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Overcoming floating wind challenges is key to the global energy transition

Published:  12 April, 2023

Developers will need to install high-capacity farms in deeper offshore sites to scale up renewable energy capacity and ensure a successful global energy transition. To achieve this, key considerations around floating foundation type must be evaluated. Houlder’s Director of Offshore Engineering, Mark Goalen, shares his specialist insights.

Floating ideas…

One of the key technical barriers to floating wind commercialisation faced by developers is selecting the most suitable floating foundation type for a given location. Every development is unique; water depth, seabed type, environmental conditions are just some of the factors that must be accounted for. There are many floating foundations to choose from, but they can essentially be categorised into four main structure types: spar buoy, tension leg platform, semi-submersible platform, and barge.

They all have fundamental differences in their characteristics that affect how the turbine responds to the environmental conditions, so a fundamental factor that should heavily influence foundation selection is the foundation’s motion response to environmental conditions. Understanding the effect of motion characteristics on the whole system is essential. It directly impacts all components from nacelle, tower, to the dynamic cable, and the mooring system.

No single, definitive structure type or floating foundation will be optimal for every site. There are many variables that will impact the decision, including a technologies’ operability, reliability, practicality, readiness, CAPEX, OPEX and potential longevity to name a few. A developer must choose a foundation that is most suitable for the wind farm they are developing and, given that many developers’ portfolios are global, that will vary from site to site.

Effectively selecting a floating foundation involves collaborating with the right partners to analyse a combination of technical and operational factors. Importantly, it should be recognised that operational factors may have a bigger impact than technical ones over the asset’s lifecycle.

Understanding supply chains

One vital operational factor that will determine floating foundation choice is the project’s supply chain. Indeed, constructing the required infrastructure and putting in place the appropriate supply chain is one of the largest barriers to quick and effective floating offshore wind commercialisation.

Turbines, foundations, mooring system components, cables, and port infrastructure, are all critical elements of the supply chain that must be considered. Transport routes, logistics, infrastructure as well as installation and O&M (operations and maintenance) vessels make matters complex. To attain a clear understanding of all supply chain requirements and optimise their floating wind projects, it is key that developers and other stakeholders have a holistic understanding of the development and how it varies from fixed wind which many are more accustomed to.

Investing in port infrastructure

Until the foundation type is known, the supply chain cannot form, and investment cannot be made in port infrastructure. Infrastructure, location, water depth, available space for fabrication, and storage are all important for ports that will support new floating wind development.

Up to now, the lack of port infrastructure has made concrete look to be an attractive option over steel as the core foundation material. It would appear easier to manufacture concrete structures because it requires a less skilled workforce. These structures only require the moulds and raw materials, not the specialised welding equipment or qualified welders. Steel can be prefabricated elsewhere and assembled, but that builds in additional fabrication risk and requires additional transport of large components, potentially increasing costs and carbon footprint.

Planning for the long term

Cost and resource efficient operations and maintenance (O&M) is another key element that developers must consider from the outset of a project. If not properly considered, O&M can become a major barrier to the commerciality and day-to-day running of a floating wind farm.

Floating foundations are currently towed back to port for maintenance and repairs. However, this will not remain feasible or economical as wind turbines are located further offshore and the distance to O&M ports increases. The ability to conduct O&M on-location must be developed, because the risk and costs associated with connection and disconnection and transportation of the wind turbines will prove too high over time. A combination of modifying the turbine, as well as developing the tools and offshore support vessels required to support this O&M phase, will be crucial to the success of floating wind projects.

Realising floating wind’s potential

To summarise, floating offshore wind is a truly exciting global opportunity that will play a key role in the energy transition. However, there are barriers to full commercialisation that must be addressed and overcome. Choosing the right structure type and floating foundation for each site is a key step in the right direction. This is not an easy decision to make. Technical challenges, such as a floating foundation’s motion response to environmental conditions, must be considered. Plus, there are several operational factors to analyse, including supply chains, port infrastructure, and O&M.

The bottom line is that, to effectively commercialise floating wind, developers can benefit from independent consultancy. Involving marine and offshore design and engineering specialists from the start of a project can ensure that costs and risks are minimised, timeframes are realistic, and efficiency is maximised. With the right collaboration, and investment supported by technical analysis, the barriers to floating wind can and will be overcome. Ultimately, this will allow floating offshore wind to fulfil its potential in supporting the global energy transition.

Houlder’s Director of Offshore Engineering, Mark Goalen

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