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We have been using wind energy since the days of sail some 3500 years BC acording to Mainstream history.
The first vertical axis machines were European and date back to the 12th century as far as we know.
They were post mills, used by farmers as water rights were only available to nobility.
The first patents were granted for Verticlal Axis Wind Turbines or VAWT systems in 1927 in Europe
Wind energy is created by the difference in energy that the poles and the equator receive from the sun, as well as the convection effect created by the temperature difference between water and land masses.
The USA is aiming at 20% of total energy requirements comming from wind energy by 2030. The EU has similar targets, with Denmark, Germany and the UK leading the field. China is ernestly entering the space as are numerious other countries and regions.
It is estimated that Globally there is sufficient wind resources to supply 72 Terawatts of energy, and South Africa can generate 32Gwh's of wind energy every year.
Governmental historical data for average wind speeds is available. Average wind speed is only one factor to consider. A great deal of power is generated by higher wind speed, much of the energy comes in short bursts. Half of the energy available arrives in just 15% of a given time period.
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The current norm is Horizontal Axis Wind Turbines or HAWT and Only Recently has VAWT become available for Utility scale applications.
What Are The Physics Of Wind Energy Generation?
The evolution of wind power technology and market development has been influenced by three physical relationships.
Wind Speed: If wind velocity doubles, wind turbine's power output increases eight-fold. Winds at 80 meters are marginally stronger and -- more importantly -- steadier than those closer to the ground. The rule of thumb has been -- the higher the turbine, the better.
Swept Area: Power output varies with the area on turbine blades (or the air foil) while a the blades or airfoil rotate. Doubling a turbine blade’s swept area will quadruple its power output. Traditionally, this has meant ever larger wind turbine blades.
Air Density: Finally, power output increases directly with air density. Density is typically higher in winter months and at low altitudes, and lower in summer months and at high altitudes. Winds near a chilly Lake Erie, for example, contain more exploitable energy than those of the hot, high-altitude deserts of the American Southwest
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Savonius
Wind tunnel spectrograph image
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Algae Production Performance, comparison graph
