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Germany's Baltic 1 project: So near and yet so far

Construction of Baltic 1 offers valuable lessons for greater challenges further out to sea.

Germany’s first bona fide offshore wind farm is on track to be switched on this year, after the last of 21 turbines were installed at utility EnBW Energie’s Baltic 1.

Once up and running, the 48.3MW project, located in water depths of just under 20 ­metres off the Darß/Zingst peninsula in the Baltic Sea, is expected to flow 185GWh a year into the national grid — enough to supply 50,000 households.

Construction of Baltic 1 has been an education, says EnBW managing director Werner Götz.

“We believe [offshore wind power] is feasible on an economic scale and [Baltic 1] is partly about proving this is true. We do believe that offshore wind still has some challenges when it comes to the supply chain, so we are looking into finding ways of improving essential links such as logistics,” he states.

The development lies 16km offshore as the crow flies, but sailing distance to the wind farm is 62km. “Even if it shows up in the statistics as near-shore, from an operational or installation standpoint, it is more like a far-offshore project,” notes Götz. “We have structured the whole project on the basis of forming partnerships to help us accomplish this challenge.”

Baltic 1 is the first of a quartet of wind farms on the slate for EnBW. Next up is Baltic 2, which lies 32km offshore in water depths of 30m. It will be made up of 80 Siemens 3.6MW-120 turbines with a combined output of 288MW, and start-up is scheduled for 2012-13.

“When we entered the offshore wind sector [in 2008], we felt Baltic 1 could be state-of-the-art as a wind farm that is in shallow water and is relatively close to shore,” Götz explains.

“We saw that it could be something like a proof of concept from which we could follow the learning curve to move to the more challenging offshore projects such as Baltic 2, and then on to still more challenging ones in the North Sea.”

From a project portfolio in which renewable energy contributed 10% to production, chiefly from hydropower, EnBW has set a target of doubling its total green output by 2020, with offshore wind — in the form of ­Baltic 1 and 2, along with the North Sea’s He Dreiht and Hohe See — seen as “a significant component” in the resource mix.

In May, the supervisory board rubber-stamped the lead-off investment in Baltic 2 as the next step in its €3bn ($3.85bn) plans to build up production of about 1.2GW off Germany.

“To meet these targets, we are basically spending the profits from our fossil-fuel, nuclear and hydropower units,” says Götz. “We need to do this in order to invest in the future.”

Construction of Baltic 1 started in May, with the monopile foundations, supplied by Erndtebrücker Eisen­werk (EEW), piled in by A2Sea’s Sea Worker installation vessel using a giant hydraulic hammer that drove the 37-metre, 215-tonne pieces 20 metres into the seabed.

The 25-metre, 250-tonne transition pieces, fabricated by EEW in Ålborg, Denmark, were installed next, followed by the arrival of A2Sea’s Sea Power sheer-leg crane vessel, which was assigned to lift the towers, nacelles and rotors into place.

EnBW opted to use Siemens’ workhorse SWT-2.3MW-93 turbines for Baltic 1. The 140-tonne machines, which have a rotor diameter of 93 metres, were linked up via 45km of NKT-supplied intrafield lines to the offshore substation, which was delivered by WeserWind and kitted out with ABB electrical equipment.

Installed by Bonn & Mees’ floating crane vessel Matador, in tandem with Sea Worker, the 900-tonne steel substation topsides are set on a 1,450-tonne monopile and transition piece outfitted with an “ice cone” skirting to protect it against ice floes.

Wind and waves will place extraordinary strains on Baltic 1, with gusts of more than 120km/h and 5.5-metre whitecaps buffeting the turbines and substation.

Power will course through a 150kV three-phase export cable to an onshore substation at Bentwisch, then flow on to the German grid.