this post was submitted on 26 Dec 2023
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[–] u_tamtam@programming.dev 6 points 10 months ago (3 children)

Could you please run us through your maths? I'm legit curious.

[–] SaltySalamander@kbin.social 14 points 10 months ago (3 children)

An ICE is only, at most, 35% efficient. In contrast to lithium batteries and electric motors, which is more like 90% efficient. Electricity produced from the dirtiest coal plants that exist, used in an EV, is more efficient and, thus, more environmentally conscious, than burning gasoline in an ICE.

[–] labsin@sh.itjust.works 5 points 10 months ago (2 children)

Coal power plant efficiency is less than 40%. You'd also not get 90% of the outlet on the wheels. There is also a lot of loss on the grid, but there is also on the production of fuel. The two pollute almost the same.

Burning coal however is a lot worse for the air quality.

[–] RubberElectrons@lemmy.world 3 points 10 months ago* (last edited 10 months ago)

I'd like to prefix this all by pointing out that coal is absolutely terrible to use in several ways.

However: most thermal plants get about 45% efficiency, based on using very high steam temperatures. We all know that the theoretical max efficiency for a thermal process is limited by the Carnot cycle, which explicitly depends on the difference in temperature between the working fluid and the surroundings.

I'd also like to point out an important point: carbon plants are not constricted by the need to keep the engine lightweight, we can capture most fly ash and other process exhaust.

I again, do not care to bring such an arcane tech back online, it's terrible to mine, process and use. Just remember there's a bit more to all of this that engineers have indeed thought of.

E: https://www.sciencedirect.com/science/article/abs/pii/S0196890415007657

[–] Admetus@sopuli.xyz 3 points 10 months ago* (last edited 10 months ago)

It's the put the pollution somewhere else policy so that cities are more liveable. It was hurting China's reputation and too many rich Chinese were going overseas and siphoning away the economy (and still are).

[–] Xavienth@lemmygrad.ml 2 points 10 months ago (1 children)

The coal plants are not 100% efficient though. In fact they're probably in the realm of 40%

[–] u_tamtam@programming.dev 1 points 10 months ago

Yup, and that's ignoring the loss in transforming and transporting the energy across the grid, and in the chemistry of the battery itself through charges and discharges. Energy density of batteries is also a fraction of that of petrol, so every EV is also carrying around a lot of extra weight.

[–] tigerjerusalem@lemmy.world -1 points 10 months ago (1 children)

What about the billions of cells that must be produced and replaced as the scale grown unto millions and millions of cars? And all the mining of rare earth elements it requires?

[–] RubberElectrons@lemmy.world 3 points 10 months ago

It turns out that the lithium is very recyclable. The process of disassembly is what's tricky, but one of Tesla's pre-musk founders is working specifically on this problem.

We can already do it. Mining is (for now) cheaper. Something legislation, applied carefully, can resolve.

[–] zhunk@beehaw.org 4 points 10 months ago

I don't know if their statement is universally true, but the EPA's fuel economy / total emissions calculator seems to show it for what I've put in. You can put in a Prius or random EV and see how they compare.

https://www.epa.gov/greenvehicles/electric-vehicle-myths#Myth1

https://www.fueleconomy.gov/feg/Find.do?action=bt2

[–] lustyargonian@lemm.ee 1 points 10 months ago* (last edited 10 months ago)

My guess would be the efficiency of coal power plants (35%) and electricity transmission (90%) + battery charging of an EV (80%) would be more than efficiency of transporting oil in ships (50%) , then in an ICE truck (40%) to fuel pumps and then finally the efficiency of the ICE car (40%).

I picked the numbers from internet, but they seem plausible.