Environmental Engineering Reference
In-Depth Information
Useful energy
is energy in its eventual form, such as light for illumination, warmth
for heating and power for machines and vehicles.
The different forms of energy are most frequently compared on a primary energy basis.
More than 90% of the original energy content is lost during the conversion of primary
energy to usable energy.
Figure 1.6 shows global primary energy needs per head. It is evident that the
Western industrialized states and countries with large supplies of crude oil have a
high rate of consumption. Prosperity and cheap energy prices boost consumption.
When it comes to the geographical pattern of consumption, the map clearly shows
that the countries with very high consumption - with the exception of Australia,
New Zealand and South Africa - are all in the Northern hemisphere. Germany and
France alone consume more than the entire African continent.
<25
%
150
% ... 200
%
200
% ... 300
%
300
% ... 400
%
>400
%
25
% ... 50
%
50
% ... 150
%
Figure 1.6
Primary energy usage per head related to the world average.
Countries with especially high energy consumption mostly use fossil energy sources
to satisfy their energy needs. On the other hand, countries with particularly low
energy needs rely to a large degree on traditional biomass. This includes fi rewood
and other conventional animal or plant products, such as dried animal dung. More
than two billion people worldwide use fi rewood and charcoal for cooking and
heating. In Africa south of the Sahara about 90% of the population is totally depend-
ent on fuels from traditional biomass.
