Environmental Engineering Reference
In-Depth Information
Figure 2: A Chinese VAWT used for pumping brine (photo taken in early 20th
century) from King [4].
2.2.1 Savonius turbines
The need to pump water in rural/remote locations has long been a driver for the
development of wind turbines. In the early 20th century a number of innovations
were developed by inventors such as Savonius who patented his device in 1929 [6].
This utilised a rotor made from two half-cylinders held by a disc at each end of the
rotor shaft, as shown in Fig. 3. The Savonius turbine has been popular with both
professional and amateur wind turbine developers over the years, not least because
of its simple and robust construction.
Many variations of the Savonius rotor have been developed and tested. How-
ever, because of the inherently high solidity and hence high mass of the Savonius
turbine it has not been used for large-scale electricity production. Nevertheless, it
continues to fi nd favour in a number of areas of application, including building-
integrated wind energy systems which are now attracting attention as building
designers seek to reduce the ecological footprint of building structures and their
operations. Müller
et al.
[3], for example, explore the potential of VAWTs installed
on buildings. Figure 4 shows an example of this type of application where Savonius
turbines are mounted on the natural ventilation stacks of the landmark Council
House 2 (CH2) Building in Melbourne, Australia. The low tip speed of rotors such
as the Savonius has a number of attractions, not least that they are likely to produce
less aerodynamic noise, which is an important issue for turbines included as part
of inhabited structures. However, a number of considerable challenges remain to
be overcome before building-integrated wind turbines can provide a cost-effective
means of generating electricity. These include the fact that the urban environment
is characterised by low wind speeds and high turbulence.
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