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Comment by erelong | Hacker News Reader

not sure I understand the petrol car using 3x as much energy as an EV... wouldn't it make sense to convert gasoline to electricity then? I presume that must not be as efficient as other ways to convert fuel to gasoline? (I understand the math is there but... I'm temporarily failing to get it)

I think lists like these might be useful for energy audits and thinking about ways to make better use of energy

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70% of the energy in a petrol car is lost as heat. Only around 30% or less of the energy actually propels the car. I imagine that's why there's a big difference.

Gasoline engines are around 30-35% efficient, the rest is lost as heat. That goes for whether they’re spinning an alternator as part of an engine-generator set or just moving a vehicle.

You can’t get more than 35-40% efficiency so converting to electricity is a wash, you lose the energy to heat no matter what.

Also, the chart does not take into account how the electricity for the EV is generated, it would be just as inefficient as the gasoline car if the electricity was generated by burning hydrocarbons, but that detail is left out.

To get those types of numbers you would have to be charging from a grid that is nearly 100% coal. Real grids heavily favor EVs.

Yeah I probably should’ve mentioned that the more solar/wind/hydro you use to charge an EV, the more the efficiency goes up, thanks.

Yeah I'm not sure that EV number maths out. That's 18kw at 60mph for 10 minutes. It sounds really low to me. Going 45mph on a 110lb eMoto with 180lb rider takes ~6kw.

If everyone had their own turbine to generate electricity from gasoline then it would be. But from a central power plant there are transmission losses which cuts out a lot of the potential efficiency increase. The obvious upfront and maintenance cost of everybody owning a personal turbine though makes that method kind of iffy.

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