Offshore Wind Technology and Status - Structural Integrity of Offshore Wind Turbines - page 14

300
280
260
240
220
200
180

250 m
20,000 kW

Future wind
turbines

150 m
10,000 kW

125 m
5,000 kW

100 m
3,000 kW

160
140
120
100
80
60
40
20

Rotor Diameter (m)
Rating (kW)

80 m
1,800 kW

70 m
1,500 kW

50 m
750 kW

30 m
300 kW

17 m
75 kW

0

1980-
1990

1990-
1995

1995-
2000

2000-
2005

2005-
2010

2010-? 2010-? Future Future

FIGURE 2-1 Wind turbine growth over time: modern wind turbine rotors
exceed 400 ft in diameter, or almost twice the wingspan of a Boeing 747.
(S OURCE : National Renewable Energy Laboratory.)

Why Go Offshore?

Renewable sources for electricity generation, such as wind and solar
energy, can be exploited only where these resources are available in suf-
ficient quantities—windy areas for wind, and so on. As demand increases
for electricity generated from wind energy, additional sites with suffi-
cient wind resources must be identified.
In the United States, land-based wind resources are abundant but are
concentrated in the center of the country. Adding wind-energy capacity
in these locations to service distant markets with lower wind resources is
feasible but may be limited by insufficient electricity transmission access
and capacity and by the cost of adding to this capacity. Moreover, the
densely populated coastal energy markets do not have good sites for
onshore wind, and given the lack of available land, siting new facilities in
such areas can be difficult.
Offshore wind does not suffer from these drawbacks and has the
advantage that offshore winds are stronger and steadier than those on
land, allowing higher power output. Of the contiguous 48 states, 28 have
a coastal boundary, so that transmission requirements from offshore wind
to load centers in these areas can be minimized (Musial and Ram 2010).
U.S. electricity use data show that these same states use 78 percent of the
nation's electricity (USDOE 2008). Coastal regions pay more for electric-