I've been struggling to find some hard numbers for sulphur dioxide emissions from UK electricity generation, accounting for our actual fuel mix. The numbers don't seem easily available but could be worked out from the known fuel mix and typical numbers for different generation types. Nor is it helpful that the office for national statistics lumps generation from pumped storage into an "oil and other fuels" category so it's hard to see how much, if any, heavy fuel oil is actually still burned (I suspect very little). If however we take a stab at it and say UK electricity SO2 is entirely dominated by the 5% of generation from coal, and that the coal used is 1% sulphur (the upper limit allowable in the UK for power generation), and that the scrubbers remove 90% which seems to be fairly typical for modern designs. One tonne of coal is about 24 GJ, at a typical 37% efficiency that's 8.9 GJ /2.47 MWh of electricity generated, with 10 kg of sulphur burned to 20 kg SO2, of which 90% is removed leaving 2 kg SO2.
My annual average in the Zoe is about 4 miles per kWh, so that tonne of coal and 2 kg SO2 would get me about 9900 miles. The UK grid is actually about 5% coal with the remainder largely negligible sulphur, so that 9900 miles would come closer to 100g SO2. If I drove that same distance in a diesel car at 50 mpg, that would be 900 litres / 765 kg of ultra low sulphur diesel. At 10 ppm sulphur (by weight?) that's about 15 grams of SO2. So, SO2 emissions for a diesel car burning 10ppm sulphur diesel *are* lower than for an EV charged from the UK grid, by a factor of around six (though please check my maths). That's not entirely surprising because modern diesel is very low sulphur, there is an open question as to what the public health implications are of a lesser amount being emitted on city streets versus a greater amount from a tall chimney.
I guess I should do the same calculation for nitrous oxides. Coal power station exhaust seems to be 1-5 ppm NOx which compares very favourably with 50-1000 ppm for diesel exhaust (I'm not sure why, perhaps the lower combustion pressure?) I am struggling to find a source for per-unit-energy numbers. I have seen a US paper claiming coal plants come in at 0.04 to 0.07 lb per million BTU, I guess that's BTU thermal not electrical. Can't see any numbers for natural gas (which will dominate UK electrical NOx emissions).
My suspicion is that piston engines generally and diesels in particular end up better than EVs on SO2 but much worse on NOx (and last time I did the calculation better but not hugely so on CO2). Just need to find some references for CCGT power station emissions to back that up.
Of course this was supposed to be the EV experiences thread where drivers discuss stuff related to EV use and ownership rather than the wider "EVs are good/bad/whatever" thread that we've already had so many of.