a) In the UK, first generation bioethanol is mostly produced from feed wheat. If
ID: 31701 • Letter: A
Question
a) In the UK, first generation bioethanol is mostly produced from feed wheat. If feed wheat is composed of approximately 80% starch, roughly how much feed wheat is needed to produce a tonne of ethanol? Explain how you arrived at your estimate.
b) Second generation bioethanol is produced from non-food lignocellulosic material such as wheat straw, which is composed roughly of 40% cellulose, 25% arabinoxylan and 35% lignin. How many tonnes of straw are needed to make 1 tonne of ethanol using conventional yeast fermentation? Explain how you arrived at your estimate.
Explanation / Answer
My answers is:
a) Starch is a polymer of glucose which can be fermented at 50% conversion to make ethanol, so need 2.5 tonnes of feed wheat to make 1 of ethanol
b) Yeast only ferments hexose sugars effectively, therefore only the cellulose is a substrate and will be converted at maximal efficiency of 50% into ethanol, thus, 20% yield is as good as it gets, therefore need 5 tonnes of straw for 1 tonne of ethanol
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.