I dont think is about diesel or generators .
First and foremost they are the worlds industry hub , all the dirty industry that we offshored ended up there.
Second more important is the emission regulations, in the west coal power plants built anytime in past 30+years all have filltration to reduce emmisions many older chinese ones don't .
Folks have no idea about the magnitudes of difference between emissions from old vs new plants.
For example in 250+ coal fired powerplants in EU produce a fraction of the emissions of one single old powerplant in Ukraine. One fucking plant . Imagine having multiple such plants. China is full of these older gen plants without filtration.
Burshtynska TPP is the dirtiest power plant in Europe, Ukraine emits more toxic dust containing heavy metals than all EU countries,Turkey, and the Western Balkans combined.
Ukraine produces 72% of all emissions of fly ash, 27% of sulfur dioxide, and 16% of nitrogen oxides in all of Europe combined with Turkey.
Continental Europe emissions, Ukraine is like China. , note the emission share of tiny Balkan countries, which is down to old primitive coal plants not the number or power these plants generate