People, nature, dikes, ancient sites and monuments, soil, landscape – many factors need to be considered in the location of large onshore facilities

Green transition has a price. Utilisation of the electricity generated by the large offshore wind farm requires high-voltage substations which receive the electricity from the wind turbines and convert it from alternating current into direct current. Such a high-voltage substation has an effect on the landscape, and, in addition to the visual impact, there are many considerations to take when Energinet must find the best suitable location for a new substation. Explains Bent Sømod, Senior Project Manager in Energinet’s Environment and Geoscience Department.

The Danish Energy Agency and the Danish State have identified the locations where large-scale offshore wind farms are to be established. One of the places is in the sea at Rønne Bank south of Bornholm. Bent Sømod has participated in the work which resulted in Energinet pinpointing an area south-west of Aakirkeby for the substation on Bornholm and an area at Solhøj, west of Ishøj, for the substation on Zealand. The substations are absolutely key to ensuring that the electricity from the offshore wind farms can reach the consumers.

“We need to place the facilities so that they don’t have material impacts on the environment, including human health, recreational opportunities etc. It’s an overall, important framework that we always bear in mind,” he says. 

“Our task is then to create technically good solutions that do not cost a disproportionate share of the consumers’ money. For example, this means that it will be best to place the facility on Bornholm close to the offshore wind turbines, because we then save money for cables – the longer the cables, the more expensive they are, and the more landowners will be inconvenienced by the facility and will therefore also need to be compensated for this. As the offshore wind turbines must be located in the sea south of Bornholm, the substation is therefore best located in the southern part of the island.”

Good conditions for a substation
Bent Sømod adds that, precisely in this location, there are large suitable areas and good terrain conditions for establishing a substation. An area of 264 hectares has been designated and, within this area, Energinet must find a suitable site of 70-90 hectares, including based on consultation opinions from landowners and other stakeholders.

“We needed to find an area which inconveniences as few landowners as possible and with as little vulnerable environment as possible – be it protected natural areas, dikes, woodlands and ancient sites and monuments. In addition, there should preferably be as little housing and infrastructure as possible – roads, cables, sewer pipes, district heating etc. The soil conditions and terrain must also be suitable,” says Bent Sømod, and adds: “The area we’ve located is the best place for establishing a location for the substation.”

Considerations for the coastal landscape
Energinet have received many questions – for example why the substation will not be located closer to the coast?
“We’ve chosen to place the substation a little further inland so as not to ruin the coastal landscape. In principle, we could have placed it a little further to the south, i.e. south of Søndre Landevej for those who know the local area, but this would have ruined the view of the sea from the highway. We’ve also been asked why we do not bury the substation underground, but this is technically very expensive and complicated, one reason being that we need to pump out groundwater.”

Similar considerations on Zealand
On Zealand, many similar considerations have been made. It will also be a completely new substation, with the added dimension on Zealand that Energinet needs to connect the facility to the existing 400 kV transmission grid.

“On Zealand, we are at the outskirts of the Greater Copenhagen area, close to residential areas, which means that there are many more considerations and interests that need to be weighed in relation to the use of the areas. Nature protection interests are also great on Bornholm, which is an island with recreational facilities and much nature. However, because the Zealanders in this area have less nature, it is obviously extra vulnerable. We also believe that we’ve found the best location on Zealand. It is a technically good solution, and we’re also trying to find a solution so that the substation will fit in well with the landscape with good shielding, occupy as little space as possible and inconvenience as few people as possible,” says Bent Sømod.

New high-voltage substation in Jutland
Henrik Thomsen is an energy analyst in Energinet, and he has been a project manager on the work to select areas for the large onshore facilities. In addition to Bornholm and Zealand, a high-voltage substation is to be located in Jutland, where the power will come ashore from the North Sea Energy Island. In Jutland, Energinet is pointing at a location at Revsing just north of Vejen. Here, Energinet is already constructing a high-voltage substation for the Viking Link electricity connection.

Energinet is recommending a location at Revsing just north of Vejen for a new high-voltage substation for North Sea Energy Island. The buildings for the converter station for the new Viking Link electricity connection have just been completed.

Many hundreds of hours have gone into identifying the areas. In Jutland, Energinet’s employees have studied six different locations.

“We’ve analysed them on the basis of various criteria – for example environment, technical solutions, consequences for the electricity grid and long-term energy system perspectives. Then we sat down together in a room and locked the door, until the white smoke came out. In completely practical terms, we gave the locations points based on the different criteria, and we found that Revsing is the most advantageous place,” says Henrik Thomsen.

"It is well located in relation to the electricity connections towards north and south. The location does not require reinforcement of the electricity grid. It is also close to the east coast of Jutland where we expect electricity consumption to increase in the future and close to areas where we expect that there may be Power-to-X production. On Zealand, we’ve had similar considerations – it will cost new overhead lines if we choose a different point than Solhøj, and we generally try to minimise the impact with overhead lines.”
"The locations are well considered, and we place the substations where they have as little impact on nature and on as few people as possible. These are robust choices. Even though the world seems to be changing much more rapidly than we expected, our recommendations will remain the same,” says Henrik Thomsen.

Dialogue underway
Energinet is already in dialogue with the affected municipalities regarding the location of the plants. The first public hearing phase will begin this autumn. Citizens will have the opportunity, among other things, to come up with ideas and proposals for the location, architectural design and adaptation of the landscape.

Follow the process here (Danish only)