What is a major disadvantage of the fermentation method for producing ethanol?

What is a major disadvantage of the fermentation method for producing ethanol?

• A. It is slow, requires land to grow sugar, ethanol needs further separation, is batchy and less controlled, and requires more workers
• B. It is instant and fully automated
• C. It never requires any separation
• D. It uses non-renewable feedstocks

Answer: (A)

The method uses a biological process where yeast converts sugars into ethanol and carbon dioxide. The major drawback is that fermentation is slow and the ethanol produced is in a dilute solution. Yeast can tolerate only a relatively low percentage of alcohol, so the liquid must be heavily processed to separate the ethanol from water, usually by energy-intensive distillation. Since the process is typically run in batch steps rather than continuously, production isn’t steady and requires more handling and supervision. Growing enough sugar crops to supply the feedstock also demands substantial land, and farming adds to labour needs. All these factors together explain why fermentation has significant drawbacks for large-scale ethanol production. In contrast, the other statements don’t fit: fermentation isn’t instant and fully automated; separation is necessary; and the feedstocks for fermentation are renewable, not non-renewable.

The method uses a biological process where yeast converts sugars into ethanol and carbon dioxide. The major drawback is that fermentation is slow and the ethanol produced is in a dilute solution. Yeast can tolerate only a relatively low percentage of alcohol, so the liquid must be heavily processed to separate the ethanol from water, usually by energy-intensive distillation. Since the process is typically run in batch steps rather than continuously, production isn’t steady and requires more handling and supervision. Growing enough sugar crops to supply the feedstock also demands substantial land, and farming adds to labour needs. All these factors together explain why fermentation has significant drawbacks for large-scale ethanol production. In contrast, the other statements don’t fit: fermentation isn’t instant and fully automated; separation is necessary; and the feedstocks for fermentation are renewable, not non-renewable.