Europe’s offshore network development plans set out

ENTSO-E has published the first offshore network development plans to support the delivery of Europe’s offshore renewable energy targets.

The new plans, part of ENTSO-E’s ‘Ten-Year Network Development Plan’ (TYNDP) for 2024, are aimed at assessing the offshore transmission infrastructures required to provide visibility and guidance on the integration of the planned growing offshore renewable capacity to the European electricity grid.

Offshore renewables are proposed to become the third most important energy resource in the European power system, providing 18% of the dispatched energy by 2040 and 2050 – sufficient to supply up to 55 million households in 2040.

Moreover, the size of this task and the speed required is huge. As of today, just a small fraction, around 30GW, of the envisaged offshore renewable capacities have been installed.

Have you read?
Action plan for Europe’s grids launched
Site visit: Europe’s biggest offshore wind port

To reach the 2030 ambitions of around 182GW, annual installations of approximately 25.5GW have to be installed, with EU countries needing to deliver 15GW and Norway and Great Britain together 10.5GW each year.

This corresponds to a factor 10 increase in the installation rate, based on Wind Europe’s quoted data of an average annual installation rate during the last 10 years of 2.5GW.

Potential equipment supply chain challenges also may arise. Looking ahead to a 2050 target of almost 500GW of offshore renewables, the plan estimates the need for up to 54,000km of additional offshore network transmission infrastructure routes compared to 2025.

Priority offshore grid corridors

The plan, the subject of eight documents, identifies five priority offshore grid corridors, with the associated infrastructure requirements for each:

• Northern Seas Offshore Grids encompassing the North, Irish and Celtic Seas and the English Channel;
• Baltic Energy Market Interconnection Plan centred on the Baltic Sea;
• Atlantic Offshore Grids encompassing the north Atlantic from Ireland south to Portugal and Spain;
• South and West Offshore Grids in the western Mediterranean;
• South and East Offshore Grids covering the eastern Mediterranean and Black Sea.

The plan foresees the offshore connections in the northern European sea basins, the Northern Seas and the Baltic Sea in particular, developing from point-to-point connections towards a more integrated offshore and onshore network with an increasing share of offshore hybrid interconnections.

Offshore infrastructure in the Atlantic – in this area floating technology is the solution of choice, given the depth limitations – the Mediterranean and the Black Sea will instead be characterised by the radial connection of the offshore renewables and interconnectors.

Overall by 2050 most of the offshore renewables is expected to be connected via radial connections, with about 14% connected via dual purpose hybrid infrastructure and up to 9% connected to more than one jurisdiction.

Modelling assumptions include an average wind farm size of 900MW and 2GW cable capacity by 2040 and a 525kV reference voltage level.

The plan finds that capital expenditures of around €400 billion ($436 billion) are necessary for offshore transmission infrastructure, with the largest proportions, around €150 billion and €120 billion respectively, for offshore DC converters and offshore and onshore DC cables.

The availability of commercially attractive DC circuit breakers is expected to make a difference to the costs and hydrogen also can have a role, especially in the Northern Seas corridor, where it has been identified and is being pursued by some countries.

“We are proud to be presenting the first European Offshore Network Development Plan, as the development of offshore wind generation and strong interconnections across all European sea basins are essential to create a carbon neutral, resilient and cost-effective European energy system,” commented Damian Cortinas, Chair of the Board of ENTSO-E and a senior executive at RTE.

“The deployment of the fit-for-purpose offshore grids is a necessary condition to achieving the European energy transition to carbon neutrality.”

The plan also reviews environmental protection issues and recommends that the development of the offshore network infrastructure should happen in synergy with the protection of the maritime environments in order to achieve a sustainable energy system coexisting with biodiversity.

ENTSO-E also has indicated that in future editions, it intends to further integrate the offshore network development plans into the TYNDP process to enable synchronised planning of the onshore and offshore developments to provide a holistic approach to maximise the benefits of a decarbonised power system.