Offshore wind farms: the engine behind the European energy transition
The energy transition aims to shift from traditional fossil fuels to clean, renewable sources like solar and wind energy. This transition is well underway in electricity production. Where solar and wind energy contributed less than 1 percent of Europe’s generated electricity in 2000, it has risen to more than 31 percent in May of this year, surpassing the total share of fossil fuels for the first full month. While this trend is positive, it pertains to a rather exceptional month and only concerns electricity as the energy vector. However, a carbon-neutral future requires not only the production of renewable electricity but also a significant increase in the use of electricity as an energy vector. Specifically, this means increasing the share of electrification from the current 20 percent to 60 to 80 percent by 2050. The demand for renewable electricity is growing, making its production increasingly urgent.
A crucial contribution to renewable electricity production comes from wind farms, which have the potential to generate significant amounts of clean energy. While the first parks were established on land, we now see a rapid increase in offshore wind farms. Besides the obvious advantages of more space and less disruption, offshore locations offer stronger, faster, and more consistent winds. The combination of these benefits makes offshore wind farms an attractive and highly efficient source of sustainable energy.
Belgium as an energy hub in the North Sea and mainland Europe
Belgium has played a key role in developing offshore wind energy for 30 years and hosted the North Sea Summit in Ostend in April. In this summit, nine European countries committed to making the North Sea the world’s largest green energy powerhouse, as outlined in the Oostende Treaty. The goal? Achieving 120 GW of offshore wind capacity by 2030 and at least 300 GW by 2050. This is no small ambition considering the current installed capacity of 30 GW, but it is ultimately sufficient to provide North Sea power to 300 million European households or 100 times the combined output of all Doel nuclear power plants. As a result, a significant portion of this electricity will be transported through the North Sea countries (such as Belgium) to other countries.
Such technological innovation naturally demands investments. The European Commission estimates that achieving the offshore energy goals for 2050 will require an investment of 800 billion euros, with two-thirds allocated to network infrastructure .
Therefore, the federal government’s energy transition fund has already supported the NEPTUNE project. Tinne Van der Straeten, Minister of Energy, stated at the project’s closing event last Wednesday,
“We proudly look back on our support for the NEPTUNE project, which has played and will play an important role in supporting Belgium as a pioneer in offshore wind energy in the North Sea. We can only achieve European climate goals through collaboration. Contributions from academic research groups, such as the NEPTUNE project, are essential.”
Switching to direct current
The expansion of new wind farms will occur at increasingly greater distances from land, while their installed capacity grows. To bring this energy to land in an affordable and socially acceptable way, as well as to connect it to the electrical transmission system, technological innovation is essential. Such innovations are needed not only in overseas and underground cable connections but also in strengthening the existing electricity grid. Conventional alternating current (AC) cables, for example, can no longer be used to bridge such distances and transport such large capacities.
High-voltage direct current (HVDC) provides solutions. With less energy loss and simpler transmission over long distances, HVDC is a key technology for transmitting electricity through long submarine cables. In the long run, it also allows for the gradual establishment of a “meshed” network of electricity connections in the North Sea, uniting the electricity supply of multiple countries.
However, these benefits bring additional complexity; alternating current must be connected to the existing direct current grid, resulting in a hybrid electricity network, where AC and DC work together harmoniously. HVDC converters, which convert electrical energy from alternating current to direct current and vice versa, behave fundamentally differently from traditional AC components. They are composed of thousands of power electronic switches and have a complex control system. This same complexity and full controllability offer new options for a smarter operation of the electricity system, enabling power redirection and the provision of support services.
NEPTUNE: Building energy innovation in Europe
Determining the most effective utilization of large investment volumes and establishing the energy infrastructure with technical reliability requires extensive study as a first step. Over the past five years, the NEPTUNE project, short for the ‘North Sea Energy Plan for the Transition to sUstainable wiNd Energy,’ has breathed new life into energy research, elevating it to new heights.
“European goals are technically achievable but also bring many challenges, such as integrating vast amounts of wind energy into the existing electricity system, which is already operating at its limits,” emphasizes Prof. Dirk Van Hertem, project leader. “Within the NEPTUNE project, we have built the necessary knowledge to prepare Belgium for these challenges.”
