Offshore Cabling: The Hidden Arteries Of The Wind Industry
Posted: 02/09/2012 12:00:00 AM EST | 0
Renewable energy production through offshore wind farms is an increasingly important part of modern life, as providers look to supply power through sustainable means.
While it looks from a distance like it is just the blades which are doing the hard work, much of the success of this technology is down to the underwater cables.
These are responsible for 10 per cent of the cost of a project, with engineers needing to ensure that any power which is created from the windmills is transported back to land and onto the grid.
Furthermore, faults with cables account for 70 percent of insurance claims in this sector, and repairing them can be a major job.
In January 2012, Vattenfall's 300MW Thanet offshore wind farm had to run a reduced service because of cable issues. The project is the biggest offshore-based energy initiative in the world, and relies on two export cables to take power back to the onshore network.
The farm cost £780 million and is home to 100 turbines which help to generate enough electricity to power up to 200,000 properties.
One of these cables developed a fault after two separate problems and it led to costly repairs being carried out. "We completed work on a section of the cable that had been bent at too acute an angle in November. But on energisation, we identified another fault on a different point closer to the substation," a spokesperson for Vattenfall told RechargeNews.
Pointing to one of the major considerations of offshore work – the weather – the representative added that the company was hoping to have the repairs completed in February, although "there is no guarantee".
It appears that the secret to success when laying cables for an offshore project is in the planning, according to one expert.
John Davies, Global Marine Systems' managing director of subsea services, told RechargeNews that installers should be involved in the preparation phase from the earliest possible opportunity.
He noted that "understanding the concept, getting the engineering right, and building proper processes" were the keys to forming a successful and trouble-free offshore wind farm.
Mr Davies went on to say that not only is personnel shortage a problem, but so too is the availability of the types of barges which are capable of installing more than 100km of cable.
"Personnel with plenty of experience in project work are in short supply. While the client wants the A-team out there, quite often we can only find the B-plus team. As an industry, we have to invest in new people," he added.
Mike Prowse, business manager for the renewable energy market at Global Marine Systems Limited, previously explained that some of the biggest threats to offshore cabling are anchor damage from vessels, trawler board harm from fishing boats and general abrasion.
While there are options to counter these threats, such as choosing the appropriate burial into the seabed, there are a host of environmental constraints which should be taken into account.
A presentation delivered by Mr Prowse pointed to restrictions on burial tools which will cause sediment plumes affecting shellfish, along with timing the installation correctly to avoid restrictions in fish spawning grounds.
Towards a European supergrid
The prize for combating all of these cable installation problems could be a European supergrid. This would allow countries like Scotland – where wind farms are prevalent – and Spain, whose use of solar panels is growing, to connect together and share generated power through underwater systems.
Currently, Britain is working with European neighbours like France, Germany, Norway and Sweden to build the North Sea Countries Offshore Grid Initiative. Although some way off at the moment, the project could be the start of something special, which would see power being carried anywhere between Ireland and North Africa.
The initiative will also be boosted by founding member Denmark, which is taking up a six-month stint as president of the European Union. The country is one of the top nations when it comes to wind energy and Martin Lindgreen, head of department at its Ministry of Climate, Energy and Building, told Utility Week that green projects will be a strong focus over the next half year.
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