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The thermodynamics of electric vs. internal combustion cars
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this post was submitted on 03 Sep 2024
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The grid is still natural gas or coal mostly. And even solar enthusiasts don't charge their cars primarily in the day (we all charge our cars at night, when solar no longer is helping).
We shouldn't be tracking electricity -> motion per se. We need to be tracking natural gas -> electricity -> motion, which has a rather inefficient step.
Hybrids at 40% thermal efficiency, like Prius / Toyotas Atkinson engine, should lead to less overall burning of fossil fuels than a 40% coal plant making electricity -> 5% losses in wires -> 20% losses in the battery -> 10% losses in the electric motor.
Now combined cycle natural gas is 60% thermally efficient. And that's where EVs gets their biggest boost IMO. But not all Nat Gas is combined cycle, it differs strongly from location to location.
This varies from region to region. My region is primarily hydro, in fact, about 0.1% is non-renewable. So, depending on where you live, electricity may be more thermally efficient than ICE. Also, you're ignoring the pollution control aspect. Even if your hybrid is more thermally efficient, it will still generate more pollution than any electrical generation method except perhaps coal, and I'm not certain about that. Your car's ICE engine also won't benefit from any of the upgrades to the electrical grid, while your electric car will. This also may not matter in some regions, since some places like America in general, don't expect to see a reduction in coal use for a decade or more. And yes, I'm aware that the electricity generation mix in America varies a great deal from region to region.
ACEEE actually thinks that Prius Prime emits the least pollution for cars today, including EVs.
https://www.aceee.org/greener-cars
EVs universally weigh more, leading to more PM2.5 / micro plastics pollution from the brakes and tires. (Remember that Prius / Hybrids also have regenerative braking, so EVs cannot take Regen as an advantage).
Weight is key. Not only for pollution but also for efficiency. Prius / Prius Primes lighter weight allows for higher efficiencies.
Prius is on the list if you look it up and would be in the top 10. But I think ACEEE preferred encouraging people to buy the Prius Prime instead of something.
Yes, the Prius has a lot going for it. I personally would rather have a smaller EV instead, but that's not an easy thing to find right now, either.
Your grid is, perhaps. And I happily charge my EV from my installed solar most times when I need to charge.
You don't ever charge at night?
Occasionally, but I work from home and my wife's commute is fairly short, so we can often time the roughly once a week charging so it's during the day.
Here's a snapshot of the UK grid's energy mix this morning: https://www.energydashboard.co.uk/live
Gas is the largest single component, but gas plus coal together comprise only 42% of the energy mix. The rest is nuclear and renewables (though I quibble about biomass being counted as a renewable).
And if you look at the change of the energy mix over time, fossil fuel usage has been declining, though taking massive powerplants offline is not a quick process.
I appreciate the stats.
Its going to be difficult to dislodge combined cycle natural gas. Its very efficient, very cheap to spinup. Yes its still a fossil fuel, but its the best of fossil fuels. 60% efficiency means getting 50% more energy per CO2 (compared to 40% traditional plants). As far as I'm aware, natural gas is cheaper than most battery technologies.
Nuclear is good, and continues to be a major supplier at night (when people are likely charging cars). Natural gas drops by 5GW at night, so that's a good sign and the grid at night might be less carbon (even if there's less overall energy due to missing solar). So more nuclear energy into the mix might mean that night energy was better overall. Hmmmmmmm. Okay, I'll accept your point overall.
My solar panels charge my Powerwall during the day. My powerwall powers our house and charges our EV at night. When the panels are no longer generating anything.