Powering the Future: Biofuels
Activity: Yeast fermentation
• Describe the production of ethanol from renewable sources
• Describe the process of fermentation
• Carry out fermentation to produce ethanol
• Analyse the rate of fermentation of different sugars
• Evaluate the use and economic advantages of producing liquid
biofuels (gasohol) from sugar
Facts and Figures
• To help combat climate change the UK has a target to reduce carbon
emissions by 80% by 2050.
• 30% of the UK renewable energy could come from biomass heat and
electricity by 2020.
• To meet the European Renewable Energy Directive, the UK is aiming for
10% of transport energy to be from renewable sources by 2020.
• 18% of the sustainable renewable road transport fuel used in the UK
between April 2012 and April 2013 came from UK feedstocks.
© Rothamsted Research
Bioenergy is the energy derived from harvesting biomass such as
crops, trees or agricultural waste and using it to generate heat,
electricity or transport fuels.
© Thinkstock®
Sugar cane: Currently sugar cane (27%) is a significant source of sugar for bioethanol
production using current methods. Sugar cane is produced on a large scale in Brazil and
sugar beet is cultivated in the UK.
© National Collection of Yeast Cultures
Scanning Electron Microscope image of yeast: Researchers are developing novel yeast strains
and fermentation processes that optimise bioethanol production. Bioethanol is produced by
fermentation of simple monosaccharide and disaccharide sugars by yeast such as
Saccharomyces cerevisiae.
© University of Nottingham
To harness the potential of lignocellulosic (plant cell wall) materials, we need to optimise the
release of sugars from agricultural and wood-industry wastes to produce a fermentable
feedstock that microorganisms can use to produce fuels. Developing robust microbial
strains that can use these feedstocks will enable sustainable production of bioethanol.
Professor Katherine Smart
BSBEC LACE Programme
School of Biosciences
University of Nottingham
© National Collection of Yeast Cultures
Scanning Electron Microscope image of Yeast:The yeast Saccharomyces cerevisiae
produces ethanol by fermentation of sucrose or glucose but is unable to ferment
pentose (C5) sugars.
© National Collection of Yeast Cultures
Scanning Electron Microscope image of Yeast: Sugars from sugar cane can be fermented by
Saccharomyces cerevisiae without prior treatment as they are already disaccharides, but starch polymers
from maize or wheat need conversion to di- or monosaccharide sugars, by a hydrolysis reaction prior to
fermentation.
© Institute of Food Research
Food Waste: Scientists at the Institute of Food Research are investigating
how our waste problem can be turned into an energy solution.
© University of Dundee at SCRI
Plant Cell Walls: Woody plants, such as miscanthus and willow, convert much of the
carbon that they capture into lignocellulosic polymers, which are not a readily
fermentable form of carbohydrate.
© University of Dundee at SCRI
Plant Cell Walls: Feedstocks rich in lignocellulose require treatment with acids,
alkalis or steam explosion methods to hydrolyse hemicellulose and break
down lignin, enabling access to the cellulose by enzymes.
© Institute of Food Research
Steam explosion unit: We need to optimise the release of sugars from agricultural and woodindustry wastes to produce a fermentable feedstock that microorganisms can use to produce
fuels. Pretreatment of feedstocks with steam opens up the structures in plant cell walls to
enable access by cellulase enzymes.
Activity: Yeast fermentation
• Describe the production of ethanol from renewable sources
• Describe the process of fermentation
• Carry out fermentation to produce ethanol
• Analyse the rate of fermentation of different sugars
• Evaluate the use and economic advantages of producing liquid
biofuels (gasohol) from sugar
Contributors