Fuel - most energy dense. Non renewable (sort-of).
Ethanol - renewable, but need a good supply of plant materials and catalyst.
Biofuel (MFR bio reactor) - Have not used this myself but others report it is awesome.
Creosote - byproduct of coke ovens. Need a lot to feed a max size HP boiler.
???
Fuel is probably your best bet. If I did my math right, creosote needs almost 50 ovens to power a max size boiler off of just the creosote from logs. Half that if you use coal. I've got about 15 right now, and I switch over to creosote oil whenever I fill my tank. (about 2000 buckets) It takes me over almost a day of running it before I run out. I plan on eventually going to 50 ovens, but I have to clear out a bit of room first.
I currently have 1 solid fuel boiler running off charcoal, and 1 liquid fuel boiler running off of plant balls (MFR harvester in shear leaves mode). I'm just using the vanilla oak along with an mfr fertilizer. I have 2 fermenters and 2 stills. I still have way more ethanol than I can use, and about 40k plant balls and about 80k oak logs. I don't have quite enough coke ovens to produce all the charcoal I need, but have a steam oven that kicks on any time I start running low. Once I build my 50 coke ovens, I will have 2 boilers running off charcoal, 1 on creosote oil and one on ethanol. All from 1 MFR tree farm planting a single sapling (to maximize leaves).
Ethanol - renewable, but need a good supply of plant materials and catalyst.
Biofuel (MFR bio reactor) - Have not used this myself but others report it is awesome.
Creosote - byproduct of coke ovens. Need a lot to feed a max size HP boiler.
???
Fuel is probably your best bet. If I did my math right, creosote needs almost 50 ovens to power a max size boiler off of just the creosote from logs. Half that if you use coal. I've got about 15 right now, and I switch over to creosote oil whenever I fill my tank. (about 2000 buckets) It takes me over almost a day of running it before I run out. I plan on eventually going to 50 ovens, but I have to clear out a bit of room first.
I currently have 1 solid fuel boiler running off charcoal, and 1 liquid fuel boiler running off of plant balls (MFR harvester in shear leaves mode). I'm just using the vanilla oak along with an mfr fertilizer. I have 2 fermenters and 2 stills. I still have way more ethanol than I can use, and about 40k plant balls and about 80k oak logs. I don't have quite enough coke ovens to produce all the charcoal I need, but have a steam oven that kicks on any time I start running low. Once I build my 50 coke ovens, I will have 2 boilers running off charcoal, 1 on creosote oil and one on ethanol. All from 1 MFR tree farm planting a single sapling (to maximize leaves).