In going over the various stages of production, I made a point of noting how much each step limited the eventual power production, in EU/tick. Last time around I didn't pay enough attention to that, and overestimated the value of some fuel production lines.
Light Fuel's limiting factor is the Oilsand -> Crude Oil step. That's 10 liters / second. 1 L of Light Fuel costs 29 EU to process from Oilsand, so it's (256 - 29) * 10 / 20 = 113 EU / tick. Since the next limit is Crude Oil -> Sulfuric Light Fuel at 25 L /sec, adding another centrifuge without adding to the rest of the line doubles the production.
Cetane Diesel's steps limited by both fermentation and ammonia production time. Both limit production to 5.2 L Cetane Diesel / second. The Fermented Biomass -> Ammonia step is also very energy intensive, adding 30 EU per liter of Cetane Diesel produced. Total cost is 66 EU / L, so net is 446 EU / L, or 446 * 5.2 / 20 = 115 EU / tick. It's about the same production rate as Light Fuel, only you have to double 2 stages to double production, not just 1. Still, it's a net of 223,000 EU / oilsand block instead of 113,500 EU / oilsand.
I seem to remember Nitro Diesel production in 0.28 was much faster, working out to around 500 EU / tick or something. Once you have HV and can produce ammonia efficiently, you're only limited to oilsand centrifuge speed, and 2 centrifuges can give you 900+ EU / sec of Cetane Diesel.
Of course mining oilsand for fuel is a big PITA, so the real low-maintenance solution is an oil rig - same as it was in 0.28.