I don't think it works like that. The only known way to make antimatter is to convert energy into matter-antimatter pairs, so basically you need the same 100% of energy to produce antimatter in the first place. (In fact, I think the current physical theory prohibits any kind of matter-antimatter conversion, but I'm not a physicist so I might be wrong.)

So, if we had enough energy to make these antimatter, we could simply use the energy directly, without going through the massively inefficient step of funneling that energy into liquid helium and superconducting magnets and city-wide vacuum circles and so on.