Environmental Engineering Reference
In-Depth Information
into deeper water, as indicated in Figure 2-10. They may include more
robust multi-pile substructures and foundations capable of resisting the
greater overturning forces in deeper water, construction and transport
strategies that maximize work at quayside, and new vessels for construc-
tion and installation that are capable of operating at greater depths. In
addition, deepwater floating systems are being developed for depths
greater than 50 m to 60 m (164 ft to 197 ft). These technologies will allow
expansion of the resource area for offshore wind and increase the poten-
tial for more benign siting.
Offshore wind turbines are produced mainly by a small number of
European turbine manufacturers, although there has been some very
recent activity by at least one Chinese original equipment manufacturer.
The New York State Energy Research and Development Authority
(NYSERDA) developed a table summarizing the commercial availability
of offshore wind turbine models, including the number installed as of
December 2009 (NYSERDA 2010). Table 2-1 updates this information to
December 2010 based on Musial and Ram (2010) and other available
data. Not all models have a 60-Hz version, which would be needed for
grid-connected projects in North America (European versions are 50 Hz).
Five offshore wind turbine models are available today for installation
in the United States: the Vestas V80, V90, and V112, and the Siemens
SWT-2.3 and SWT-3.6. Manufacturers that do not currently produce
60-Hz versions are likely to offer them once they are confident that a sus-
tainable U.S. offshore wind turbine market has been established. Siemens,
for example, has tentative plans to produce a 60-Hz version of its 3.6-MW
model in 2011.
OFFSHORE WIND ENERGY FOR THE UNITED STATES
Offshore Wind Energy in State Waters
Many of the first offshore wind energy projects that have been proposed
in the waters of the United States are small demonstration-sized wind
clusters (around 20 MW or less) located close to shore (usually within
3 nautical miles). These projects are generally supported by state govern-
ments. Some state projects are likely to precede larger-scale developments
in federal waters, and they may set the U.S. precedent for safe design,
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