> oil products have energy density that batteries are barely starting to be capable of "Grandpa, tell me again about combustion engines." "Well, they burned g

> oil products have energy density that batteries are barely starting to be capable of "Grandpa, tell me again about combustion engines." "Well, they burned gasoline in a series of tiny explosions, and they were set up so that the timing of those explosions would generate motion." "Haha, that sounds like a Rube Goldberg machine." "Yes, and the worst part is that fire is hot. So even though gasoline contains a lot of energy, the process of turning it into motion was fantastically inefficient. They turned so much of the energy into useless heat that they needed whole separate systems just to throw it all away so the darn things wouldn't melt."