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That will be a long long time coming. Gasoline is about 46 MJ/KG or 34 MJ/L. The best lithium-metal batteries are about 2 MJ/KG or 5 MJ/L. The best lithium-i
by rmah 8y ago
That will be a long long time coming. Gasoline is about 46 MJ/KG or 34 MJ/L. The best lithium-metal batteries are about 2 MJ/KG or 5 MJ/L. The best lithium-ion batteries, about half that. Gasoline is extremely energy dense. For a comparison, TNT is only 5 MJ/KG and 7 MJ/L.
- jdhawk 8y agoICE efficiency brings that down a decent amount, no? 35-40% at best. The fuel is much more dense, but converting it is not as efficient.
- prolepunk 8y agoBack of the napkin calculation Ice is 18% efficient at the wheels. So the energy spent on propelling the car is 46*0.18 = 8.28MJ/Kg Let's say efficiency of electric car is 60%, 8.28/0.6 = 13.8 MJ/kg. In order to have batteries occupying the same amount of space as gas tank they need to be almost 7 times as energy dense. But then it's possible to get rid of a lot of other systems that support ICE engine, like transmission, cooling, lubrication, led acid batteries engine itself is a lot smaller.
- prolepunk 8y agoEven more, electric engines don't use any fuel at idle, so I for city driving batteries can be even less dense.
- NegativeLatency 8y agoEspecially in an older car with a less efficient engine.
- akira2501 8y ago> ICE efficiency brings that down a decent amount, no? In terms of power to the wheels, yes. Some of that latent energy can be useful, especially after it's converted into heat.
- hwillis 8y agoRoughly 15-20% during actual driving.
- mecameron 8y agoFortunately, gasoline cars are so inefficient that you only need about 1/3 of the comparable energy in an electric car to move the vehicle. Still a ways to go, but we don't need to get to all the way gasoline energy density for the equivalent range.