CABLE PROTECTION FEATURE
CABLE PROTECTION IN THE OFFSHORE WIND INDUSTRY
CABLE PROTECTION IS A VITAL PART OF ANY OFFSHORE WIND FARM (OWF). DESPITE CABLE PROTECTION BEING A WELL TRODDEN PATH IN SIMILAR INDUSTRIES, SUCH AS OIL & GAS AND TELECOMS, THE CHALLENGES FACED BY OWF’S CALLED FOR NEW INNOVATIVE ENGINEERING TO ENSURE THAT OWF’S BECAME A VIABLE OPTION FOR EUROPE’S RENEWABLE ENERGY PLAN.
CHALLENGING SUBSEA ENVIRONMENT The OWF’s have a particularly challenging subsea environment due to the shallow depth of water and windy conditions in which where they are located. These conditions create strong currents and tides which cause corrosion of the seabed around the base of the wind turbine foundation, known as scour development. This scour development causes the cable to be suspended across the free-span formed by the scour, which exposes the cable to various forces over its 25 year service life. Further to these forces, the cable protection must also be able to cope with extreme “freak” waves which are predicted every 1, 10, 50 and 100 years. These forces will both fatigue and over-bend the cable if it is not sufficiently protected and will ultimately render the cable useless for power transmission.
BENEFITS This system had a number of benefits to the industry; being J-Tubeless it allowed developers to save significant costs by reducing the amount of steel fabricated, assisted installers to improve the cable installation process and gave confidence to added security to cable manufacturers.
LESSONS LEARNED Overall the industry has seen failures and learnt lessons in the true requirements for cable protection in terms of both installation and service life, particularly during the UK round 1 phase of construction. These lessons learned are currently being demonstrated with the successful installation of Tekmar’s Teklink® Cable Protection System on Walney, Thornton Bank, BARD & Anholt Offshore Windfarms which are the biggest windfarms in construction or operation in the UK, Belgium, Germany and Denmark respectively.
HISTORY Early OWF’s adopted cast iron cable protection systems that were commonly found in the Oil & Gas and Telecoms industries. Although cost effective and easy to install over long distances, protecting cables in an OWF with cast iron proved unsuccessful due to its weight and brittleness in a dynamic subsea environment.
MODERN DAY SOLUTION
So what has changed in the industry to mitigate against these challenges faced by OWF’s? One of the key developments to cable protection over the last 3 years has been the increase use of J-Tubeless cable protection designs, which was first championed on the Bard OWF in Germany with the Teklink® Cable Protection System.
FUTURE The future of Cable Protection is set to evolve even further with OWF being constructed in deeper waters. Deep jacket foundations and even floating foundations present new, exciting challenges which will ensure that Offshore Wind remains the renewable energy of choice for the European market.
Jack Simpson Tekmar Energy
www.tekmar.co.uk
www.windenergynetwork.co.uk
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