Environmental Engineering Reference
In-Depth Information
Energy alternatives
Faced with the major risks which have been mentioned concerning
energy supplies and climate change, it is essential to adopt more durable
solutions which do not suffer from the disadvantages of fossil energies
in terms of greenhouse gas emissions and depletion of resources.
The objective is therefore to reduce as quickly as possible the proportion
of fossil energies in the global primary energy supply, while supporting the
vital needs of the world population.
We must therefore look towards alternative energy sources, namely
nuclear and renewable. In principle, the renewable energy resources are
inexhaustible on a human scale.
With the future technologies, the nuclear sector will be capable of
producing energy for a very long period of time, despite the issue of
uranium availability for the nuclear power plants based on current
technology (see Chapter 6).
Presently, however, these alternative energies represent only a very
small fraction of the world
s total primary energy supply (less than 20%).
Moreover, this share is only growing very slowly.
The alternative solutions (nuclear and renewable) pose problems in
terms of technological maturity and economic profitability in the case of
massive development of the renewable energies and, as regards nuclear
energy, there is also the question of safety and social acceptability.
Until new technical breakthroughs allowing broader distribution of
these alternative solutions become available, we must implement all
possible means to make the transition without suffering a major crisis.
A long transition
It will take a long transition period to reverse the respective shares of fossil
and non-fossil energies, starting from the current system which is 80%
based on fossil energies.
Figure 4.1 illustrates the predicted trends in non-fossil energies for the
period 2000-2100. The general trend expected is an S-shaped curve,
changing slowly at first then accelerating up to a point of inflexion before
slowing down at the end of the transition.
To reverse the respective shares of fossil and non-fossil energies by the
end of the century, the point of inflexion must occur at 2050, with a share
of non-fossil energies of about 50%. Most analyses conducted for periods
up to 2050 predict a significantly lower share of the non-fossil energies,
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