Page 357 - Wind Energy Handbook

ROTOR DIAMETER 331

Table 6.1 Component Costs Expressed as a Percentage of Total Machine
Cost for a 1.5 MW, 60 metre diameter Wind Turbine on Land (from Fuglsang
and Thomsen (1998))
Component Cost as a percentage Component Cost as a percentage
of total of total
Blades 18.3% Controller 4.2%
Hub 2.5% Tower 17.5%
Main shaft 4.2% Brake system 1.7%
Gearbox 12.5% Foundation 4.2%
Generator 7.5% Assembly 2.1%
Nacelle 10.8% Transport 2.0%
Yaw system 4.2% Grid connection 8.3%
TOTAL 100%

the cost of all components apart from generator, controller and the grid connection,
for a machine of diameter D, is given by:

3 !
D
C 1 (D) ¼ 0:8C T (60) 0:9 þ 0:1 (6:2)
60

where C T (60) is the total cost of the baseline machine.
The rating of the generator and the grid connection is proportional only to the
diameter squared. It is assumed that Equation (6.1) applies to the cost of these
components, but with mass replaced by rating. Thus, if ì is taken as 0.9 once more,
the cost of the generator and grid connection are given by:
2 !
D
C 2 (D) ¼ 0:158C T (60) 0:9 þ 0:1 (6:3)
60

The controller cost is assumed to be fixed. Hence the resulting turbine cost as a
function of diameter is:
( ) ( ) !
D 3 D 2
C T (D) ¼ C T (60) 0:80:9 þ 0:1 þ 0:158 0:9 þ 0:1 þ 0:042
60 60
!
3 2
D D
¼ C T (60) 0:72 þ 0:1422 þ 0:1378 (6:4)
60 60

As the tower height, along with all other dimensions, is assumed to increase in
proportion to rotor diameter, the annual mean wind speed at hub height will
increase with rotor diameter because of wind shear. The energy yield should thus
be calculated taking this effect into account. The cost of energy (excluding operation
and maintenance costs) can then be calculated in A/kWh/annum by dividing the
turbine cost by the annual energy yield. The variation of energy cost with diameter,