Offshore Wind Questions

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What does an offshore wind turbine look like?

Why offshore over onshore wind energy?

Does the Federal government subsidize offshore wind?

How much offshore wind capacity exists in North America?

How much wind capacity exists in the world?

Which US State contains the most onshore wind potential?

What factors must be taken into account before constructing a wind turbine?

What are the costs of offshore wind?

Do wind turbines hurt bird life?

What are the aesthetic impacts of wind turbines?

What defines federal vs state waters in the US?

Which companies make offshore wind turbines?

What does an offshore wind turbine look like?

A detailed offshore wind turbine diagram


A detailed explanation of offshore wind turbine foundations


Images of offshore wind project construction
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Why offshore over onshore wind energy?

A trend in Europe has been to move wind turbines offshore because of higher wind speeds, smoother, less turbulent air flows, larger amounts of open space and the ability to build larger turbines that are more cost effective in the ocean, offshore. The wind offshore tends to flow at higher speeds, thus allowing turbines to produce more electricity.

The potential energy produced from the wind is directly proportional to the cube of the wind speed, meaning a few mile an hour increase in wind speed would produce a significantly larger amount of electricity. For instance, a turbine at a site with an average wind speed of 16 mph would produce 50% more electricity than at a site with the exact same turbine with average wind speeds of 14 mph. The power of the wind is significantly less on land: “The wind is slowed dramatically by friction as it brushes the ground and vegetation, it may not feel very windy at ground level. Yet the power in the wind may be five times greater at the height of a 40-story building (the height of the blade tip on a large, modern wind turbine) than the breeze on your face.” Lager turbines are more economically feasible.

For instance if wind averaged 18 mph, in February of 2005, a 3 MW wind turbine would deliver electricity at a cost of $.059 per kWh while a 5 MW turbine would deliver electricity at $.036 per kWh, or 40% cheaper electricity. Offshore wind can be significantly more marketable.
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Does the Federal government subsidize offshore wind?

The U.S. Government provides an incentive program called the Federal Production Tax Credit (PTC). This program allows a tax break for wind energy at a rate of 2.2 cents per kilowatt hour produced (PTC is adjusted from time to time). The PCT has been through a “boom and bust” cycle in which Congress lets the PTC expire before renewing the program. The expiration of the PTC hurts the wind energy market; giving developers mixed signals as to whether they can plan to receive a tax credit when performing economic modeling for their wind projects.
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How much offshore wind capacity exists in North America?

According to a study conducted in part by the US Department of Energy about 900 GW exist off the coasts of the US.

US Offshore Potential Breakdown:

GW by Depth (m)
Region 0-30 30-60 60-900 >900
New England 10.3 43.5 130.6 0.0
Mid-Atlantic 64.3 126.2 45.3 30.0
Great Lakes 15.5 11.6 193.6 0.0
California 0.0 0.3 47.8 168.0
Pacific Northwest 0.0 1.6 100.4 68.2
Total 90.1 183.2 517.7 266.2

Source: US DOE, NREL

California Selected Site Breakdown:

Nameplate capacity of turbines (MW) in each geographical
area, depth, and wind speed cutoff, assuming a 33% exclusionary
factor for each area.
Turbine Nameplate Capacity (MW)
Ocean Depth 80 m Avg. Wind Speed Northern Calif. SF Bay Area Southern Calif. Total
0-20m >=7.0 m/s 3,052 8 309 3,369
>=7.0 m/s 746 0 0 746
20-50m >=7.0 m/s 8,139 362 580 9,081
>=7.0 m/s 2,713 0 0 2,713
50-200m >=7.0 m/s 66,325 31,802 4,846 102,973
>=7.0 m/s 14,771 6,210 0 20, 980

Source: California Offshore Wind Energy Potential, Stanford University pp. 8

SouthWest Breakdown:

State Total Potential Capacity (MW) Projected Feasible Capacity (MW)
AL
FL 40,300 612
GA 71,412 17,180
LA
MS
NC 140,097 73,789
SC 149,768 43,360
VA 92,410 44,450

No studies have identified significant offshore wind resources for Alabama, Louisiana or Mississippi.

Source: Southern Solutions for a National Renewable Energy Standard

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How much wind capacity exists in the world?

The U.S. Department of Energy states that the world’s winds could provide 5,800 quadrillion BTUs (quads) of energy each year. This number is over 15 times the worlds current energy demand. (1 quad= 172 million barrels of oil).
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Which US State contains the most onshore wind potential?

North Dakota. This state has a potential to produce 1,210 billion KWH per year. If the transmission capacity existed, this state could produce almost a quarter of the electricity needed in the U.S. through utilizing its wind resources.
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What factors must be taken into account before constructing a wind turbine?

*Wind Speed

*Wildlife and habitat considerations

*Proximity to the power grid-the
closer the hookup the better. Does
the grid have sufficient capacity to
accept the turbine in this location?

*Sites that can hold bigger and more
turbines are preferable since the
cost per turbine is less and the
power production is greater

*Is the location remote? Wind
turbines can be a cheaper
alternative to diesel generators in
remote locations that have no
hookups to a power grid.

