The European Union (EU) has set an ambitious target of generating 300 GW of offshore wind (OSW) by 2050, a significant jump from the currently installed 16 GW capacity. OSW energy has become a key element for countries bordering the North Sea and the Baltic Sea in reducing their dependence on Russian energy imports in the current geopolitical situation while achieving the EU’s Green Deal objective of carbon neutrality by the middle of the century. In September 2022, Belgium and the other seven countries of the North Seas Energy Cooperation (NSEC) including Denmark, Germany and the Netherlands jointly announced that they had set an OSW capacity target of at least 76 GW by 2030, 193 GW by 2040 and 260 GW by 2050. As part of the joint statement, Belgium has agreed to a non-binding target of 6 GW of OSW capacity by 2030 and 8 GW by 2040.

Building a future-proof electricity grid that includes onshore and offshore interconnectors will thus be critical building blocks for meeting the OSW energy goals for countries in the region. A key project being undertaken to accelerate OSW energy development in the North Sea is the development of a multi-functional artificial energy island in the North Sea, which is being built by Belgium’s transmission service operator Elia with a proposed capacity of 3.5 GW. Through its subsidiaries in Belgium (Elia Transmission Belgium – ETB) and northeastern Germany (50Hertz), the Elia Group operates 19,276 km of high-voltage connections and is one of Europe’s top five transmission system operators (TSOs).

To be located approximately 45 km off the Belgian coast, the proposed energy island is an innovative project that will combine both high voltage direct current (HVDC) and high voltage alternating current (HVAC). The island’s high voltage infrastructure will bundle the wind farm export cables from Belgium’s new wind production zone in the North Sea, the Princess Elisabeth zone, while also serving as a hub for future interconnectors with the UK (Nautilus) and Denmark (Triton Link). Thus, the island will act as a hybrid interconnector by not only bringing renewables from the Princess Elisabeth zone, but also creating the opportunity to trade renewable energy with Denmark and the UK.

OSW development in Belgium

Despite having only 67 km of coastline, Belgium’s success in the OSW sector can be attributed to the early designation of exclusive zones for OSW. Belgium’s latest Maritime Spatial Plan (2020-2026), which came into force in March 2020, provides for the development of a new wind power production zone in the Belgian part of the North Sea: the Princess Elisabeth zone, which aims to almost double the energy capacity (from 10 per cent of Belgium’s electricity needs at the end of this year to 20 per cent by 2025/2026).

In October 2021, the Belgian government announced that it would expand the OSW capacity of the Princess Elisabeth zone from 1.75 GW to 3.5 GW. Together with the existing offshore wind farms, Belgium’s OSW capacity is envisaged to increase to 5.8 GW (from 4.4 GW previously) by 2030, more than two and a half times the current OSW capacity. Belgium’s first OSW zone,
which has a capacity of 2.26 GW and comprises eight wind farms, was completed in 2020.

The Princess Elisabeth zone will be awarded through a competitive bidding process that will give winners concessions for developing and installing OSW parks west off the Belgian coast. The zone consists of three separate areas – Noordhinder Noord, Noordhinder Zuid and Fairybank. The federal government plans to hold the first tender for this zone in 2023.

To ensure coordinated transmission connection to the zone, in December 2021, Belgium’s Federal Council of Ministers approved the planned extension of the Belgian Modular Offshore Grid (MOG II) and its integration of the future Princess Elisabeth wind farm zone. This approval confirmed that energy islands are the most appropriate solution for integrating additional OSW energy into the system.

Construction details of the energy island

The Princess Elisabeth island will occupy an area of approximately five hectares above the waterline. The artificial island will be constructed from concrete caissons filled with sand. A high wall will protect the island from strong waves, winds, rain and flooding. A small harbour and helicopter pad are also planned to be built for maintenance teams.

Elia will next install the transmission infrastructure, including converter substations that will help transform voltages to minimise grid losses. The island will collect HVAC power from OSW farms, transform it partly to 220 kV and to direct current electricity and then export it to Belgium’s onshore grid as well as to Denmark and the UK through subsea cables. For the latter, the landing points of the interconnectors with the UK and Denmark will be constructed. The connection of the wind farms to the Elia grid is linked to the commissioning of two onshore grid reinforcement projects: Ventilus and Boucle du Hainaut. The island will mainly house transmission infrastructure that will be linked to new wind farms (with maximum capacity of 3.5 GW) and will form part of connections to future interconnectors. The island will be linked to the mainland via approximately 300 km of AC cables and 60 km of HVDC cables.

Elia also plans to adopt a nature-inclusive design and undertake various measures to minimise the impact of its activities on the marine ecosystem. Along with a group of experts, it is working on a smart design for this island, which will have positive effects on the local environment. Norway’s independent energy experts and certification body, DNV GL, is supporting ETB by undertaking an independent assessment of the energy island’s design, providing inputs to Elia on improvements required to minimise construction and operation risks. The tender process for the island is under preparation along with the environmental impact assessment, permitting procedure and application for a concession of public space. The construction of the island is due to start in 2024 and the island is expected to be completed in mid-2026.

