Basic problem: watts is instantaneous power, watt-hours is total quantity of energy. This launcher uses tremendous amounts of power but only over a very short period of time. That does not translate to “as much energy as needed to handle a city...”
Just what I was thinking - powers n homes for how long?
Other wise, the launcher running at full capacity consumes as much power as n homes, period.
And, watts are units of power, that is, a rate of energy transfer. Watt-hour is a unit of energy.