Each time, a cable is installed between wind turbines at an offshore wind farm, time spent offshore can be reduced by approximately three days. A new cable laying concept from DONG Energy points the way to reducing costs.
Each time they can move work from the offshore site onshore, they become more independent of the changeable weather, and consequently, they can work more efficiently and reduce the costs. And that is exactly the idea behind a new concept, where DONG Energy pre-terminates the cables, as it is called, and install plugs onshore instead of offshore at the offshore wind farm. For a long period, DONG Energy has been working on developing the new concept and is now looking for business partners to help further develop the concept.
Three days faster
Today, DONG Energy and their partners lay, pull and cut the cables to the right length between the wind turbines at the offshore site, and afterwards, install the plugs, so that the cable can be connected between two wind turbines. With this new solution, it will be possible to cut the cable to the right length onshore and install the plug, which means that all you more or less have to do is pull the cable and connect it directly to the wind turbine. They can save a significant amount of time – almost three days’ offshore work per cable.
“Our calculations show that we can save approximately DKK one million per cable by using this new approach. When you look at how many wind turbines we use on our projects and thereby also how many cables are required, the savings are considerable,” said Tue Keller, Lead Offshore Cable Installation Manager in Wind Power .
Today, it takes 36 hours on average per cable end to install a cable between two wind turbines corresponding to approximately three days per cable. This new method means that they can reduce the time used for each cable end to just one hour on average, and this means substantial savings.
“It’s relatively cost-intensive to have vessels laying in port waiting for the weather to clear up, just as it’s notably more expensive to work offshore compared to working at the quayside on firm ground. Therefore, it’s crucial that we can use the time in the best possible way onshore, and consequently, make us less vulnerable to the weather, and altogether reduce offshore work to a minimum,” said Majbrit Høyer, Head of HV Cables at DONG Energy Wind Power.
It is safer to work onshore
But there’s also a safety aspect in being able to do a larger part of the work onshore instead of offshore.
“When reducing the amount of work offshore, we also reduce the number of eg crew transfers where our employees must go from one vessel to another or from a vessel to a foundation. This always involves a risk, and this risk is reduced by moving the work onshore,” said Tue Keller.
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Press release, May 6, 2013; Image: dongenergy