Solar Energy Part 4
Have you ever listened to an AM radio that is not tuned to a station? You hear noise - lots of it! In electronics, noise has a different meaning altogether. It is not necessarily the audio noise that our ears hear, but defines any unwanted or unexpected voltage riding on top of the expected signal. Noise, which often consists of random short duration spikes, may be generated both internally and externally. Every semiconductor device generates its own noise! The hotter it is, the more noise. Now if we could collect all the different types of noise together, plus throw in a few radio signals as well, we should have quite a large electrical signal. This is of course quite the opposite of what most radio engineers want to achieve. But it makes sense to actually create noise, or encourage its buildup, in order to use the electrical power it consists of.
Imagine how many radio waves are passing through your head right now. All the radio and TV stations, mobile phones, civilian and military radio, etc. Then add the natural electrical noise caused by lightning, static buildup on clouds, etc - the stuff you hear on an untuned radio. Finally add all the radio frequency signals coming from outer space, and including our own Sun. There's a hell of a lot of power in all that!
If we made an antenna array that could capture all that stuff, and then heat it almost to the point of destruction, so that it generates its own maximum internal noise as well... We should have a lot of power. Note that we are not talking about a few antennae but millions.
Far fetched? Not really. Antenna arrays don't normally cover a sufficiently wide range of frequencies for this to work well. The arrays would also be impossibly large for regular radio frequencies. But there is a way to capture much of the microwave energy that is generated by the Sun. Each element has its own radio signature - this is how astronomers know what elements make up the stars and planets. The Sun, being mostly Hydrogen, generates known frequencies that can be captured, probably by an orbiting space antenna system. Since radio signals 'go through' antennae, we are not limited to a two dimensional array. It has been calculated that a one cubic meter array in space may collect one megawatt of power. Other estimates suggest even more.
This is no more than a theoretical design at present (who knows what NASA might be doing with it!) but I really like the general idea. The idea of using the garbage put out over the air by radio and TV appeals to me. Who knows, perhaps our politicians' speeches may eventually become useful! That might never be possible but capturing the Sun's signals is definitely feasable.
This shows that there are many more possible methods of utilizing the Sun's energy other than by light and heat. It is so easy to forget the invisible forms of energy, but these may actually be more profitable if properly researched.
This concludes the introduction to electronic solutions. Next we look at the real solar engineering.