Powering Clean Competitiveness

POWERING CLEAN COMPETITIVENESS

FOREWORD

THE VIRTUOUS CIRCLE OF OFFSHORE WIND BENEFITS

→ Reaching fair agreements regarding the distribution of costs and benefits for joint offshore projects is one of the biggest challenges that lies ahead.

Dear reader,

A virtuous circle is a positive cycle of events, where each step contributes to the success of the next. In the context of offshore wind energy, this means that overcoming one challenge makes it easier to tackle the next. For example, implementing risk-reduction strategies can lower project financing costs, so attracting more private investors, and ultimately accelerating Europe’s transition to net zero.

This forward-thinking mindset is typical of how we at Elia Group operate. As the owner of two system operators in Belgium (Elia Transmission Belgium) and Germany (50Hertz), we are fully committed to accelerating the energy transition in order to help Europe meet its climate targets. Our strategic presence in the North and Baltic Seas – Europe’s prime hubs for offshore wind – puts us in an excellent position to develop projects that are speeding up the Union’s decarbonisation.

Our commitment to the transition has already led to groundbreaking projects such as the Kriegers Flak - Combined Grid Solution: the world’s first hybrid interconnector that links Germany to Denmark. In Belgium, Elia is currently constructing Europe’s first artificial energy island. These solutions will be indispensable as Europe works to fully harness the potential of its seas and successfully fight climate change.

The speed at which our projects are realised is not just important for the climate; given current geopolitical tensions, Europe’s establishment of a more independent and resilient energy system has never been more important. Decarbonisation and electrification go hand in hand – and to make them a reality, we need strong and future-proof grid infrastructure.

Whilst our goal seems clear, fulfilling it is not without its challenges. Indeed, Europe’s offshore renewable energy potential is not evenly distributed across the continent. Some countries have an abundance of offshore renewable energy that far exceeds their domestic demand, while others do not have enough to meet their needs. Reaching fair agreements regarding the distribution of costs and benefits for joint offshore projects is one of the biggest challenges that lies ahead. If we want Europe to maintain its position as a global leader in offshore energy, collaboration will be key.

To maximise our success, we are investing an unprecedented €26.8 billion in our infrastructure over the next three years. Of this, €7.5 billion will be allocated to our activities in Belgium, and €19.3 billion will be allocated to our activities in Germany. Significant parts of these sums will go towards offshore development.

This brochure outlines our offshore projects – both those that have been completed, and those which are in progress. It demonstrates how our work is carried out with efficiency, safety, and innovation at its heart, and how we are helping to shape the offshore grid of the future.

Enjoy the read!

Bernard Gustin, CEO of Elia Group

In October 2024, Elia Group launched a vision paper, “Going Like The Wind”, on unlocking the clean energy potential helped by Europe’s seas. The study offers a comprehensive perspective on bridging the gap between the continent’s current offshore wind capacity and its targets, highlighting the need for a coordinated approach.

The analysis for this study calculated the potential outcome of fully unlocking the benefits of international collaboration, derisking investments, and an effective approach to offshore spatial planning. From 2030 to 2050, this could produce savings for the European energy system that amount to more than €1,000 billion.

Elia Group urges the new European Commission to take prompt action and adopt a new approach to the distribution of costs and benefits that better reflects actual electricity flows. Moreover, maintaining the current status quo would not only put clean competitiveness at risk, it would also mean missing out on significant efficiency savings.

→ There is a pressing need for Europe to create a framework that encourages increased investment, enabling us to remain technical leaders in offshore wind.

I believe we have the potential to establish several ‘Silicon Valleys’ across Europe that focus on offshore wind. Imagine dedicated hubs for turbines, cables, platforms, and vessels, amongst other asset components. What a great opportunity that would be for innovation and job creation across the European continent.

Bernard Gustin

CHARTING EUROPE’S CLEAN ENERGY TRANSITION

2020: European Green Deal

A package of policy initiatives whose ultimate goal is to enable the EU to reach climate neutrality by 2050. The Green Deal Industrial Plan, which aims to provide a more favourable environment for the scaling up of the EU’s manufacturing capacity related to net zero technologies and products, was published in 2023.

2021: FIT FOR 55

A legislative package which focuses on ensuring all sectors of the EU’s economy work towards meeting its target of reducing its net greenhouse gas emissions by at least 55% (compared with 1990 levels).

With the ambitious aim of achieving net zero emissions by 2050, the European Union’s energy policy is supported by key frameworks such as the Clean Industrial Deal and the REPowerEU plan. Positioning itself as a global leader in offshore energy development, the EU’s offshore energy policy plays a crucial role in reinforcing its energy security, the competitiveness of businesses, achieving its climate targets, and transitioning to a sustainable, low-carbon energy system.

The EU wants wind to be 35% of Europe’s electricity by 2030. Currently, wind is 19% of Europe’s electricity. Aligned with the EU’s broader commitment to diversifying the energy mix, offshore wind has become a key pillar in the EU’s strategy to reduce carbon emissions and enhance energy security.

Published in response to Russia’s invasion of Ukraine, this plan aims to diversify Europe’s energy supply, save energy, and produce clean energy, so reducing the EU’s dependence on Russian fossil fuels.

2022-2023: North Sea Summits

Two summits held in Esbjerg, Denmark (May ’22) and Ostend, Belgium (April ’23), which saw politicians, heads of state, and industry leaders committing to transforming the North Sea into Europe’s biggest power plant.

With a goal to increase offshore wind capacity to 300 GW by 2050, the aim is to unlock the full potential of Europe’s offshore wind resources, particularly in the North Sea and the Baltic Sea. The EU’s policies on offshore energy reflect its dedication to green energy innovation, energy security, and economic growth.

Offshore wind is expected to reduce electricity prices in the long run. Increasing the supply of renewable energy, which includes offshore wind, can help to lower the overall cost of electricity. Additionally, the EU’s Wind Power Package launched in October 2023 is a game-changer for Europe’s wind industry. Among others, the plan includes measures to accelerate wind energy deployment, improve auction design, and provide access to finance. As the industry scales up and technology improves, the costs of producing offshore wind energy are expected to decrease, further contributing to lower electricity prices.

2023: Green Deal Industrial Plan

The plan aims to enhance the competitiveness of Europe’s net zero industry and so accelerate the Union’s transition to climate neutrality. It does so by fostering a more favourable environment for the scaling up of the EU’s manufacturing capacity with regard to net zero technology and products. A light reform of the EU’s electricity market design is included.

2023: European Wind Power Action Plan

2023: EU Action Plan for Grids

Part of the EU Wind Power Package, this plan outlines 15 actions that can be quickly taken by the EU Member States and industry to strengthen Europe’s wind energy industry, enabling it to meet its climate and energy goals.

Aims to address the main challenges in expanding and better using EU electricity transmission and distribution grids. It identifies concrete short-term measures to help unlock the needed grid investment for the European energy transition.

During the 2023 North Sea Summit in Ostend, Elia and 50Hertz were among the signatories of the Offshore Renewable Industry Declaration. The latter states that whilst Europe’s offshore industry welcomes Europe’s commitments, it recognises that more can be done.

The declaration calls for large-scale investments in infrastructure and human capital to be undertaken, alongside the modernisation of permitting and financing processes and the fostering of political and industrial partnerships.

2024: Baltic Sea High Level Energy Security Meeting

Highlighted the region’s commitment to sustainable energy production, emphasising the importance of offshore wind potential in the Baltic Sea region. In the spotlight are infrastructure development and security.

2025: Clean Industrial Deal

A comprehensive approach to ensure that Europe’s industries can thrive while contributing to the global fight against climate change, setting a regulatory framework for decarbonisation, clean technologies, and incentivised investment.

2022: REPowerEU

ELIA GROUP COMMITS TO IMPROVING OFFSHORE RENEWABLE INDUSTRY

ELIA GROUP’S OFFSHORE PROJECTS A LARGE PORTFOLIO OF CUTTING-EDGE PROJECTS

Over the past two decades, Elia Group has acquired a high level of expertise in offshore development.

Beyond our portfolio of cutting-edge projects and techniques, we help to shape regulatory frameworks and European policy through official networks and the regular publication of position statements and research papers.

In addition to Elia and 50Hertz’s regulated work in Belgium and Germany, Elia Group also offers energy consultancy and engineering services to international clients through Elia Grid International (EGI). WindGrid, our newest subsidiary, was established to act as a conduit for the experience that we have gained over the past couple of decades in building and operating high-quality offshore assets. WindGrid is therefore working with governments, grid operators, and renewable energy developers, helping to further the energy transition abroad through the planning and construction of offshore grids (see page 40).

We are currently witnessing an international race to implement projects that accelerate the energy transition. This is putting immense pressure on the supply chain and the availability of sufficient technical skills.

Combined with rising material costs and inflation, this has led to a significant increase in overall expenses. In some instances, the cost of specific equipment has even doubled. As a result, we are seeing unprecedented market prices for direct current infrastructure.

