Sähköautot, energiatehokkuus

Minua on jonkin aikaa mietityttänyt sähköautojen todellinen energiatehokkuus. Asiasta näkee usein laskelmia, mutta ne ovat kovin sekavia. Tarvittaisiin laskelma, joka huomioi koko prosessin: energian raaka-aineesta ajettuihin kilometreihin. Koska sellaista ei ole olemassa, päätin tehdä sen itse. Ohessa:

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Electric cars and energy efficiency

Electric cars are in the core of the Smart Grids. It has been said, that their energy efficiency is superior to the traditional cars. Is this the case?

Energy needed for 100 km drive with an electric car 300 kWh, while it is 1 MWh for a car with combustion engine.
Let us assume, that electricity is produced on coal-fired power plant. We have the following inefficiencies:



Thus, the efficiency of an electrical car is 25%.

We can do similar calculation for a traditional car with combustion engine:



The total efficiency of a traditional car is 12%, which is half the efficiency of an electrical car.

While the above figures may not be the most accurate, this gives an idea of the ballbark of electric car efficiency.

Electric car is twice as efficient as compared to car with combustion engine.