In an effort to lower the price to link projects from the 7GW next Dutch offshore wind expansion to the shore, transmission system operator TenneT and government departments are researching the possibility of building an artificial island in the about 4GW Ijmuiden Far offshore zone.

The island would accommodate a converter and transformer station to which wind farms can be connected.

“ This may be more cost-effective than installing multiple large offshore DC [direct current] platforms,” TenneT says in a release.

Direct current links will need to be used to transport power on a large scale and across greater distances in a cost-effective way.

TenneT already has experience with sub-sea high-voltage direct current (HVDC) links at German offshore wind parks that usually lie far offshore. But those connections do require a separate converter platform to transform alternate current (AC) from wind turbines into direct current (DC) for transportation, rendering grid links considerably more expensive than elsewhere in the North Sea.

The TSO gave details of its plans for future grid connections today after the Dutch cabinet approved an ‘offshore wind energy road map 2030’ that aims at an even more rapid expansion of wind at sea of 7GW between 2024 and 2030 to be tendered off in annual auctions from 2021 on.

The expansion is slated to bring the Netherlands’ cumulated offshore capacity to 11.5GW in 2030, from an expected 4.5GW at the end of 2023, and 1GW operating now.

Out of the planned additional 7GW, the about 4GW Ijmuiden Far offshore zone will be the largest chunk. It is slated to be located about 60-80 kilometres from the coast of the Dutch province of North Holland. The expansion up to 2030 also includes the 1.4GW Hollandse Kust West zone, and the 700MW North of the Wadden Islands site.

A remaining about 900MW could be located in the Hollandse Kust South-West zone, or also be added to Ijmuiden Ver.

Tennet plans to connect the Hollandse Kust West and the North of the Wadden Sea Islands zones via a standardised 700MW design with AC grid links it already uses to transport power from the current 3.5GW offshore expansion through 2023 that includes the Borssele and Hollandse Kust South sites.

The DC links for Ijmuiden Ver would have a higher capacity of 1.2-2GW, the TSO says.

Hydrogen conversion

TenneT adds that a possible artificial island for Ijmuiden Ver would also offer opportunities for converting wind power into hydrogen, facilitating a so-called “Wind Connector’, and creating port and maintenance facilities.

“A Wind Connector to the United Kingdom will make it possible to use the infrastructure for both connecting wind farms and further integration of the international electricity market,” the TSO says.

“This will significantly improve – potentially even double – the usage efficiency of the offshore grid, and will contribute to a reduction of the cost price of offshore wind energy. “

TenneT in February had already raised the possibility of building artificial islands in the North Sea that could connect wind parts to both the UK and the Netherlands.

This is not the same as plans for larger artificial islands in the Dogger Bank zone in the middle of the North Sea that has been proposed by TenneT and other European TSOs for the longer-term horizon (2030-50), in a North Sea Wind Power Hub that would bundle and redistribute up to 100GW of offshore wind power to the Netherlands, Belgium, the UK, Denmark and Germany.

Wind

Dutch 7GW offshore build-up makes artificial islands more likely