|
Electric motors are up to 94% efficient. Plug to wheels is about 85% efficient. Single speed reduction gears used on some EV lose about 2%, which is included in the plug to wheels number.
IC engines are up to 38% efficient for gasoline (Prius) or ~42% for some diesels. Transmissions and clutches/automatics have some losses -- maybe 5-7%?
If you want to add in source to car losses for EV's, then you have to add them for liquid fuels, as well. But remember that if you have solar PV on your roof, or if you pay for renewable-generated electricity, then you only lose about 8% for grid losses. Oil is getting harder and harder to get -- the numbers on tar sands bitumen for example is the equivalent of about 1:2 for the resulting energy. If that is worth it, then we have passed peak oil.
As the oil runs out, then we will have to use renewable energy more and more. Renewable energy will last as long as the earth does -- about another 5 Billion years.
|