While the rest of the world was celebrating New Year’s Eve, the crew aboard the installation vessel Svanen was beginning construction on the largest offshore wind farm in Denmark. State-owned Dong Energy announced the installation of the first monopile of the 400-megawatt (MW) Anholt Offshore Wind Farm, sited about 10 miles off the coast of Denmark, between Djursland and the island of Anholt in the Kattegat Sea. With a total of 111 wind turbines, the wind farm will generate enough electricity to power 400,000 Danish households, and meet about 4 percent of the country’s total electricity consumption.

Like other offshore wind farms, the turbines at Anholt will be installed on platforms attached to a monopile foundation. The monopile is a 450-ton round steel pipe with a diameter of about 5 meters and a thickness of 5-9 cm. In order to tow the monopile from the port at Aalborg to the installation site, the ends of the pile are sealed with two end caps. Once the pile is placed at its final position, the caps are removed. The crew then uses a hydraulic hammer to drive the monopile 18-36 meters into the seabed, depending on water depth and seabed conditions.

image via DONG Energy

The Anholt Offshore Wind Farm will play a significant role in helping the Danish government meet its goal of generating 30 percent of its electricity from renewable resources by 2020. The project, which is owned jointly by DONG Energy, PensionDanmark and PKA, is expected to be complete by the end of this year.

“Anholt Offshore Wind Farm is a giant offshore wind farm – even for us – but it’s exactly the capacity we need to speed up the industrialization to ensure that offshore wind power stays competitive,” Christina Grumstrup Sorensen, senior vice president in renewables for DONG, said in a statement. “Now we can take the next step in the development of the Danish energy sector towards a fossil-free energy supply.”

After securing financing late last year, DONG Energy was able to begin the project a few days ahead of schedule. But, according to Project Manager Claus Bojle Moller, the winter weather will pose challenges to the installation process. Work was already suspended on January 3 and 4, due to high wind and waves at the site.

Anholt offshore wind power project, Denmark
image via DONG Energy

Winter weather was not the first challenge DONG Energy encountered since it was awarded the license for construction of the project in July 2010. Later that year, while performing geophysical surveys of the project site, DONG Energy found several undetonated explosives from World War II. After a diving inspection, the mines were classified as high-risk, and the frogmen were sent out to detonate the mines.

In addition to the Anholt project, DONG Energy is obviously expecting an onslaught of offshore development: The company has partnered with ScottishPower Renewables to build a new port terminal designed specifically for the assembly of offshore wind turbines at Belfast Harbor in Ireland. The project will be the first offshore wind installation and pre-assembly harbor in the U.K.