Environmental Engineering Reference
In-Depth Information
Figure 8.4
Small building integrated wind turbine. (Reproduced with permission of Windsave)
a good wind farm site. The cubic power law therefore indicates that the expected energy yield
per kW capacity from the small wind turbine in these circumstances would be approximately
one eighth of that from its large scale counterpart, and this ignores the substantial advantage
of the higher wind speeds at the hub height of the large machine. Additionally, in urban
locations wind turbulence is considerable due to the presence of buildings and trees and this
can affect energy capture and the life of the turbine. On the positive side, small wind turbines
if manufactured in, say, hundreds of thousands, can gain enormously from mass production
economies of scale and present costs may be more than halved. Government subsidies may
accelerate their adoption and their progress down the learning curve.
In general, however, because of long current payback periods, the market for such machines
is limited with the unfortunate side effect that the low costs that may result from mass pro-
duction are unachievable at present. There are in addition concerns about potential noise and
vibration problems, as well as the challenge of obtaining planning permission,
2
especially if
neighbours object to the installation, and as yet untested arrangements for selling any excess
energy fed to the grid. However, there will be some urban areas on hilltops and on coastal
locations where the wind speed is high enough, when taken together with escalating electricity
costs, to justify the investment in this technology.
Small wind turbines are already economically viable in remote locations not serviced by
the grid and for the provision of modest amounts of electricity to caravans and sailing boats.
This is an already established market, but one for which the costs of alternative electricity
supply is substantially higher than that supplied from the grid.
Enterprising architects have produced futuristic designs that incorporate wind turbines
within the building structure, frequently with a ducting effect to enhance the energy capture.
One such design is shown in Figure 8.5, where two 43-fl oor offi ce towers are connected by
2
Interestingly, the UK Government has been considering legislation that could remove the requirement for plan-
ning consent for suitable small turbines.
