It all comes down to $, in the end. All the battery/kinetic, etc. solutions have the problem of weight. For a vehicle; ship, plane or car, weight = money.
The Europositron battery, if it can be made commercially, still stores only 10% of the energy per pound of gasoline*.
Flywheel problem ditto. No known material is able to withstand the huge hoop stresses needed, [ say 2 million psi ] to achieve comparable storage capacity kWh/lb. And a flywheel containing the energy of 10 gallons of gas in a crash would probably take out 2 blocks if it burst!
* The person who really unlocks a practical way of using Aluminum/hydrogen/WHY for vehicles will be made:
Europositron, 2065 btu/lb = 0.6kWh/lb
Gas, 23000 btu/lb = 6.7kWh/lb
Al.[to Al(OH)3] 22000 btu/lb = 6.4kWh/lb
H2 [to H2O] 60000 btu/lb = 17.5kWh/lb
We ain't there yet!
Alan
