Where will offshore wind farms be built?
Currently, there are two projects along the East Coast of the
United States that are vying to be America's first offshore wind
farm. One is in Nantucket Sound, off the southern coast of Cape Cod
and the other is off the southern coast of Long Island. There is
great potential for wind power in many places along the East Coast
from Maine to Georgia.
How far out to sea will they be? And how deep?
In the near future offshore wind turbines will generally be
built in water less than 100 feet deep. This determines how far off
the coast that they are likely to be sited. In some parts of the
country this could be much further out than in others.
For example, the Cape Cod wind project will be between six -
nine miles from the shore and the closest area of the Long Island
wind farm will be a little less than four miles out to sea. The
sites being studied in Georgia, however, are 10 to 20 miles
offshore.
Another factor is the cost of getting the electricity to shore
and the practicality and cost of building and maintaining turbines
further out to sea. For example, the cables needed to plug the
electricity into the grid onshore become longer and more expensive
the further offshore the wind farm is located.
Nevertheless there are advantages further offshore. Wind speeds
tend to be higher and the wind is steadier. This means that
turbines built further offshore should capture more energy. As a
result many hope that the challenges will be overcome and that in
the future offshore wind farms will be built much further offshore,
perhaps even on floating platforms.
Will they interfere with shipping?
Wind turbines at sea will be spaced between about 1,500-3,000
feet apart so the physical barriers for all but the largest vessels
will be minimal. Nonetheless at certain sites developers may want
to restrict navigation within the site for safety reasons.
Any restriction of shipping would be done in accordance with
domestic and international laws. Developers expend significant
effort and financial resource on ship surveys to ensure that wind
farms are sited where the will have minimum impact on recognized
shipping lanes as well as on pleasure boats.
Will they interfere with fishing?
Given the relatively small area of sea-bed that is required
there is no evidence to suggest that total fish catch will decline
as a result of wind farm developments; if anything the opposite is
more likely to be the case.
Offshore wind terminals can serve as artificial reefs, creating
new habitat and attracting fish and invertebrates. In many cases,
introducing hard substrate and geometric complexity in otherwise
sandy, uniform habitat can lead to increased biomass at the site.
Wind farms can also provide a localized refuge from intensive
fisheries activity, potentially allowing fish stocks to rebuild and
seed adjacent areas. In addition, as wind farms move further
offshore the fishing grounds occupied by the farm will occupy a
smaller portion of the total fishing area available to the larger
deep water fisheries vessels that could theoretically fish in
them.
In any event the wind industry in Europe is working actively
with the fishing industry to ensure that fishing is not
disadvantaged by the growth of offshore wind farms. Several
offshore wind farm developers have also developed good
relationships with local fishermen, and have employed them to help
with the surveying of sites and the preparation of work for wind
farm installation.
How big will they look from the shore?
It obviously depends on how close the turbines are to the shore,
and on weather conditions. Most offshore wind farms are barely
visible from shore. But visibility may even be a benefit as
communities in Europe with offshore wind proposals near them, such
as the Norfolk/Suffolk regions of Great Britain, are now planning
tourism around the expected desire of people to see and visit the
farms.
What if there's a storm at sea?
As with onshore turbines, offshore turbines are built to
withstand extreme wind and weather conditions. In the event of
severe weather, the blades turn out of the wind and will slow down
for safety reasons when wind speeds become gale strength (i.e. 50
miles per hour and above.)
Will they disturb the seabed and cause coastal erosion?
Any proposal will undergo extensive biological and geological
reviews prior to construction as part of the required Environmental
Impact Statement process. In addition, some offshore projects have
been given consent to go ahead on the condition that they also
monitor the effects on coastal processes during and after
construction.
However, the turbine structures and distance offshore are such
that it is very unlikely they would affect the sea bed or wave
patterns - indeed there is no evidence from the Danish experience
of offshore wind farms of any detrimental effects on coastal
processes.
The coastal erosion effects of higher sea levels and more
extreme weather patterns due to global warming are already
scientifically recognized, and these far outweigh the potential
effects of offshore wind farms.
Will they affect marine life?
There are three significant stages of a wind farm from the point
of view of marine life: construction, operation and
decommissioning. Construction and decommissioning have the
potential to generate the most amount of disturbance, and the wind
industry, as well as several marine conservation groups, is
currently investigating these impacts on marine life.
However it is important that such impacts are considered in the
context of all the other marine activities such as global warming,
fishing, shipping, oil and gas, etc. In addition, it is also of
note that the duration of the construction and decommissioning will
only be about six months. For the 20-year operational period there
are no known impacts on marine life. Nonetheless the industry is
actively investigating potential effects. Efforts will be taken to
minimize the impacts on marine animals prior to and during
construction; the area of tower placement will be subjected to
harmless sonic "pings" to clear the area before installation begins
along with other mitigation efforts.
It has been suggested that the noise from the turbines travels
underwater and would disturb sea life. But studies carried out on
the impact of noise from existing offshore turbines note that the
noise is very low frequency, and many species are actually unable
to hear it.
As with any other local impact issues these concerns must and
would be addressed by the project Environmental Impact
Statement.
Will the wind turbines use oil?
The wind farms will use a small amount of mineral oil in the
project's transformer. This is more like the oil you use around
your house than it is the oil you put in your car. In the example
of the Cape Cod project, the oil will be stationary, there won't be
ships coming and going to replace it and it will be triple
protected against spill.