Ultra-deep water port: feasibility study

Report compiled by Ernst & Young following their feasibility study looking at the most cost effective locations for an ultra-deep water port in the UK.

Appendix F: Analysis of floating wind market

Appendix F provides a high level review of the potential multi-use opportunities available to an UDW port within the floating offshore wind sector.

When performing this review, we undertook a desktop exercise of publicly available research material, with particular focus on the reports shared by the Scottish Government and its partners.

The technology

To date the fixed bottom foundation technology is the preferred technology for offshore wind farms, with 3.15 GW of new capacity being installed and total installed capacity reaching 15.78 GW in Europe alone by the end of 2017[34]. Of that new capacity over 50% has been installed in the UK, solidifying the North Sea's position as a leading destination for offshore wind development.

However, as the number of developments increase fewer shallow water near shore sites will remain, necessitating the development of ever larger foundations and therefore increasing costs. This creates an opportunity for floating offshore wind, which could exploit the stronger winds in near and far shore deep water locations and deliver high volumes of low carbon electricity at a competitive cost of energy. The technology, however, is still in the early stages as no large scale commercial projects have been deployed to date.

Approximately 40 different floating wind concepts have been identified by the Carbon Trust as being in various stages of development[35]. These concepts can be grouped into three dominant platform types, but no one technology been identified as preferred to be deployed at scale. The three dominant technologies consist of the following:

  • Semi-submersible platform - Is a buoyancy stabilised free surface structure, which is anchored to the seabed with catenary mooring lines. Its low draft allows for flexibility to different site conditions, but is often heavy requiring a high steel mass to maintain stability;
  • Spar platform - The structure is stabilised by a cylindrical ballast, which gains its stability from having the heavier parts beneath the water, while the upper parts are lighter. The design provides stability and is relatively easy to fabricate. However, it requires a large draft which may create challenges during assembly, transportation and installation; and
  • Tension-leg platform - It is a tension stabilised structure that is anchored to the seabed with tensioned mooring lines. Its design allows for a lighter structure and a shallower draft, but may present higher operational risk and limit locations due to specific requirements for soil conditions at site.

The opportunity

Floating offshore wind is an emerging low carbon energy technology, which has been identified as one of the leading technology options to support the UK government's ambition of decarbonising the energy system. Current industry aspirations are for global wind farm deployment to reach 8GW by 2025 and 30GW by 2030[36]. However, the Carbon Trust has noted that 12GW of installed capacity by 2030 would be more realistic, with a number of industry participants supporting this view[37]. The UK is well positioned to become a world leader in floating wind as it already is one of the leading destinations for fixed bottom wind farm development. Further, the UK also benefits from a skilled supply chain that has the relevant experience and capabilities gained from operating in the shipbuilding and O&G sectors.

Scotland, in particular, is considered well suited for floating offshore wind due to its high wind speeds, abundant near-shore deep water sites and access to a skilled supply chain. In 2014 Marine Scotland published the "Regional Locational Guidance" document, which identified seven areas in Scotland that are well suited as test sites for deployment and potential commercial expansion of floating wind farm project[38]. These include the following locations:

  • North of Minch
  • West of Colonsay
  • West of Barra
  • South East of Aberdeen (Dogs Hole, Kincardine)
  • North East of Aberdeen (Buchan Deep, Peterhead)
  • East of Shetland
  • East West of Orkney

Buchan Deep is already home to Hywind Scotland, a 30 MW wind farm which is the first pre commercial array deployment[39]. Further, Dogs Hole has been chosen as the location for the Kincardine Offshore Windfarm Project, a 7 turbine floating windfarm with maximum capacity of 50 MW[40]. Even though, activity in Scotland is growing there is concern that it may be constrained by policy uncertainty resulting from the closure of Renewable Obligations Certificates in October 2018. This will reduce the funding support available and result in floating offshore wind projects having to compete with more established technologies, such as fixed bottom wind, for Contract for Difference feed in tariffs.

Hywind Scotland

The Hywind project has been developed by Equinor, formerly Statoil, in partnership with Masdar and is one of the most mature floating wind farm projects. Initially a 2.3 MW prototype was deployed off the coast of Norway in 2009. The prototype had a traditional spar-buoy structure and a draft of 100m[41]. Following extensive research and the success of the prototype, Equinor elected to scale up the device to 6 MW and install a pre-commercial array of 5 turbines off the coast of Scotland. The wind farm became operational in October 2017 off the coast of north east Aberdeen.

In comparison to the prototype the new devices were not only more powerful, but also had a smaller draft of 78m. Further, Equinor claim to have reduced the cost of the device by 60-70%[42]. The project was delivered through a pan European approach, with the initial spar and tower fabrication taking place in Spain. Works relating to the electrical systems interface were performed by UK based Balfour Bettie and the suction anchors were prepared at the Nigg Energy Park by Global Energy Group. The final upending and turbine assembly was executed at an UDW Port in Norway. This was required so the S7000 vessel could transport the wind turbine generators from the quay onto the floating support structures. After which, the fully assembled structures were towed to site, 30km off Peterhead, Scotland[43].

The total amount invested was approximately NOK 2 billion or £200m, with the project estimated to generate enough energy to power over 20,000 homes[44]. Over the first three months of operation the windfarm achieved average capacity factors of 65% which, as noted by the Carbon Trust, proves the commercial viability of the project[45].

Port availability

In section 6.3.1 we identified the key port requirements for floating wind farm development. Within the UK and Scotland in particular there are a number of facilities that could be used for the fabrication and/or installation of floating wind platforms. The National Renewable Infrastructure Plan[46] published by the HIE and SE identified 11 locations in Scotland that offered the greatest potential for attracting and facilitating floating wind projects.

A separate report by the Carbon Trust[47], analysed the ability of Scottish port facilities to accommodate all three dominant platform types. The analysis identified that two facilities, Nigg Energy Park and the Port of Peterhead, were already suitable to accommodate all three technologies. In addition, the report also found that conditional upon some minor to moderate infrastructure upgrades a further twelve facilities had the potential to accommodate all three platform types.


Floating offshore wind is an emerging low carbon technology that has the potential of becoming one of the leading technologies for decarbonising the energy system. Nonetheless, the technology is still in the early stages, with considerable research and work still required prior to the commissioning of the first large scale commercial projects. However, the opportunity is there for the UK to become the preferred location for floating offshore wind projects. Attracting floating wind projects will not only require favourable geographical features, but also an experienced supply chain and suitable port infrastructure.

There are a number of requirements that UK port will have to meet to accommodate floating wind projects, such as sufficient depth of draft and width of port entrance. In spite of those requirements solely in Scotland there are two ports that at present can accommodate floating wind projects using any of the three dominant platform types. A further twelve being suitable after undergoing minor or moderate infrastructure upgrades.

As such, there does not appear to be a specific need for an UDW port to support the floating offshore wind industry.


Email: Claire Stanley

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