Environmental Engineering Reference
In-Depth Information
With wind farms deductions are made for factors such as mutual interference (farm
effi ciency), turbine breakdowns and downtimes (availability) as well as a provision
for other unanticipated losses. Various applications available online offer approxi-
mate calculations of turbine yield.
Professional planning departments use sophisticated computer programmes to
develop even more detailed calculations. However, the principle of the calculations
is always the same as that presented here. In addition to providing calculations on
yield, the object of planning is to provide calculations on wind farm optimization.
Different aspects are considered. Building higher towers and installing larger rotors
will increase the output of an installation. However, this will also increase costs
dramatically. The selection of a certain tower height and rotor size will ultimately
provide the optimum installation from an economic point of view. Furthermore,
losses caused by overshadowing can be minimized through minor changes in the
positioning of individual turbines.
■
http://www.volker-quaschning.de/software/
windertrag/index_e.html
Online output calculations for
wind power plants
■
http://www.windpower.org/en/tour/wres/pow
8.5 Economics
Very small wind generators can already be bought for a few hundred euros. A simple
60-watt wind generator for charging batteries costs about 500 euros. This price does
not include the mast and installation. At about 8 euros per watt the costs of wind
generators exceed even those of photovoltaic systems. Therefore, small wind
systems only make economic sense at very windy locations and only then when
electricity does not also have to be fed into a grid.
The costs per watt drop as the wind generator size increases. Around 900 euros per
kilowatt (O/kW), thus around 90 cents per watt, should be included in the calcula-
tions for a grid-connected wind turbine in the megawatt range. The cost of the
turbine, tower and installation is included in this price. The tower and the rotor
blades account for around half of the cost (Figure 8.17).
The ancillary investment costs for planning, development, foundations and grid
connections amount to about 30% of the wind turbine costs (Deutsches Windenergie-
Institut GmbH DEWI, 2002) and need to be added on to the price. Around 1200
euros per kilowatt should be estimated for a turnkey wind farm. The project costs
for a small farm with four turbines of 2.5 megawatts each will amount to 12 million
euros. Depending on the location and the technology, these costs can vary consider-
ably upwards or downwards. A fi gure of around 5% of the wind turbine costs should
be allocated for annual operation and maintenance.
Wind farms are usually built by operating companies. A group of private investors
extends about 20 to 30% of the cost of erecting the wind farm. The remaining
