Wind Turbine Types

Utilising wind energy with various technologies and forms dates back many centuries. Historic evidences show, that windmills using wind energy grinding corn are already operating in Persia in the 7th century.

 

An obvious difference within the different types of windmills is the position of the axis. While in the early days windmills with vertical axis where constructed it changed to horizontal axis with modern wind turbines producing electricity.

Maybe the most visible sign of technical progress in wind energy is the number of rotor blades.

At the turn of the 19th century American windmill makers were producing 100,000 farm windmills each year, mostly for water-pumping. With increasing energy demands in the late 1930s and connection to public grid not given windmills for electricity became common on farms. All these windmills where equipped with multiple blade rotors.

Wind turbines of the newer generation are mostly (>90%) equipped with three blade rotor systems turning at 5 to 32 rpm.

A further criteria to differenciate wind turbines is the tip speed ratio.