Ørsted and Vattenfall want Hesselø tender started despite muddy waters

Even though Danish offshore wind site Hesselø was deemed unsuitable a year ago, both Vattenfall and Ørsted reckon the project could work despite the soft mud seafloor. Both utilities want the tender started.
Photo: PER FOLKVER/pxpf01962.JPG
Photo: PER FOLKVER/pxpf01962.JPG

When Denmark's offshore wind tender for project Hesselø was paused in June of 2021 due to an excessively soft seafloor, sector lobby Danish Energy called it a "gut punch". Since, the Danish Energy Agency (DEA) has been searching for a suitable alternative placement for the 1.2GW facility. However, the project could succeed despite the soft subsea terrain, says both Ørsted and Vattenfall, reports media Klimamonitor.

"Europe has more need than ever to accelerate the green transition. Despite the significant technical challenges at the Hesselø site, we deem it possible to complete the project. We therefore think a tender should be held as soon as possible," says Ørsted Vice President, Head of Regulatory Affairs Ulrik Stridbæk in a written comment to the media.

Vattenfall agrees with its Danish peer, however, adding that the tender should be done differently than the Thor solicitation, settled by drawing straws.

Back in 2018 when engineering group Cowi conducted a fine screening of Danish offshore wind sites, the Hesselø B area ranked best in terms of seafloor conditions.

Upon closer inspection, though, it turned out that roughly half of the site designated for the project featured seabed so muddy that foundations would have to be hammered 50-60 meters below sealevel in order to sit tight.

That prompted the DEA to set the project in hiatus while screening efforts continued at five alternative sites in the event that the initial plan failed.

In three of these alternatives, the southwestern part of the designated Hesselø area is maintained where geological conditions are best.

One of these will be supplemented with a new Hesselø site southwest of the nominated area, while the other two take respective bites off another further toward the Danish region Djursland and one north of the Kriegers Flak wind farm.

The latter is dubbed Kriegers Flak Nord and omits entirely the Hesselø site, and compensates with a smaller area south of Kriegers Flak. Moreover, parties have looked into the large area south of the coming Thor farm in the North Sea.

Screening of the new areas has, though, not meant that public authorities have given up on the original plans. Market players were invited in connection with released screening information to offer their thoughts about whether it would be possible to build at the designated site within current policy framework.

Thor offshore wind park decided by drawing lots 

Danish Energy Agency seeks alternative sites for muddy offshore wind farm 




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