Performance - Wind Energy: Renewable Energy and the Environment - page 153

TABLE 8.1
Specific Output, kWh/m 2 for Wind Turbines (Most, but Not All Manufacturers) in
California, 1989

Diameter Rated Capacity Per Turbine

Turbine m kW No. Units MW kWh kWh/m 2

Fayette 10 90 1,363 123 41,000 522

Bonus 65 15 65 644 42 113,000 640

Vestas 15 15 65 1,330 86 53,000 300

Micon 60 16 60 531 32 95,000 473

Nordtank 60 16 60 152 9 170,000 846

Micon 65 16 65 126 8 184,000 916

Nordtank 150 16 65 375 24 100,000 498

Vestas 17 17 100 1,071 107 145,000 639

U.S. Windpower 18 100 3,419 342 220,000 865

Micon 108 20 108 967 104 230,000 732

Bonus 120 20 120 316 38 276,000 879

Carter 250 21 250 24 6 250,000 722

Nordtank 150 21 150 164 25 240,000 693

Flowind 19 21 250 200 50 142,000 410

Danwin 23 23 160 151 24 390,000 939

Vestas 23 25 200 20 4 434,000 885

WEG MS2 25 250 20 5 560,000 1,141

Mitsubishi 25 250 360 90 486,000 991

DWT 400 a 35 400 35 14 1,000,000 1,040

a Estimated kilowatt-hour.

Average 756

In the 1990s, the older wind turbines, primarily in the range of 50-100 kW (55% of the MW capac-
ity installed), were being cannibalized for parts and uneconomic wind turbines were dismantled.
The following trends are noted: wind turbines became larger (now megawatts), capacity factors
were better, and reliability increased. Also, the drop in production in 1997 was due to older, smaller
units being taken out of production and then replaced with bigger turbines in 1998.
As the poor-performing units were taken out of service and newer wind turbines installed, spe-
ciic output ( Figure 8.4 ) increased. The larger specific output shows the type of performance that
can be expected with good wind turbines in an excellent wind regime. For both annual capacity
factor and specific output, for the same turbines, there will be annual variations by year due to dif-
ference in the yearly wind regime and between locations, as wind is site specific.

8.3.2 O THER W IND F ARMS IN THE U NITED S TATES
Wind farms generated an estimated 26.3 TWh in 2006, and some capacity factors were over 40% [6].
The capacity factor ( Figure 8.5 ) and specific output ( Figure 8.6 ) were analyzed for four wind farms
( Table 8.2 ) in the Southern High Plains, same wind turbine, but with smaller rotor diameter and
hub height for White Deer and part of Fluvana. Capacity factors ranged from 33% to 45%, and the
largest annual specific output was 1,350 kWh/m 2 . The yearly variation is the same across the region;
however, the slight downtrend in capacity factor at White Deer may be due to a decline in reliability.
Manufacturers are now offering wind turbines with different sized rotors for different wind regimes.
For Texas, estimated energy output would improve with an increase of the wind turbine rotor diam-
eter by 8%, rather than increasing hub height from 75 m to 100 m.