The Finnish energy company Ilmatar is starting a technical survey of the seabed over an area of 600 square kilometres north of Åland. The planned wind farm is intended to be connected to both Sweden and Finland and is projected to supply around 10 per cent of Finland’s annual electricity consumption.

– This is the operational launch of Ilmatar’s investment in offshore wind power, says Anna Häger, regional manager for Ilmatar Offshore.

The technical surveys of the seabed started by Ilmatar Offshore are within the maritime areas north of Åland that, according to the Åland maritime spatial plan, have been proposed as suitable for offshore wind farms. In total, the area comprises about 600 square kilometres divided into two project areas which, using existing turbine technology, would allow for a wind farm with a capacity of 2.1 GW and an annual output of 10 TWh. Connections to both the Swedish SE3-region and Finland are planned.

– This is the operational launch of Ilmatar’s investment in offshore wind power. The wind farms Stormskär and Väderskär have now formally been given the status as projects for development at Ilmatar, says Anna Häger, regional manager of Ilmatar Offshore.

The Finnish Defence Forces have stated they have no objection to Ilmatar Offshore’s surveys and construction of wind power plants in the areas in question. Survey permission was granted by the Parliament of Åland at the end of August 2022.

The seabed surveys are funded by Ilmatar Offshore and conducted by the Finnish company Arctia, using their ship Kaiku. The preliminary work is projected to be completed by the start of 2023, whereupon the material gathered will be analysed and used as a basis for Ilmatar’s environmental impact assessment.

Launching a seabed survey is a serious investment for Ilmatar Offshore, but it also places the company at the forefront of efforts to develop large-scale offshore wind power in the waters around Åland.

– We are the first to conduct this type of comprehensive technical analysis of the seabed in the waters around Åland. It is an expensive but necessary investment in preparation for a high quality and all-encompassing environmental impact assessment, says Häger.

Arctia are experts in technical marine mapping and utilise several different survey methods – multibeam echosounders, side-scan sonars, sub-bottom profilers, and seismic boomers.

– The surveys will use only acoustic methods, that is to say sound waves, which means we do not physically touch the seabed at all. The instruments all operate at relatively high frequencies with low acoustic power and are entirely harmless to marine animals and vegetation, explains Patrik Niskanen, project manager at Arctia.

The results will consist of high-resolution images of the seabed and information on sub-bottom sedimentation, its underlying bedrock, and water depths across the whole area.

Environmental and marine biologist Stefan Husa, who is the Head of Maritime Spatial Planning at Ilmatar, states that the results of the surveys will greatly impact the shape the project will take.

– The data we will receive from Arctia will be very detailed and will, in the long term, determine where the wind farm as a whole and the individual turbines can and should be placed to minimise their effect on the marine environment, species, and cultural heritage. Without a comprehensive understanding of the seabed environment, any attempts at prognosing the future potential and form of offshore wind farms remain just that – a prognosis. That is why our first step is a technical seabed survey rather than, for example, analysing existing data or collecting easier samples. We are building our knowledge base from the ground up.