Cellulosic Ethanol

This is a WWII-era plant originally built to produce ethanol as an input to a synthetic rubber process. The fermentation tanks are not unlike the wooden casks at a distillery, though the scale is a bit bigger. The waste liquor from the Kraft (wood pulping) process contains 2-3.5% sugar; just add yeast, wait a bit, and the sugar becomes alcohol.

These casks fed into a four story high still. After distillation, ether was used to remove the remaining water, resulting in anhydrous alcohol that was consumed elsewhere in the plant.

Sadly, there's a current fad (driven by distorting subsidies) for trying to fuel cars based on this same process.