Technical University of Denmark: Major cost savings in construction of coming energy islands

The future energy islands in the North Sea and at Bornholm are important elements in Denmark’s green transition. The work with their construction has now entered a phase in which the design of the solutions is beginning to take shape, initially for the Bornholm energy island.

A new large joint project between partners from the entire value chain behind energy islands expects to play a decisive role in this connection. Over the coming four years, the project—headed by Professor Jacob Østergaard from DTU—will deliver tangible specifications for the design of the solutions to be used on the energy islands.

“We’ve never built an energy island before, so—based on our previous research and the combined knowledge of the group of partners—we will be testing a number of different technologies. This will be done both in the PowerLabDK laboratory at DTU—which is directly connected to the Bornholm energy system—and by preparing a test site on the Bornholm energy island. On this basis, we will develop the solutions that will form part of the energy islands,” says Jacob Østergaard, DTU Wind and Energy Systems.

The other project partners are Aalborg University, Siemens-Gamesa Renewable Energy, Green Hydrogen Systems, SuperGrid Institute, Cenergy Holdings, Energy Cluster Denmark, Energinet, and Ørsted.

Focus on Power-to-X and stability
The project focuses on three different areas which are important to clarify before the energy islands are constructed.

One area is related to the stability of the electricity system. The energy islands differ from our current electricity grid in that they consist entirely of converter-based turbines and DC connections without large stabilizing power plants. This results in much faster fluctuations and thus a requirement for electronic control that can react at a similar speed to avoid risks of outages in the European electricity grid.

The second area is to develop solutions for how Power-to-X—which converts the power from the wind turbines into, for example, hydrogen—can best be incorporated in the energy islands. There are several aspects that need to be examined, including how Power-to-X solutions can be included on the energy islands or in connection with the individual wind turbines with services that can actively contribute to stabilizing the energy islands concurrently with the production of hydrogen.

Finally, the third area is to develop the requirements for the wind turbines and wind farms that are connected to the energy islands. The requirements must be redesigned because the energy island wind turbines are not connected directly to our electricity grid—unlike the current wind turbines—but are connected to the surrounding countries through large DC connections. Therefore, the turbines do not have to meet the same strict requirements as those applicable to today’s wind turbines.

“The work with the three tracks will take place in parallel, and the end goal is that the developed solutions will cut the costs for construction of the two energy islands by at least DKK 20 billion,” says Jacob Østergaard.

The recommendations from the project will be published and communicated to the stakeholders on an ongoing basis, so that the developed solutions can be included in public procurement procedures and construction of the energy islands. All solutions will be developed with a view to future-proofing the energy islands, so that the construction of the first energy islands can provide a basis for future expansion with more islands and even more offshore wind power.

The future energy islands in the North Sea and at Bornholm are important elements in Denmark’s green transition. The work with their construction has now entered a phase in which the design of the solutions is beginning to take shape, initially for the Bornholm energy island.

A new large joint project between partners from the entire value chain behind energy islands expects to play a decisive role in this connection. Over the coming four years, the project—headed by Professor Jacob Østergaard from DTU—will deliver tangible specifications for the design of the solutions to be used on the energy islands.

“We’ve never built an energy island before, so—based on our previous research and the combined knowledge of the group of partners—we will be testing a number of different technologies. This will be done both in the PowerLabDK laboratory at DTU—which is directly connected to the Bornholm energy system—and by preparing a test site on the Bornholm energy island. On this basis, we will develop the solutions that will form part of the energy islands,” says Jacob Østergaard, DTU Wind and Energy Systems.

The other project partners are Aalborg University, Siemens-Gamesa Renewable Energy, Green Hydrogen Systems, SuperGrid Institute, Cenergy Holdings, Energy Cluster Denmark, Energinet, and Ørsted.

Focus on Power-to-X and stability
The project focuses on three different areas which are important to clarify before the energy islands are constructed.

One area is related to the stability of the electricity system. The energy islands differ from our current electricity grid in that they consist entirely of converter-based turbines and DC connections without large stabilizing power plants. This results in much faster fluctuations and thus a requirement for electronic control that can react at a similar speed to avoid risks of outages in the European electricity grid.

The second area is to develop solutions for how Power-to-X—which converts the power from the wind turbines into, for example, hydrogen—can best be incorporated in the energy islands. There are several aspects that need to be examined, including how Power-to-X solutions can be included on the energy islands or in connection with the individual wind turbines with services that can actively contribute to stabilizing the energy islands concurrently with the production of hydrogen.

Finally, the third area is to develop the requirements for the wind turbines and wind farms that are connected to the energy islands. The requirements must be redesigned because the energy island wind turbines are not connected directly to our electricity grid—unlike the current wind turbines—but are connected to the surrounding countries through large DC connections. Therefore, the turbines do not have to meet the same strict requirements as those applicable to today’s wind turbines.

“The work with the three tracks will take place in parallel, and the end goal is that the developed solutions will cut the costs for construction of the two energy islands by at least DKK 20 billion,” says Jacob Østergaard.

The recommendations from the project will be published and communicated to the stakeholders on an ongoing basis, so that the developed solutions can be included in public procurement procedures and construction of the energy islands. All solutions will be developed with a view to future-proofing the energy islands, so that the construction of the first energy islands can provide a basis for future expansion with more islands and even more offshore wind power.

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