The Bioreactor in SN2 burns Biofuel Blocks. You can craft Biofuel Blocks from three sources at the Processor: Crab Feces, Fibrous Pulp, and Pents. Picking the wrong source for your situation costs you 3-5× more farming time.
Pents (best raw efficiency): Pents are waxy bodies of sulfuric acid found around hydrothermal vents and Karakorum. They process 1:1 into Biofuel Block at the Processor — the highest single-item energy density of any Bioreactor source. Trade-off: respawn is slow, so they don't scale once your base demand grows.
Crab Feces (best passive farm): If you have a Coral Crab habitat within a 100m radius of your base, you have a Crab Feces farm. Crabs drop feces continuously in their territory. The Processor converts them 1:1 into Biofuel Blocks. Trade-off: you need to not kill the crabs, which means routing around them whenever you collect.
Fibrous Pulp (best volume, lowest energy): Fibrous Pulp is harvested from various reef plants. It converts at the Processor into Biofuel Block, but each Pulp gives the lowest energy of the three sources. Use Fibrous Pulp only when you have a temporary spike in demand and want immediate power, not for steady-state base load.
The single biggest error we see is players building only a Bioreactor for their main base power. The Bioreactor is excellent as a power buffer — never as your only generator. Once you have Copper Wire and a Power Cell, you should be running:
