MP Multi Use

Basics

• 4 partners

• Coordinator: VUB

• Project type: Fundamental research

• Start Data: 1/11/2023

• Duration: 2 years

• Total Budget: €1.607.145

• Funded by the Energy Transition Fund (ETF)

Project Context

Belgium has established itself as a pioneering leader in offshore wind energy, with the already installed 2.3 GW and additionally planned 2.5 GW bottom-fixed capacity. The federal government has committed to maximize the yield and economical use of its offshore energy production in the Belgian Part of North Sea (BPNS). This needs to be achieved in the most sustainable way by maximizing the use of the existing supporting infrastructure (foundations, scour protection layers and cables).

In parallel, the Belgian government has also initiated a working group on sustainable decommissioning of offshore wind projects where the option to re-purpose these offshore infrastructures is also considered. However, it is not clear yet which possible routes are technically and economically useful to date. There are currently 399 wind turbines installed in the Belgian part of the North Sea. The oldest wind turbines are already operational for about 15 years. The rapid developments and improvements in this sector combined with this turbine age amplifies the need to possibly repower the older wind farms and therefore prepare the corresponding decommissioning phase. By the end of the decade, decommissioning and replacing offshore wind turbines will start.

Project Description

The project will study the feasibility of (re)-using existing infrastructure for hybrid energy generation and/or repurposing it for wave/tidal or accommodating storage technologies. It therefor aims to improve the yield and lower the LCOE of the Belgian offshore zone and to provide an alternative for full decommissioning of the existing infrastructure. In MP Multi-Use the experienced consortium partners will perform a conceptual, economic, legal and structural reliability study, of the multi-(re)-use of existing infrastructure and the combined use of the maritime space.

Project Objective

This project aims to increase the knowledge with respect to potential hybrid-re(use) of monopile foundations for attaching different forms of energy production such as wave energy converters (WEC), tidal energy converters (TEC), or floating solar panels in combination with energy storage solutions if appropriate.

The project is also motivated by EU targets (Ocean energy (europa.eu) on deployment of tidal and wave energy to develop:

• 100 MW by 2025,

• 3 GW by 2030 and

• 40 GW by 2050

Some potential benefits for hybrid (re)-use include:

• Increased energy generation: By combining multiple sources of energy generation, hybrid offshore wind farms can potentially produce more energy than wind farms that rely on wind turbines alone.

• Improved energy reliability: Wind and wave/tidal energy production can complement each other, with wind typically being more consistent and wave/tidal energy being more predictable. This can lead to a more reliable and stable offshore power supply with lower balancing costs as current standalone offshore wind farms today.

• Cost savings: Hybrid offshore wind farms may be able to take advantage of economies of scale and shared infrastructure, leading to system cost savings compared to separate wind and wave/tidal energy projects.

• Reduced environmental impact: Hybrid offshore wind farms may be able to reduce the overall environmental footprint of offshore energy production by using multiple sources of renewable energy and further reducing the need for fossil fuel. Re-using existing infrastructure if possible is the one of the most sustainable ways to deal with waste management.

• New industrial offshore value chains: Being an early adopter of new emerging energy trends is essential these days to excel in the offshore energy business. Belgium has a unique opportunity once again take a leading role in multi-use and re-used offshore wind infrastructure if projects as this provide the needed scientific possibilities for hybrid (re)-use.

This project also wants to evaluate the potential re-use of the existing infrastructure as alternative for a full decommissioning. Part of the foundation might serve a new purpose in future offshore energy endeavors. Past studies based on field monitoring data showed that current OWT monopile supported structures are over dimensioned. Therefore, it is expected that the structural integrity of the offshore foundations structures in Belgium can be guaranteed for re-purposing them. Similarly, the technical lifespan of the used subsea cables far exceeds the durations of the concession agreements, also hinting to opportunities for re-usage.

Partial decommissioning of offshore wind foundation structures can provide several benefits, including:

• Lowering the cost of decommissioning: By partially decommissioning the structure, rather than fully removing it, the cost of decommissioning can be reduced as only certain parts of the structure need to be removed.

