Offshore wind for Delaware

Questions from Delaware residents, and answers from UD researchers


Willett Kempton, Meredith Blaydes and Philip Whitaker

College of Earth, Ocean, and Environment

University of Delaware


Following are questions often asked by the public about offshore wind, with answers tailored to Delaware. These are based on research and experience of the University of Delaware College of Earth, Ocean, and Environment research group working on offshore wind. This is meant to be readable and accessible to the public, and has only web sites for references. For research papers with detailed calculations and references, see our web site and suggestions for further reading at the end of this document.


Why is wind power being discussed now in Delaware?
Why not put the wind turbines on land?
How much electricity if Delaware fully exploited its offshore potential?
What about birds?
Won’t it harm sea life?
Will fishing be restricted? Will the areas of the wind farm be off limits for other users of the area?
What happens when the wind is not blowing?
What happens when the wind turbines eventually wear out?
Isn’t wind economic only because it is subsidized by government?
Aren’t utility-scale wind turbines new, experimental and risky?
Are they reliable?
Can they fail catastrophically?
How about terrorism?
Who is bidding to build wind for Delaware?
Why is Bluewater proposing three sites?
How large would the proposed facility be?
Will Delaware residents oppose offshore wind, as has happened on Cape Cod?
Overall, what are the negatives?
Overall, what are the positives?
Where can I find more information?



Q: Why is wind power being discussed now in Delaware?

A: The state has requested 400 MW of new power, through a “request for proposals” (RFP) via Delmarva Power and Light. The goals of this RFP are to provide stable electric power prices and environmental improvement, and to take advantage of new technologies. Private companies have submitted proposals for coal, natural gas, and offshore wind. The state, assisted by Delmarva, is to pick one in May 2007. The rules are set by Delaware’s HB 6, find it at: For the RFP rules, click on legis.html and search for “new generation”.


Q: Why not put the wind turbines on land?

A: Delaware has very few locations on land that are windy enough to be economically efficient. The wind over the Atlantic, and parts of the Delaware Bay, are stronger and steadier.


Q: How much electricity if Delaware fully exploited its offshore potential?

A: According to UD researchers, Delaware has an immense offshore wind energy resource. An analysis by Dhanju, Whitaker and Kempton estimate a resource of over 7,000 MW average output in the waters off Delaware out to 50 m depth, even after excluding shipping lanes, bird flyways, etc. This is over five times the electricity use of the entire state of Delaware. If Delaware accepts the current bid and builds the proposed 600 MW wind farm, we can just maintain that, or can build more and continue to expand. Expansion beyond the needs of Delaware would also require expanding power transmission capacity, which is planned anyway. If Delaware’s resource were fully exploited, it would have a value of over $2 billion per year at current electricity prices.


Q: What about birds?

A: Some wind generators have been put in areas that have caused significant bird or bat deaths. Those cases make the news but are not typical. The average US wind turbine kills 2.4 birds per year, fewer than are killed by other structures such as skyscrapters and communication towers. The one thorough study of an offshore wind farm had about half this number. For comparison, studies have shown that the average ‘outdoor’ cat kills 3 to 5 birds/year ( From our preliminary analysis, the three possible sites proposed appear to be well outside of bird migration pathways. We would expect the Atlantic sites in particular to cause fewer bird fatalities than the national average. In conducting offshore wind site planning, which by law will include a study of the bird species in a proposed area as well as their migratory pathways, wind sites can be optimally sited and avian impacts minimized.


Q: Won’t it harm sea life?

A: Studies of Danish offshore wind farms, and projected impacts from the Cape Wind (Mass.) EIS, show very little effect on sea life. The main effects are that a few species avoid the area, while others are attracted to it (for example, see In comparison, a single fossil fuel power plant can cause from hundreds to literally billions of deaths of fish and other sea creatures per year (see Christina Jarvis thesis,


Q: Will fishing be restricted? Will the areas of the wind farm be off limits for other users of the area?

A: The turbine towers use less 1% of the area that hosts them; they will be spaced approximately 1/2 mile apart. At their lowest point the blades are 7-8 stories above the water's surface. The riprap placed around the turbine's foundations is expected to attract fish and thus attract recreational fishermen. Similar facilities in Europe have proven to be tourist attractions. The wind bidder has said they will allow navigation and fishing, but not mooring to the towers.


