The role of innovation - Solar, Wind and Land: Conflicts in Renewable Energy Development - page 197

Deep offshore wind energy
Many of the most impactful technological advancements for renewable
energy over the next few decades are likely to involve “deep” offshore
wind energy. The European Wind Energy Association defines deep
offshore wind energy as the installation of wind turbines in waters
more than 50 meters in depth. 2 Deep offshore wind energy technologies
are nearly ready to hit the marketplace and have tremendous growth
potential. Roughly 70 percent of the earth is covered with water, 3 and
excellent wind energy resources are flowing above much of that vast
area. 4 Deep offshore wind energy technologies have the potential to
allow developers to site wind farms several miles further out at sea and
access an enormous set of wind energy resources that are less vulnerable
to many of the conflicts that complicate onshore wind farms.
Several characteristics of offshore wind energy make it a particularly
attractive energy source. Winds blow about 40 percent more often offshore
than onshore on average, 5 and there typically are no buildings, trees, or
mountains capable of altering or diminishing wind currents over water. 6
Consequently, a wind turbine of a given size and type can be as much as
50 percent more productive if sited over the ocean than if it is installed at a
good site on dry land. 7 Offshore turbines are also exposed to less turbulence
because of the relatively steady flow of wind over water, enabling them to
last longer and require less maintenance once installed. 8 And developers can
erect much larger turbines over the sea than would ever be commercially
viable onshore, where there are land-related constraints on turbine size. 9
As offshore wind energy technologies improve, the relative costs of this
type of development are decreasing and offshore wind is finally becoming
commercially viable in more parts of the world. For instance, dramatic
increases in offshore wind energy development are predicted for the North
Sea in the next decade, with the United Kingdom planning to install 32 GW
of offshore wind capacity in that sea between 2015 and 2025 alone. 10 After
several years of lagging behind Europe, it appears that North America is
finally poised to commence significant offshore wind energy development
on that continent as well. A major offshore wind energy project is in the
advanced planning stages of the shores of the Canadian province of British
Columbia, and multiple offshore wind farms are purportedly in the works
on both coasts of the United States. 11
Even Japan, which continues to aggressively pursue alternative energy
sources in the wake of the 2011 nuclear disaster at Fukishima, 12 is making
unprecedented investments in offshore wind energy. With more total miles
of coastline than the United States and one of the ten largest maritime
“exclusive economic zones” in the world, Japan has tremendous offshore
wind resources but has historically been limited in harnessing them
because so few of its offshore areas have shallow water depths amenable
to traditional anchored offshore turbines. 13 To overcome this water depth