From then on, construction of the electrical infrastructure on the energy island will start. As mentioned earlier, the government will facilitate the construction of future OSW projects through a series of tenders. ETB aims to have the full connection capacity of the new OSW farms by 2030. Funding from the European Commission’s (EC) Recovery and Resilience Facility will be used for the development of the island. The Belgian government has sought EC approval for its plan to utilise EUR100 million for the energy island from the facility.

The hybrid interconnector projects

The two HVDC interconnectors that are planned as part of the energy island project are the Nautilus link and the Triton link.

The Nautilus link is planned for interconnecting the Belgian and UK power grids. The two power grids are already connected via the Nemo link interconnector, which has been operational since 2019. In 2020, Elia and UK’s National Grid Ventures (NGV), the international arm of the UK TSO National Grid, decided to build the Nautilus link as a hybrid interconnector. The EC, which recognises the project’s importance in a European context, has already called Nautilus a project of common interest (PCI). The EC notes that hybrid projects can be an intermediate step towards a fully meshed electricity grid with multiple offshore nodes, which is necessary to fully utilise the potential of the North Sea and exchange sufficient electricity.

The Nautilus project would include underground cabling works and onshore infrastructure, located in East Suffolk. Nautilus is expected to connect up to 1.4 GW of OSW and facilitate a connection of up to 2.8 GW of OSW – with 1.4 GW being imported to Britain and 1.4 GW being exported to Belgium. The link between the UK and Belgium will exceed 100 miles end to end. The project is still at an early study phase with construction expected to take place between 2025 and 2028. Elia and NGV are currently carrying out the necessary regulatory studies and market-related and technical studies needed to make the construction of Nautilus possible. These studies will have to determine, among other things, which route the interconnector will take, both on land and in the North Sea.

Meanwhile, for the Triton link, Elia and its Danish counterpart Energinet signed a new cooperation agreement in November 2021 to continue collaborating on the implementation of what could become a world’s first: a subsea connection between two artificial energy islands. The Triton link project will facilitate the exchange of power between the two countries and at the same time transport electricity from OSW farms to the mainland using hybrid technology. The new hybrid interconnector will be an innovative and challenging project, both because of the distance it will cover (more than 600 km) and the technology involved. The Triton link will give Belgium direct access to the large volume of renewable energy that it needs to decarbonise its energy-intensive industry and meet European climate targets. The construction of the Triton link will take approximately four years and is due to be completed in 2030.

Elia’s transmission investments

In recent years, as a system operator, the Elia Group has been investing large sums in the development of its onshore and offshore high-voltage grid to support the integration of renewable energy into the system and in the construction of interconnectors to facilitate the integration of the European energy market. The group has set a capex plan of EUR9.6 billion for the next five years, which includes a capex of EUR4 billion in Belgium and the rest in Germany.

ETB has been carrying out important on-grid reinforcement works along the existing Belgian 380 kV backbone. Particularly, the commissioning of the 380 kV Ventilus and Boucle du Hainaut projects each with a transmission capacity of 6 GW are vital for connection with the energy island. The Ventilus project involves the construction of the 90-km Stevin−Izegem/Avelgem (Kustlus) line while the Boucle du Hainaut or the Hainaut Loop project comprises the new 80-km Avelgem−Courcelles overhead line. Both projects are scheduled for commissioning in 2028.

For the offshore grid connection, Elia had initially planned the 220 kV MOG 2 system for integrating up to 4.4 GW of OSW capacity from the Princess Elisabeth zone. However, in 2022, ETB re-initiated its offshore system integration study taking into account the additional capacity of the zone. Tendering for this project is now expected after mid-2023. The project is scheduled for commissioning by 2030, to export the first power from the Princess Elisabeth island.

Outlook and way forward

Going forward, with the growth in OSW, subsea interconnectors that contribute to the further integration of the European electricity grid will become key to meeting EU OSW targets. However, more measures will be needed to scale up hybrid interconnectors in the region. According to Elia, some of these include reviewing the criteria and increasing the size of EC’s Connecting Europe Facility (CEF) funding available for PCIs and other funds to support hybrid interconnectors, simplifying and speeding up permitting processes, ensuring national marine regulations are harmonised and developing regional win-win partnerships via memoranda of understanding. To boost the development of new projects, Elia Group urges the EU to set ambitious hybrid offshore interconnector targets and to set up a task force of TSOs, OSW developers, industrial suppliers and regulators to standardise technical parameters for hybrid interconnectors and OSW projects.

Elia’s energy island is expected to form part of the first steps being taken across Europe to build an integrated offshore electricity grid in the North and Baltic seas. The establishment of an offshore grid will play a major role in making the EU’s Green Deal a reality, as well as encourage the use of a more efficient technology.