I like critters like these for agitating biomass in a 15gal keg
You’ll need at least a 4" hole in the top of the vessel (keg?) to get it in there. I’ve got 6" in the top & 10" in the bottom. Getting the biomass out is still no fun.
I’ve got an air powered drill to run mine, although Ethanol at -40C is not super easy to set on fire with a dewalt**. If you’re going larger than 15 gal of solvent, you’ll want a longer reach, and two handles on your drill. Clamping the agitator down would probably be more appropriate.
I did fabricate a version that clamps to my kegs, and seals the vessel while stirring, but my CUP came in the door yesterday so I won’t be using it in this application again. Mixing freehand was also more effective imo, but required considerably more strength from the minions.
** the dewalts I’ve tried had over-heat protection. They’d work great for mixing, but they would get over-whelmed at about the 2min mark. I had a no-name cordless I picked up for $5 that did NOT have thermal protection. It would run considerably longer than the dewalts, but got hot enough that it likely would have worked as an ignition source if appropriately drenched.
Edit: I don’t recommend trying to fit a 10" tri-clamp ferrule to the bottom of a beer keg. it’s a hair too big. I had to notch the bottom rail, and that compromised the structural integrity, leading to warped mating surfaces on the 10" ferrules. They do fit on the TOP though, just…but that leaves no room for the 15PSI PRV I add. Most mods put the PRV on the tri-clamp lids, I prefer them directly on the keg, so the apparatus cannot be assembled without one.