*Is the site near an airport? or, if the wind turbines are offshore,
they may present a navigational hazard.

*Accessibility-How easy is it to
transport the turbine to the location
as well as perform regular
maintenance checks (O&M)?

*How great of a shadow, visual and/or auditory
impact will the turbine have on a
landscape or structure in the area?

*Is the surrounding community in
favor of a wind project?

*Soil conditions-Can the soil support
a wind turbine?

For more information on the environmental impact of offshore wind turbines, click here

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What are the costs of offshore wind?

Cost is currently a major inhibitor of offshore wind energy development. Land based projects cost significantly less and since their potential in North America is still strong, developers are currently focusing most of their efforts on onshore wind projects. Several offshore projects have signaled cost concerns including LIPA, Georgia Tech, and Gulf wind.

According to a presentation by Exeter Associates Inc, offshore wind costs between $1.95 million/MW to $2.86 million/ MW and generating costs range from $80/MWh to $150/MWh (Source: Kevin Porter- Introduction to Windpower) Developers in North America have released project costs which are much higher. BlueWater Wind estimates that its 450 MW project off the coast of Delaware would cost approx. $3.5 million/MW while FPL Energy’s 144 MW project with LIPA is estimated to cost approx. $5.6 million/MW.

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Do wind turbines hurt bird life?

While each site is its own unique habitat to birds, studies examining offshore wind sites in Denmark show that wind turbines have little effect of birds. Denmark’s National Environmental Research Institute conducted a two year study of bird life impacts from the Danish 80 turbine project Horns Rev. The study finds that “The low number of seabirds and waterfowl recorded inside the wind farm by migrating birds recorded by radar, indicate that most bird species generally exhibit an avoidance reaction to wind turbines, which reduces the probability of collision.”

Projects in the United States, like those Europe, take the impact on bird life into account as part of the permitting process. Cape Wind contends that bird life has been carefully studied and that cameras and radar from projects in Europe show birds flying around wind turbines instead of into them.  The company also suggest that turbines have been constructed with bird safety in mind, that the blades move slower and the tower is more inhospitable for birds to land on. Cape wind has spent over $400,000 on avian research.  The company has hired experts to observe bird life in the sound and uses a radar system on Cape Poge to measure every bird from sea level to about 8,500 feet which records 23 attributes about each bird in order to better understand the patterns of migration in the area. Chris Miller, a climate and energy campaigner for Greenpeace International, states that average wind turbine presents less of a threat than cars, buildings and cats do to bird life. Not all environmental groups agree that turbines have little effect on bird life.

“Danish experience from the past 15 years shows that offshore wind farms, if placed right, can be engineered and operated without significant damage to the marine environment and vulnerable species. ” See a 2006 study published on the impacts of danish offshore wind projects click here

“Bird kills have caused serious scientific concern at only one location in the United States: Altamont Pass in California, one of the first areas in the country to experience significant wind development. Over the past decade, the wind community has learned that wind farms and wildlife can and do coexist successfully. Wind energy development’s overall impact on birds is extremely low (<1 of 30,000) compared to other human-related causes, such as buildings, communications towers, traffic, and house cats. Birds can fly into wind turbines, as they do with other tall structures. However, conventional fuels contribute to air and water pollution that can have far greater impact on wildlife and their habitat, as well as the environment and human health.”
-National Renewable Energy Laboratory
(http://www.nrel.gov/docs/fy05osti/37657.pdf)

“We have reviewed reports indicating the following estimated annual avian collision mortality in the United States:
• Vehicles: 60 million – 80 million
• Buildings and Windows: 98 million – 980 million
• Power lines: tens of thousands – 174 million
• Communication Towers: 4 million – 50 million
• Wind Generation Facilities: 10,000 – 40,000”
– National Wind Coordinating Committee
(http://www.nationalwind.org/publications/wildlife/avian_collisions.pdf)
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What are the aesthetic impacts of wind turbines?

Many individuals think that wind turbines are actually quite beautiful. For instance, residents in the town of Hull, Massachusetts have an onshore wind turbine in which they get very few complaints about. The turbine has been so successful that the town has constructed a second turbine and is currently looking at a small offshore project. Visual impact of offshore wind turbines depends on how far offshore turbines are located. Some turbines may be miles out to sea and hardly visible from shore. Of course, whether a citizen likes the look of a turbine is in the eye of the beholder. However, many individuals dismiss turbines based on visual impacts without ever having seen one.
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What defines federal vs state waters in the US?

Three nautical miles is the jurisdictional limit for US states with the exception of Texas and the west coast of Florida whose jurisdictions extend to nine nautical miles. In Federal waters permitting is overseen by the Minerals Management Service of the Department of the Interior.

StateVSFederalwaters
Source: Ocean Commission- Primer on Ocean Jurisdictions: Drawing Lines in the Water
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Which companies make offshore wind turbines?

Several companies make offshore wind turbines including GE/Alstom, Siemens, Vestas/MHI, Senvion, and Gamesa. Turbine sizes range from 3.6 – 8 MW in size.

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