Frequently asked questions

• Practical questions about enzymatic deinking.
• General comments about cellulase and xylanase assays.
• Information on carbon dioxide emissions
• Extensive information on carbon dioxide emissions at The Common Purpose carbon dioxide emissions website
• Literature on biomass energy conversion available from the Biomass Energy Foundation e-mail Catalogue
• Many articles on wood can be found at the Forest Products Laboratory Homepage
• Selected publications on bioconversion available by e-mail.
  

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• Questions about biomass:
  

  Could you give us a brief explanation of exactly how biomass works?

  Green plants use photosynthesis to trap carbon dioxide using the energy from light. This generates biomass. The chemical energy trapped by photosynthesis is stored in sugars. This can be stored as fruit sugars (fructose) which is found in peaches, grapes and berries, or as sucrose (a disaccharide found in such things as sugar beet and sugar cane), starch or lignocellulose. Starch is a storage polymer made out of alpha-(1, 4) linked glucose units. It is found mostly in grains. Cellulose is a structural polymer made out of beta-(1, 4) linked glucose units. Hemicellulose is a structural polymer made out of xylan, glucose, mannan and other components. Lignin is a polymer made up of phenyl propane units. Lignin is more nearly an aromatic material, but it has many side chains and cross linkages. The percentages of cellulose, lignin and hemicellulose vary from one plant to another, but they mostly differ between major taxonomic groups such as hardwoods (angiosperms) and softwoods (gymnosperms). Angiosperms tend to have less lignin and more hemicellulose than gymnosperms. Most agricultural residues are angiosperms.
  

  What materials can be used?

  Starchy materials found in grains are easiest to use. Because starch is an energy storage polymer for the plant, it is biochemically designed to come apart easier than cellulose or hemicellulose. Also the glucose in starch is easier to ferment than the hemicellulosic sugars.