Floating Wind and Ground Risk - New Thinking Required? - Part 3/3

A personal view from Mark Finch, Managing Director

We need a new mindset to address the challenges of floating wind. Large areas of seabed, multiple mooring lines, potentially significant uncertainty around WTG layouts, the drive to try and use drag embedment anchors or emerging anchoring solutions – and the iterative nature of design, can present challenges which are not common in fixed bottom offshore wind. Can we afford to get geotechnical data at all points where we touch the seabed? Do we even know where these might be? Assuming we can get a vessel to perform the work at an appropriate time?  

Detective Board 1 with border

A more soil province focused (I was going to say 'zonal approach' but based on recent discussions, people don't seem to like this term…) to site survey and mooring system/anchor design is, I believe, almost certainly the way ahead. A focussed (and integrated – there are many disciplines that need input here) desk top study, using all available information, supported by a high-quality geophysical survey (which is not easy or cheap for large sites in often exposed locations but necessary nonetheless) and relatively limited geotechnical information at as early a stage as possible can be used to develop a high-quality ground model with – critically – a clear understanding of the inherent limitations and uncertainties of the acquired datasets. This can then be used – with preliminary engineering analyses to define the sensitivities of potential anchor solutions – to inform a more detailed geotechnical campaign, aimed specifically at reducing the uncertainty within the ground model – this does not have to be site specific and indeed probably can't be given the nature of floating offshore wind projects. In conjunction with good foundation design, I believe that the design risks can be effectively controlled. Floating offshore wind projects have a different dynamic to fixed bottom projects. The selection of an optimal anchor and mooring design is more iterative than a typical fixed bottom project. Timelines may not allow for anchor-specific (in terms of either type or location) site investigation. New thinking (innovation) is required.

DNV is currently proposing a Joint Industry Project (JIP) on this very subject. This is very welcome and will hopefully show a clear way forward.

So how can we – as an industry - move forward?

This approach will need discussion, challenge, debate and co-operation between developers, engineers, and certification bodies. We are all trying to achieve the same thing. Mindsets will need to shift, and a level of pragmatism is required. Recommended Practice and 'industry best practice' needs to be challenged. The guidelines that exist today are – in my opinion – not appropriate for floating offshore wind projects. Change is needed and fast.

I understand several of the IVB's are currently reviewing their current advice and this is to be supported. 

Business as usual won't work for the floating wind industry. Innovation and pragmatism are needed. Non anchor specific approaches to site survey and foundation design need to be part of the solution – or at the very least part of the conversation. If we stick with old habits, we’ll create more problems than we solve.

"We've always done it this way" won't work for floating offshore wind. 

Get good advice. Get it early. Listen to the answers. To (badly) paraphrase Bill Clinton, "It's the soil stupid." But it's a problem that can be solved and, with the right amount of effort, might even turn out to be an opportunity.