The ambitious project, led by researchers from KU Leuven and EnergyVille, addressed these challenges through three essential work packages:
The first work package focused on strengthening the financial and technical foundation for large-scale electricity transmission in Europe. Researchers developed optimization models to accurately determine the future installed capacity of energy sources in both the North Sea and mainland Europe. By identifying where renewable energy can be most efficiently generated, without considering national borders as in previous models, bottlenecks in transmission networks can now be better identified throughout Europe. The project developed computer models to analyze how hybrid AC/DC electricity networks should ideally develop and how classical investments in transmission lines can be replaced by relying on reserve storage and flexibility (e.g. PowerModels, FlexPlan and CbaOPF on GitHub, a webbased platform to share and store code). Additionally, the researchers bridged the gap between theoretical models and practical application by developing operational procedures (such as rapid responses in emergencies), significantly enhancing the viability of offshore wind farms. The result? Optimal investment advice to ensure reliable electricity infrastructure on a European scale [2,3].
The second work package focused on the security of the electricity system, with the development of advanced algorithms to address challenges related to hybrid networks of direct and alternating current, as well as providing practical solutions. This included improvements to cable and inverter models to enable more detailed analyses, which in turn led to enhanced security algorithms, especially in proximity to HVDC inverters. Researchers also explored precise voltage detectors that allow measurements directly on electricity cables, near potential fault locations. Furthermore, they developed groundbreaking DC security algorithms capable of detecting faults in the electricity grid in less than one millisecond, more than ten times faster than what was previously available for alternating current networks.
The development of future hybrid electricity networks depends on the dynamics and stability of the inverters that convert direct current into alternating current, as well as their interactions with each other and the rest of the network. The third work package of NEPTUNE focused on simulation and control models for these hybrid networks. The resulting models provide insight into the stability and interactions among these inverters, offering advanced solutions for managing these complex electrical systems. This represents a crucial step forward in realizing the inverters necessary to transport large amounts of offshore wind energy to the mainland.
“The knowledge and tools developed in this project make this research group a leading player in high-voltage direct current,” emphasizes Prof. Jef Beerten of EnergyVille/KU Leuven. “Individuals involved have taken on important positions in the industry.” In short, the NEPTUNE project has paved the way for future hybrid energy networks, with smart planning, improved safety, and advanced management.
The highlights of the project? View them here in the Z Energy report (Dutch):
New horizons for NEPTUNE
These insights not only contribute to the European innovation agenda, but the acquired human capital has already acted as a catalyst for further development. “By making the developed models and software tools publicly available, we can contribute to the energy transition in a community-driven manner. Furthermore, we have already established more than 20 national and international collaborations with industry and academia,” says Dr. Hakan Ergun, NEPTUNE work package leader.
For example, there’s the HC3 ‘HVDC and Underground Cable‘ expertise center within EnergyVille, in which the Flemish government is investing 14 million euros to research underground high-voltage connections, also led by Prof. Van Hertem. Future challenges, such as the security, control, and operational risks of underground direct and alternating current cables, are being examined alongside the development of the much-needed “meshed” direct current network. The HC3 will also develop a simulation laboratory in which such innovative underground high-voltage lines will be demonstrated and tested in as realistic an environment as possible. This way, Flanders will remain at the forefront of underground high-voltage networks both scientifically and in the industry.
Moreover, in November, in collaboration with Elia (the Belgian transmission network operator), the ETF-DIRECTIONS project was launched, in which the electrical challenges of connecting energy islands to the grid are being investigated. An application of this is the Belgian Princess Elisabeth Island; the world’s very first artificial energy island. With an expansive area of over five hectares, the island will serve as a crucial hybrid hub where electricity from North Sea wind farms converges before being transported to the European mainland. This way, even more energy can be integrated into our transmission network in the future.
EnergyVille and other Belgian research centers have built strong expertise through their efforts in establishing and monitoring offshore wind farms and electricity networks in the North Sea, continuing to contribute to a more sustainable future.
- ENTSO-e (2021),Ten Year Network Development Plan 2020, Main Report, Version for ACER opinion.
- Dave, J., Van Hertem, D. (sup.), Ergun, H. (cosup.) (2022). DC Grid Protection Aware Planning of Offshore HVDC Grids, PhD Thesis KU Leuven.
- Jat, C.K., Dave, J., Van Hertem, D., Ergun, H., (2022). Unbalanced OPF Modelling for Mixed Monopolar and Bipolar HVDC Grid Configurations, arXiv preprint arXiv:2211.06283