Denmark's government has agreed to take a majority stake in a £25bn artificial "energy island" which is to be built 80km offshore, in the middle of the North Sea.
The island to the west of the Jutland peninsula will initially have an area of 120,000 square meters - the size of 18 football pitches - and in its first phase will be able to provide three million households with green energy.
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It will be protected from North Sea storms on three sides by a high sea wall, with a dock for service vessels taking up the fourth side.
In a broad deal struck on Wednesday night, the Social Democrat government agreed with its support parties and the rightwing opposition that the state should hold a 51% stake in the island, with the remainder held by the private sector.
"This is truly a great moment for Denmark and for the global green transition," Denmark's climate minister Dan Jørgensen said in a statement.
"The energy hub in the North Sea will be the largest construction project in Danish history. It will make a big contribution to the realisation of the enormous potential for European offshore wind."
The project builds on an inter-party deal struck in June on energy policy, in which the parties agreed to construct two wind energy hubs, one artificial and another centred on the Baltic island of Bornholm.
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The two hubs will initially support 5GW of wind generation, triple Denmark's current installed offshore wind, with this later expanded to as much as 12GW.
In the text of the agreement, the parties warn that the North Sea island might be difficult to complete before 2033, meaning it might not help Denmark reach its ambitious 2030 target of cutting greenhouse gas emissions by 70% from 1990 levels.
But the text calls on the government to work with private sector partners to try to accelerate the process so that it can be brought online earlier.
The government has committed to launching discussions with windfarm developers and other companies and investors "as soon as possible", with the aim of developing a legal framework for tendering for the remaining 49% stake.