We at Elia Transmission Belgium are ready to fully cooperate with all involved parties to weigh up different concepts and implement appropriate measures, if necessary. By working together, we can navigate these challenges and contribute to a successful energy transition.

Frédéric Dunon,

Elia Transmission Belgium

ELIA’S OFFSHORE PROJECTS IN BELGIUM

PRINCESS

CEO at

→ The Nemo Link interconnector is an excellent example of an asset that contributes to all dimensions of the energy trilemma. Nemo Link has had world-class operational performance since it started operations in 2019. It has also outperformed commercially, which was to the direct financial benefit of consumers. I’m proud to have been part of this amazing international team and company from day one.

BELGIUM’S FIRST HVDC OFFSHORE INTERCONNECTOR

Nemo Link, Belgium’s first submarine HVDC interconnector, which links the country to the UK, celebrated its sixth anniversary at the end of January 2025 with an outstanding operational and commercial performance. This success led to the reimbursement of over €200 million to consumers in both the UK and Belgium by 2024. A joint venture between Elia Transmission Belgium and National Grid Ventures (the UK), the interconnector facilitates an increased integration of renewables, increases security of supply, and leads to lower prices overall.

The interconnector was Elia’s first construction project involving High Voltage Direct Current (HVDC), which is best suited to exchanging electricity over long distances. Its cables, running a distance of 140 km from Richborough (Kent) in the UK to Herdersbrug (Bruges) in Belgium, are linked to converter stations and high-voltage substations in both countries, allowing electricity to flow in either direction.

With a capacity of 1,000 MW, Nemo Link also helps to facilitate security of supply, balance out electricity grids, and limit price spikes. The interconnector’s operational performance during its first six years is among the best in the world for this type of asset, having already saved an estimated 1.4 million tonnes of carbon by 2024.

NEMO LINK

→ Thanks to our driven and highly skilled teams, the MOG could be completed on time and on budget. Elia looked beyond Belgium’s borders to find the right people for the project. The combination of internal and external experience was a real success. A strong team spirit developed. This enabled us to move mountains because everyone believed in the project.

MOG

ELIA’S FIRST OFFSHORE ELECTRICITY PLUG

The commissioning of the Modular Offshore Grid (MOG) six years ago marked a true milestone in offshore wind development in the Belgian part of the North Sea, as evidenced by His Majesty King

Philippe’s visit in September 2019 as part of its inauguration. Fully operational since 2020, the MOG has enabled Elia to gain unique and internationally recognised experience in the offshore sector.

The high-voltage switchyard platform, which is located 40 km off the Belgian coast, bundles electricity generated by four offshore wind farms together and then transmits it to Stevin, the high-voltage substation in Zeebrugge, through three export cables. Together, these four wind farms (Rentel, Northwester 2, Mermaid, and Seastar) can generate up to 8 TWh of green electricity per year, which amounts to approximately 10% of the electricity demand in Belgium – so helping the country to meet its climate targets. The MOG has transported more than 14.75 TWh of carbon-free electricity to Belgium since it was commissioned and boasts an impressive availability rate (99.998% in 2020 and 100% in the other years).

The MOG’s design is more efficient and environmentally friendly than previous (radial) approaches to the connection of offshore wind farms to electricity grids: its design saved on the use of over 40 km of cabling that would have been needed if each wind farm had been connected to Stevin independently. Having three cables also guarantees that, should one of the cables become temporarily unavailable, wind power can continue to be transported to the mainland.

KEY FACTS

SUCCESSFUL REPAIR OF RENTEL WIND FARM CABLE

In January 2024, the MOG cable connecting the Rentel platform to the Belgian mainland suddenly failed. The fault was located just below the Rentel transformer platform, where the cable enters the high-voltage platform. Carrying out repair work at this location was very challenging and complex. A new section of cable to replace the damaged cable, approximately 400 m long, was attached to the platform and connected to the existing cable under the seabed. Special lifting techniques involving ships and divers were used. To connect the new and existing cables, an offshore rigid joint was used that was repositioned on the ground 30 m below sea level. As the operation could only be performed during an extended period of low wind, it took approximately four months to complete the repair work. During this time, the four connected wind farms were still able to generate electricity as they are part of the meshed offshore high-voltage grid via Elia’s offshore power hub, MOG.

→ In early 2024, the offshore grid once again demonstrated its worth when, despite the failure of one of the export cables connecting the Rentel wind farm to the mainland, a record amount of electricity from the four wind farms was brought onshore.

We are grateful to Elia for repairing the cable under difficult circumstances, thanks to its teams’ expertise, knowledge, and drive.

Markus Berger, Chief Infrastructure Officer at Elia

Mathias Verkest, CEO of Otary

→ Princess Elisabeth Island in the Belgian North Sea is a unique project that will play a leading role in the country’s energy transition. It will allow us to harvest the full potential of renewables in the modest space available in our waters. My team and I are very proud to be on the frontline of this exciting initiative and are fully committed to delivering the project in the best way we can with the highest regard for quality and safety.

Tim Schyvens, Offshore Programme Manager at Elia

PRINCESS ELISABETH ISLAND

THE WORLD’S FIRST ARTIFICIAL ENERGY ISLAND

In December 2021, the Belgian government approved the development of the world’s first artificial energy island: the Princess Elisabeth Island. The latter will be located in the centre of the Princess Elisabeth Zone (PEZ) – Belgium’s second offshore wind zone in the North Sea.

The island is an electricity hub which will act as a link between new offshore wind farms in the PEZ and Belgium’s onshore grid. The AC substations on the island will bundle all the cables from the offshore wind farms and transmit the electricity generated via a meshed grid of six alternating current (AC) cables to the Belgian mainland. This ensures security of supply to the windfarms to get their produced electricity to the consumption centres. When completed, the island will give Belgium access to offshore wind energy produced by the wind farms in the PEZ and in the future, it might become a building block of an integrated European offshore grid.

The area occupied by the energy island above the waterline will cover 6 hectares, with its area across the seabed stretching up to a maximum of 25 hectares (equivalent to 37.5 football pitches).

The island, which is being constructed by Belgian companies, Jan De Nul and DEME, will be made of sand and will be surrounded by an outer perimeter of concrete caissons (see page 16). A tall wall will also be built to protect the transmission infrastructure housed on the island from being flooded during rough sea conditions.

The island will be linked to the mainland via six HVAC export cabling systems

230 m x 520 m

The island’s size above water is 6 hectares of useful surface area

the Princess Elisabeth Island Project. Earmarked for the realisation of the first phase of the project, the agreement further broadened ETB’s financing portfolio, allowing Elia and customers to benefit from lower interest rates compared to other solutions, while advancing Europe’s transition from fossil fuels to green energy.

As the energy island will inject a large amount of electricity into the Belgian onshore high voltage grid, two reinforcement projects of the electricity backbone are being realised: Ventilus and Boucle du Hainaut.

In February 2025, due to the unprecedented price increase for high voltage direct current (HVDC) infrastructure and a changing market context, Elia temporarily postponed the signing of the HVDC contracts for the Princess Elisabeth Island. This will give the newly elected Belgian government and all parties involved more time to reach a consensus decision. While discussions on alternative feasible plans continue, construction of the artificial island (foundations) and implementation of the already-signed alternating current (HVAC) contracts remain on track, meaning that two of the three future offshore wind farms (700 MW + 1,400 MW) – representing 60% of the new Princess Elisabeth wind zone – can already commence.

Project receives substantial EU support

In October 2024, a €650 million green credit facility agreement was signed between Elia Transmission Belgium (ETB) and the European Investment Bank (EIB) for

The signing ceremony took place at the island’s caisson yard in Vlissingen, in the presence of the then-Belgian Minister of Energy, Tinne Van der Straeten; the Head of the European Commission Representation in Belgium, Thomas de Béthune; and various diplomatic dignitaries from countries around the North Sea. The EIB’s support highlights ETB’s leading role in connecting offshore wind capacity to Europe’s onshore grid and strengthening the integration of the European energy market. The project is also backed by the REPowerEU initiative, which aims to reduce Europe’s reliance on fossil fuel imports and accelerate the shift to sustainable energy.

Additionally, as a flagship project within Belgium’s recovery and resilience plan following COVID-19, the island project was endorsed by the Belgian federal government in December 2022 as the spearhead project for the EU COVID-19 recovery fund which had been established in the midst of the pandemic for a greener European economy and sustainable growth. The project secured a €99.7 million grant from the European Recovery and Resilience Facility.

→ We finance projects that push the boundaries of what is possible, and the Princess Elisabeth energy island is a real testament to our commitment to a more sustainable future in Europe. And at the same time, the development of such projects creates jobs and continues to position Europe as a leader in the global green economy. From our perspective, this is more than just an energy project. It symbolises innovation, determination, and a shared vision of a sustainable future.

