Can we harvest electricity from the radio waves emitted by the Sun?

16 July 2006

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Question

It's my understanding that you can send electricity wirelessly. Although microwaves are apparently the best way, even radio waves contain small traces of electricity. So if the Sun emits a huge and powerful spectrum of radio waves and other kinds of electromagnetic waves, would it not be possible to pick up this free energy using a big antenna?

Answer

I wish it was! The total energy we get in every square metre on the surface of the Earth from the Sun is about 1kW. If we could turn all of that into electricity, that would be marvellous. But I'm afraid the laws of thermodynamics stop that. The temperature of the Sun isn't so great as to turn it all into possible work, and antennae would just pick up very faint signals like the old early radio waves when you had a crystal set and got a weak signal. I'm afraid it isn't going to be useful to turn that into practical energy to power your house.

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