Reducing the Energy Carbon Content - Energy and Climate: How to Achieve a Successful Energy Transition - page 75

energies, however, is that they are intermittent and diluted. On account
of being intermittent, their contribution can only be limited unless an
expensive storage system is installed.

Wind energy: an already mature energy

Wind power technology is already relativelymature, producing electricity
under almost profitable conditions. Current machines can develop powers
from 1.25 to 2.5MW. The rotors fitted on 2.5MWmachines have a span
of up to 80m [59].
Virtually all high-power wind turbines have a three-blade rotor, which
offers higher efficiency than two-blade rotors, without making construc-
tion of the wind turbine overcomplicated.
Wind energy is almost competitive, the cost price of the electricity
produced being in the region of 50/MWh. The main drawback with

wind energy lies in the fact that it is intermittent and cannot be modulated
to match demand. Intermittent operation must be compensated by the
grid, which limits the share of electricity that can be supplied by wind
energy.
In the future, the price of fossil fuels, together with constraints on CO 2
emissions, should make wind energy more competitive.
Recently, the development of wind energy, especially within the Euro-
pean Union, has been supported by a voluntary policy, imposing an
attractive buy-back price. The installed power has therefore increased
considerably over the last few years, especially within the European
Union.
The global figure reached 74GW in 2006 and 94MW in 2007. The
installed power in Germany reached 22GW in 2006. The two other
European leaders are Spain with 11.6GW and Denmark with 3.1GW
installed in 2006. In the USA, the installed capacity in 2006 was at the
same level as in Spain.
We can expect to see offshore projects developing in the future, despite
higher costs, to take advantage of stronger and more regular winds and
also to avoid the visual and sound nuisance associated with land-based
constructions. Denmark already has an offshore installed power of 400
MW. Germany is considering the installation of offshore sites which will
produce 10GW in 2015 and 20GW in 2020.
In addition towind energy production at sea, there is a revival of interest
in the possibility of using sea movements (currents, waves), a field which

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