Energy - Wind Energy: Renewable Energy and the Environment - page 20

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6

4

2

0

0 1000 2000

Ye a r

FIGURE 2.2 World population, year 0 to 2005.

There are numerous historical examples of growth: population, 2-3%/year; gasoline con-
sumption, 3%/year; world production of oil, 5-7%/year; electrical consumption, 7%/year. Notice
that if we plotted the value per year for smaller rates of growth, the curve would be the same as
Figure 2.1 , only the time scale along the bottom would be different (Figure 2.2). The projection
of the growth of population in the future (Figure 2.3) assumes the growth rate will decrease to
0.5% in 2050. The United Nations projects a leveling off at 9 * 10 9 to 11 * 10 9 people by the
year 2200.
However, even with smaller rates of growth, the final result is still the same. When consumption
grows exponentially, enormous resources do not last very long. Order of magnitude calculations
make the analysis quite clear.

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1900 1950 2000 2050

Ye a r

FIGURE 2.3 World population, 1900 to 2050, with United Nations projections for 2010 to 2050, under median
variant.