Energinet Eyes Savings for Bornholm Consumers Through Energy Island Connection

Danish transmission system operator (TSO) Energinet has started onshore field investigations for the Bornholm Energy Island on both Zealand and on Bornholm, and is also working on ensuring that consumers on Bornholm can tap into the energy island’s electricity.

At the beginning of this month, Energinet said it was ready to design the future high-voltage substation so the power grid on Bornholm can be connected to the new electricity connections that will be established between Bornholm Energy Island and its offshore wind farms.


Based on a preliminary analysis, it will most likely be possible to link the Bornholm power grid to the energy island’s electricity infrastructure with a 60 kV connection. The cost estimates of the various technical options are still uncertain, but the most expensive solution is currently estimated to cost an additional DKK 230 million (approximately EUR 31 million) in construction costs.

The analysis has shown it will probably be technically possible to connect the energy island’s power cables to Bornholm’s power grid without compromising stability or security of supply in the overall power grid on Bornholm or elsewhere, and without compromising the overall project’s schedule, Energinet said.

Furthermore, this will result in socioeconomic savings, according to the TSO, which currently pays for a power station on Bornholm to be ready to generate electricity in the event of damage or faults in the subsea cable that connects Bornholm to the power grid on Zealand via Sweden.

Over 40 years, the savings will amount to DKK 676 million (approx. EUR 91 million), converted to present value.

Energinet sais it would now start to develop the technological solutions, which will be “innovative and by no means standard, off-the-shelf products”.

“Connecting a large DC installation with a very high-voltage level to a small local AC power grid with a relatively low voltage level has never been done before. So we need to start a dialogue with market players and researchers as soon as possible on how to best solve the task”, said Kim Søgaard Mikkelsen, Energinet’s project manager for Bornholm Energy Island.

On 11 March, the TSO also announced it was preparing to carry out preparatory environmental studies on Zealand and on Bornholm where underground cables or high voltage stations may be located. 

Energinet, which Energinet is initially investigating a larger area and will determine the final locations later, has sent letters to landowners who have property in the area to notify them about the field investigations that will take place in the period from the end of March until October 2022.

The surveys and the mapping will also be an important part of the basis for the authority’s approval of Energiø Bornholm.

Bornholm Energy Island will be a collection point for green electricity from offshore wind farms in the Baltic Sea. 

On the island, the current must be converted to direct current, which can be transported over long distances by subsea and land cables. Initially, there are plans for an electricity connection to Zealand, just as an agreement has been entered into on cooperation on a possible connection to Germany.

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On Zealand, the new plants will consist of buried cables and a new high-voltage station that connects the power from Bornholm Energy Island to the high-voltage network on Zealand.

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