I'm only beginning to scratch the surface of higher level Physics and, despite my usual haunt being the EE area, I enjoy reading the responses and discussion in this section of the forum. I was talkin' to a friend about Fusion power and he asked me why it wasn't used instead of Fission. Now, I know just enough about fusion to speak intelligently; but I could not give him an answer that made sense to either of us. I know, or, at least, I've read, that fusion takes much more power than it gives in return. Is this correct? Why? Which method of producing Fusion has the highest yield, i.e. highest Ein/Eout ratio? Please forgive me if this question is annoyingly basic for you folks. I searched on Google but I couldn't find anything that gave a coherent answer; perhaps I wasn't holding my tongue right.