this post was submitted on 26 Dec 2023
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It's worth noting that this is not being done for environmental reasons (more half of all coal pollution comes from China), but for strategic reasons as China has limited access to oil near it's borders.
An EV running on a coal fired grid still has less emissions that a prius. Facts dont care about your feelings.
Could you please run us through your maths? I'm legit curious.
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.
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.
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
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).
The coal plants are not 100% efficient though. In fact they're probably in the realm of 40%
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.
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?
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.