All About Wireless Electricity

Wireless electricity is quite literally the transmission of electrical energy without wires. People often compare the wireless transmission of electrical energy as being similar to the wireless transmission of information, for example, radio, cell phones, or wi-fi internet. The major difference is that with radio or microwave transmissions, the technology focuses on recovering just the information, and not all the energy that you originally transmitted. When working with the transport of energy you want to be as efficient as possible, near or at 100 percent.

Wireless electricity is a relatively new area of technology but one that is rapidly being developed. You may already be using the technology without being aware of it, for example, a cordless electric toothbrush which recharges in a cradle or the new charger pads that you can use to charge your cell phone. However, both of those examples while technically wireless do not involve any significant amount of distance, the toothbrush sits in the charging cradle and the cell phone lies on the charging pad. Developing methods of efficiently and safely transmitting energy at a distance has been the challenge.

How Wireless Electricity Works

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There are two important terms to explain how wireless electricity works in, for example, an electric toothbrush, it works by "inductive coupling" and "electromagnetism". According to the Wireless Power Consortium, "Wireless charging, also known as inductive charging, is based on a few simple principles. The technology requires two coils: a transmitter and a receiver. An alternating current is passed through the transmitter coil, generating a magnetic field. This, in turn, induces a voltage in the receiver coil; this can be used to power a mobile device or charge a battery."

To explain further, whenever you direct an electrical current through a wire there is a natural phenomenon that occurs, that a circular magnetic field is created around the wire. And if you loop/coil that wire that wire's magnetic field gets stronger. If you take a second coil of wire that does not have an electrical current passing through it, and place that coil within the magnetic field of the first coil, the electric current from the first coil will travel through the magnetic field and started running through the second coil, that's inductive coupling.

In an electric toothbrush, the charger is connected to a wall outlet that sends an electric current to a coiled wire inside the charger creating a magnetic field. There is a second coil inside of the toothbrush, when you place the toothbrush inside of its cradle to be charged the electric current passes through the magnetic field and sends electricity to the coil inside the toothbrush, that coil is connected to a battery which gets charged.

History

Wireless power transmission as an alternative to transmission line power distribution (our current system of electric power distribution) was first proposed and demonstrated by Nikola Tesla. In 1899, Tesla demonstrated wireless power transmission by powering a field of fluorescent lamps located twenty-five miles from their power source without using wires. As impressive and forward thinking as Tesla's work was, at that time is was actually cheaper to build copper transmission lines rather than build the type of power generators that Tesla's experiments required. Tesla ran out of research funding and at that time a practical and cost efficient method of wireless power distribution could not be developed.

WiTricity Corporation

While Tesla was the first person to demonstrate the practical possibilities of wireless power in 1899, today, commercially there is little more than electric toothbrushes and charger mats available, and in both technologies, the toothbrush, phone, and other small devices need to be extremely close to their chargers.

However, an MIT team of researchers led by Marin Soljacic invented in 2005 a method of wireless energy transmission for household use that is practical at much greater distances. WiTricity Corp. was founded in 2007 to commercialize the new technology for wireless electricity.