Q: What happens when the wind is not blowing?

A: Delaware’s offshore wind is pretty steady. At the locations proposed—5+ miles off shore, and 80 meters up in the air--they would generate power 85% of the time.  This is coincidentally the same up-time as one of the competing bids for Delaware power, IGCC coal. The coal bid says it eventually hopes to get up to operating 85% of the time.  (The Coal would produce more power on average, because that 85% of the time it would usually be running full power, the wind will most often be at partial power.) In neither case will the lights go out, because Delaware is connected to a power grid of interconnected generators and loads, called “PJM”.  When one power plant goes down, others further along the power lines ramp up—whether new wind, new coal, or one of today’s generators.


Q: What happens when the wind turbines eventually wear out?

A:  Decommissioning costs are generally bonded in advance, or accumulated as a toll from operating revenues.  Thus, even if the operator goes bankrupt, the money is there to take them down.   There are some arguments for replacing the working parts with new ones on the same tower, or leaving part of the substructure in place as fish habitat. Nevertheless, we recommend that the Delaware proposal have a provision for decommissioning.


Q: Isn’t wind economic only because it is subsidized by government?

A: In Delaware, small solar and wind installations qualify for the Green Energy Fund, which pays half their cost. No state subsidy will be given to this large, “utility-scale” offshore wind project.  There is a Federal production tax credit (“PTC”), based on the amount of power actually sold. The tax credit for wind is shorter term and smaller than the tax breaks for nuclear power.  As far as direct cash support, there are no Federal subsidies for wind, whereas there are subsidies for "clean coal" (perhaps more accurately called "somewhat cleaner coal").  Fossil fuel extraction has no PTC, but enjoys depletion, accelerated depreciation, and other favorable tax treatments.  We have not analyzed the combined effect of all these, but utility-scale wind energy is less subsidized than some others. (The forgoing does not include the health costs of dirty power, which are a major cost borne by local residents and the health system, nor the costs of climate change which will be very costly to Delaware.)


Q: Aren’t utility-scale wind turbines new, experimental and risky?

A: According to a recent GE press release (23 October 2006) "The first 1.5-megawatt machine was installed in 1996 in Germany."  At 10,500 MW of installed US capacity, wind power currently supplies enough electricity to power 2.5 million US homes. Wind power is growing faster than any other power source, with more US wind installations last year (2006) than existed in the whole country in 2000. For annual wind capacity installations in the US since 1981, see  President Bush has set a goal for the US to generate 20% of our electricity from wind power. No offshore wind farms have yet been built in the US, but two are in various stages of permitting or review, both now delayed. The Delaware pre-bid specified 3 MW turbines, such as those which have been operating offshore at Kentish Flats (UK) since September 2005 (see  for an offshore UK project list).   Offshore wind farms near Denmark have been operating since 1990.  


Q: Are they reliable?

A: Wind turbine downtime due to mechanical failures is about 1%, much better than fossil power plants. Some new machines have done much worse. Gearboxes have in particular required more maintenance than expected in some models.  Failures at Horns Rev (Denmark) almost bankrupt Vestas, a relatively small manufacturer.  It's a learning process.  We expect that Vestas is much more cautious (and smarter) now.   But in any event. the manufacturer (or service contractor) eats these costs, because the contract will be a power purchase agreement.  Neither Delaware ratepayers, nor Delmarva Power and Light, as the power buyer, will assume this risk.


Q: Can they fail catastrophically?

A: In the old days of wind turbines--30 years ago--there were some spectacular failures.   That is rare today (in 2006 one tower in Japan fell over, a rare event).   Most US wind turbines are far from population and buildings--the DE proposal is miles offshore--so it would not seem to be a great risk even one did fall over.   We judge the risk to Delaware residents much greater from overflying aircraft, buildings during earthquakes, or sleep-deprived 20-year-old drivers of tractor-trailers.


Q: How about terrorism?

A: It would take a long time and some very large tools to cut down 200 wind turbines. Each is continuously monitored, so the gendarmes would be called soon after the first one was damaged.


Q: Who is bidding to build wind for Delaware?

