3 ms·
It depends. Electric motors also have losses in their controllers, which removes another 5% or 10%. If you want mechanical power output and have 1kg of pre-char
by avhon1 6y ago
It depends. Electric motors also have losses in their controllers, which removes another 5% or 10%. If you want mechanical power output and have 1kg of pre-charged batteries and 1kg of liquid fuel, the efficiency of electric motors might close the density gap. Lets assume 95% efficient controller+motor (slightly optimistic) and 30% efficient ICE (somewhat pessimistic).
1kg * 14 MJ/kg * 95% = 13 MJ mechanical
1kg * 47 MJ/kg * 30% = 14 MJ mechanical
It comes out pretty close!
If you want mechanical power and also heat (for keeping people, animals, or equipment warm, decreasing the viscosity of fluids, etc), ICE is definitely the way to go.
-- edit --
/u/ash points out Tesla's energy density is is 0.576 MJ/kg
1kg * 0.58 MJ/kg * 95% = 0.55 MJ mechanical
...not even slightly close.
- varjag 6y agoYou should factor in regenerative braking of EVs, which is lost as heat for fossils vehicles.
- petre 6y agoOne can't really charge a battery with power spikes from randomly hitting the brakes. Only part of the braking energy is recoverable, for example when braking to reduce speed while descending a long slope. Braking strategy should also be different in this case: similar to engine braking in regular vehicles. Since most EVs rarely have a multi speed gearbox, regenerative braking should be built into the brake pedal.
- NeutronStar 6y agoRegenerative braking is built into releasing the gas pedal.
- varjag 6y agoIn practice it works fine on all EVs I driven. Doesn't take much getting used to.
- rootusrootus 6y agoI'd wager there are far more fossil fuel vehicles on the road with regenerative braking than there are EVs.
- varjag 6y agoIntrigued, how would that work?
- organsnyder 6y agoI think OP is referring to hybrid ICE vehicles.
- bluGill 6y agoNot very much when you are on the freeway.
- varjag 6y agoI guess if you never ever use brakes it has no advantage.
- Hypx 6y agoThere's also hydrogen fuel cells to consider, which at 142 MJ / kg and 50% efficiency looks like this: 1 kg * 142 MJ / kg * 50% = 71 MJ mechanical The dominant solution above all else.