>On the other hand, it's an amazingly small amount of energy. A 90kWh battery holds the equivalent energy of 2.7 gallons of gasoline. The only problem with tha

>On the other hand, it's an amazingly small amount of energy. A 90kWh battery holds the equivalent energy of 2.7 gallons of gasoline. The only problem with that kind of comparison is that the energy in combustible liquids isn't actually usable for propulsion like that. There's no way (that we know of yet) to turn 90+% of the energy in gasoline into propulsion; most of it is just going to be wasted as heat due to the Carnot Cycle. Of course, if your goal is to simply produce heat (like for heating a building), fossil fuels are pretty effective at that. Gasoline-powered fuel cells might do somewhat better than regular ICEs, but still nowhere near 90+%. In a nutshell, electricity is by far the most efficient form of energy transfer we've found so far. Everything else ends up wasting lots of energy to heat any time it's converted from one form to another, but a good electric motor can convert electric energy to mechanical energy with 98% efficiency (and vice-versa, with generators).