Offshore wind design

Floating wind turbine technology offers the freedom of the seas with three crucial points to watch out for. Project management will be much more focussed, costs will come tumbling down and early demonstration projects are essential.

( Text content written by Twenty6 for Danny Bonnett, LIC Energy )

Floating wind turbines and bottom-fixed offshore wind turbines share many similarities. However, while fixed structures are restricted to depths of some 50m, ‘floaters’ set us free to follow, harvest and optimise more of the world’s winds efficiently out in much deeper waters.

Floaters are very different in other ways too. They need a much more nuanced approach to project and risk management. They must also appeal to a new set of more adventurous investors. Plus, through close collaboration between specialist partners, a detailed understanding is needed to provide the roadmap of how early stage innovative technology can be taken from development through to end-product.

In fact, from design to manufacture, supply chain, installation and operation, floaters pose tough challenges. But I believe we are now in a very strong position to meet and overcome these.

There is one further point that I would like to stress. That is that demonstration projects are also essential to prove that novel aspects of floating wind technology not only work well but are robust and reliable too. We need careful and efficient engineering that avoids excess but delivers reliability.

The more we change, the more we stay the same

I thought it would be helpful to quickly summarise what needs to change, what can stay the same and how what might appear to be potential problems are actually opportunities.

Still in their relatively-early small-scale experimental days, floating wind farms share all the potential for scaling up size, and dramatically forcing down energy costs, of conventional offshore monopiles and jackets.

The first thing to note is the similarities between fixed and floating wind assets – field layouts are basically the same to optimise wind flow. Downwind wake effects are unchanged. Many elements of the supply chain are common.

How do they differ? It is important to remember that floaters although moored do move continuously and so track a series of loci around a fixed tethering point.

This means that dynamic cables are needed to hold structures that oscillate with the sea surface conditions. Linking floating structures to local interconnectors taking power onshore is another challenge. Wind turbine generator (WTG) hardware can also be crucially if subtly different for floating versus fixed installations. Obviously, foundation structures are considerably different, as are moorings systems.

‘Soft’ skills and experience

But these are mainly the ‘hardware’ differences. The ‘soft’, but equally important, differences that I have already mentioned include: –

• The need for innovations in project execution – different sequences, processes and expertise between start and final delivery points

• Risk levels – a different attitude to long-term opportunities and inevitable hurdles. Careful management of the pertinent risks to protect your investors

• Finance options – linked to risk and potential reward, finance of floating projects will be potentially of interest to a different type of investor. For projects to move up from demonstrator, to pre-commercial and commercial project scale, the required finance levels increase by orders of magnitude!

Modified approach essential

This last point of a different investor profile is an important one. Although the renewable energy sector offers – and delivers – good returns on investment, as recent offshore wind energy market growth has shown, investors who need to ensure a stable and predictable income, such as pension companies, are not usually drawn to pioneering technical sectors.

Alternatively, innovation-friendly organisations, with strong balance sheets and an appetite for well-calculated risks linked to higher returns, are likely to be early players. Norway’s Statoil is an example.

At present, the scale of floaters is small, although they do benefit from large turbines. The only true floating wind farm to date has five units. Therefore, it is too early to expect economics of scale. Yet going by the last half-decade track-record of fixed wind farms, when the tipping point is reached prices will tumble, so increasing the investor appeal of floaters.

Another aspect is the use and type of construction materials. These are basically common between fixed and floating wind. However, it is extremely unlikely that we will see with floaters a successful repetition on a par with the ubiquitous, if humble, monopile. That exemplifies the cost benefits resulting from industrialisation and efficient production.

Gaining ground

I think it is also important to further emphasise commonalities and big differences at this point. Fixed wind experience is going to be very valuable in floating wind project development. So too will be some aspects of oil and gas expertise, particularly around mooring structures, FPSO (floating production storage and offloading) and semi-submersible vessels.

However – and this is a big however – another key attribute will be the ability to understand the ways in which technologies are brought on and matured from very early stages of development. We need to consider how progress can be made up the Technology Readiness Levels (TRL) – a systematic approach created by NASA to assess the maturity of new technologies for on-site deployment – to a point of commercial viability for the end product.

Power of partnerships

My own company, LICenergy, works with a highly-collaborative design and engineering approach as our default position; with partners, we are already working to put some of the new building blocks into place.

On 25th April 2018, we were very pleased to be able to co-launch at FOWT 2018 in Marseilles a joint initiative with Principia that now combines the complementary skillsets and geographic locations of both companies to provide the best possible global solutions for customers.

While LIC has an exceptional track record in detailed jacket and monopile structure design, Principia are specialists in the floating wind field and have pioneered fully-coupled aero-elastic modelling techniques for both fixed and floating structures. LIC has offices in Denmark and the UK, plus strategic US partnerships; Principia has teams across Southern Europe and in Malaysia. Between us we can now can cover any wind project, anywhere.

Sledgehammers are counterproductive

LIC’s team also has a fundamental understanding of how the impressive UK fall in costs and energy prices was achieved for fixed offshore wind turbines. Experience here has shown us that some aspects of utility-scale offshore wind could actually be counter-productive in the medium term – a sledgehammer approach to project management to crack the nut of project risk control is one that smaller projects can’t carry. Innovative projects on smaller scale need more focussed risk management, not just more management.

The upshot is that we won’t be able to do everything as we have done before. Even to get projects in the water will need genuine innovation in structures, systems, materials and methods. This is where our partnership with Principia is so important.

One other point that’s extremely important to make is that we will also need innovative contracts that distribute the upsides fairly to those who give active support to this embryonic industry – return on Investment as incentive and reward.

All in all, it’s a big challenge, but one that the industry is rising to.