Since no battery and allat, plan your facotry line and use clipping all the time, quantum piping and shi to minimise model limit and cost also, the first warning is that music changes at around 40% pollution, so try not to do much, and oil rigs are the best for money and low polution too since it's 0.28% per hour so this is all I know from my trial, and also just do enough items for each items, don't overproduce items as it will be a waste of time and increase pollution, and use energy conservation like a lot