Environmental Engineering Reference
In-Depth Information
Table 4-. Scale Classifications of Wind Turbines
Scale
Rotor Diameter
Power Rating
Small
Less than 2 m
Less than 40 kW
Medium
2 to 45 m
40 to 999 kW
Large
46 m and larger
.0 MW and larger
early U.S. Federal Wind Energy Program (described in Chapter 3), but with some variation in
numbers.
Significant expansion of the wind turbine market and engineering experience has
occurred since the 980s, but the early wind turbines of this period were instrumental in pro-
viding data to refine the technology required for the following generations of HAWTs. Over
the next 5 years the commercial wind energy industry began scaling up small-scale ma-
chines to the 00- to 200-kW power range and more government programs began emphasiz-
ing long-term research applicable to all machine sizes. By the early 990s the commercial
sector produced machines with ratings of 300 kW and more. The average capacity rating of
wind turbines installed in California wind power stations almost quadrupled from 49 kW in
98 to 9 kW in 992. Over the same period, the maximum rating increased from 55 to
600 kW. The trend to produce larger machines is a result of at least four factors:
-
Wind turbine costs per rated kilowatt generally decrease as machine size increases.
-
Balance-of-station costs
per kilowatt (the price of the land and infrastructure) de-
crease as the turbine size increases (
e.g
. less wiring and land are required).
-
Many good wind sites comprise ridges that enable the production of more energy
per unit of land using larger wind turbines, because ridges frequently have only
enough space for a single line of wind turbines.
-
A segment of the O&M costs increases with the number of turbines, and therefore
decreases with increasing turbine size for a given wind power station rating.
Although wind turbines continue to be produced in each of the small, medium, and large
size categories, the distribution of turbine has shifted over time to the large sizes, as listed in
Table 4-2. It should be noted, however, that the total number of small machines sold is very
large and increasing.
Table 4-2.
Size Distribution of Turbines Deployed in the U.S from 998 to 2006
[AWEA 2006]
Rated power
range
998-99
,03 MW
,48
turbines
2000-0
,758 MW
,987
turbines
2002-03
2,25 MW
,784
turbines
2004-05
2,782 MW
,937
turbines
2006
2,454 MW
,523
turbines
0.00 to 0.5 MW
.3%
0.4%
0.5%
.9%
0.7%
0.5 to .0 MW
98.4%
73.9%
44.2%
7.6%
0.7%
.0 to .5 MW
0.0%
25.4%
42.8%
56.6%
54.2%
.5 to 2.0 MW
0.3%
0.4%
2.3%
23.9%
7.6%
2.0 to 2.5 MW
0.0%
0.0%
0.0%
0.%
6.3%
Over 3.0 MW
0.0%
0.0%
0.%
0.0%
0.5%
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