aerodynamics of wind turbines second edition pdf
In the mid 1950s Juul introduced what was later called the Danish concept by constructing the famous Gedser turbine, which had an upwind three-bladed, stall regulated rotor, connected
to an AC asynchronous generator running with almost constant speed. With the oil crisis in 1973, wind turbines suddenly became interesting again for many countries that wanted to be less dependent on oil imports; many national research programmes were initiated to investigate the possibilities of utilizing wind energy.
Large non-commercial prototypes were built to evaluate the economics of wind produced electricity and to measure the loads on big wind turbines. Since the oil crisis, commercial wind turbines have
gradually become an important industry with an annual turnover in the 1990s of more than a billion US dollars per year. Since then this figure has increased by approximately 20 per cent a year..
Why Use Wind Power?
As already mentioned, a country or region where energy production is based
on imported coal or oil will become more self-sufficient by using alternatives
such as wind power. Electricity produced from the wind produces no CO2
emissions and therefore does not contribute to the greenhouse effect. Wind
energy is relatively labour intensive and thus creates many jobs.
In remote areas or areas with a weak grid, wind energy can be used for charging
batteries or can be combined with a diesel engine to save fuel whenever wind
is available. Moreover, wind turbines can be used for the desalination of
water in coastal areas with little fresh water, for instance the Middle East. At
windy sites the price of electricity, measured in $/kWh, is competitive with
the production price from more conventional methods, for example coal fired