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Tracing Hadrian's Wall

Day 12: Kendal to Edmundbyers

by Brad Smithling

After a long day of driving across the country of England, we finally arrive on the Coast of Blyth where we can park our vans and see what awaits us.  We exit the vehicles and are immediately awestruck by the massive twin – 2-megawatt turbines that stand ever so gracefully turning before us in the resplendent blue water of the North Sea.  Standing one kilometer from shore, the Blyth Offshore Wind Farm was the first offshore wind farm to be built in the North Sea, and these two turbines which make up the farm were the largest in the world when they were constructed in December, 2000.  As if the sight of these offshore turbines isn’t impressive enough, when we turn our heads 90° to our right we are pleasantly surprised by the sight of nine more wind turbines, each of 300 kilowatts, planted firmly into the East Pier of Blyth Harbour.  These turbines are part of a separate project called the Blyth Harbour Wind Farm. 

The first to be constructed of the two projects, the Blyth Harbour Wind Farm became the UK’s first semi-offshore wind farm when it was built in 1992.  The nine – 300 kW turbines were shipped from Antwerp, Belgium in October 1992 and installation of them ensued shortly after by the Blyth Harbour Wind Farm Company Ltd.  The foundations of each turbine were constructed on the existing 100-year-old East Pier.  Each turbine’s foundation consists of a reinforced concrete block tied to the pier by steel rods (up to 22 rods) and they extend seven meters down into the bedrock.  The turbines were constructed with a 100-ton floating crane barge.  They stand 30 meters high and have the capacity to generate a total of 2.7 MW of electricity.  These turbines are designed to shut off at wind speeds below 5 m/s and higher than 25 m/s.  The optimum wind speed is 13 m/s and the blades rotate at 52 rpm’s  (rotations per minute).  The owner of the farm, Blyth Harbour wind farm company Ltd. is comprised of the Blyth Harbour Commission, HMZ Belgium NV, and Borderwind. 

Described as the first truly offshore wind farm ever built in the world, being fully exposed to the brutal forces of the North Sea, The Blyth Offshore Wind farm was constructed by drilling 15 meter deep holes 3.7 meters in diameter into the seabed.  The two turbines, which comprise the farm, are located 200 meters apart from each other.  The blades of these monsters turn at 21.3 rpm’s and the turbines stand 58 meters high.  These turbines shut off if the wind speed goes below 4 m/s (meters per second) and above 25 m/s.  The optimum wind speed for electricity generation with these turbines is 17 m/s.  These two turbines alone can generate enough electricity to power 3,000 homes and it is calculated that they will displace 10,000 tons of CO2 per year.  The farm is owned by Blyth Offshore Wind Ltd., which is comprised of Powergen Renewables, Shell, Nuon, and Amec Border Wind.

It certainly isn’t everyday that you see a windmill sticking up out of a body of water; at least not for most of us Americans who don’t have such things in our country yet.  But since 1991 when Denmark installed the world’s first offshore wind farm at Vindeby, more and more farms have been springing up throughout Europe.  There are currently ten operating offshore wind farms in the world, with turbines located in Denmark, Holland, Sweden, and the UK.  Countries such as Ireland, Italy, Belgium, and Germany have proposed offshore wind projects to be built in the future and the United States has announced its first proposed project to be built in Cape Cod, Massachusetts.

Offshore wind, as with anything, has its pros and cons.  Offshore wind speed is generally higher than that of on shore.  Offshore wind is also more constant and has less turbulence, which decreases fatigue loads on the turbines.  However, it is a toss up, as the forces imposed from the water on the base of each offshore turbine will result in more fatigue endured than those of onshore turbines.  One downside to offshore wind farms is that they cost 30-70% more to build as compared to an onshore farm. 

However, constructing a wind farm offshore allows the use of much larger turbines, which can generate up to 30% higher energy yields as compared to onshore turbines.  When constructing an offshore wind farm, additional studies such as coastal processes, fisheries, archaeology, radar, marine mammal, socio-economic, noise, and ship collision studies must also be carried out to ensure success of this type of wind farm and respect the environment and the local community.  The advantages of offshore wind will not truly be experienced until wind farms with turbines of gigantic size (upwards of 10MW) are constructed.  And with recent pushes for renewable energy, it is only a matter of time before we begin to see things like this.

Brad Smithling is a Senior in Engineering Science and Mechanics.

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Last updated: Thursday March 25, 2004