A: The wind bidder in Delaware is Bluewater Wind.  They have a tiny state office here in the 25th district, in Delaware Technology Park (and a main office in the New York area). Their land-based sister company, Arcadia Wind Power, recently developed the 90-turbine Judith Gap project in Montana, which went on-line January 2006. For this project, they would partner with construction and engineering firms with offshore wind experience. See company information at


Q: Why is Bluewater proposing three sites?

A: Because full public review and environmental assessment was not complete by the time of the bid submission deadline, Bluewater gave a bid with the specifications and pricing for three sites, and will build whichever one the state chooses.


Q: How large would the proposed facility be?

A: The two Atlantic sites would have a maximum (“nameplate”) capacity of 600 MW. This could be met with 200 Vestas V90-3.0 MW turbines ( University of Delaware calculations of the wind resource in this area show a “capacity factor” of about 40%. Thus, a 600 MW facility would, on average, generate 240 MW. (The third site is in the Delaware Bay; it would be slightly smaller and have a slightly lower capacity factor.) The RFP offers a long-term contract to buy up to 400 MW, which means that when the power is above 400 MW, the wind operator would have to sell the excess to another party. The average output of 240 MW is about 18% of Delaware’s average consumption of 1300 MW. The whole facility can be installed in one construction season.


Q: Will Delaware residents oppose offshore wind, as has happened on Cape Cod?

A: Members of our group at UD has conducted a statewide survey of Delaware residents. Some questions were designed to be identical to a survey we conducted two years ago on Cape Cod, which found a majority opposed to the wind project in Nantucket Sound. In Delaware, we find substantial majorities in favor, even those who live near the shore and even if told it would cost more than continued use of coal and natural gas. The Delaware survey report is at, and a summary is at The full results from Cape Cod are at, and a summary is at and a press release at .


Q: Overall, what are the negatives?

A: The power from this first facility may initially cost more than our existing supplies (it is more expensive than the natural gas bid but less than IGCC coal bid). A consultant for the state has estimated the price impact. That consultant assumes lower than standard projections of future costs of carbon dioxide emisisons, but if we accept those assumptions the total bill impact for the average Delmarva residential customer is about a 3% rise. Some people do not want to see anything on the ocean horizon other than ships. Up to 1.4 birds per turbine per year would be killed (based on a Danish offshore wind study), or 280 birds/year.


Q: Overall, what are the positives?

A: The wind power price would be almost constant over the 20-25 year life of the facility; coal and natural gas will have fuel price increases as well as expected carbon dioxide fees or taxes. By reducing the amount of fuel burned for electricity and thus reducing air pollution, the wind generators would improve health in Delaware and literally save lives. If higher carbon cost projections were used, and if any consideration of health costs were included in "cost", the wind bid would be cheaper than today's electricity. A small fraction of the 640,000,000 yearling fish killed by cooling systems in the Delaware bay would be saved, as would some wildlife now killed and some habitat now lost by mountaintop removal for coal. By being the first or one of the first US offshore wind installations, Delaware would not only create jobs for this one installation but develop skilled tradespeople and business experience in an industry expected to continue growing rapidly. Because of Delaware’s huge wind resources (five times greater than our electric use), this first installation would give us the experience to decide whether or not we want to encourage this as a major growth industry for the state. Perhaps most important, the US offshore wind industry is stuck in planning in two other states—Delaware can move it forward, and thus make one step toward stopping climate change before it does great damage to our State.



Q: Where can I find more information?


A: For current research on offshore wind, see our research-oriented web site,, and links from there.  


On that site, two of the more readable overview papers from our group are:

"Comment submitted to Minerals Management Service”, at ANPR AltEnergyOCS-UD-Comment-2006.pdf


Offshore Wind Power On The Horizon: A New Energy Frontier For Oceans, People And Wildlife” Wind--Coastal Society06.pdf


For references to more technical reading, see the web site for our class, and our class syllabus, at  


For Delaware’s RFP for new power (to start, see the State Agency's Consultant Report):



Willett Kempton is Associate Professor, Meredith Blaydes is a PhD candidate, and Philip Whitaker is a Master’s of Marine Policy candidate at the College of Earth, Ocean, and Environment, University of Delaware.



revised 14 March 2007