UNESCO resource kit - science and technology educa...

UNesCOModule 4: Problems with fossil fuels - Teacher'sNotes,_~ ~ __ .
Page 2: The advantagesof using ethanol and bio-diesel are:
• they are renewable fuels;
• they don't add to the carbon dioxide in the atmosphere;
(they just keep on re-cycling the same carbon dioxide)
• they pollute the atmosphere less with other gases.
The main disadvantage of bio-fuels is their greater cost compared to fuels made
from crude oil.
This is the main reason that they are not more widely used. (Producing them
also requires a lot of agricultural land though this point isn't raised until the next
section of the module.)
The question about Brazil is_intended as a 'trailer' for the next section of the
module. Brazil is not a particularly wealth countryand its govemmentwanted to
reduce the cost of imported fuels the price of which increased greatly during the
second half of the 1970s.
Page 3: The ethanol debate. The information is given on the students' sheet in
four blocks and can be used in a number of different ways. Each student could,
for example, be given access to all four blocks of information and asked to use it,
individually, in small groups or in a whole class situation, to reach a considered
judgement:
• about whether the Brazilian policy was a good one and whether it should be
developed further;
• about whether another country, actual or fictitious, should adopt a similar
policy.
Alternatively, the above topics could be debated, within small groups or on a
whole class basis, with individual students each being provided with only one of
the four blocks of information and therefore having different points of view.
Notes
• The processes of fermentation and distillation are well-established topics on
most science curricula and have, therefore, not been included in this module.
Teachers may, however, wish to include them, as .student practicals or as
demonstrations, prior to embarking on the ethanol debate.
• Students could be asked to look at the labels on wine bottles to ascertain the
maximum alcohol (ethanol) concentration. Spirits have, of course been
distilled and drinks such as sherry and port have been fortified with distilled
spirit.
• Ethanol transfers far less energy than petrol when it bums per gram but very
nearly the same amount of energy per litre.
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