Robert de Groot, Vice President at the European Investment Bank

→ The caissons - which form the contours of the Princess Elisabeth Island - are being built by the contractor TM Edison, a Belgian consortium that includes DEME and Jan De Nul. We need 23 of these caissons to completely surround the island. During good weather in 2025, the first caissons will be floated to their respective spots where they will then be ‘sunk’. These operations require a great deal of precision. We are looking forward to it!

Valérie Daloze, Head of Programme Management at Elia Asset

→ With a fantastic team at Elia, we are building the first man-made energy island, consisting of huge concrete blocks known as ‘caissons’ which will be filled with locally dredged sand. This island will be a robust foundation facilitating electrical cables and substations, protecting Elia’s assets against 1000-year storms.

Pierre-Yves Guillermin, Package Manager Princess Elisabeth Island at Elia

KEY FACTS

3D

Construction and installation of the concrete caissons

The caissons are huge concrete structures which will form the contours of the island and provide stability in extreme offshore conditions. There are 23 caissons being constructed for the Princess Elisabeth Island. Each caisson measures 57 m (length) by 28 m (width) by 22 m (height), and weighs 22,000 tonnes, excluding fill.

The construction of these caissons is taking place in the port of Vlissingen in the Netherlands. Each caisson is constructed across 5 different stations, with each station involving a lead time of about 20 days. All the caissons are carefully transferred between the stations through a combination of heavy lifting with hydraulic jacks and a skidding technique.

To begin, the floor slab, measuring 30 m by 57 m (and 80 cm high), is cast at the first station. Containing about 350 tonnes of steel that is braided manually by about 100 technicians, the floor slab weighs 3,500 tonnes. After at

least two weeks, the floor slab is ready and moved to Station 2. Here, for eight to ten days at a time, a sliding formwork slides up an average of 10 cm per hour daily. After at least two weeks, the walls of the caisson are slightly more than 20 m in height.

At Station 3, the pipes that will receive the power cables on the island – known as J-tubes – are installed. Once the J-tubes have been installed, the caisson is moved to Station 4 where the roof plate will be installed. At the last station, 10 m high storm walls, which will protect the island from extreme storms, are installed.

After Station 5, the load out takes place: the caisson is pushed onto a semi-submersible barge that will launch the caisson a little further out into the harbour, where the water is deep enough. The caissons are then towed to a local wharf where they remain until weather conditions allow them to be transported out to sea and installed.

Furthermore, before the caissons can be installed on-site, the seabed is prepared via pre-construction dredging and the installation of several layers of rock to provide

sufficient stability. When the caissons are installed, they will be filled with locally dredged sand (2.3 million cubic metres) and the inside of the island will be completely reclaimed. When the island is sufficiently compacted, it will be ready to have the electrical infrastructure installed on it, including transformer stations and a huge number of cables.

Nature-Inclusive Design

Since the PEZ lies in a Natura 2000 site in the North Sea, Elia wants to go beyond mitigating the impacts that the island will have on the marine ecosystem. It is working closely with nature conservation experts and scientists to explore how the island can have positive impacts on the surrounding area through the use of Nature-Inclusive Design. See page 47 for more information.

50Hertz is the only transmission system operator that connects wind farms off both German coasts to the German extra-high voltage grid. We have now built up a capacity of over 1.8 GW in the Baltic Sea and are currently constructing the infrastructure for our fifth offshore project, Ostwind 3. In the future, we will also be present in the North Sea; planning for the 2 GW grid connection LanWin3 has begun, and contracts for converters and cables have already been concluded.

50Hertz thinks and acts on a European scale. Together with Energinet, we have put the world’s first hybrid interconnector, Kriegers Flak - Combined Grid Solution, into operation. Furthermore, together with our Danish neighbour, we want to realise Bornholm Energy Island, located in the Baltic Sea, as an innovative cross-border project with an electricity hub on it that has significantly more transmission capacity. This is not only a technical but also a regulatory challenge for the partners involved.

We also want to work more closely with the Baltic states and realise the Baltic WindConnector project together. There is still a lot of potential in the Baltic and North Seas. 50Hertz is doing its part to tap this potential and achieve the statutory expansion targets for offshore wind energy on time and on budget.

Stefan Kapferer, CEO of 50Hertz

50HERTZ’S OFFSHORE PROJECTS IN GERMANY

→ During the replacement of the land cable, the grid connection to the existing interconnector was always guaranteed. Nevertheless, with the new extra-high-voltage direct current cable on the German side, KONTEK continues to stabilise European grid infrastructure, secure the electricity supply in Germany and southern Denmark, and ensure the continuous integration of renewable energy into our electricity grid.

FIRST INTERCONNECTOR TO LINK GERMANY TO DENMARK

Germany and Denmark have been connected since 1995 via a point-to-point DC interconnector: KONTEK. Elkraft – a Danish transmission system operator which was Energinet’s predecessor – was responsible for building the interconnector, which runs from Bjæverskov on the Danish island of Zealand, via the landing point on the German mainland, to the substation in Bentwisch near the city of Rostock.

After about 25 years in operation, the subsea section of the cable, which is 150 km long, had reached the end of its operational capacity and was replaced by Energinet. The interconnector had been designed and constructed before the liberalisation of the European electricity sector, meaning it was not as flexible as required in the modern age.

The replacement of the land section of the cable in Germany, which is 50Hertz’s responsibility, was officially approved by the Mecklenburg-Western Pomerania authorities in February 2022 and completed in the summer of 2023.

INTERCONNECTOR

Dr. Clemens Unger, Offshore Project Manager at 50Hertz

→ Installing the first offshore grid connection (Baltic 1) and subsequently operating it, as well as being allowed to connect the second wind farm (Baltic 2) to the grid directly afterwards, were major challenges for 50Hertz and our partners. The pioneering work done, the experience gained from the installation and operation of the assets, and our good teamwork with the wind farm operator EnBW are valuable ingredients that we have implemented and further developed in subsequent projects.

BALTIC 1 / BALTIC 2

FIRST CONNECTIONS TO WIND FARMS IN THE BALTIC SEA

50Hertz’s first projects that involved building offshore infrastructure were Baltic 1 and Baltic 2. These connections link two offshore wind farms in the Baltic Sea to the German onshore grid.

The Baltic 1 offshore wind farm, which was built and is operated by the energy company EnBW, is Germany’s first commercial offshore wind farm. It lies approximately 15 km off the coast of Mecklenburg-Western Pomerania, north of the Darß peninsula. On 2 May 2011, the then-Chancellor Angela Merkel attended the inauguration of the wind farm in Zingst.

The construction of the grid connection for the wind farm was an offshore first for 50Hertz. The wind farm comprises 21 wind turbines and the Baltic 1 offshore substation, which is used by both 50Hertz and EnBW. The substation steps up the voltage of the electricity generated by the wind farm from 33 kV to 150 kV; following this, 50Hertz’s subsea cable system transports the electricity across a distance of 60 km to Markgrafenheide, to the east of Ros-

tock. From there, the power is transported to the onshore substation in Bentwisch via a 14 km land cable, where it is then fed into the 50Hertz transmission grid.

The Baltic 2 wind farm, which is also operated by EnBW, has been connected to the grid since 2015. Baltic 2 is located 32 km to the north of the island of Rügen. The wind farm covers an area of 27 square km and can generate 1,200 GWh of electricity for approximately 340,000 households every year – saving 900,000 tonnes of CO2 in the process. Baltic 2 is connected to the 50Hertz grid via the Baltic 1 cable system and three other subsea cables.

336.3

Marian Mügel, Offshore Cable Manager at 50Hertz

→ The MIO allows us to make optimum use of offshore assets for the integration of wind into the system and make optimum use of the interconnector for the exchange of energy between Germany and Denmark. The MIO is a blueprint for future innovative offshore control systems for AC and DC grids.

Dr. Anne-Katrin Marten, Head of Operational Systems Management at 50Hertz

KRIEGERS FLAK

COMBINED GRID SOLUTION

THE WORLD’S FIRST SUBSEA HYBRID INTERCONNECTOR

The Kriegers Flak – Combined Grid Solution (KF-CGS), which was inaugurated in 2020, connects Denmark and Germany. The interconnector, which gives both countries access to offshore wind produced in the Baltic Sea, is the first hybrid offshore interconnector in the world. It allows electricity to be traded between Germany and Denmark and, at the same time, is connected to three offshore wind farms, making the wind power they generate available for cross-border electricity trading. No comparable project has yet been completed anywhere else in the world.

Dr. Henrich Quick, Head of Offshore at 50Hertz, shares more about this groundbreaking project.

What are the key benefits and significance of the KF-CGS?

Dr. Henrich Quick: The KF-CGS efficiently integrates wind power from offshore wind farms into the electricity grid. By connecting the German and Danish offshore wind farms, this innovative project allows for better utilisation of offshore infrastructure. When wind conditions are favourable, the grid infrastructure transports wind power, and during low wind periods, it facilitates electricity exchange between Germany and Denmark. It adds additional security of supply for Zealand (Denmark) and is a black start option for Germany in case of a blackout.

