Intel recently announced a display of some new technology which looks like another step along the way to a good proof of concept of efficient wireless electricity.
Building on Marin Soljacic’s work at MIT (it’s unclear to me whether Intel is actually building on top of the work of Marin’s group or if they’re working in parallel) the group from Intel is displaying the transfer of energy without wires from a transmitter to a receiver separated only by air which in result lights a light bulb.
Intel’s demonstration was covered by Gizmodo and has a nice description and some great pictures.Two years ago Marin Soljacic’s group out of MIT made their first announcements of their plans to use electromagneticinduction (the transfer of energy through the conversion of electric charge to magnetism and vice-versa) to transfer energy through the air from a sending device to a receiving device. The trick to keeping everything safe for humans and electronic devices sharing the air in between was to use a very low power signal and to then use the principle of resonant energy transfer.
This is essentially pushing on a wave at a frequency that in result magnifies the strength of the wave. In plain English, think about pushing someone swinging on a play groun dswing. If you push them at the right time during their swing you will increase the speed at which they swing and the distance they cover. Push at the wrong time and you slow them down. The same concept allows your standard AM/FM radio to tune into a radio wave frequency..
How Wireless Power Works
Unless you are particularly organized and good with tie wrap, you probably have a few dusty power cord tangles around your home. You may have even had to follow one particular cord through the seemingly impossible snarl to the outlet, hoping that the plug you pull will be the right one. This is one of the downfalls of electricity. While it can make people's lives easier, it can add a lot of clutter in the process.
For these reasons, scientists have tried to develop methods of wireless power transmission that could cut the clutter or lead to clean sources of electricity. While the idea may sound futuristic, it isn't particularly new. Nicola Tesla proposed theories of wireless power transmission in the late 1800s and early 1900s. One of his more spectacular displays involved remotely powering lights in the ground at his Colorado Springs experiment station.
Tesla's work was impressive, but it didn't immediately lead to widespread, practical methods for wireless power transmission. Since then, researchers have developed several techniques for moving electricity over long distances without wires. Some exist only as theories or prototypes, but others are already in use. If you have an electric toothbrush, for example, you probably take advantage of one method every day.
The wireless transmission of energy is common in much of the world. Radio waves are energy, and people use them to send and receive cell phone, TV, radio and WiFi signals every day. The radio waves spread in all directions until they reach antennae that are tuned to the right frequency. A similar method for transferring electrical power would be both inefficient and dangerous.
For example, a toothbrush's daily exposure to water makes a traditional plug-in charger potentially dangerous. Ordinary electrical connections could also allow water to seep into the toothbrush, damaging its components. Because of this, most toothbrushes recharge through inductive coupling. See the next page to learn more about how inductive coupling works.
Inductive Coupling
Inductive coupling uses magnetic fields that are a natural part of current's movement through wire. Any time electrical current moves through a wire, it creates a circular magnetic field around the wire. Bending the wire into a coil amplifies the magnetic field. The more loops the coil makes, the bigger the field will be.
If you place a second coil of wire in the magnetic field you've created, the field can induce a current in the wire. This is essentially how a transformer works, and it's how an electric toothbrush recharges. It takes three basic steps:
Current from the wall outlet flows through a coil inside the charger, creating a magnetic field. In a transformer, this coil is called the primary winding.
When you place your toothbrush in the charger, the magnetic field induces a current in another coil, or secondary winding, which connects to the battery.
This current recharges the battery.
You can use the same principle to recharge several devices at once. For example, the Splash power recharging mat and Edison Electric's Power desk both use coils to create a magnetic field. Electronic devices use corresponding built-in or plug-in receivers to recharge while resting on the mat. These receivers contain compatible coils and the circuitry necessary to deliver electricity to devices' batteries.
A newer theory uses a similar set-up to transmit electricity over longer distances.
Feel free to write