Helium-3 is a potential energy source, sure. But for the moon. you are forgetting about the energy and resource requirements to ship this stuff to the earth.
It is actually possible to ship nuclear fuels such as He3 from other celestial bodies to earth and release net energy -- this is because nuclear fuels pack several orders of magnitude more energy per mass unit than is needed to move the same mass from one planet to another. That said, while there is a lot of noise being made about He3 mining on the moon, it would probably be impractical, because it is very diluted in the regolith (moon dust). More realistic (but of course also more futuristic) might be to "mine" the atmospheres of Uranus and Neptune for it, using maybe some kind of ramjet-like contraption to do so. If you are keen on moon mining, you should rather set your eyes on the moon's Thorium resources!
Not that there will be any neccessity to do something like this in the foreseeable future. Earth is very rich in all manner of nuclear fuels, Actinides (Uranium and Thorium) as well as fusion fuels (Deuterium and Lithium). It does not have He3 but this is not a big problem because the first generation of fusion plants will run on Deuterium and Tritium (which will be bred from Lithium) which are abundant on earth. He3 fusion is more difficult to achieve than D-Li-T fusion, and thus will probably be rather used for propelling spaceships than for power generation on earth. It is often claimed that "fusion will give us nearly unlimited energy", but we don't need to wait for fusion. Once we set up some
Integral Fast Reactors or
Liquid Fluoride Thorium Reactors (both technologies have been developed and successfully tested by American National Laboratories), we can run our entire civilization on Actinides for millenia.
But back to our friends, the free energy lolcows. These come in several flavors:
- The scientifically semi-literate. These usually have some science background, maybe engineering, sometimes even physics. They claim they have discovered something revolutionary, that is, an energy source which doesn't pose even the slightest risk of accident, creates absolutely no hazardous waste and takes energy out of thin air. They may allude to some effect which has been studied by mainstream scientists, such as "cold fusion" (in which there has been a waxing and waining interest from theorists and experimentalists but so far has proven elusive and probably doesn't work) or zero-point energy. Nonetheless, so far none of their inventions could be replicated by independent researchers, and so we are left with the realization that once more wishful thinking has overpowered reason.
- The Snakeoil Salesmen. "YOU! Your support is needed to make our fantastic clean energy source a reality! Just invest ten thousand US$ to make it happen! You don't want to deprive humanity of clean energy, do you?!"
- The total crackpots. No scientific knowledge here. Einstein's wrong cuz user WorldsBigestGeinus on forum so-and-so has said so. Relativity is a scam by the international financial elite! I can run my car on water, but the insidious oil industry suppresses my invention and even threatens to kill me! My clean energy generator pulls orgon vibrations out of a pink parallel universe. No, you can't see it in action because... you know... it broke down yesterday and I, like, need to repair it. Often, these guys don't stop at "clean energy" and go the full way and "invent" a perpetuum mobile. (But they can't demonstrate it right now because the evil oil industry has sent out its henchmen to kill them!)
Examples:
1st type:
Claus Wilhelm Turtur (who actually is a TRUE and HONEST professor of physics).
2nd type:
Andrea Rossi
3rd type:
Daniel Dingel
Keep in mind that if something is said to have ZERO negative side effects it is probably useless. Like in medicine, everything that has an effect also has some side effects.
BTW zero-point energy is a real effect -- quantum field theory predicts that vacuum is full of tiny particle fluctuations creating pairs of virtual particles which exist for a very short time. This energy cannot be used to drive a machine though: because it is evenly distributed throughout space, you cannot exploit it. For this to be possible, there has to be an energy gradient, that is a concentration of energy at one point and a lack of energy at another, so that you can create an energy flux from the high-energy place (e.g. a hot nuclear reactor) to the low-energy place (the cooling tower or cooling pond) and on the way you can re-route a certain fraction of the energy to do useful work. Zero-point energy, which exists everywhere at constant concentration, thus does not offer this possibility.
