efficiency

Introduction To Witricity

Witricity, standing for wireless electricity, is a term coined by MIT researchers, to describe the ability to provide electricity to remote objects without wires.

Witricity is based upon coupled resonant objects to transfer energy between objects without wires. The system consists of a Witricity transmitter, and devices which act as receivers.

Like radio receivers, the devices must be in range of the transmitter. Unlike the conduction-based systems built by Nikola Tesla in the late 19th century, Witricity uses resonant magnetic fields to reduce wastage of power. Currently the project is looking for power transmissions in the range of 100 watts.

As they put it: "Using self-resonant coils in a strongly coupled regime, we experimentally demonstrate efficient non-radiative power transfer over distances of up to eight times the radius of the coils. We demonstrate the ability to transfer 60W with approximately 40% efficiency over distances in excess of two meters. We present a quantitative model describing the power transfer which matches the experimental results to within 5%. We discuss practical applicability and suggest directions for further studies."

3. Efficiency

The efficiency of wireless power is the ratio between power that reaches the receiver and the power supplied from the transmitter. Generally wirelessly transmitted energy is dispersed as the energy radiates into the environment or is lost as heat at the transmitter or receiver. Wired transmission techniques on the other hand lose far less power as wires are good conductors and help to confine and guide the energy to where it is needed.

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