Introduction - Wind Energy Meteorology: Atmospheric Physics for Wind Power Generation - page 4

were operated in Europe for the purpose of pumping water and producing flour in
the eighteenth and nineteenth century, an era ending however, with the advent of
steam engines and electricity. See Ackermann and Söder ( 2000 ) for further
historical notes.
The history of producing electrical energy from the wind is much shorter. The
Dane Poul la Cour (1846-1908) built the first wind turbine in Askov (Denmark) in
1891. The German engineer Betz described the aerodynamic theory of wind
turbines for the first time in 1926 (Betz 1926 ). Betz' factor (16/27) is still known
today as a limiting factor for the amount of the energy which can be extracted from
wind flow by a turbine.
But it is not before the last two decades of the twentieth century that wind
turbines have been erected in larger numbers and growing sizes. An early failed
attempt was the construction of the German 3 MW turbine ''Growian'' (große
Windenergieanlage) in 1983. It was a two-blade turbine with a rotor diameter of
100 m. It produced electricity for only 17 days due to a number of technical
problems and was removed in 1988. Development was then re-started beginning
with small turbines. This ''evolutionary'' approach was successful so that today
even larger turbines than Growian are standard, especially for offshore wind parks.
1.4 Potential of Wind Energy Generation
Wind energy is a renewable form of energy. It is available nearly all over the
world, though having considerable regional differences. Wind energy forms from
solar energy and is replenished by it continuously. Solar energy is practically
available without any limits. The transformation from solar energy into wind
energy does not involve the carbon cycle either, with the exception of the pro-
duction, transport, erection and maintenance of the turbines. Wind energy results
from horizontal air pressure differences which in turn are mainly due to latitudinal
differences in solar irradiation. In the natural planetary atmospheric energy cycle,
wind energy is mostly dissipated by friction occurring mainly at the Earth's sur-
face and is thus transformed into the last and lowest-ranking member of the
planetary energy chain: heat. Generation of electrical energy from the wind does
not really disturb this planetary energy cycle. It just introduces another near-
surface frictional force which partially produces higher-valued electrical energy
and only partially heat. When this electrical energy is used by mankind it is also
transformed into heat and the planetary energy cycle is closed again. As electrical
energy is practically used without any delay and the conservation law for energy is
not disturbed, the global planetary energy cycle seems to be undisturbed by energy
production from the wind. Therefore, wind power can be considered as a sus-
tainable form of renewable energy. But the entropy budget is affected as well.
Large-scale energy production from the wind increases the entropy in the Earth
system and could slow down atmospheric circulations. See Sect. 7.4 for further
discussions on the interaction between wind power generation and climate.