Page 47 - e-Modul

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