Statkraft Heads Successful Marine Operations

The landlubbers in Statkraft got in on the deep end when the company entered the offshore wind industry in 2009, with many competitors having broad experience from the offshore oil and gas industry.

This summer, Statkraft got its feet wet and for the very first time took charge of what is termed “marine operations”.

“This is an important milestone for us. I’m proud that we, for the very first time, have taken charge of maritime operations. In order to be able to take on a leading industry role in future developments on Dogger Bank and other places, we need to establish new expertise step by step,” says Olav Hetland, director of offshore wind energy in Statkraft.

Two turbines out of order due to faulty parts

This spring saw the gearbox of one offshore wind energy turbine at the massive Sheringham Shoal field give out. Then the transformer in another turbine decided to throw in the towel. As 2 x 3.6 MW out of operation for months would mean a significant loss of production, the operator Scira wanted the damaged parts replaced a.s.a.p.

Siemens, the supplier of the parts, has the warranty liability, but the customers must install the parts themselves. In this case, this involved carrying out seabed  surveys, organising transport of necessary personnel to and from the field, and last, but not least, directing major vessel operations involving offshore heavy lifts.

Statkraft sea dog takes the lead

Statkraft secured the assignment from Scira, in stiff competition with others. Mats Lund was assigned as Project manager. Mats is a salty sea dog with broad experience from offshore operations in the petroleum industry.

“We set sail immediately. Our goal was to get the job done as quickly as possible. The assignment includes a number of the same operations as to be executed for a complete development; including having to obtain the necessary authority approvals in time, carry out seabed surveys at the turbines in question, good weather conditions to perform the lifting operations, and not least, an appropriate vessel to be available,” Mats says.

He was able to secure the Fred Olsen Wind Carriers vessel the Bold Tern, a jack-up, which sets four legs on the seabed and then elevates the entire hull above the surface in order to provide a stable platform before lifting begins.

Over the top

“The Bold Tern is a big vessel for such small units. It was much over the top for the job, we could have done this with a smaller vessel, but there were none available,” he says.

A new gearbox and transformer were collected at the port in Esbjerg, Denmark, where they also dropped off the faulty parts. The deck of The Bold Tern made these large components appear like toys. Before the Bold Tern arrived at the field, the damaged gearbox and transformer had been prepared in order to save valuable time for the jack-up.

Landlubbers can have a hard time fathoming the sheer size of such operations, but imagine a big vessel moving into position with decimetre precision, while taking into account wind, waves and not least, strong tides. The four legs lowered onto the seabed have a base of more than 100 square meters each and they were pushed seven to eight meters into the seabed to create stable foundations. Then add that these legs cannot touch any of the subsea cables, or be placed in the same spot as the legs were placed during the initial installation of the turbines.

The operation was completed at the end of July this year, without any injuries or serious HSE incidents, less than two months after the job was initiated, and within budget and schedule. The two faulty turbines are back in full operation. Since then, the 317 MW offshore wind farm has managed to produce 317.4 MW at maximum production.

How is Statkraft using this experience in its expertise-building efforts?

“We are retaining the experiences and processing them into a project execution model for similar tasks,” says Mats.

“This was the very first time we headed a maritime operation, but not the last. There will be many, many more,” he adds.

Press release, October 1, 2013; Image: Statkraft