Vattenfall’s Ormonde offshore wind project sets record on large-scale jacket installation

When Vattenfall acquired the Ormonde hybrid wind and gas project from Eclipse Energy back in 2008, it promised to be one of the company’s most exciting acquisitions. But following months of exhaustive analysis, the company reluctantly relinquished its licence to develop the Ormonde gas fields.

“We looked into so many alternatives as we wanted to find a way to [develop the wind project and gas fields as a hybrid project]…we thought there would be ways to make it work, so we engaged consultants from the oil and gas industry. But in the end we had to hand the gas field production licence back to DECC as it was not economically viable,” concedes Veijo Huusko, who was brought onto the project to analyse the economic viability of a hybrid gas and wind project.

“We probably wouldn’t actively seek out another hybrid project,” he adds.

Since then, Vattenfall subsidiary Ormonde Energy has been full steam ahead on developing the wind farm side of the project, which is currently being built in the Irish Sea, 10km off Barrow-In-Furness.

On completion the wind farm will comprise 30 RePower 5M wind turbines with the capacity of 150 megawatts and expected to produce around 500 gigawatt hours of electricity every year.

In terms of speed of installation, the project has so far outperformed project director Ole Bigum Nielsen’s highest expectations.  From July 23, a total of 31 jackets were installed for the turbines and substation. The final jacket was installed Sunday October 17.

“It has given us a very good feeling for the Norfolk project, where we will also need to use jackets,” says Nielsen. “Ormonde is the first large-scale installation to use jackets to date,” he adds.

Team-led success

Ole Bigum Nielsen is no stranger to the offshore wind industry. Since 2000, he has worked on a range of wind projects and was involved in the Horns Rev, Frederikshavn and Havn offshore wind farms.

More recently, he headed up Sweden’s largest offshore wind farm, Lillgrund and the UK’s largest wind farm, Thanet, as project director. He is currently project director of the Ormonde offshore project and serves as Vattenfall’s head of offshore projects, UK.

Considering that multiple jacket installation is no mean feat, the Ormonde Offshore wind team achieved a cracking pace for the foundation installation phase. So what is Nielsen’s secret? “The planning phase was definitely more challenging than the installation phase, which incidentally went much smoother than expected,” admitted Nielsen.

“At Vattenfall we don’t tend to use the same supplier, but the suppliers we do use have to be experienced in the business – this is key to success. The overall team is very important. There must be a good balance between less experienced and highly experienced”, he explains.

Vattenfall is a multi-project company, which has up to 80 suppliers working for it at any given time. But Nielson noted that from a contract management perspective the Ormonde project has been different, in that it used a smaller number of suppliers. “We have used 6-7 main suppliers for the project, so it has been much easier to manage and control the interfaces.”

Big kit calls for precision strategy

The sheer size of the equipment being installed at Ormonde (5MW turbines on jacket foundations) implies longer lead times and complex logistics. Yet, while the project incurred some minor delays, they were not in the areas expected.

“We had a very tight installation schedule. We loaded out from Burntisland Fabrications Ltd.’s (BiFab) production facilities onto barges. Our installation vessels have been able to load faster than the load-out from the BiFab. In this respect there was a lot of extra waiting as there were not sufficient jackets lined up on the site,” said Nielson.

That is not to say that Nielson wasn’t pleased with the pace of progress. “We had hoped we would be able to do it as fast as we have and we have proven that jacket installation can happen quickly,” he said.

Looking forward to the next phase, turbine installation, the REpower 5MW turbine parts will be transported form German to Belfast. Pre-assembly will take place at the Harland & Wolff facility, where the turbines will be loaded out onto A2SEA’s SeaJack installation vessel and transported to site for installation.

Purpose-built tools in demand

A key aspect of the installation phase of this particular project is that the REpower 5MW turbines are much heavier than, say, a Siemens 3.6MW or a Vestas 3MW turbine. The former weighs more than 500 tonnes, whereas the latter weigh roughly 230 tonnes.

The size and weight of the 5MW turbines means that only two turbines can be loaded onto the vessel at a time, which means there will be a total of 15 turnarounds. This raises some important issues for wind farm installation going forward – particularly for far-shore wind farms that will likely use bigger equipment.

“We are dealing with much heavier equipment, which really limits the number of vessels you can use for the job,” notes Nielsen. “If you were installing a Vestas turbine, roughly 10 vessels out there are capable of doing it, whereas if you are installing a REpower turbine, only around 3 vessels are capable. Okay, the figures aren’t precise, but my point is that with the larger turbines, the vessel options are narrowed significantly,” he adds.

During the turbine installation phase of the Thanet project, the vessel took 9 turbines per trip. Fewer turn-arounds and a greater number of turbines installed in one go led to significant time and cost savings. “The fact that we had a vessel out there all the time meant that we could make use of even very small weather windows,” points out Nielsen.

In light of this fact, Nielsen stresses the need for new vessels on the market. “If you look at Round 3, it is not realistic to install large turbines with a vessel that can only carry 2 turbines, given the distance that needs to be covered and the sheer number of turbines that need to be installed.”

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