An aerial photo of the Kårehamn offshore wind farm in Sweden, owned by RWE

RWE completes two surveys for 1.6 GW offshore wind project in Sweden

RWE Renewables has completed geophysical and environmental surveys for the Södra Midsjöbanken offshore wind project in the Swedish part of the Baltic Sea, for which the German-based developer is preparing an application for a Natura 2000 permit.

Illustration; Kårehamn offshore wind farm in Sweden; Photo source: RWE
An infographic on the Södra Midsjöbanken offshore wind project

“Despite some tough winter conditions in the Baltic Sea the project reached this important milestone before the end of the year together with the Dutch contractor N-Sea Group and the Hydrograf vessel. Both the offshore site and cable corridors were surveyed during the offshore campaign”, RWE said via social media.

The data collected through these surveys will be used to continue the permitting process and to further develop the project, according to RWE’s project manager, Anton Andersson.

RWE expects to obtain the necessary permits in 2024/25, subject to the permitting process going according to plan, and to have the offshore wind farm operational in 2027/2028.

With between 100 and 120 wind turbines and a planned installed capacity of up to 1.6 GW, the Södra Midsjöbanken offshore wind farm would have an annual production of 6.5 TWh and could deliver 5 per cent of Sweden’s total electrical consumption, according to the developer.

The project would feature wind turbines of a capacity of between 15 MW and 20 MW each and would connect to the Swedish grid in Nybro, close to Kalmar.

The site being investigated for the wind farm is located on and at Södra Midsjöbanken, an offshore bank situated in the middle of the south-east Baltic Sea, in water depths between 15 and 35 metres. The site is located approximately 70 kilometres south-east of the southern tip of Öland and some 90 kilometres north-west of the northernmost coast of Poland.

Project requested to add Natura 2000 permit

First project plans and investigations started back in 2006 with E.ON Wind Sweden exploring the options for establishing a major offshore wind farm in southern Sweden. This is now RWE, as the company took over all of E.ON’s major renewable energy activities in an asset swap started in 2019 and completed last year.

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Initially, Södra Midsjöbanken, Norra Midsjöbanken and Hoburgs Bank had been considered as potential areas for building offshore wind farms. However, preliminary investigations had shown Södra Midsjöbanken as favourable in terms of coexistence of environmental assets and wind power.

In 2007, the company received a survey licence for bed sampling, peak pressure sounding, and drilling at Södra Midsjöbanken, which was valid until March 2012. The validity of the licence was then extended until 2018 on the grounds of the anticipated need for supplementary surveys for establishing a wind farm in accordance with a construction and operation licence application submitted in February 2012.

In December 2016, the authorities designated an area of more than 10,500 square kilometres in area in the Baltic Sea as a Special Protection Area (SPA) under the Birds Directive. A year later, the same area was designated as a Site of Community Importance (SCI) in accordance with the Species and Habitats Directive. The area includes the offshore banks Hoburgs Bank, Norra Midsjöbanken and parts of Södra Midsjöbanken as well as parts of Öland’s southern bed, which is a smaller offshore bank.

In March 2019, the Swedish Ministry of the Environment requested that RWE’s application for the licence to build and operate an offshore wind farm at Södra Midsjöbanken be supplemented with a Natura 2000 licence.

In December of the same year, the Swedish Maritime Administration’s sea plans for the Gulf of Bothnia, the Baltic Sea, and the North Sea indicated Södra Midsjöbanken as an investigation site for energy recovery with regard to nature and defence interests. The two offshore banks Hoburgs Bank and Norra Midsjöbanken are prioritised for natural environment interests.

The application for the Natura 2000 permit includes carrying out supplementary investigations and surveys, and an environmental impact statement (EIA) that describes the results of the investigations and the intended solutions to ensure a favorable conservation status for protected species and habitats.

RWE screening wider area

In a consultation response relating to the application to build a wind farm at the site, objections were submitted against a specific location within the actual Södra Midsjöbanken offshore bank, stating that this location could have a potential impact on the adjacent Natura 2000 site’s designated habitats and species.

An aerial photo of the Kårehamn offshore wind farm in Sweden, owned by RWE
Kårehamn offshore wind farm in Sweden, owned by RWE. (Built by E.ON and operational since 2013.); Photo source: RWE

Following the response, RWE extended the investigation site to also include deeper offshore areas, primarily west of Södra Midsjöbanken, which could potentially situate the wind farm entirely or partly within the boundaries of the Natura 2000 site.

“Assessments by experts and referral bodies indicate that such a location could be preferable with regard to the wintering bird life at the Natura 2000 site, particularly longtailed duck, which head for the actual offshore ground at depths of less than approximately 20–30 metres”, RWE said in a consultation document from May 2020.

The company said that prior to applying for the Natura 2000 permit it was examining the option of adjusting the location of the wind farm within the extended investigation site, with a view of minimising the impact on natural assets in the area and a number of investigations performed between 2019 and 2020 for this purpose.

The investigation site for the wind farm is made up of two areas covering approximately 490 square kilometres, within which alternative locations for the wind farm are being investigated, with the wind farm itself to take up an area of approximately 200 square kilometres.

The results from geotechnical and geophysical surveys of seabed conditions and foundation criteria within the investigation site, together with surveys of the area’s natural assets that are performed prior to submission of the Natura 2000 application, will govern which wind farm locations are viable and appropriate within the investigation site, RWE stated in the document.

The extent to which the wind farm will be situated within the boundaries of the Natura 2000 site is dependent on its final location. Parts of the cable corridor, which will link the farm site with the Swedish coast in the south-eastern part of Småland, are situated within the Natura 2000 site.

Potential locations within the investigation site, plus the alternative finally selected, will be described in the environmental impact assessment (EIA), which will also contain alternative locations for the project elsewhere.