Storm adds to German offshore pain

Weather that reached hurricane-force with Storm Xaver last week was the latest, albeit most extreme, example of conditions that have caused delays at some German offshore wind projects over recent months – despite also pushing power output from existing plants to new highs.

Wind power generation in the area covered by network operator TenneT on Thursday at times exceeded 10.5GW, a record output this year and one that forced it to take grid-balancing measures, the transmission system operator said.

But the bad news was that gale-force winds that reached more than 170km per hour and towering waves forced companies to stop their offshore wind construction activities – as has already happened several times this autumn.

Trianel, a consortium of German and Austrian municipal utilities, told Recharge that construction costs at its 400MW Borkum West 2 wind project likely will go up as an indirect consequence of the bad weather conditions.

“We indeed had unexpectedly lengthy periods of bad weather,” a Trianel spokesman said.

“Because of that, installation now has been pushed into winter, where bad weather periods are more frequent anyway.”

The commissioning by TenneT of the DolWin1 converter platform, which will bundle power from Borkum Trianel and other wind farms has been delayed further due to the weather, Trianel says.

While first electricity was planned to flow to the mainland in October, DolWin1 now will start preliminary operations in January, with full service available only in May.

Trianel’s own construction activities also came to a halt, with the installation vessel Adventure stuck at port for the past two weeks.

Bad weather this autumn, combined with some technical problems, also pushed out the expected completion of the Meerwind offshore farm to February from the end of this year, said Jens Assheuer, managing director of WindMW, which is building the 288MW project and will operate it.

WindMW is owned 80% by US private equity firm Blackstone, while developer Windland Energieerzeugung holds another 20%.

Construction at Meerwind only came to a complete halt for six days during Hurricane Xaver and the earlier Storm Christian that hit Germany hard in late October, as installation can continue even at wind speeds of up to 12 metres per second, Assheuer said.

But those interruptions related to heavy storms come on top of the 60%-70% bad weather periods that sweep over the North Sea from November to February anyway, he explains.

Operations at the 400MW Global Tech 1 wind park in the North Sea are still likely to start next summer as planned, the project team says – but with a forecast for 17-metre-high waves during Xaver, even the large vessel Innovation used at the construction site had to stay in port.

“We’re haven’t advanced (construction) as planned,” a spokeswoman for Global Tech 1 tells Recharge, and admits that the company is observing the situation and may take measures if it becomes clear that the summer switch-on date cannot be met under current installation plans.