Questions for people with some knowledge of engineering (I got none). It is about the 56-oven pizza truck: - How much power (or propane or whatever) do you nee

Questions for people with some knowledge of engineering (I got none). It is about the 56-oven pizza truck: - How much power (or propane or whatever) do you need to run these ovens? - How much heat they emit in the truck, as a waste? Looks like some cooling is required. How much power for that. - What is the power source for the above items. Fuel, propane, batteries? - It kind of looks dangerous to have fuel or propane or batteries next to a bunch of running ovens? If so, where to put the fuel and where to put the engine. - Having flammable cardboard where the ovens are looks too dangerous. How do they get the pizza from the oven to the cardboard? I hope it's not the poor driver squeezing between a bunch of running ovens to get to the right one and get the pizza out?