The manufacturing of jacket structures for offshore wind turbines is a growing market, which is expected to increase in the coming years to meet growing energy needs while also increasing sustainability of energy production globally.

The manufacturing of offshore jacket structures has earlier been dominated by the oil and gas industry, where large one-off projects are the norm. In order to support the transition to offshore wind energy production there is a need to understand how the industry can shift production from typical one-off, project based production to the mass production of standardized jacket structures for wind turbines.

Project-based manufacturing, also called Engineer-to-Order, is often a suitable manufacturing strategy for complex projects where the importance of design, the size and complexity of the product, and the complexity of the supply chain are key factors. Such projects often have a long time horizon, undergoing many engineering changes in the course of design, purchasing, and manufacturing phases.

In mass production, however, the goal is to efficiently produce products that meet the needs of the end-user in terms of quality, cost, lead times, and variety requirements, while also being cost-efficient to produce for the company.

In this study, we apply a Lean approach and use the Value Stream Mapping method to analyze a supply chain for offshore wind jacket structures. We analyze the characteristics of the supply chain and manufacturing logistics of an offshore jacket structure manufacturing company to understand the current manufacturing strategy, to identify challenges to achieving production flow, and come with propositions on the key measures which are necessary for transitioning the supply chain to meet demands of production for offshore jacket structures. The study is based on interviews, internal documents, and publicly available information.

Preliminary findings show that transitioning to mass production of offshore jacket structures is possible, although there are some key elements of the supply chain and manufacturing logistics which need to be addressed. First, the design of the jackets need to be standardized to the degree possible, while still allowing for necessary adjustments or customizations. Second, the procurement of materials should be adapted to meet the volume and requirements of mass production. Third, the manufacturing logistics must adjust production layouts, internal storage, and use of internal transport. Fourth, the collaboration and organization of the functions at the manufacturing company needs a more operative model for production rather than being solely based on a one-off project model.

Future research could analyze the production of actual offshore wind jacket structures in various companies in order to gain further insight and understanding on the what strategies work well and what needs to be changed in the offshore wind value chain to enable scaling up.

Monopile foundations comprise one large steel tubular member that supports the tower and turbine, either directly or through a transition piece. The monopile is driven into the seabed where its embedment provides the required support needed for the wind and wave loads. Due to demand for even thicker steel cans, the cost related to steel supply and fabrication increases. Wind energy itself delivers clean energy, and LVEB welding further enhances the environmental benefits, with great reductions in energy use compared to conventional welding techniques. LVEB is currently not covered in fabrication codes today and the current qualification is based on requirements in DNV-OS-C401, ASME IX, ISO 15614-11. The purpose of the technology qualification is to document the applicability of using LVEB welding instead of Submerged Arc Welding (SAW) welding for production of transition piece and monopile foundation structures longitudinal seam welding.
The RapidWeld project, launched in 2020, brought together TWI (PM), Sif, SSE Renewables, and Cambridge Vacuum Engineering (CVE), with DNV serving as a subcontractor. The primary objective of this research project was to validate and qualify Local Vacuum Electron Beam Welding (LVEB) for application in offshore wind structures. DNV’s role focused on facilitating the technology qualification process in accordance with DNV-SE-0160 and DNV-RP-A203.
Through the RapidWeld project, DNV has documented the applicability of using LVEB welding instead of Submerged Arc Welding (SAW) in the production of transition pieces and monopile foundation structures employing longitudinal seam welding for heavy wall thicknesses. The new method seeks to provide a more efficient alternative to ordinary SAW, for longitudinal seam welds.
This paper outlines the technology qualification process and the electron beam welding (EBW) technology that enabled the acceptance of two longitudinal seam welds, performed using Local Vacuum Electron Beam Welding (LVEB). These welds are currently being monitored on the first monopile foundation installed in the North Sea.

As the demand for sustainable energy grows, floating wind turbine substructures must evolve to meet environmental and performance challenges. Traditional steel-reinforced concrete faces issues like corrosion, weight, and high carbon emissions. Using alternative materials—such as aluminum reinforcements or advanced composites—can enhance durability, reduce maintenance, and significantly lower CO2 emissions. These innovations also enable lighter, more efficient designs better suited for harsh marine environments, making them essential for the future of offshore wind energy.
However, aluminum reinforcement offers promising benefits for concrete durability by eliminating corrosion and reducing maintenance. Its compatibility with low-pH binders supports high SCM usage, potentially lowering CO₂ emissions. Additionally, aluminum rebars enable thinner concrete sections, which can also potentially lead to greenhouse gas reductions. Despite these advantages, concrete–aluminum composites are often avoided due to chemical incompatibility: aluminum corrodes rapidly in the highly alkaline environment of conventional concrete (pH >12). Research has therefore successfully focused on developing low-pH cement formulations to mitigate this issue for application in onshore construction industry. Yet, structural challenges persist—particularly thermal expansion mismatch and weak bonding between aluminum and concrete—requiring alternative design approaches for aluminum-reinforced TLP floaters to become a viable alternative.
The study presented in this paper was conducted within the Made4Wind and SFI BLUES projects and investigates how thermal expansion mismatch between aluminum and concrete can lead to stress concentrations and crack formation during curing and operation. The study was performed using a combination of FE structural analyses for estimation of stress concentration and experimental campaign for determining adapted concrete formulation, and the thermo-mechanical properties of the Alu and concrete developed. It focuses on the interaction between geometry, loading and material properties in the case of a structural part subjected to curing conditions. The part design is inspired by the PrecoBeam concept which exploits the possibility of aluminum protrusion to increase resisting momentum and decrease concrete mass. The thermal load is computed from the heat production caused by concrete crystallization. The mechanical properties evolution is modelled from liquid pour to hardened concrete. Using linear thermoelasticity, numerical simulations then allow to track the nature and intensity of stress states and provide quantitative estimators on the structural soundness of this production step.
The study highlights the importance of optimizing the geometry of aluminum reinforcements to reduce these effects and enhance the durability of reinforced concrete in TLP substructures and discusses certain principles when designing alu-reinforced concrete components. The research presented significantly advances sustainability and circularity in future floating wind turbines, supporting the development of TLP floaters using low-CO₂ concrete and enhancing circularity in decommissioning due to the use of Aluminum reinforcements. It aligns strongly with Theme 4: Sustainability and Circularity, particularly addressing Milestone 2.