The interconnector has a transfer capacity of 400 MW, enabling significant cross-border electricity trading. This helps in balancing the supply and demand of electricity between the two countries. Interconnectors are highly needed in order to balance the systems in highly volatile power markets. Thus, the KF-CGS is a significant step towards a more integrated and sustainable European energy market.

How does the KF-CGS enhance the offshore sector?

Dr. HQ: For the first time ever, an offshore power grid connects wind farms located in two different countries. The KF-CGS links together the German wind farms Baltic 1 and Baltic 2, and the Danish wind farm Kriegers Flak, establishing the world’s first hybrid offshore electricity grid. Two subsea cables, each 25 km long and with a capacity of 200 MW, allow for fossil-free energy to be shared between Denmark and Germany. Jointly owned and operated by Energinet (Denmark) and 50Hertz (Germany), the European Commission provided funding for the CGS through a Grant Agreement and has recognised it as a Project of Common Interest.

Furthermore, the project utilises innovative technology: a newly developed Master Controller for Interconnector Operation (MIO), which maximises feed-in from wind farms and controls electricity exchange between grids. This ensures that the generated wind power is efficiently integrated into the electricity grid.

KF-CGS is the first hybrid interconnector and has opened the field for other hybrid interconnectors to be built. The learnings from this project provide important experience on how to shape the markets, and share liabilities and risks between partners. We tested these aspects in real life for the first time here, and the project exemplifies strong European cooperation between partners.

What are your reflections on the five-year milestone of the KF-CGS?

Dr. HQ: KF-CGS is a pioneering hybrid interconnector project that offers several valuable lessons in terms of technical and operational challenges. Firstly, hybrid interconnectors are effective and add significant value by enabling the integration of renewable energy sources and enhancing energy security. Additionally, they operate reliably. Secondly, many insights gained from operating KF-CGS, the initial hybrid interconnector, remain relevant and transferrable to future projects. Thirdly, technological development is progressing much faster than anticipated, with innovations such as Voltage Source Converter (VSC) technology and 525 kV XLPE cables driving the development of more efficient and powerful systems.

Thus, KF-CGS has laid a strong foundation for future hybrid interconnectors, contributing significantly to the integration of renewable energy sources and enhancing energy security across Europe.

→ Working with our Danish partners was a great success. We will be able to use the experience we have built up with them as we continue to expand our offshore activities and further connect offshore wind in an efficient and flexible manner to different countries. Through the KF-CGS, we have demonstrated that we have the technology and the necessary project knowledge to harness the full potential of the Baltic Sea.

Dr. Henrich Quick, Head of Offshore at 50Hertz

→ The elimination of a complete 90 kmlong cable system not only meant that an enormous amount of resources was saved (raw materials, time, budget), but also meant that we significantly reduced the amount of areas that the project impacted, including those located in ecologically sensitive areas such as the Bay of Greifswald. We were thus able to successfully demonstrate that economic and ecological considerations do not have to contradict each other, but can, in fact, complement each other.

Dr. Wolfgang Thießen, Project Director Ostwind

50HERTZ’S FIRST SHARED CABLING PROJECT

The Ostwind 1 project, which was finished in 2019, was a first for 50Hertz. It involved building three cables for two offshore wind farms in the Baltic Sea, with one of these cables being a shared cable.

Ostwind 1 connects the Wikinger and Arkona wind farms to the 50Hertz grid, transporting the electricity they generate in a highly efficient, safe, and sustainable manner. The wind farm developers and 50Hertz oversaw the construction of the offshore substations for each wind farm together.

impact of the project on the environment. This unique approach was only made possible due to the collaborative partnership that 50Hertz established with the two wind farm developers.

OSTWIND 1

One of the project’s cables is used to transport the electricity generated by Wikinger to shore, whilst another is used to transport the electricity generated by Arkona to shore. The third cable is connected to both wind farm offshore substations, allowing the electricity from them to be transported to 50Hertz’s onshore grid.

The Ostwind 1 project was the first of its kind for 50Hertz. It prevented the construction of a fourth cable – due to the fact that the cables leading from the offshore substations to the onshore substation have a transmission capacity of 250 MW – resulting in cost savings and a reduction in the

The project involved several international partners working together: Wikinger was constructed by Iberdrola (from Spain), whilst Arkona was constructed by Eon (from Germany) and Equinor (from Norway). Moreover, the two offshore substations for the wind farms were manufactured in France and Spain and the supplier of the cable systems, Prysmian, manufactured them in Italy and Finland.

The wind farms were commissioned in 2018 and 2019, earlier than planned due to 50Hertz’s work on the cabling systems, and they have been running steadily ever since.

In terms of time, quality, and budget, Ostwind 1 was, and still is, a success story.

Together, Wikinger and Arkona comprise 130 wind turbines and have a combined nominal capacity of 735 MW

Ostwind involved 50Hertz building three cables for two offshore wind farms in the German Baltic Sea

The three cables that link Wikinger and Arkona to 50Hertz’s grid have a transmission capacity of 250 MW each

at 50Hertz

→ The completion of the Ostwind 2 project will provide another substantial contribution to the delivery of offshore wind energy to households and businesses in Germany. The execution of this technically complex project reinforces the position of 50Hertz in the offshore infrastructure environment.

HARNESSING WIND ENERGY OFF THE COAST OF RÜGEN

Ostwind 2 comprises the construction of cables for two offshore wind farms located to the northeast of the island of Rügen: Arcadis Ost 1, built by Parkwind from Belgium (now owned by JERA); and Baltic Eagle, built by Iberdrola from Spain. Whilst closely related to the Ostwind 1 project, Ostwind 2 uses the latest innovative techniques in offshore development.

50Hertz built three 220 kV subsea cable systems for the project. They were laid in 2021 and 2022 and run parallel to the Ostwind 1 cable systems, joining the German mainland via the same landing point in Lubmin.

Both Arcadis Ost 1 and Baltic Eagle are now connected to the 50Hertz grid via these three cable systems and were fully commissioned in summer 2024. The Arcadis Ost offshore substation was installed in June 2022, with its first wind turbines feeding electricity into the onshore grid

in February 2023; it was commissioned in the autumn of 2023. Also in February 2023, the Baltic Eagle offshore substation was successfully installed at sea and the cables were connected a few months later. The Baltic Eagle wind farm is due to meet the electricity demand of half a million homes, so saving 800,000 tonnes of CO2 each year.

OSTWIND 2

→ Ostwind 3 will contribute an additional 300 MW towards German and European climate targets and is the first project for which 50Hertz carries full responsibility for the offshore wind farm platform. Our project team is also responsible for the OST-6-1 grid connection, allowing us to create synergies. I am extremely proud of the team and their outstanding work –they have taken on these projects and challenges with high levels of commitment and a sense of enjoyment for what we are achieving.

Manuel Wildmann, Technical Project Manager at 50Hertz

FIRST OFFSHORE SUBSTATION FULLY OWNED BY 50HERTZ

Ostwind 3 is 50Hertz’s third offshore grid connection project that relates to wind farms located to the northeast of the island of Rügen. However, the project marks the first time that 50Hertz will carry full responsibility for and ownership of the offshore substation that is built for an offshore wind farm.

OSTWIND 3 OSTWIND 4

The above follows a new regulation from the German Federal Maritime and Hydrographic Agency (Bundesamt für Seeschifffahrt und Hydrographie), which stipulates that transmission system operators are to bear full responsibility for offshore substations which enter into operation from 2026 onwards. Despite this development, cooperation between wind farm developers and transmission system operators will remain very important.

The Windanker wind farm, which Ostwind 3 will connect to the onshore grid, will be located to the north of the Wikinger and Arkona wind farms (see Ostwind 1 project on page 26) in the Westlich Adlergrund Cluster. The route of the cabling system for Ostwind 3 will therefore largely follow the same route as the cables for the Ostwind and Ostwind 2 projects. However, unlike for Ostwind 1 and 2, the cables for Ostwind 3 will land at a new substation which will be built in Stilow on the German mainland.

A 220 kV three-phase AC cable with a transmission capacity of 300 MW will be used for Ostwind 3, which is due to be commissioned in 2026. After obtaining all necessary permissions, the work for laying cables both onshore and offshore, as well as constructing the onshore substation near the city of Greifswald, is ongoing. The offshore substation OSS Jasmund is under construction at shipyards in the Netherlands.

HVDC OFFSHORE GRID CONNECTION

50Hertz will be using DC technology to build its next generation of offshore grid connections in the joint Standards 2 GW/525 kV. Ostwind 4 will be the first HVDC offshore wind grid connection system in the Baltic Sea. The wind farms that will be connected to Ostwind 4 will be able to supply as much wind energy as Wikinger, Arkona, Arcadis Ost 1, Baltic Eagle, and Windanker combined (see pages 22-23 and 26-27). 50Hertz signed contracts with NKT for the HVDC cable and with GE Vernova/ Drydocks World for the construction, engineering, and installation of both an offshore and an onshore converter station.

