Thanks again for taking the time to submit your Stump the Scientist questions via GE’s Facebook page! We had some great questions submitted this week, hope you enjoy this one!
This week’s question: Is wireless power transmission possible?
Response from Chief Scientist Jim Bray
Rohan, the answer is a definite “yes.”
Normally, we think of electric power as being carried by metal (copper) wires, and this is usually the case. However, little bit of power is carried wirelessly when we receive signals on our cellphones, TV antennas, radios, or wireless computers. This wireless power is carried by electromagnetic (EM) radiation (also called photons) from the antenna at the source, and it is imprinted with useful communication signals, which our receiving device amplifies and gives to us on a screen or in words. However, Rohan is probably thinking of providing a lot of power this way, for example for running motors. This can also be done, but it is a harder problem and is the object of current research to improve it (e.g., see Witricity). Just as in the cellphone case, the power is carried by EM radiation, but large power can only be carried efficiently a short distance, like a foot or so. The reason for the short distance is that the electric power must first be transformed to EM radiation at an antenna and then received by another antenna, where it is converted back into electricity for power. The EM radiation tends to spread out between the antennas, and so too much is lost if the antennas are too far apart. Some power is lost an any case, and so the wireless method will never be as efficient as a wire connection. However, the convenience of power transfer where wired connection is difficult (e.g., to vehicles or to hard-to-reach places) is the reason for the current work on this subject. We are likely to see more use of this in the future.
Jim