This week I read the article “Britain’s massive offshore wind power potential” by Paul Eccleston published on Telegraph.co.uk on October 5, 2007. This article immediately grabbed my attention because my first though was, “England? Wind power? How does that work?” Since the most common way I have seen wind harnessed is through giant windmills in the plans of West Texas, I was intrigued at how such a tiny island could extract enough profitable power from the wind to actually be useful.
However, the technology that the UK is using to harness the wind power is giant offshore wind turbines. These seem to be much more preferable than the windmills I’m used to seeing on land because they are placed so far out to sea that they don’t bother anyone’s property. Also, because they are so far out to sea, they can be built on a much larger scale.
Another interesting fact is that the UK is “the windiest place in Europe”, so extracting power from the wind will be a feasible idea. Currently, there are 5 offshore wind farms that are operational, with many more on the way. The British Government has a goal of obtaining 20% of their energy needs from sustainable sources by the year 2020. With the amount of wind that is available, this seems reasonable.
The rest of the article discusses the corporations that are behind these wind farms in the sea and the economics behind it, reading the article really spurred my interest in design and construction of the wind turbines that are actually used at sea.
As it turns out, the offshore wind turbines that are places out at sea are identical to the 3-bladed ones that cover West Texas. The only difference is, that they are in the middle of the ocean.
Even though these offshore wind farms seem like great ideas because wind is free, there is a great abundance of it, and it doesn’t really bother the people that are using the energy in the end, I can’t help but think that there are some disadvantages to these farms. And, it raised some questions with me.
What is the maintenance of an offshore turbine compared to an onshore one? I would assume that the constant interaction with the salt water would be somewhat corrosive to the turbines, so they would require more maintenance than one that resides on land. And, even though the turbines are non-obtrusive to humans that live on land, what about the animals that live in the sea? It certainly has to disrupt the surrounding ecosystem by placing giant wind turbines in the middle of the sea, especially while they would be under construction. Once they are in place, I wonder how long it takes for the ecosystem to stabilize and whether or not it has been permanently damaged.
Even though the British seem to be way ahead of us Americans on this technology, July 15, 2008 CNN’s Paul Courson published “Wind farm to be built off Delaware shore” where it was announced that Delmarva Power and Bluewater Wind will be constructing the US’s first offshore wind farm offshore of Rehoboth Beach, Delaware. This company projects that they will be able to get 16% of their energy from the 150 wind turbines that will be constructed. This farm is expected to be up and running by 2012.
Since the US has substantially more coastline than Britain, I think that it would be a sustainable technology worth investigating. Now, whether or not we have the quality of wind that the British Isles get would have to be studied. However, before any company jumped into the construction of these turbines, I hope that both the companies and local governments do their research to make sure they aren’t harming the local ecosystem of the sea as well as research the maintenance of the turbines to see if they are cost efficient.
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Offshore wind power generation does have several advantages over onshore wind, several of which you mention in your post. However, unmentioned is the greatest incentive for developing offshore wind, offshore or coastal winds are more correlated with high periods of electric demand than onshore winds. Therefore, offshore wind power generation can be much more valuable to electric utilities and can provide a peak power (afternoons and early evenings when demand is highest) generation source.
See AE's Resource Guide pages 28-30that discuss for wind power potential for the onshore wind farms it purchases power from in West Texas:
http://www.austinsmartenergy.com/divison.php?page=learn_more&sub=resource_guide
The following report released by ERCOT in 2006 contains wind profiles for different areas of Texas including the Panhandle, Far West Texas, and coastal areas.
http://www.ercot.com/content/news/presentations/2006/ATTCH_A_CREZ_Analysis_Report.pdf
On pages 13-15 one can see that the availability of wind on the coast correlates much more with ERCOT electric demand(statewide for electricity). Offshore and coastal winds are typically the strongest during the afternoon and early evening hours while onshore winds tend to be strongest at night and the early morning hours.
While offshore wind turbines are more costly to maintain, the "value" of the electricity at the time it is produced may offset these costs. Offshore winds and onshore winds should be viewed as complementary energy sources due to their almost reverse profiles. The first coastal (onshore) and first offshore wind farms are in the works in Texas. See the links below for information on these sites and the difficulties with siting and building these facilities.
Offshore wind farm-Galveston, Texas
http://www.geotimes.org/apr08/article.html?id=feature_wind.html
Coastal on-shore wind farm-Texas, near Corpus Christi
http://74.6.146.127/search/cache?ei=UTF-8&p=coastal+wind+farm+texas&fr=yfp-t-501&u=www.wind-watch.org/documents/wp-content/uploads/2008-special-edition-coastal-update.doc&w=coastal+wind+winds+farm+farming+farms+texas+tx&d=SKvZ752uScjW&icp=1&.intl=us
Texas should be focusing on its efforts to develop offshore wind as it has done with onshore wind.
I think that offshore wind power will continue to grow as a viable option around the globe particularly where there is a lot of coastline (islands like the UK certainly fit in this category).
One other potential advantage of offshore wind power that should be considered is the proximity to population densities. Historically, humans have settled near coastlines or waterways for navigational and resource purposes. Australia, for example has over 90% of their population living on the coast.
While the offshore farms may be closer to the population densities worldwide, the cost/mile of installing and maintaining transmission lines from these farms is greater than over land. However, it is likely that some of this extra cost can be offset by not having to purchase any additional land for these lines.
As far as the environmental impact is concerned, there is no doubt that there will be one as is the case any time you “stick your finger in the petri dish.” However, the North Sea has long been exploited for its natural resources and I would expect that the drilling and production platforms that these turbines are indirectly replacing have the same or greater ecological impact.
On a side note, in some parts of the world we have seen oil platforms actually providing structure for wildlife to form and congregate around. Similar to an “artificial reef.” While most hard core marine biologists would probably say this is a band thing, I have personally benefited from diving and fishing around the platforms in the GOM.
The American Wind Energy Association (AWEA), on their website (http://www.awea.org/faq/wwt_offshore.html) provide answers to many of the questions and concerns that you have raised, besides others which you have not mentioned w.r.t offshore wind farms.
As far as impact on the marine life is concerned, it is only during the construction and decommissioning phases that most of damage if any is likely to be caused. This lasts for only about 6 months of the 20+ years of service life expected in the wind turbine. These impacts are being analysed. However, many such problems as well as problems of corrosion that you mentioned are similar to that faced while constructing and decommissioning oil platforms for offshore oil and gas production.
Other potential ecological problems include the impact of the noise generated by wind turbines on marine life. However, studies have shown that this noise is of low frequency, beyong the audiable range for most species. There are also concerns about their effect on the seabed and coastal processes. Experience in Denmark suggests that no such effects are likely. Thus the benefits of offshore wind farms far outweigh its potential impacts on the ecology/environment.
The good news is that according to the AWEA, most of the US coast has "at least some potential" for wind farm development. A large windfarm has been proposed at Cape Cod off the Massachusetts coast. Offshore wind farms thus have a great potential in the US.
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