Any of the bees that make phosphorous is the core of a maintenance-free setup.
Alveary with Infernal branch (ex. Demonic) queen/princess/drones --> Simmering Comb
Centrifuge simmering comb --> phosphorous
Igneous Extruder --> cobblestone
Pulviverizer cobblestone --> sand
Squeezer w/phosphorous and sand --> lava
You can then put lava into Magmatic Engine or whatever kind of engine you want.
The Refined bee is also an excellent infinite energy source. It produces combs that centrifuge to oil and fuel.
Personally, I'm a fan of (bred) trees for high-quality saplings for ethanol. It's one of the longest and most complicated infinite-loop setups, assuming you make *everything* (dirt, fertilizer) renewable. Need:
- 1x farm for saplings
- 1x farm for fruit
- source of dirt (preferred source is a peat farm)
- MFR sewer and composter for fertilizer or, if no MFR, need ash from Peat Engines or bees
- Squeezer
- Fermenter
- Still
- Engines or boiler to burn Ethanol
Takes a while to get all that setup, especially if you take the time to breed a good sapling tree and a good fruit tree.