What is an advantage of the fermentation method for producing ethanol?

• A. Sugar is renewable and the process uses low energy
• B. It is fast and uses no labour
• C. It produces ethanol without separation
• D. It requires only a single batch

Answer: (A)

Fermentation uses sugars from plants as the feedstock and operates at relatively mild conditions, so it generally needs less energy than high-temperature chemical routes to make ethanol. Because plant sugars come from renewable crops such as sugar cane or corn, the feedstock can be replenished each season, making the process sustainable. Yeast converts these sugars to ethanol at moderate temperatures and ambient pressure, which keeps energy usage down compared with other synthesis methods. After fermentation, the ethanol must be separated from the liquid broth, but the energy cost of the fermentation step itself is still relatively low.

This is why this option is the best choice. It isn’t the fastest method and it does involve labour and processing steps; ethanol must indeed be separated, and fermentation often runs in batches or continuously rather than a single, instantaneous batch.