better explanation with pictures, see this how wireless electricity works. ( side note: I would like to understand better how the resonance induces a bigger current than just a regular magnetic field. I understand the basics of resonance, but I'm just not sure how the resonance causes a larger current induction in the receiving wire. Please feel free to explain in the comments)
As we know, wireless electricity is not a new idea, and in fact, I already use it in my house with my electronic toothbrush. The charger is plugged in, but the toothbrush just rests on the charging stand, getting charged wirelessly. However, the distance separating the stand from the toothbrush is probably a millimeter, with just some plastic in between.
Another type of wireless electricity transfer exists where a tiny amount of energy is transferred over a long distance.
WiTricity is breaking ground because it is sending a decent amount of power over a large distance. They are achieving this by what they are calling "magnetically coupled resonance". Which relies on the magnetic resonance to induce a larger current in the devices the power is being beamed to, or at least that's how I understand it.
So, what does this mean for energy conservation? Well, in regards to actually saving energy I really dont think wireless charging will be more efficient. The CNN article says the charging devices are about 70 to 90 percent as efficient as using a wire. But apparently they do shut off when the device is done charging, so that would lead me to believe there is no vampire load.
The biggest environmental benefit that is mentioned in the article is that wireless charging would eliminate the need for batteries in many appliances that are used in the home. The CEO, Eric Giler, stated in the article that:
... wireless electricity has many environmental benefits. Companies make about 40 billion disposable batteries each year, he said, and wireless electricity could do away with that.
I'm a little skeptical at how many devices will really be able to be directly powered (that means without batteries) by wireless electricity transmission. Laptops and cell-phones will still need batteries if you ever need to take them out of the house. For instance, in my office right now, there is only one device that would benefit from wireless charging by getting rid of batteries, and that is my wireless mouse. But I use rechargeable batteries in it! I think "getting rid of 40 billion batteries" may be a bit of an exaggeration. Sure, it may remove a few batteries, but it is less efficient than wired power. I'd love to see more data on the environmental benefits of wireless electricity transmission!
There are other questions to this technology, like what it does to our health? I'm sure we'll be hearing a lot more on this one as the technology matures. (Especially if Japan is really going to attempt their death ray space power transmitter.
Nevertheless, wireless power transmission is pretty darned cool. I will say that it would be great to drive my electric car (not yet purchased) into my garage and have the battery charged without me having to get my hands dirty!
***Update 1/21/10: Popular Science recently had an article on RCA Airnergy. Basically, it's a battery that is charged by wireless networks. Pretty cool stuff.