The development of wind turbine technologies has allowed wind energy to perform a relevant
step forward in local production of clean electric power inside the built environment. The
present technical design relies exclusively on horizontal axis turbines and is not yet adequate
to develop reliable wind energy converters, particularly for conditions corresponding to low
wind speeds and/or urban areas. This has renewed interest in vertical axis wind turbines
(VAWT), like the Darrieus turbine, which appear to be particularly promising for such
conditions. These VAWTs can be used to power remote or off-grid applications such as
homes, farms, refuges, or beacons. Intermediate-sized wind power systems (100 kW to 250
kW) can power a village or a cluster of small enterprises and can be grid-connected or off-
grid. They can be coupled with diesel generators, batteries and other distributed energy
sources for remote use where there is no access to the grid. However, the disadvantages of
VAWTs stem from the fact that there is cyclical variation in the angle of attack on the
aerofoils as the rotor rotates. As a result, optimal loading cannot be sustained for all
azimuthal angles, leading to inherently low aerodynamic efficiency compared to horizontal
axis wind turbines (HAWT)[1]. The rotation of the turbine in a 3-D environment leads to