[sjburt]

Fuel mass is very much the limiting factor. "Electric" or "ion" propulsion of this general type are used on satellites for things like orbit raising or orbit maintenance. They don't provide very much thrust, but they provide a very high ISP (often 10x what would be possible for a chemical reaction propellant), which typically translates to a longer lifespan for a vehicle or the ability to carry less reaction mass and more payload.