Elia Group has a lot of experience with HVDC technology in offshore development; for example, Nemo Link (pages 10-11) uses HVDC. Moreover, other offshore HVDC projects such as Bornholm Energy Island (pages 38-39) are being planned.

→ As 50Hertz’s first HVDC connection in the Baltic Sea, the Ostwind 4 project makes an important contribution to Germany’s goal of developing 30 GW of offshore wind capacity by 2030. 50Hertz is using its extensive experience from AC offshore wind grid connections and interconnector projects to realise the next generation of offshore wind grid connections. More power can be transmitted across fewer cable routes, reducing the impact on the environment.

Tamara Landgraf, Programme Manager –Ostwind 4 at 50Hertz

→ One particularity of the OST-6-1 project is that the team involved is also in charge of the Ostwind 3 grid connection [see page 30]. Managing two projects at the same time means that synergies can be created, and efficiency can be encouraged across both. I’m proud of how committed the team is to ensuring both projects are a success.

Marc Riudalbas, Programme Manager AC Offshore at 50Hertz

CONNECTING GERMANY TO A 927 MW WIND FARM IN THE BALTIC SEA

The OST-6-1 project involves connecting 50Hertz’s onshore grid to an offshore wind farm located approximately 15 km north of the Fischland-Darß-Zingst peninsula. Once completed, the offshore wind farm will be huge: it will have a nominal capacity of 927 MW.

The OST-6-1 project encompasses the construction of:

• three AC cable systems, which will include onshore and offshore sections and be up to 88 km in length each;

• two offshore substations (OSS Darß; OSS Zingst), both connected via a 220 kV cable, forming a mini grid to transport the generated power in the most efficient way;

• a new onshore substation in Gnewitz, 30 km to the east of Rostock in Mecklenburg-Western Pomerania.

In December 2022, the Dutch-Belgian consortium HSM Offshore Energy, Smulders, and Iv-Offshore & Energy was officially awarded the contract to construct the two offshore substations for the project. As of the summer of 2023, 50Hertz had awarded the contracts for the construction of the project’s cables to Hellenic Cables and Jiangsu Zhongtian Technology Submarine Cable. 50Hertz has submitted the planning approval application for cable installation onshore, offshore, as well as for the offshore platforms. The onshore substation in Gnewitz is already permitted.

→ The innovative concept of this programme aims for nothing less than kicking off a new era of offshore wind development in Europe. The set-up in HVDC multi-terminal technology will be a major step forward towards our overall vision of creating a meshed DC offshore grid that increases security of supply and cost efficiency, while at the same time reducing the use of maritime space. This will be key for achieving the German and European offshore wind expansion targets.

Stefan

CONNECTOR NORTH SEA

Bornholm Energy Island

50HERTZ GAINS ACCESS TO THE GERMAN NORTH SEA

The North Sea Connector project will, for the first time ever in 50Hertz’s history, connect its onshore grid to two offshore wind farms located in the North Sea. The project, parts of which will be jointly built by 50Hertz and TenneT, includes two main strands: the North Sea Connector 1 Program and the North Sea Connector 2 Program.

0-6 Ostwind 3

1

Ostwind 2

Ostwind 4 Ostwind 1

The North Sea Connector 1 Program will involve the construction of an onshore section (the NordOstLink) and an offshore cable system (LanWin3), complete with an offshore HVDC substation for one offshore wind farm. The North Sea Connector 2 Program will comprise an onshore cable system (DC32) and an offshore cable system (LanWin6) that will include a second HVDC substation for another offshore wind farm.

Bentwisch

Rostock Gnewitz/ Dettmannsdorf

Kemnitz/ Brunzow

Lubmin Stilow

Güstrow

The NordOstLink will run from the west of Schwerin (the capital of Mecklenburg–Western Pomerania in 50Hertz’s control zone) to a multi-terminal hub in the area near Heide on Germany’s North Sea coast, which lies in TenneT’s control zone, and to which LanWin3 will be connected. 50Hertz and TenneT will construct both the NordOstLink and the multi-terminal hub together, safely connecting their HVDC networks via the latter.

The multi-terminal hub, or DC switchgear, will be among the first of its kind in Europe. It will sit between the HVDC converters of both 50Hertz and TenneT’s systems, deviating from the classic ‘converter-pair’ configuration which has been used to date. The hub will be connected to 50Hertz’s offshore cable system Lanwin3 and to TenneT’s offshore cable system LanWin2, which will each connect one wind farm to the mainland. The technology for the multi-terminal hub is being developed by an innovation partnership that includes key contributors from the HVDC converter industry.

The NordOstLink, for which both 50Hertz and TenneT will be the final permit holders, is currently undergoing a fasttrack approval process led by the German authorities. This faster process – which applies to grid construction – was implemented by the German Government in 2023. It followed emergency regulations that the European Union adopted at the end of 2022 to speed up the permitting process for renewable energy projects. As of the summer of 2023, the auction process for the site connected to LanWin3 had been completed.

The exact route of the cables as part of the North Sea Connector 2 Program is currently being planned out. To accelerate the energy transition, and encourage a reduction in the number of permitting processes that grid expansion projects must undergo, the DC32 part of the program has been included in the permit procedure for the NordOstLink. LanWin6 will then be linked to the 50Hertz control zone via DC32, so connecting another 2 GW offshore wind farm from the North Sea Cluster to its grid.

NORTH SEA CLUSTER

The North Sea Connector project is one of several projects that aim to link future offshore wind farms in the North Sea to Germany’s onshore grid. In addition to 50Hertz and TenneT, Amprion is also exploring projects that would connect it to the offshore North Sea Cluster zone.

Westhues, Programme Manager for the North Sea Connector at 50Hertz

PLATFORM LANWIN3 (SIEMENS ENERGY/DRAGADOS OFFSHORE)

→ By connecting Bornholm Energy Island to the Danish and German grids, it is possible to fully exploit the potential for offshore wind energy production around the island of Bornholm. At the same time, the island will contribute to the establishment of a meshed offshore grid in the Baltic Sea. Indeed, its hub design will enable further interconnectors and offshore wind farms to be connected to it in future.

BORNHOLM ENERGY ISLAND

ENERGY HUB IN THE BALTIC SEA

Drawing on the experience gained through their work on the Kriegers Flak - Combined Grid Solution project (see page 24), 50Hertz and Energinet are, once again, collaborating on a distinctive project in the Baltic Sea. The Danish island of Bornholm – which is located 88 km from the German coast and 135 km from the Danish coast – will be transformed into an important power hub. It will provide electricity to consumers in both countries, depending on the market and demand in Germany, Denmark, and Europe more widely.

As part of the project, a hybrid interconnector will be built; this HVDC connection will run across 200 km from the island of Zealand in central Denmark, via Bornholm, to the coast of Mecklenburg-Western Pomerania in northeastern Germany. A joint energy hub with converters and substations for the distribution of electricity to either country will be built on Bornholm itself. The energy hub will therefore allow electricity to be traded between both countries, including green electricity generated by two Danish offshore wind farms which will be built off the coast of the island.

In June 2023, the German and Danish governments signed an agreement which allows Energinet and 50Hertz to allocate responsibility for different tasks related to the realisation of the energy hub, including the construction of the several hundreds of kilometres of offshore and onshore cable systems. As stipulated in the agreement, both transmission system operators will split the infrastructure costs for the project, the target renewable energy amounts produced by the offshore wind farms, and the congestion revenues linked to the cables leading to either country in an equal manner.

Dettmar-Wilhelm Knieriem, Programme Manager –

Bornholm Energy Island at 50Hertz

BALTIC WINDCONNECTOR

PROVIDING EUROPE WITH OFFSHORE WIND ENERGY FROM THE BALTICS

50Hertz and its Baltic States counterparts, AST, Elering, and Litgrid, are further progressing in outlining their plans to build a hybrid interconnector: the Baltic WindConnector. As well as joining Germany to the Baltic States, if the project goes ahead, this interconnector will be linked to large offshore wind farms located off the Baltic States’ coasts. In addition to enabling cross-border electricity trade, including offshore wind power, both the Baltic States and Central Europe will benefit from increased security of supply. Moreover, the interconnector will provide the Baltic States with the opportunity to become an exporter of green electricity to the European electricity market whilst enabling Germany to diversify its green electricity supply as it aims to achieve climate neutrality by 2045.

A first agreement relating to the Baltic WindConnector was signed during the Baltic Offshore Wind Forum in May 2023. The signing parties were 50Hertz and its counterparts from Estonia, Latvia, and Lithuania. In this, the four partners pledged to foster their cooperation with a view to integrating increasingly higher levels of renewable energy into their grids – ultimately, by establishing a meshed offshore grid off the coasts of the Baltic States.

