Energinet puts the check mark on the construction activities in connection with the connection of Thor Offshore Wind Farm off Nissum Fjord. The construction work has been underway for just over two years and has been completed on time.
A big step on the road to the green transition. That's what you could call the construction work for the connection of the new upcoming Thor Offshore Wind Farm.
Energinet's part of the Thor project is complete, and that means that green electricity for 1 million households can be fed into the electricity grid.
Two new 220 kV high-voltage substations. One of Denmark's largest under-drilling contracts and 30 kilometers of power cables are ready for operation.
Energinet's task was to establish the technical facilities so that the green electricity from the future offshore wind farm can come from the collection point near the coast and into the national electricity transmission grid - and from there on to Danish electricity consumers and customers abroad.
Power for 1 million households
The offshore wind farm being built in the North Sea by the German energy company RWE will have a capacity of approximately 1000 MW. This means that it can cover the consumption of up to one million households with green electricity. It is Denmark's largest offshore wind farm to date.
"In Energinet, we are now ready with our part of the project, so that we can help the green electricity out into the country. This will happen through our station in Idomlund and out onto the high-voltage grid to consumers in both Denmark and our neighboring countries. It is a huge milestone that we have been looking forward to. The project is a good step on the road towards the green transition that we are working on in Denmark," says Søren Dupont Kristensen, Chief Operating Officer at Energinet.
Among Denmark's largest subsea drilling contracts
The THOR project has laid just over 30 kilometers of 220 kV cables, which will transport the electricity from the offshore wind turbines' transition station Volder Mark to the high-voltage station Idomlund near Holstebro.
"Electricity infrastructure may not always be such a visible part of the green transition. The cables are also buried in the ground between Volder Mark and Idomlund, which is a new, large hub in the high-voltage grid - but electricity connections are absolutely crucial for us to create an electricity system with more renewable energy and transport, for example, electricity produced at sea around the country," says Martin Hinrichsen, Chief Project Manager at Energinet.
The project is one of Denmark's largest underground drilling contracts. Due to environmental requirements, seven of the 30 kilometers had to be established via controlled underground drilling, instead of buried cables in the ground. And since there are two cable systems with three cables in each, a total of just over 42 kilometers of pipes have been drilled into the Jutland soil, distributed over a total of 264 individual drillings of varying lengths. The rest of the cable system is buried in the ground in the normal way.
Finished on time despite several setbacks
Energinet has finished on time, despite several challenges along the way. The weather has been rainy, and the environmental approval came late – not until 2022 – so there was no room for further delays in the schedule. The war in Ukraine led to a shift in the supplier market, which affected time and finances.
"The environmental approval had many restrictions because there were several areas with vulnerable nature. This meant that we had to drill under some of the cables, and then there was also the stork Keld, who had settled in Bækmarksbro. He was monitored day and night and Energinet was not allowed to work in the area from March to October. Therefore, it is with an extra good feeling that we can now deliver the project on time. I am really proud of the great effort that the entire team has made", says Martin Hinrichsen.
The expectation is that the first of a total of 72 wind turbines at Thor Offshore Wind Farm can begin delivering electricity in 2026. RWE should have the entire park up and running by the end of 2027.
Facts
Thor Offshore Wind Farm is being established in the North Sea off Nissum Fjord, at least 20 kilometers out to sea. The offshore wind farm, which is being built in the North Sea by the German energy company RWE, will have a capacity of approximately 1000 MW (1 GW). This will be able to cover the consumption of up to one million households with green electricity.
Energinet makes it possible to connect Thor Offshore Wind Farm to the electricity grid using two new 220 kV high-voltage stations (one at Idomlund near Holstebro and one at Volder Mark in close proximity to the west coast) and 30 kilometers of electricity cables.
Energinet began construction work in January 2023. More than 95,000 cubic meters of soil have been moved to build the station in Idomlund. This required just over 150 220kV cable drums. A 220kV cable drum including cable weighs an average of 25 tons. Each 220kV cable is an average of 1256 meters long.
Idomlund in its entirety, with voltage levels of 400kV, 220kV and 150kV, is one of the largest high-voltage stations and it will grow even larger. Today it is 172,500 m2, which is equivalent to 24 football fields. Thor's part of the station (220kV) covers 65,500 m2. The highest point on the high-voltage station is the lightning arrester masts, which are 25 meters high. Over one kilometer of fencing has been erected around the station in Idomlund.
The three transformers, which are located at the 400 kV high-voltage station, transform the voltage from 220 kV to 400 kV. They each weigh 300 tons. 87,000 liters of transformer oil have been poured onto each transformer, which corresponds to approximately 75 tons per transformer.
