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12. Saving Fossil Fuels:


              Fuel From Fermentation



      OBJECTIVES
      > To recall that microbes carry out fermentation reactions
      > To appreciate that fermentation products may be used as fuel rather than as food
      > To list examples of fuels generated by microbial fermentation reactions


     Fermentations  make  products  which  can  be  used
     as fuel. Biomass fuels use raw materials produced
     by photosynthesis. These materials are from plants
     and  can  therefore  be  regenerated.  Biomass  fuels
     include:
         solid  fuels  —  wood,  charcoal  and  vegetable

         waste
         liquid fuels — alcohol and vegetable oil
         gaseous  fuel  —  biogas  (a  methane/carbon
         dioxide mixture).
     The production of these biomass fuels is described
     in the diagrams on the right: this can help to reduce
     our use of fossil fuels, which are non-renewable.


















                                                               Sustainable forests

                                                               Using wood as fuel contributes to deforestation,
                                                               but:
                                                                   selective felling (only a small proportion of
                                                                   trees are cut down) is better than clear felling
                                                                   — less erosion and more wildlife habitats
                                                                   replanting can replace clear-felled trees, but
                                                                   tends  to  be  a  monoculture  and  is  a  poor
                                                                   wildlife habitat
                                                                   education  can  explain  the  benefits  of
                                                                   forests, particularly in terms of tourism. Local
                                                                   people can be introduced to alternative fuels

                                                                   (see biogas opposite).

              Learning Module Organisms and Their Environment | Class 11                                     38
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