Robotic welding of offshore steel substructures relies on beforehand laser scanning to compensate for manufacturing tolerances and large variability in tube geometry and placement. While pre weld scanning enables automation of major fabrication steps in the first place, the required path accuracy of ±0.5 mm is not consistently achieved, resulting in high failure rates and labour intensive manual corrections. The principal source of error is uncertainty in the relative transform between the laser scanner and the welding torch, commonly known as hand eye calibration.
Traditionally, the torch tip calibration and the laser scanner calibration are carried out separately. We propose a fused calibration strategy that combines the welding torch’s probing capability and laser scan data to improve the estimation of the scanner to torch transform. Two calibration workflows are implemented and evaluated: one that uses a precision sphere as a compact geometric reference and one that uses a planar artifact.
We experimentally compare the two methods with respect to the geometric accuracy of the recovered transform, the repeatability depending on the number of scans considered for the identification and the practical feasibility for integration in a production line. We benchmark both approaches against the current industrial procedure by evaluating the path following accuracy along a reference edge. We also study the sensitivity of the calibration to the robot workspace region used for identification. This is of specific importance when the calibration process cannot be performed in immediate proximity to the working environment or for large working envelopes. To mitigate this problem, a method for improved robustness against position-dependent errors by using several calibration artifacts spread over the robot workspace is tested.
To maintain the calibration quality during continuous operation, we introduce an online monitoring procedure that continuously evaluates the hand-eye consistency and triggers automated re-calibration when configurable thresholds are exceeded. The monitoring approach enables early detection of process instabilities and reduces manual rework. The lab experiments are done in SINTEF laboratories followed by deployment testing at Aker Solutions’ automated production line in Verdal, demonstrating practical improvements under real-world conditions. The enhanced hand eye calibration and online monitoring will reinforce robotic systems used in automated manufacturing of large offshore substructures, enabling mass production through increased automation and reduced manual rework.

Supply chain management for mass production has been identified as a key focus within Industrialization, Scale-up, and Competitiveness, a priority theme in the EU’s NeWindEERA program under EERA. Achieving Europe’s target of 420 GW of wind capacity by 2030 will require serial manufacturing of next-generation turbine components at scale, moving away from current supply chain dependencies that challenge the sector. While automation and digitalization have improved efficiency, high defect rates remain a persistent issue. Rework and scrap increase both production costs and environmental impacts through wasted materials and energy.

Traditionally, OEMs have used supply chain models to estimate cycle times and costs before production. However, these approaches often fail to capture how defects propagate through manufacturing processes. A critical constraint in turbine component manufacturing is that order fulfilment is often limited more by quality-driven inefficiencies than throughput. Addressing this gap requires modelling approaches that explicitly integrate quality dynamics into supply chain analysis.

To address this, we developed a discrete-event simulation (DES) framework within the Modular Root project, funded by the Renewable Energy Transition (HER+) program. The study investigates the supply chain dynamics of a modular wind turbine blade design compared to a conventional one-piece blade. The modular concept allows blade sections to be manufactured and inspected independently, enabling earlier defect isolation and reducing the need to scrap entire blades. The blade is used as the demonstration case for applying the proposed methodology; however, it is also applicable to other turbine components.

In the DES framework, turbine blade production is represented as a batch-oriented process that reflects real manufacturing conditions. Several subcomponents of a unit blade are processed and inspected in parallel through sequential stages. The number of parts handled decreases as they are assembled into a finished blade. Each stage involves defined process times, yield probabilities, and defect rates. Inspections are represented as imperfect, with specified sensitivity and specificity, meaning that some defects may escape detection while others may be incorrectly flagged. Components identified with reworkable defects are routed through additional processing steps that incur time penalties and have associated probabilities of success. By linking process durations, inspection accuracy, and defect propagation, the framework realistically reflects the stochastic and quality-driven dynamics of the blade manufacturing supply chain.

The model supports key performance indicators including order fulfilment rate, first-pass yield, rework, and scrap ratios. Comparative analysis shows the modular blade concept offers clear advantages over the conventional design: order fulfilment improves by 3–5%, first-pass yield by 6–8%, blade-level scrap decreases by 40–60%, and rework hours per good blade fall by 12–18%. These improvements also provide environmental benefits, reducing material waste by 20–30% and associated greenhouse gas emissions by 15–25%.

This research offers a practical methodology for OEMs, component manufacturers, and supply chain planners to evaluate and optimize production systems for both efficiency and quality. As the wind industry scales toward gigawatt-level deployments, integrating quality dynamics into supply chain modelling will be essential for enhancing cost competitiveness, sustainability, and supporting Europe’s broader energy transition goals.