Wind power density
Wind power density
Nowadays, a yardstick used to determine the best locations for wind
energy development is referred to as wind power density (WPD). It is a
calculation relating to the effective force of the wind at a particular
location, frequently expressed in terms of the elevation above ground
level over a period of time. It takes into account wind velocity and
mass. Color coded maps are prepared for a particular area are described
as, for example, "mean annual power density at 50 meters." The results
of the above calculation are included in an index developed by the
National Renewable Energy Lab and referred to as "NREL CLASS." The
larger the WPD calculation, the higher it is rated by class.[54] At the end of 2008, worldwide nameplate capacity of wind-powered generators was 120.8 gigawatts.[55] Although wind produces only about 1.5% of worldwide electricity use,[55] it is growing rapidly, having doubled in the three years between 2005
and 2008. In several countries it has achieved relatively high levels of
penetration, accounting for approximately 19% of electricity production
in Denmark, 10% in Spain and Portugal, and 7% in Germany and the Republic of Ireland in 2008. One study indicates that an entirely renewable energy supply
based on 70% wind is attainable at today's power prices by linking wind farms with an HVDC supergrid.
