English: Flow chart showing the production of ethanol from plant material.

First Generation: -Starting Material is a fermentable sugar or a polysaccharide easily converted to one by the yeast.� -Much less effiecient in reducing GHG emissions. �-GMO strains or , exogenous enzymes can be used to increase productivity.�

Second Generation: -Much more abundant as waste e.g. rice husk, straw, chaff etc.�-Second Generation Pretreatments –cellulose, hemicellulose and lignin build up plant cell walls and need to be treated to break these components -The components are then separated physically – different stages to give the different components isolated. -Enzyme can act upon once broken and -Cellulose is made up of beta1,4 linked glucose – broken down by enzymes – cellulases �-Xylose is a major component of hemicellulose. The latter can be hydrolised, however a different biochemical pathway acts on xylose to give ethanol. Yeast, GMOs used immobilised exogenous enzyme could also be. �-Lignin cannot be fermented there is scientific focus on converting it to a fermentable sugar on industrial scale.

-The enzymes are not reactants. 1 molecule converts many molecules of substrate- see turn over number, conversion speed and conversion amount before poisoning