wasting food can be gross, but i think in the US where food is generally overabundant, wasting food (or even donating leftovers to the needy) might actually be good way to promote improved public health

They've always had air-powered engines... the concept attracts us but ultimately it requires some sort of energy/electricity to compress the air - that might need gas/coal.

Safety around pressurized tanks is another issue. I usually don't comment but i felt like i could contribute a little bit to clear up misguidances