5 ms·
You’re missing density of storage. Gasoline and natural gas are in the region of 50 MJ/kg, while batteries are more like 10MJ/kg or lower. That 5x factor is wha
by spenczar5 3y ago
You’re missing density of storage. Gasoline and natural gas are in the region of 50 MJ/kg, while batteries are more like 10MJ/kg or lower. That 5x factor is what stops us from having electric airplanes.
- timerol 3y ago10 MJ/kg is way overstated for batteries. Current Li-ion is around 1 MJ/kg (278 Wh/kg)
- maerF0x0 3y agoI actually think the reason we don't have electric airplanes has to do with traction vs propulsion. Eg: spinning a jet engine to propel air backwards is very different than spinning a motor that is (through a series of solid objects) directly connect to the ground. and while a battery is only 1/5th density, the motors on a tesla deliver 3x the range per energy compared to a prius. (not true break even, but impressive that one of the most efficient hybrid ICE cannot compare KWh for KWh to a battery + electric)
- XorNot 3y agoNo it's just energy density. Hydrocarbon fuels have more. There's also the benefit that getting lighter as you expend fuel increases range (batteries don't meaningfully change mass when they discharge). Nothing about electric powertrains causes any problems here: it's just hydrocarbon fuel is more energy dense. It's not inconceivable you could build a hybrid electric aircraft if a suitably high power hydrocarbon fuel cell was developed, since removing the combustion stages from a jet engine would simplify the design considerably.