UNESCO resource kit - science and technology educa...

Wood as fuel
Renewable but scarce
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sunlight
water
As a tree grows it stores energy from the Sun in the
wood of its trunk and its branches. Energy is stored
in the biomass of the tree. We can release this energy
by burning the wood. So wood is a fuel. As long as
there are trees growing more wood is being made. So
wood is a renewable fuel.
As the numbers of people increased, more wood was
needed, so people started to chop trees down. Once
this started to happen things went from bad to
worse: less wood was produced and even more trees
were cut down. People (usually women) may have
to spend several hours each day walking long
distances from their villages to collect the wood they
need for cooking their food.
1 "Wood is a renewable energy source".
(a) Explain what this means.
(b) Explain whywood is said to be renewable.
UNESCO Module 11: Wood as a fuel
About half of the 6 billion people in the world
depend on wood as a fuel for cooking their food.
Most of these people live in developing countries.
Until 20 or 30 years ago they collected dead wood or
cut off just a few branches so that trees stayed alive
to continue making new wood. As old trees died,
young seedlings grew up to take their place.
If there are more people to feed, more land is needed
to grow food. This often means that woodland has
to be cleared for agriculture. In Nepal, for example,
there were once large areas of forest and enough
wood for everyone. But clearing forests to grow food
means that there now isn't enough wood to go
round. Wood which was once free is now expensive
and poorer people can't afford to buy it.
2 In many parts of the world, wood is not being properly renewed.
(a) Why not?
(b) How does this affect people in those countries?
3 What do you think should be done to help solve the shortage of fire-wood?
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