MP Multi Use

Project Context

Belgium has established itself as a pioneering country in offshore wind energy, with 2.3 GW of installed capacity and an additional 2.5 GW of bottom-fixed offshore wind capacity planned. The federal government aims to maximise the yield and economic use of offshore energy production in the Belgian part of the North Sea while making optimal and sustainable use of existing offshore infrastructure, including foundations, scour protection and cables. 

There are currently 399 wind turbines installed in the Belgian part of the North Sea, with the oldest wind farms already operating for approximately 15 years. With decommissioning and repowering becoming increasingly relevant, the question arises whether existing offshore infrastructure should always be fully removed or whether parts of it can be given a second life.

MP Multi-Use investigates this opportunity by studying how existing offshore monopile foundations could be reused for other forms of renewable energy generation.

Project Description

The project investigates the feasibility of reusing existing offshore infrastructure for hybrid energy generation and/or repurposing it for other green energy solutions. The aim is to explore alternatives to full decommissioning while improving the utilisation of offshore infrastructure and maritime space. 

The MP Multi-Use consortium performs a multidisciplinary assessment covering the technical, structural, hydrodynamic, economic, environmental, operational and legal aspects of multi-use and reuse of offshore monopile foundations.

Project Objective

The main objective of MP Multi-Use is to increase knowledge regarding the potential hybrid use and reuse of monopile foundations for new forms of energy production, including wave energy converters (WEC), tidal energy converters (TEC) and floating photovoltaic systems (FPV), complemented by energy storage solutions where relevant. 

The research assesses different potential future use cases from an economic, practical, environmental, legal and structural perspective. By this multidisciplinary approach, we explore different alternatives to provide a scientific basis for future decisions regarding multi-use and reuse of offshore wind infrastructure. 

Potential Benefits of Hybrid Use and Reuse

Potential benefits investigated within MP Multi-Use include:

• Increased energy generation through the combination of different renewable energy technologies within the same offshore area. 

• Improved use of existing infrastructure by giving foundations and other offshore assets a potential second application. 

• Cost savings through shared or reused infrastructure compared with completely standalone offshore energy developments.

• Reduced environmental impact by potentially avoiding new offshore construction and contributing to more circular use of existing infrastructure. 

• Development of new offshore value chains, supporting innovation in emerging renewable energy technologies and offshore infrastructure reuse/co-use. 

Key Results

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

The project identified tidal kite systems, attenuator-type wave energy converters and floating photovoltaic systems as relevant concepts for further investigation. Among the technologies studied, floating PV emerged as the most credible reuse candidate under the economic assumptions considered in the project. Infrastructure reuse improved the economic performance of all three technologies, although tidal and wave energy remain challenging under the studied cost and yield assumptions. 

The project also investigated installation and maintenance requirements, offshore renewable energy resources, environmental impacts and the Belgian legal framework. The legal analysis identified challenges surrounding concessions, permitting, ownership, liability and decommissioning-for-reuse scenarios. 

From an engineering perspective, experimental, numerical and digital-twin studies were performed to evaluate hydrodynamic loading and the structural reliability of reused monopiles. The structural analyses showed substantially lower fatigue consumption following turbine removal and demonstrated sufficient monopile capacity for the investigated tidal energy converter and floating PV cases. 

Overall, the project shows that monopile reuse can represent a technically feasible option under selected conditions. However, its viability depends on the selected technology, remaining structural lifetime, economic case, regulatory framework and site-specific conditions. MP Multi-Use therefore positions reuse as a selective redevelopment opportunity rather than a generic alternative to decommissioning. 

Project Outcomes by Work Package

WP1 – State of the Art, TRL Roadmap and Concept Selection

WP1 established the technological and regulatory foundation of the project. A comprehensive review of wave, tidal, floating PV, energy storage and other potential multi-use technologies was performed, combined with a Technology Readiness Level roadmap focused on technologies suitable for Belgian North Sea conditions. 

A multi-criteria decision analysis was applied using 17 sub-criteria grouped into five main categories: LCOE and economics, energy generation, constructability and operability, environmental and social impact, and business support. This process resulted in the selection of tidal kite systems, attenuator-type wave energy converters and floating solar for further assessment. Energy storage was retained as a potential complementary technology. 

