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Re:How green is blue hydrogen? by diarrhea on Friday August 13, 2021 @05:34AM (#28167055)
You're comparing apples and oranges. The around 40% efficiency modern ICEs have is thermal. The 90%+ going from battery to electric motor is not thermal. You're just converting high-exergy to high-exergy (kinetic) at that point. The interesting, potentially low-efficiency part happens before the battery, before charging it in the first place. Where does the electricity for that come from, at what efficiency? Perhaps there's a thermal engine involved, at said 40% thermal efficiency. Then you're at 0.4*0.9 total, and the EV looks pretty dull suddenly. (Just an extreme counter-example)

Your comparison reminds me of advertising for electric water kettles. 95%!! 97%!! Wow!! ... or not, because you're converting pure exergy (highest quality energy) in the form of electricity to heat. You're dissipating it (heat), using a resistor. That's child play and the efficiency is meaningless. The other way around is the interesting part.

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