Ethanol is a renewable energy source because it is produced through the

• A. distillation of crops
• B. fermentation of crops
• C. combustion of natural gas
• D. cracking of petroleum

Answer: (B)

Ethanol is renewable because it comes from plant material that can be grown again each season. The production path uses fermentation, where yeast converts sugars from crops (like corn or sugarcane) into ethanol, which is then purified by distillation. The key idea is that the feedstock—the crops—are renewable and capture solar energy as they grow. In contrast, using natural gas or cracking petroleum relies on finite fossil resources, not renewables. Distillation cleans up the ethanol but doesn’t on its own make the process renewable.