WP1 also provided a high-level analysis of the Belgian regulatory framework and the opportunities and constraints associated with multi-use of existing offshore wind infrastructure. 

WP2 – Feasibility and Requirement Studies

WP2 translated the selected technologies into concrete multi-use and reuse scenarios and assessed them from resource, operational, environmental, legal and economic perspectives. 

A detailed offshore resource assessment was conducted for the Belwind area, including wave and tidal resources and the influence of existing monopiles on current velocity patterns. Conceptual monopile-integrated designs were developed alongside transport and installation concepts, installation duration and cost assessments, HAZID workshop and high-level O&M evaluations. 

The environmental study screened tidal, wave and floating PV reuse concepts across relevant environmental topics, while the legal work examined possible arrangements for concessions, permits, ownership transfer and phased decommissioning for reuse. 

The economic assessment demonstrated the potential value of infrastructure reuse. Under the investigated assumptions, floating PV emerged as the most credible near-term reuse case, while tidal kite and wave energy technologies require further improvements in costs, energy yield and/or operating lifetime to become competitive. 

WP3 – Hydrodynamics and Structural Reliability

WP3 investigated whether existing offshore monopile foundations can safely accommodate the additional loads associated with new energy technologies.

Experimental campaigns and CFD (Computational Fluid Dynamics) simulations were performed in the COB (Coastal & Ocean Basin) to investigate hydrodynamic behaviour and loading. In the tidal kite case, the experiments generated measurements of mooring loads, current velocity, wave elevation and device motion. The numerical modelling was benchmarked against physical testing, providing input for subsequent structural assessments. 

These loads were incorporated into digital-twin models of existing Belwind monopiles to assess structural dynamics, fatigue and ultimate limit states. The analyses showed that removing the original wind turbine makes the remaining foundation significantly stiffer and substantially reduces fatigue consumption, thus guaranteeing a longer lifespan. For the studied cases, the existing monopiles showed sufficient capacity to withstand the loads associated with the investigated tidal energy converter and floating PV reuse scenarios. 

Assessment of secondary steel attachments technologies have been studied through 3D finite-element modelling, following structural hot-spot stress evaluation and fatigue assessment according to current design standards for offshore engineering. 

Research Output and Valorisation

MP Multi-Use generated scientific, technical and policy-oriented output beyond the project deliverables. Project results have been disseminated through scientific publications and international conferences, while the datasets, modelling approaches and engineering tools developed within the project provide a basis for further research and future offshore infrastructure reuse studies.

Scientific Publications and Conference Contributions

• K. Winkler et al., “Full-scale measurements of offshore monopile foundations and numerical benchmark,” presented at the International Conference on Offshore Mechanics and Arctic Engineering (OMAE), 2024.

• “Co-location of Tidal and Offshore Wind Energy Generation: Hydrodynamic Analysis of Monopile Impact on Tidal Energy Resource,” presented at EWTEC 2025. 

• Dissemination of project results at WindEurope EoLIS 2025.

• “Capturing Residual Value from Offshore Monopiles for Energy Generation Beyond Wind: A Business Case Assessment,” presented as a poster contribution at WindEurope 2026.

• Further dissemination of the legal research through a journal publication on marine policy and law is foreseen. A contribution related to the structural research to Fatigue 2027 is also under consideration.

  
  

Technical and Policy Valorisation

Beyond scientific dissemination, MP Multi-Use produced reusable technical outputs including offshore resource datasets and a digital energy atlas, digital-twin methodologies for monopile reassessment, hydrodynamic modelling methods, and Python-based tools for wave-loading and fatigue analysis. These outputs provide a technical basis for further engineering studies and future reuse concepts.

The project also generated policy-relevant knowledge concerning the future reuse of offshore infrastructure in Belgium. The legal analysis identified barriers in the existing regulatory framework and formulated recommendations including integrated permitting procedures, coordinated environmental assessments, standardised liability rules and a dedicated one-stop-shop authority.

By combining technological, structural, economic, environmental and legal research, MP Multi-Use provides an evidence base for future pilot projects and policy development concerning the reuse of offshore wind infrastructure and the more efficient use of offshore space in the Belgian North Sea.