Environmental impact assessments for Aflandshage and Nordre Flint Offshore Wind Farms near Copenhagen

NIRAS carries out the EIA in cooperation with eight subcontractors: DCE - Danish Centre for Environment and Energy, GEUS, DNV, BioApp, Profus Naturrådning, Krog Consult, SEMCO Maritime, and DHI.

NIRAS has assisted HOFOR in preparation of scoping reports and preparation of the overall technical project description for both offshore and onshore installations.

NIRAS assistance also involved environmental assessment reports, background reports on a number of topics, documentation and material for public consultations, including ESPOO, and commenting on incoming public consultation responses.

The reporting has been carried out in close dialogue with HOFOR, and NIRAS has also assisted and participated in the dialogue with the authorities, which are the Danish Energy Agency, the Danish Environmental Protection Agency and the affected municipalities, about the EIA and the process.

As a basis for the working process NIRAS has prepared a webGIS solution, which has been used as a dialogue-tool throughout the process and as a basis for the preparation of the numerous maps for the reporting.

Two phases of assessments

The assignment was divided into two phases, and the first phase dealt with a risk assessment of the wind farms' possible impact on aviation safety, regularity and capacity at Copenhagen Airport. The second phase comprised of preparation and implementation of the EIA process of the two wind farms.

Both phases were finalized with submission of the EIA reporting to the authorities by the end of 2020. Remaining work is related to the public consultation and permitting processes.

Marine mammals and birds

The EIA’s assessments on mammals were based on existing knowledge on occurrence and distribution of marine mammals in the area.

In addition, observations of mammals were registered within and in the vicinity of the wind farm areas during eight flight counts of birds from October 2019 to September 2020.

Observations of mammals during the flight counts were used to support the conclusions regarding the occurrence of marine mammals and their use of the area.

The studies on birds included two years of field studies carried out by DCE to assess the potential impacts, i.e. displacement, barrier effects and collision risks. This was done using a combination of visual observations, 3D-tracking by laser range finder and radar-based monitoring.

By these means, data on the migration volume and flight altitude distribution were collected to obtain estimates of species-specific collision mortality from the use of advanced collision risk models.

The degree of potential displacement of waterbirds from the two wind farms was assessed by means of aerial bird counts, using the Distance Sampling line transect method.

The survey aircraft operates along pre-defined transect lines, and observers record birds on either side of the aircraft, strictly following a specified sampling protocol.

The method allows for an estimation of total numbers of relevant bird species within the study area. In other projects, spatial models provided a surface-covering estimation of density at a fine geographical scale.

From evaluations of displacement effects of Long-tailed Duck at the Nysted, Rødsand wind farm site and Common Scoter at the Horns Rev 1 and Horns Rev 2 wind farms, the degree of displacement could be established. Using this information in the Øresund project, a species-specific displacement assessment could be performed.