EnBW Baltic 2 Offshore Wind Farm, Germany

The EnBW Baltic 2 offshore wind farm is a 288MW project developed in the German waters of Baltic Sea. Formerly known as Kriegers Flak, the wind farm is EnBW Energie Baden-Württemberg's second project in the German Baltic Sea after the Baltic 1 offshore wind farm, which was commissioned in 2010.

Construction of one of the world's biggest offshore wind farms started with the laying of foundation in August 2013. The first turbine was erected in August 2014 and first electricity was fed into the grid in April 2015. The wind farm was officially put into operation in September 2015.

It is expected to generate 1.2TWh of electricity a year, sufficient to supply for approximately 340,000 households. It is estimated to reduce 900,000t of CO2 emissions a year from the atmosphere. The Baltic 2 wind farm is four times bigger and produces six times more electricity as its predecessor.

EnBW Baltic 2 offshore wind farm location and make-up

The Baltic 2 wind farm is located 32km north of Rügen Island in the western Baltic Sea. Spread across approximately 2.7 million hectares, the wind farm is four times bigger and produces six times more electricity compared with its predecessor, the Baltic 1 wind farm.

The new wind farm consists of 80 Siemens SWT-3.6 wind turbines, with a capacity of 3.6MW each, installed on monopile foundations at water depths between 25m and 35m. The turbine has a rotor diameter of 120m and a hub height of 78.25m.

The turbine foundations are installed between 36m and 55m into the seabed. Approximately 80,000t of steel was used for the foundations. The steel tower is 66m-tall and weighs approximately 256t.

The wind turbines were delivered using the Esvagt Froude offshore service fleet. The turbine components were produced at a number of sites in Denmark and delivered to base port Sassnitz Mukran for further delivery to the plant site. The steel towers, nacelle and rotor blades were stored and preassembled up to three months prior to the start of installation.

The wind farm is controlled and maintained from the control room in Barhöft.

Ownership and financing of Baltic 2 wind farm

European Investment Bank (EIB) granted a €500m loan to EnBW in January 2013 to develop the Baltic 2 offshore wind farm.German power utility EnBW Energie Baden-Württemberg holds a 50.11% stake in the project, while the remaining is held by PGGM. Macquarie Capital acquired a 49.89% interest in the wind farm on 8 January 2015, for €720m (approximately $799m), and sold it to PGGM in June 2015.

Offshore substation and electricity distribution

The offshore substation consists of a 155/33kV transformer, 170kV and 33kV GIS switchyard, protection and control equipment, emergency diesel generators and other major equipment.

The floating substation platform is 40m x 40m, 15m-tall, and weighs approximately 2,650t. Electricity generated by the wind turbines is collected at the substation and the voltage is enhanced from 33kV to 150kV for export.

The wind farm substation is connected to the Baltic 1 offshore platform by a special export cable in order to transmit electricity to the high-voltage grid at Bentwisch (near Rostock).

Contractors involved with the Baltic 2 offshore wind farm development

EnBW awarded the contract for the supply of 80 wind turbines for the Baltic 2 wind farm to Siemens in June 2010. Siemens subcontracted MADESTA for manufacturing and supplying wind tower door frames for the project.

Transmission system operator 50Hertz was responsible for the offshore grid connections in the German Baltic Sea and awarded the contract for monitoring the submarine power cables to Nkt cables.

Alstom was contracted for the installation, erection and commissioning of a self-floating, self-installing offshore substation platform for the Baltic 2 wind farm.

Bladt Industries was awarded the contract for conducting fabrication works for the jacket foundations. The joint-venture of VBMS-Boka was engaged for installing the 57km-long, 150kV export cables.

The joint-venture of HOCHTIEF Construction and Nordsee-GeoSea (DEME) was contracted to assemble major elements of the Baltic 2 wind farm. The joint venture was responsible for the delivery and erection of foundations, and logistics for the construction of the towers and the wind turbines.

General Cable was subcontracted by 50Hertz for designing, manufacturing, supplying and installing two 60km sections of 150kV high-voltage export submarine cables, three single cores of underground terrestrial transmission cables and associated accessories for Baltic 2.

FRS Windcat Offshore Logistics (FWOL) was awarded a five-year contract to provide a Windcat 34-crew transport vessel for transporting crew daily from Rostock town to the wind farm.

In March 2013, Ballast Nedam was awarded a contract for erecting monopile and transition piece foundations as well as providing logistics between the feeder ports in Rostock, Lubmin, and the Baltic 2 offshore wind farm.

Siem Offshore Contractors (SOC), a wholly owned subsidiary of Siem Offshore, was awarded the contract for the installation of the inner array grid cables. SOC engaged JDR for providing pre-commissioning, test and termination services for the project.

ESG supplied a portable cable tank for the replacement cable at the offshore wind farm, while WINDEA Offshore was engaged to provide maritime coordination services.

Ashurst advised Macquarie Capital regarding the acquisition and financing of the Baltic 2 wind farm.