In April 2024, the energy ministers from all Baltic Sea countries signed the Vilnius Declaration, which underlines the strong support for enhanced cooperation and hybrid offshore grid development in the Baltic Sea region.

→ The energy transition is most efficient when a strong focus is placed on electricity and crosssector conversions being reduced to a minimum. However, this requires different sources of renewables to be combined in the electricity system, both in terms of their type and regional distribution. This project is a great example of how to turn this vision into reality and strengthen European integration at the same time.

Dr. Klaus von Sengbusch, Head of Strategic Grid Planning at 50Hertz

The Baltic WindConnector will be around 800 km long

WINDGRID

HARNESSING THE GROUP’S EXPERIENCE TO ACCELERATE ENERGY TRANSITION

In 2022, Elia Group’s newest subsidiary, WindGrid, was formed with the aim of capitalising on the Group’s valuable experience in offshore development to accelerate the energy transition outside of the Group’s regulated businesses in Belgium and Germany. In order to support the European Commission’s goal of quadrupling Europe’s offshore wind capacity to 60 GW by 2030 and 300 GW by 2050, it focuses on developing offshore electricity grids and renewable energy production.

Markus Laukamp, CEO of WindGrid

What are the benefits of the HansaLink project?

ML: It provides a grid-friendly way to supply the UK and Germany (and EU) with green energy when needed, and optimises the utilisation of cables and converters by using them to export from the wind farm and for the interconnector.

What is the progress made on the HansaLink project thus far?

Seen as a solid partner for governments, grid operators, and renewable energy developers, WindGrid is a channel for a decade’s worth of experience and skills that Elia Group has built up, allowing the Group to remain at the forefront of offshore wind development and maintain its relevance in driving the energy transition forwards in the long run.

HansaLink project between UK and DE

WindGrid actively continues to look for win-win partnerships with complementary skill sets to deliver successful projects internationally. Markus Laukamp, CEO of WindGrid shares more about the HansaLink MultiPurpose Interconnector project between Scotland and Germany.

Is the HansaLink project part of any significant energy development plans?

Markus Laukamp: The HansaLink project is part of the TenYear Network Development Plan (TYNDP) 2024 by European Network of Transmission System Operators for Electricity (ENTSO-E). Furthermore, it has a good chance of achieving a Projects of Common Interest (PCI) status due to the strong socio-economic benefits it offers to Germany, the UK, and the EU.

ML: The idea of HansaLink was born when WindGrid identified borders with the largest value for an interconnector. UK and Germany were very supportive from the start. Today, grid connection points in both the UK and Germany have been identified and secured, and discussions with owners of suitable bottom-fixed wind farms have seen significant progress.

Partnership with US-based energyRe Giga

In early 2024, Elia Group took a big step into the US market by acquiring a minority stake in energyRe Giga, a US-based project developer specialising in clean energy solutions. We currently have three transmission projects in the pipeline.

We are seeing some challenges in the US electricity sector, particularly around the future development of wind power, and especially new offshore wind. That said, the need for new transmission infrastructure has never been more urgent. The demand for electricity is surging, not just to power AI and data centres from the Big Five tech companies, but also to meet the growing needs of major cities. Most investments through energyRe Giga are currently focused on advancing onshore activities.

The business model of energyRe Giga is about developing and building projects and then progressively divesting, in order to rotate assets over time. Our added value as Elia Group is to support de-risking the projects through their lifecycle thanks to our extensive transmission expertise in our home countries.

→ energyRe is accelerating the US clean energy transition with state-of-the-art transmission and large-scale onshore and offshore generation that will modernise the nation’s electric grids and decarbonise American cities with reliable, clean power. This strategic investment from Elia Group will support energyRe’s mission to deliver sustainable, resilient, and innovative energy systems to the communities we serve.

Miguel Prado, CEO of energyRe

→

WORKING AMONGST THE ELEMENTS: WIND, WATER, AND WAVES

A critical moment in the connection of offshore wind farms to the mainland grid or the construction of interconnectors is cable laying: securely embedding cabling systems into the sea floor along their established route. This work is challenging, not least because cables are both fragile and heavy; indeed, they can weigh up to 130 kg per metre. Moreover, staff rely on good weather and calm conditions at sea to undertake this work.

Once an offshore cable’s route has been determined – taking factors such as marine ecosystems, sites of historical interest and other offshore infrastructure into account –and the project has been granted the necessary permits, debris, large boulders and unexploded ordinance have to be cleared from the sea floor. The cable is then loaded onto the carousel of a cable laying vessel: a large drumlike structure with a vertical axis in its centre, around which the cable is wound. In cases where the cable will be used to connect the mainland grid to an offshore wind farm platform, the vessel will either start from the mainland and sail out to the platform, or start from the platform and work its way back to the coast.

Vessels which start near the mainland and set off for an offshore platform have to stay some distance from the shoreline due to their draft. As a consequence, one end of the cable has to be pulled ashore, with floats used to keep it from sinking under water. Once the cable has been secured on land, the floats are removed and the vessel begins its journey, laying the cable along the seabed in metre-long sections. A special guide track and precise offshore positioning is used to release the cable into the water, so it lands in the right spot along the sea floor in a controlled manner. Cable joints are used to connect different sections of cable together; depending on

the weight and diameter of the cables in question, these joints appear every 30-70 km or so.

Most projects in Belgium have involved the cable being pulled onto the offshore platform first, after which the vessel departs for the mainland. In this way, as the vessel approaches the coast, the vessel’s load is lightened – this means it can come closer to the shore and can be used to lay sections of the cable along the seabed for longer.

Different methods and tools are used to excavate the cable trench in accordance with the nature of the seabed.

For example, an underwater plough is used to plough through hard and stony sea floors. For softer seabeds (made of sand, mud or clay), jet trenchers are used: as part of this cable burial process, offshore cables are lowered onto the seabed and then buried underneath natural sedimentation or rock aggregate installations. This technique can also be used to further embed offshore cables which have already been laid. The time it takes to lay each cable section varies, depending on the installation method employed and the conditions of the seabed.

Once the cable laying vessel has reached the offshore platform, the cable is pulled onto the platform using a technically demanding procedure: since the cable itself is heavy but needs to be delicately handled, large amounts of force are required to pull the cable onto the platform. The teams on the vessel and platform must be well prepared for the procedure and must closely cooperate as it is performed. The weather adds an element of uncertainty to the operation: the teams need good weather and thorough contingency plans in place to be able to complete it successfully. Once in place, the cable is then connected to the electrical infrastructure on the platform.

SUSTAINABLE APPROACHES TO OFFSHORE WIND DEVELOPMENT

Offshore grid development activities disturb local marine environments and can have an impact on marine ecosystems. Elia and 50Hertz therefore undertake mitigation and compensation measures that aim to avoid, reduce and offset any negative impacts generated by their activities. These measures are outlined in the environmental impact assessments that both companies prepare as part of permitting processes. In Belgium, Elia has chosen to go one step further as part of the development of its artificial energy island (see pages 14-17), through the adoption of Nature-Inclusive Design.

Both Elia and 50Hertz have built up solid experience in implementing mitigation and compensation measures, including nature restoration measures, through research on international best practices and through collaboration with local partners and organisations such as the Renewables Grid Initiative (RGI), which promotes fair, transparent, and sustainable grid development in Europe. Both companies are also signatories of RGI’s Marine Grid Declaration, which sets out guiding principles for avoiding, minimising, and (where possible) eliminating negative impacts on the marine environment.

Mitigation and compensation measures

Mitigation measures - these are adopted as part of a project to reduce or avoid any negative impacts the latter may have on the surrounding environment, including particularly sensitive areas.

As outlined in the Group’s ESG programme, ActNow, Elia has aligned its sustainability-related goals with the United Nations’ Sustainable Development Goals (SDGs). Dimension 2 of ActNow, Environment & Circular Economy, is linked to three SDGs, including SDG 14: “Life below water”. The conservation and sustainable use of marine resources for sustainable development is therefore a key principle that Elia, 50Hertz, and their contractors adhere to.

For Elia Group, mitigation measures include taking into account valuable habitat areas when defining new cable routes and the location of substations, as well as seeking to construct infrastructure which is efficient by design. Both in Belgium and Germany, the installation of offshore platform foundations (known as ‘pile driving’) is halted between specific dates every year, to protect marine animals that inhabit the North and Baltic Seas during those periods. Further measures include ‘slow starts’ – when piling power is gradually built up, giving marine life some time to adjust to the activity and leave the area being worked on. Acoustic deterrent devices are also used; these keep animals away from the area being worked on and so avoid their being physically harmed by it.

