this game is all about pollution, i would be the most obvious choice, to upgrade from Coal/Wood.
Peersonally i am not a big fan of pullution, so i almost instantly replaced all the steam engines to an extreemly large Solar Farm, with a ton of accumulators, sadly aliens came and wasted my entire complex, as i was afk for 30 minutes, to make some dinner

anyways thats just a question from me, as i find that to be a good idea.. i guess the reason there is no Diesel Power Generators yet, is becasue oil is a pretty new thing?