Do not keep the crematorium on 24/7. It uses 200W idle and 700W working. Create a switch or use a Power Logic system (or just micro-manage by drafting a pawn to switch it on when the corpse pile hits 10). Alternatively, install the crematorium inside your freezer. If it’s cold, bodies never rot, and you can cremate at your leisure without power waste.
Here’s a concise report on the most efficient ways to cremate corpses in RimWorld , based on game mechanics as of version 1.4/1.5. rimworld how to cremate corpses best