Further examples of mitigation measures undertaken by 50Hertz include minimising the noise that is generated as it prepares the seabed for its activities. Indeed,

in the Baltic Sea, thousands of tonnes of munitions and chemical weapons dumped during World War II lay along the seabed. 50Hertz must report contaminated sites to the authorities and call upon specialised bomb disposal teams for help, who decide whether to recover or undertake controlled detonations of bombs that are found. If these teams decide that a bomb should be safely detonated underwater, bubble curtain technology is employed: using specialised technology, compressed air is released from the seabed upwards, creating a curtain of air bubbles around the bomb. This curtain acts as a barrier against the sound waves that are produced when the bomb is detonated, so protecting sea life.

Compensation measures are steps taken to offset the adverse effects that offshore activities can have on marine life. In Germany, compensation measures for these disturbances must be undertaken in a zone that stretches 12 nautical miles away from its coastal states. In Belgium, if a habitat is disturbed or lost during a project, the habitat must be restored either in the same location or within the vicinity of the project.

Examples of compensation measures undertaken by 50Hertz include the dismantling of the artificial dam that lay between the island of Görmitz and the German mainland, which was originally built in the 1960s. The dismantling of the dam was a compensation measure adopted as part of the construction of Ostwind 1 (see pages 26-27). The dam’s demolition has allowed more oxygen to flow to previously cut-off areas of the Bodden waters (Achterwasser) and marine life such as otters to move around more freely in the area. On the island of Görmitz itself, a habitat for ground nesting birds was also created.

→ The co-creation process undertaken by Elia and marine experts has proven to very enriching. It has allowed us to make important contributions to the field of NID and offshore infrastructure, and we will continue to learn and gain insights into these as the island is constructed and our approaches are monitored. Our discussions focused on finding the right balance between the encouragement of biodiversity, technical feasibility, and cost efficiency. hope our approach and work on the island will inspire other actors to work with nature conservation experts from the very start of their projects, so acting responsibly and for the benefit of society.

Nicolas Beck, Head of Community Relations at Elia

Nature Inclusive Design

In Belgium, Elia has chosen to apply Nature-Inclusive Design (NID) in its approach to the construction of its first energy island in the North Sea (see page 17). This means that, in collaboration with conservation experts, it is designing the island in such a way that it will have a positive influence on marine ecosystems and will encourage biodiversity.

The measures that Elia has chosen to adopt include the construction of:

• small ledges along the island’s floodwall. These will attract black-legged kittiwakes: a species of seagull which lives and breeds on rocky cliffs. The ledges will mimic such cliffs, providing the kittiwakes with 2.6 km of breeding habitat – enough space to accommodate over 5,000 nests.

• an artificial reef which will allow marine life to flourish.

A diverse and complex scour protection system will be installed around the island, with fine gravel beds and boulders concentrated around each of its four corners.

→ It is challenging to combine naturerelated and technical requirements, and it is really rewarding when engineers and nature experts understand each other and design solutions which everyone is satisfied with.

Riet Durinck, Offshore Community Relations Officer at Elia

structures to support oyster beds. These oysters release larvae that could then settle within this meticulously designed habitat, kick-starting the formation of a biogenic oyster reef.

relief panels which will be attached to the lower parts of the island’s foundations. These will provide small organisms and fish with places to shelter and forage for food.

In 2024, the Nature-Inclusive Design of the Princess Elisabeth Island won the ‘Environmental Protection’ category of the 2024 Renewables Grid Initiative awards. These awards are aimed at recognising exceptional and innovative practices in grid development that facilitate the integration of renewables into electricity systems.

1. Storm wall with ledges for cliff-nesting birds

INNOVATION IN OFFSHORE ACTIVITIES

Elia Group has built up a strong track record in offshore development since the early 1990s, when 50Hertz’s predecessor built and commissioned the KONTEK interconnector with its Danish counterpart (see page 20). Today, we are a European leader in the sector, as exemplified by our innovative practices and projects in both Belgium and Germany. Eva Schramm, Head of Innovation at Elia Group, and Olmo Mezger, who works in Innovation for Offshore Initiatives at Elia Group, explain how the Group optimises its offshore tools, methods, and assets.

Why is offshore so important within the Innovation department at Elia Group?

Eva Schramm: Offshore represents a key area for advancing decarbonisation efforts in Europe. The expansion of offshore wind energy is essential for successfully reducing carbon emissions across the continent. However, as this relatively new industry grows, it faces several challenges, such as human resource constraints for offshore operations, the need for optimised interoperability of hybrid grids, and stringent nature conservation and restoration goals.

It is critically important for us to address these emerging obstacles through innovation as a catalyst and safe accelerator for identifying, exploring, and integrating new solutions. These solutions support a boost of offshore construction, the reduction of environmental impacts, the enhancement of maintenance and inspection processes, the opti-

misation of operating and monitoring offshore grids and ensuring security and protection.

For instance, innovation plays a crucial role in minimising physical site visits through remote inspection technologies. This reduces costs and increases safety for our employees by deploying digital solutions for offshore maintenance that can withstand harsh marine conditions and connectivity challenges. Additionally, by implementing advanced HVDC technology and operational algorithms tailored to hybrid offshore grids, we will enhance energy flows, reduce congestion, and ensure a reliable energy supply. This approach supports the development of a future European meshed offshore electricity grid.

Is there a typical way to drive innovation in the offshore sector?

Olmo Mezger: As transmission system operators (TSOs) in Europe need to increase the speed of designing, building, and installing the offshore grid by a factor of ten, driving innovation is one major lever we have. A great advantage is that Elia Group has a solid track record in offshore activities.

Nevertheless, driving innovation in the offshore sector is challenging due to the complex offshore environment, high costs of operation, tight maintenance schedules, favourable weather, and most importantly, staff availability. Planning ahead and prioritisation are important to ensure access to infrastructure and effective testing. Innovation is a team activity, and offshore teams are very busy with engineering and operation tasks and yet, it is our objective to keep the innovation spirit alive. Decentralising innovation is key for significant progress.

What

type of future technologies can advance the offshore sector?

ES: Significant advancements in the offshore sector will stem from sophisticated energy hubs and advanced HVDC technology. By focusing on expected evolutions in digital solutions over the next three to ten years, several key technologies are expected to notably enhance offshore building and operations.

Underwater connectivity and sensing networks will enable real-time data transmission via subsea communication, supporting predictive maintenance and surveillance. Remote and unmanned inspection technologies,

equipped with advanced imaging sensors, will enhance inspection safety and efficiency.

Additionally, optical sensing technologies will provide precise fault detection, while integrated AI and immersive visualisation will accelerate planning, simplify infrastructure operations, and make processes more intuitive.

How is Elia Group working on innovation in practice?

OM: Our innovation team provides support at various points in different offshore projects in the development of new ideas or develops innovative solutions to problems together with our offshore specialists. A good example of this is the use of subsea Wi-Fi - this may sound like a no-brainer in our hyper-connected world, but there is no Wi-Fi signal underwater, and sensors in our cables are not able to send data wirelessly. This is about to change, though, as we aim to develop a technology to achieve wireless communication underwater.

We also work with different stakeholders externally, including numerous TSOs in the Baltic and North Sea regions.

↑ Eva Schramm, Head of Innovation at Elia Group ↑ Olmo Mezger, Innovation for Offshore Initiatives at Elia Group

USE OF ROBOTICS

With the aim to significantly reduce the need for offshore interventions, robots (like Sparky) are tested and used. As well as enhancing safety during emergency situations, robots can also be deployed immediately while human interventions are dependent on offshore logistics, vessels, or helicopters. Using robotics helps us to gather critical data on a daily basis from various assets, which can then be analysed to detect potential failures at an early stage. This proactive approach not only ensures the well-being of our personnel but also maintains the integrity and reliability of our operations.

OFFSHORE OPERATION TESTS HYDROGEN-POWERED VESSEL

50Hertz has initiated the pilot phase for the first hydrogen-powered Crew Transfer Vessel (CTV), named “Hydrocat 55”, to reduce reliance on diesel and move towards climate-neutral energy. It features a dual-fuel system using both diesel and hydrogen, which is expected to significantly reduce CO2 emissions by 20-30% and nitrogen oxide emissions by up to 70%.

We are currently testing → this technology on our offshore switch yard to evaluate how it can be integrated into our current and future assets - a crucial step towards a safer and more reliable offshore infrastructure.

← We can improve our ecological footprint in offshore operation by reducing diesel consumption by around 20,000 litres per year. According to our calculations, this leads to a CO2 saving of around 50 tonnes per year.

SF6 MONITORING USING GIS

With the SF6 monitoring devices installed on the OSY gas-insulated switchgear (GIS), we receive early warnings of SF6 leakages and can predict the need for SF6 refills and repairs. As the accessibility of our offshore structures is affected by the weather, this information is crucial in ensuring that an intervention can be planned and executed on time. This monitoring also supports Elia’s ambition to limit SF6 leakages.

VIBRATION MONITORING DEVICES

Offshore structures are subject to significant environmental forces like wind, current, and waves, as well as vessels pushing on the boat landings in order to transfer technicians. In order to assess the impact of such movements on our offshore assets, vibration monitoring devices have been installed on both the OSY and Rentel platforms.

