Energy islands: Europe’s future energy system

Princess Elisabeth Energy Island fully operational in 2023

With the number of o shore wind farms growing, the traditional way of connecting them to onshore grid will result in an overload of export cables and onshore grid connections. The use of energy islands will solve this issue.

Using energy islands, the wind turbines can be placed further away from the coast and they distribute the generated power between several countries more e ciently. The islands serve as hubs – or green power plants – that gather electricity from the surrounding o shore wind farms and distribute it directly or indirectly through other hubs to the grid of one or more countries. This allows electricity from an area with vast wind resources to be more easily routed to areas that need it the most, while also ensuring that the energy generated from the turbines is utilised as e ciently as possible in terms of demand for electricity.

In 2016, Dutch/German transmission system operator (TSO) TenneT presented its vision for the North Sea Wind Power Hub and took the initiative to set up a consortium. The consortium wants to facilitate the large-scale roll-out and integration of wind energy in the North Sea, far away from the coast, by jointly investigating the possibilities for the realisation of power hubs. The vision of the North Sea Wind Power Hub consortium is based on an internationally coordinated roll-out of so-called ‘Hub-and-Spoke’ projects, where wind farms are connected to centrally located o shore hubs. The hubs are connected to the North Sea countries via cables or pipelines.

Feasibility studies have shown that the hub-and-spoke concept proposed by the consortium is feasible both technically and economically. The centre of the hubs is formed by energy islands, and this way they will play an important role in Europe’s future energy system. They will host other equipment that will enable the system integration of o shore generation and storage into the high voltage grid. The possible application of power-to-x, meaning the conversion of electricity to another energy carrier, such as hydrogen, will also be considered. They could host electrolysers to convert wind power to renewable hydrogen, and energy storage facilities. This will further help align o shore wind with onshore energy demand and islands will also help the physical integration of o shore wind into the energy system by minimising the number of onshore landing points for the energy produced at sea.

Today, the consortium consists of Dutch/German electricity TSO TenneT, Danish TSO Energinet, and Dutch energy infrastructure company Gasunie. Energinet is responsible for the realisation of the two Danish energy islands that were announced last year. They will be able to supply 6GW of power. Denmark will run an auction in 2023 to decide who will build the artificial North Sea Energy Island. Various consortiums have announced that they will submit a bid to construct the island that should be up and running by 2030. In the Baltic Sea, Denmark wants to make Bornholm an energy island in collaboration with Germany (read more on the Danish energy islands on page 36).

The consortium wants to facilitate the large-scale roll-out and integration of wind energy in the North Sea, far away from the coast, by jointly investigating the possibilities for the realisation of power hubs.

Another plan for an energy island was announced last year in Belgium, where

TSO Elia wants to realise the Princess Elisabeth Island. This artificial island is an electricity hub where cables from both the Belgian 3.5GW Princess Elisabeth o shore wind farm zone and future o shore wind farms will come together. The island will also be the first building block of an integrated European o shore electricity grid that will connect various hubs and countries together. For instance, Belgium wants to build additional joint interconnections with Great Britain and Denmark. These will give access to the massive amounts of renewable energy that are needed to make the industry less dependent on fossil fuels in the short term.

The island’s high-voltage infrastructure will bundle the wind farm export cables of the Princess Elisabeth zone together, whilst also serving as a hub for future interconnectors with Great Britain (Nautilus) and Denmark (TritonLink).

The Princess Elisabeth Island will be the world’s first artificial energy island that combines both direct current (HVDC) and alternating current (HVAC). The island’s high-voltage infrastructure will bundle the wind farm export cables of the Princess Elisabeth zone together, whilst also serving as a hub for future interconnectors with Great Britain (Nautilus) and Denmark (TritonLink). These are so-called ‘hybrid interconnectors’ that have a dual function and are therefore more e cient. They facilitate the exchange of electricity between countries and are also connected with gigantic o shore wind farms in the North Sea that will in due course provide Belgium with large volumes of renewable energy.

The energy island will be located about 45km o the Belgian coast. The area set aside for the installation of the electrical infrastructure will be approximately 6ha in size, which is equivalent to about twelve football pitches. The artificial island will be constructed from concrete caissons filled with sand. A small harbour and helicopter platform will also be provided to allow maintenance crews to visit the island. The energy island has received funding from the European Covid Recovery Fund. The Belgian government decided to award the islandwith a grant of approximately USD 107 million.

On 28 February, it was announced that the Belgian consortium TM EDISON (Jan De Nul and DEME) has won the tender for the construction of the Princess Elisabeth Island. The construction of the foundations will begin in early 2024 and will take 2.5 years. After that, the installation of the high-voltage infrastructure can be started. The latter will be necessary for bringing the electricity from Belgium’s future o shore wind zone to shore. Now that the construction contract has been awarded, the design of the island can be finalised. The caissons will be built and installed in 2024 and 2025. These will form the contours of the island. After that, the base of the island will be raised and prepared for the construction of the electrical infrastructure. Elia aims to ensure all wind farms are fully connected to the mainland by 2030.

Chris Peeters, CEO of Elia Group says, “This project is a pioneering one for several reasons. It is the most cost- e ective and reliable way to bring o shore wind to shore. It will be an island that provides options for the future. When we connect it to other countries, the Princess Elisabeth Island will become the first o shore energy hub.” Julie De Nul, Director at Jan De Nul Group, adds, “As a company, we are proud to put our weight behind this project through which we, as a Belgian consortium, can support our country to achieve its climate objectives. The combined experience of Jan De Nul and DEME as o shore specialists in dredging, rock armour and o shore energy is an absolute added value.” “We are looking forward to working together to achieve this technical tour de force. The construction of the world’s first artificial energy island rea rms our country’s expertise in realising complex projects at sea”, Luc Vandenbulcke, CEO of DEME Group, states.

According to Tinne Van der Straeten, Federal Minister of Energy, the Belgian o shore expertise is recognised worldwide, “Belgium has been a pioneer in o shore wind power for fifteen years and is once again demonstrating its expertise today through its first energy island – which is also a world first.” Thomas Dermine, Secretary of State for Recovery, voices, “The multifunctional energy island – which is being subsidised by USD 106 million under the Recovery and Resilience Plan – will be the first of its kind. The expertise acquired by DEME Group and Jan de Nul Group during its construction can be shared around the world to contribute to a lower carbon, more sustainable and more resilient economy as we combat climate change.” i. eliagroup.eu i. northseawindpowerhub.eu i. tennet.eu