This is a question for those of you that are more interested in the technical how does it work facet of Star Wars. During the opening space battle we see ship to ship engagement one thing about this did stand out to me. We see a battery of cannons firing and spent shells being discharged, now what I'm wondering is what's up with that? Its not a projectile like lead being shot out rather its an energy beam that is the projectile. Wouldn't the power for the shell be coming through the same power that allows the gun to work? Or would the energy being shot out be different then that produced in the power plant of the ship?