• More sustainable development/circular economy/re-use of material: By partially decommissioning the structure, certain materials can be reused or recycled, promoting a more sustainable and circular economy.

• Environmental benefits/Maintaining the artificial reef: By leaving certain parts of the structure in place, an artificial reef can be created, providing benefits for marine life and potentially increasing biodiversity. Additionally, the structure can continue to provide habitats for marine animals, which can be beneficial for the ecosystem.

This project will investigate the existing state-of-the art of hybrid energy generation and the potential future use of offshore foundations after the decommissioning of an offshore wind farm. In particular, the research will consider the economical, practical, legal and technical feasibility for different future use cases. The proposed economic, legal, environmental and technical studies must allow to decrease the risk and increase the likelihood of the envisioned future hybrid-re(use) of the existing windfarm infrastructure and might provide good practices for new projects.

More info and related articles can be found on Researchgate

Subsidy

The MP Multi Use project is financially supported by FPS Economy, as a fundamental research project within the Energy Transition Fund (project call 2022- duration of project 01.11.23 – 31.10.2025)

Key results

The MP Multi-Use project delivered a comprehensive and multidisciplinary assessment of the feasibility of reusing existing offshore wind turbine foundations for hybrid renewable energy generation in the Belgian North Sea. The results provide a strong foundation for future multi-use concepts, combining wind energy with wave, tidal, and floating solar technologies.

A key outcome of the project is the identification of the most promising technologies for integration with existing monopile structures. Tidal kite systems, wave energy converters, and floating photovoltaic systems were selected as the most suitable options, with floating PV emerging as the most economically promising solution in the current market context.

The project developed a detailed understanding of the technical and operational feasibility of these hybrid systems. Installation and maintenance strategies were defined, including transport and installation methodologies, cost estimates, and operational constraints. These studies demonstrate that reusing existing offshore infrastructure can reduce capital expenditures compared to standalone deployments, although further technological development remains necessary.

A major contribution is the creation of a high-resolution metocean dataset and digital energy atlas for key locations in the Belgian North Sea. This dataset enables accurate resource assessment for wave, tidal, and solar energy and provides a valuable baseline for future offshore energy projects.

The project also delivered a comprehensive legal and regulatory analysis, identifying key bottlenecks in the current Belgian framework for multi-use offshore development. The results highlight the need for more integrated permitting processes, clearer liability structures, and improved policy alignment to enable large-scale deployment of hybrid offshore energy systems.

From an environmental perspective, the study demonstrates that reusing existing monopiles offers clear sustainability benefits. By avoiding new offshore construction, seabed disturbance, installation-related emissions, and environmental impact can be significantly reduced. The environmental assessment shows that hybrid deployments can be implemented with minimal additional impact when appropriate mitigation measures are applied.

On the engineering side, the project performed advanced hydrodynamic and structural analyses to assess the integration of new energy devices on existing foundations. Experimental and numerical studies confirm that the additional loads from tidal and wave technologies remain within acceptable limits. Digital twin models further show that, after turbine decommissioning, monopile structures often experience reduced fatigue loading, supporting their suitability for reuse scenarios.

In addition, new numerical tools and simulation methods were developed to support fast and accurate fatigue and load assessments of monopile structures under hybrid use conditions. These tools enable efficient evaluation of different design scenarios and can support future engineering studies and industrial applications.

The project also provided important insights into the economic viability of multi-use concepts. While standalone wave and tidal technologies are not yet competitive, the reuse of existing infrastructure significantly improves the business case. Floating solar, in particular, approaches cost levels comparable to offshore wind when deployed on existing foundations, highlighting its strong near-term potential.

Overall, MP Multi-Use demonstrates the technical feasibility and strategic potential of transforming offshore wind farms into multi-purpose renewable energy hubs. The results show that combining multiple energy technologies on existing infrastructure can increase overall energy production, reduce environmental impact, and support the diversification of offshore renewable energy systems.

The project provides a clear pathway toward more efficient use of offshore space and infrastructure, contributing to a more sustainable, flexible, and resilient offshore energy system.