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Comment by danhak | Hacker News Reader

The typical internal combustion engine is only ~30% efficient, getting only ~10 kWh of energy out of that gallon.

Indeed. That does not, however, impact the actual energy available in a gallon of gasoline.

Technically the 6kWh of energy spent on refining (or any other work) is itself subject to inefficiencies in generation, transmission, etc. It would also suffer from inefficiencies in the electrical storage and motive portions of an electric vehicle as well. And at the end of the day even if there were perfect 100% conversion it would still only be 6kWh of energy available vs 33-34kWh.

I think the point is that the energy inputs required to produce a gallon of gasoline could approximately power an EV vehicle roughly the same distance that a typical ICE could go on a gallon of gasoline. A quick google search seems to back that up.

I'm not sure I'm seeing the same comparisons that you are regarding travel distances. A Tesla Model 3 uses 24-29 kWh/100 miles (depends on drive/battery options) which would be 4-5 gallons of gasoline. That would be 20-25MPG assuming the 10kWh/gallon ICE which is pretty low for a mid-sized sedan. An Accord hybrid pulls around 48MPG, while a Dodge Charger Hellcat SRT manages an EPA combined 23MPG (hardly a typical ICE given that it puts out 707 horsepower).

The average MPG in the US is around 25mpg[1]. So assuming that 6 kWh of electricity from the grid (big assumption, see below) is used to refine a gallon of gas, then it seems like the math pencils out. Of course the MPG average includes trucks and SUVS, etc, so not a perfect comparison but very much in the ballpark.

Regarding the 6kWh number, I have been having a lot of trouble confirming it. Some stuff I have read says that refineries are major consumers of grid electricity. Others claim that they can produce most of their energy needs from the oil distillates on-site. My best guess is that it probably depends on how old the refinery is, because it seems like the older reports/estimates tend to mention the electricity consumption, whereas the newer ones mention the 'on-site' energy generation/consumption. I think a lot of the energy demand of the refinery is used for heating, so burning the oil distillates would be way more efficient than using grid electricity for that. So, it may just be the case that older refineries are way less efficient than newer ones, and the 'EV vs ICE' comparison depends on how modern the refineries are in your area.

[1] https://www.reuters.com/article/us-autos-emissions/u-s-vehic...

The Model 3 gets 126 MPGe.

That is incorrect. You have to compare the 6kWh where it is used (at the refinery) and the 10kWh available on the vehicle. Both numbers already include the inefficiencies and therefore are comparable.

Which gives to a mere 4Wh of additional power extracted from gasoline.

A "mere 4kWh of additional power" is 67% additional power.

Pretty lousy for something that we consider a primary source of energy.

That's true, but it does ignore the waste heat, which in winter months is used to warm the passenger compartment. It's one thing EVs do have working against them, though it doesn't make up for the huge efficiency gain EVs have overall.

I know several coworkers who prefer to drive their EV in the winter because it heats up quicker (waiting ~5 minutes for the ICE to warm up the car vs. an active electric heater that starts right away)

Yes, but they're having to actively use battery power to do that, instead of just passively using waste heat from the ICE engine. So this greatly reduces their range. It probably works out fine for them because the car's maximum range is probably much greater than their commute distance, so they probably have battery capacity to spare and burning some of it on heat isn't a big deal as it gets recharged at home every night (and maybe also at work). If they had more "range anxiety", however, they probably wouldn't be so eager.

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