THERMAL SENSORS TO DETECT HOTSPOTS

Integration of remote infrared cameras into the Elia network allows us to detect potential hotspots from a distance. This technology enables real-time monitoring and alerts us when temperature thresholds are exceeded. By using these cameras, we can also ensure timely and effective responses to overheating equipment in order to protect our assets.

→ By monitoring these vibrations, as well as identifying changes in the structure resonance frequency, we can better understand, anticipate, and mitigate the potential degradation mechanisms on our offshore assets.”

Tanguy Petre, Asset & Methods Manager Structures at Elia

→ It’s crucial that such information is readily available to inform or alarm us of anomalies in a timely manner. This allows the on-duty personnel to take appropriate actions and ensure operational safety and efficiency.

Dylan Stubbe, Project Leader at Elia

CABLE FAULT PIN-POINTING OFFSHORE

Pin-pointing of an offshore cable fault remains a challenging task when dealing with expensive vessels and harsh environmental conditions. Elia Group has decided to develop and test a fault pin-pointing system based on Distributed Acoustic Sensing (DAS) technology.

→ We aim to demonstrate the feasibility of standardisation and industrialisation in this field. To do so, we have defined different work packages, like proving the feasibility of using a sound generator to detect DAS signals representing cable faults and validating the obtained accuracy for pinpointing and possible applicability boundaries, among others.

and

Dries Van Gelder, Project Leader at Elia

Krisztian Jani, Asset

Methods Manager (Cables) at Elia

Marcus Köckritz, Project Leader at 50Hertz

SEE SPARKY BEING TESTED OUT IN ELIA’S SUBSTATION, STEVIN

Principle picture of the operation

Once an offshore asset is built and put into service, our Offshore Assets Team takes responsibility for its operation and maintenance. The safety risks associated with offshore work are inherently higher as our teams must deal with volatile and unpredictable weather conditions. Additionally, the harsh marine environment exposes our assets to increased levels of corrosion, UV radiation, and mechanical stress. Furthermore, offshore environments typically have lower redundancy for assets, making any potential failure more impactful.

Geert Moerkerke, Head of Offshore Assets at Elia, explains how his team and the Group continuously develop their approach to managing these challenges, given that offshore asset management is a relatively new area of activity for them.

OFFSHORE OPERATIONS AND MAINTENANCE

What does asset management at Elia Group involve?

Geert Moekerke: Our goal is to ensure the security of supply by maintaining our infrastructure at peak performance, minimising downtime, and maximising asset lifespan while keeping costs low for society. Asset management at Elia Group involves three categories of maintenance. Firstly, preventive maintenance includes regularly scheduled maintenance and inspections, including remote monitoring, to prevent issues and failures. Secondly, curative maintenance involves repairing faults or issues after they occur to restore functionality. Lastly, adaptive maintenance focuses on upgrading or replacing components with safer, more efficient, and reliable technology that requires less maintenance on increases functionality.

Our operations and maintenance plans encompass all activities necessary to keep our infrastructure running smoothly and to ensure it meets its design lifetime. This plan is continuously updated as we expand our knowledge and experience. By anticipating potential faults and having robust repair preparedness plans, we can significantly reduce outage times by knowing where to source support, resources, and spare parts.

What specific challenges does offshore asset management entail?

GM: One of the biggest challenges is the limited redundancy in the offshore grid. This means for example that if one of our cables fails, it immediately impacts the capacity to transport renewable energy back to the mainland. Additionally, our assets are quite remote, making them more expensive and dangerous to access in comparison with onshore infrastructure. Any offshore intervention must be carefully planned, considering factors such as weather, transportation methods, and the availability of qualified staff. Moreover, since emergency services are based on the mainland, our team needs the skills to handle medical emergencies or other urgent situations independently.

How does the future look?

GM: By the end of 2025, our state-of-the-art Offshore Operations and Coordination Centre at the Port of Ostend will be ready. This facility will become the nerve center for our day-to-day offshore operations in Belgium. From here, we will plan and execute our offshore interventions. The centre will feature a well-equipped warehouse for our offshore spare-parts and tools, a quay from which our teams and logistics will depart, an operations and control room, and offices and meeting rooms for our engineers, experts, and highly skilled technicians.

→ We must execute our work as quickly and efficiently as possible, minimising costs and environmental impact. These challenges necessitate meticulous planning and efficient use of time spent at sea. Given the potential for dangerous weather changes, our team also requires a high degree of flexibility to reschedule and execute the work effectively.

ELIA PLANS OFFSHORE OPERATIONS CENTRE IN THE PORT OF OSTEND

By the end of 2025, Elia is due to have built a new offshore operations centre in the Port of Ostend. It is from here that its team of offshore experts will design and manage its growing pool of offshore assets, including the Princess Elisabeth Island (see page 14). The building will house an offshore operations room, offices, a dedicated warehouse and centre of expertise. Up to 30 individuals will work on the site itself, of whom two-thirds will be technicians who carry out offshore work.

Geert Moerkerke, Head of Offshore Assets at Elia

→ Our strategic approach to security matters integrates organisational, physical, electronic, and recovery measures. The study, analysis, and implementation of all the measures take place in close collaboration with the Elia Offshore department. These efforts include advanced detection and verification techniques across multiple domains - underwater, surface-level, and aerial. Additionally, given the unique challenges of offshore environments, innovative technologies are integral to our approach.

Jeroen François, Head of Health, Safety & Security at Elia

SAFETY AND SECURITY AT SEA

When it comes to safety, Elia Group has a clear goal for both onshore and offshore activities: zero accidents. 50Hertz has received ISO 45001 certification, and Elia is Safety Culture Ladder (SCL) Level 3-certified. Going beyond operational safety in offshore development, safety and security matters are also embedded throughout the Group’s processes from tendering to monitoring construction methods and incident management.

Staff working in offshore environments must complete specific training sessions related to safety at sea, including first aid; surviving at sea; working at height; and dealing with hazards such as fires. Staff must also undergo regular medical examinations to check that they are fit and well. They are required to wear personal protective equipment – including helmets, life jackets, gloves, appropriate footwear, and immersion suits – whenever they leave the mainland.

Elia’s and 50Hertz’s offshore teams regularly undertake practice rescues, both from vessels and from offshore infrastructure, to ensure that staff are ready to deal with emergency situations of all kinds. Combined practice exercises are also organised with external partners, including maritime organisations.

In Germany, a helicopter rescue team based on the island of Rügen is on hand 24 hours a day, 7 days a week, to carry out rescue missions related to 50Hertz’s work being undertaken on offshore platforms or projects. The helicopter is also called upon to undertake emergency rescue operations that can involve members of the public along the coast. In Belgium, the Maritime Rescue and Coordination Centre (MRCC) in Ostend and maritime police are on call 24 hours a day, 7 days a week. The MRCC are the first port of call when an incident at sea has occurred.

Additionally, Elia has a comprehensive range of security measures to protect assets at sea, focusing on both proactive and reactive approaches. A multi-layered strategy provides robust protection and ensures flexibility in addressing evolving security challenges. Elia’s main public stakeholders like the defence forces, the police, and the national crisis centre, remain informed about the security measures.

Innovation plays a crucial role in ensuring the security of assets at sea. This is especially important given the complex and evolving challenges of offshore environments. Advanced technologies such as underwater drones, AI-driven threat detection systems, and autonomous surveillance platforms enhance both the scope and precision

of monitoring activities. These innovations are indispensable for addressing not only the current challenges but also future threats, ensuring offshore operations remain secure in a security landscape that is continuously changing.

See pages 48-51 to find out how new technologies are increasingly being used by Elia Group to reduce the risks associated with carrying out offshore work.

→ In life-threatening situations, it’s important to be able to collaborate with external partners so that the victim can be brought ashore quickly to receive adequate care. We don’t have the luxury of calling 112 –we need to be able to rely on our team and ourselves. Everyone needs to be conscious of their responsibilities and roles – we need to trust each other and communicate.

Working in an offshore environment is challenging and being prepared is vital. Emergency training exercises help our staff to reinforce their knowledge of incident management and improve their work with the emergency services. With this in mind, Elia’s offshore team regularly undertakes emergency training exercises on the Modular Offshore Grid (MOG), Elia’s power hub in the North Sea, where they practice evacuations with the help of the Maritime Rescue and Coordination Centre and the 40th Squadron (helicopters for emergency missions).

Nathalie Van Driessche, Safety & Operations Officer at Elia Asset

EVACUATION EXERCISE IN THE BELGIAN NORTH SEA

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EDITOR BERNARD GUSTIN

PHOTOGRAPHERS: JAN PAULS, ERIC HERCHAFT, STIJN VANDERDEELEN, MELTING PROD., JOHAN ROGGEMAN MANFRED H. VOGEL AND KATHRIN HELLER