WillDAQ, I don't think it would take much to put a steam boiler and reservoir on board. Electric cat will require a huge amount of electricity if we are talking linear motors and all the lights will go dim when it's used. You can store an awful lot of energy built up over time with high pressure steam.
That's the point though, the electricity for the launches can be tapped straight out of the Integrated Full Electric Propulsion system which can generate over 100MW. We have loads of electricity but no steam and more to the point, no space on board to put any sort of steam generating capacity.