Wireless power

Ever since Nikola Tesla lit bulbs on his grounds without wires, the promise of wireless power has stirred hope and interest but little success. Today, with the wide array of electronic devices that require power, the promise of powering the enterprise through the air seems as crackpot as it is unlikely.

Yet practical implementations of wireless power have emerged in the past few years, including the induction charging of an electric toothbrush and wireless extension cords ThinkGeek introduced in 2006 -- on April Fool's Day.

In fact, a few companies are actively pursuing wireless power, including Splashpower and Powercast.

Splashpower has developed charging systems using magnetic induction. Placing enabled devices on the charging station will charge the device without mechanical connection. Just as with that toothbrush, power in the charging platform creates an electro-magnetic field that effectively transmits power to the embedded module in the device.

Powercast has taken a different approach, as reflected in the first commercial implementation of its technology: an LED-lit wireless Christmas tree created with Philips and sold last Christmas season in the high-end Frontgate catalog.

Rather than tapping induction, Powercast uses RF (radio frequency) transmissions with high-efficiency transmitters and receivers to broadcast power to the devices. Powercast is targeting a broad range of devices, including such widely varying items as hearing aids, biological weapons sensors, and wireless headsets.

Tesla's early patents on wireless transmission of power were awarded in 1900. His diagrams show inductive coils that can transmit large amounts of power over great distances. Carrying out his invention on an industrial scale, he said, would result in electricity for cities from places where cheaper power was attainable. Given the rising cost of energy, the ability to feed a datacenter with power from a distant, inexpensive source such as a hydroelectric dam would have considerable impact on the enterprise.

In June 2007, a team from MIT's Department of Physics, Department of Electrical Engineering and Computer Science, and Institute for Soldier Nanotechnologies experimentally demonstrated wireless power using magnetically coupled resonances. Using resonance, the team demonstrated a much more efficient transmission of power over distance than is typical. Of course, the team's devices are a bit on the bulky side, but the demonstration of the concept shows promise.

Although we have yet to see the full fruition of Tesla's brilliant vision, some early work is beginning to demonstrate that there may, in fact, be some hope for moving power without wires. And hopefully without dire health consequences created by the interaction of human beings with it.

-- Stephen Sven Hultquist

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