Five tips for floating offshore wind farm development

Fugro have supported more than 20 floating offshore wind developments to date, providing Geo-data acquisition, analysis and advisory services to clients across the globe seeking to harness the potential of this exciting sector. We gain new insights every day and based upon what we’ve learned so far, here are five top tips to optimise your floating offshore wind development:

Take a robust and flexible approach

Over 20 countries across five continents have ambitions to develop floating offshore wind farms, with 85% of proposed sites being in water depths between 60 and 250 meters and the remainder being in up to 1,300 meters. 

An early, comprehensive understanding of site conditions is crucial input into the design of floating wind farms.  For example, new geographies introduce new soil types which need to be thoroughly characterised before reliable and cost-effective designs can be engineered. 

The fixed-bottom offshore wind sector developed an iterative process of data acquisition and analysis to build three-dimensional ground models or digital twins of the subsurface at prospective sites. These models are used to provide easy access to a complete Geo-data archive and efficiently evaluate different wind farm concepts as designs mature.

The geophysical, geotechnical, and environmental datasets required to build these models are acquired by specialised offshore vessels and equipment, with the results integrated into ground models by a multi-disciplinary team of specialists. This methodology is also being adopted in the floating wind sector, but differences in the nature of the asset and the interaction with the operational environment require further insights.  Fortunately, many floating wind farms are planned relatively close to existing offshore infrastructure, which provides opportunities to repurpose data to optimise site characterisation requirements.

A variety of methods and technologies are available to explore and characterise offshore wind farm sites.  Whilst equipment and expertise are growing to meet demand, to accelerate the globalisation of floating wind, clients would benefit from embracing flexible data acquisition solutions that are robust, reliable, able to operate efficiently in harsh environments and capable of consistently capturing high-quality data in (and from) greater depths.

Embrace new technologies

A wide range of floater concepts are being developed, with each concept including a dedicated mooring design that provides suitable stability for the floater along with anchor solutions that are designed to provide optimal holding capacity for the ground conditions and expected load patterns onsite. 

Because offshore wind developers often consider multiple floater or anchor designs in parallel, the significantly larger footprint of a floating foundation compared to a fixed-bottom foundation requires a larger volume of Geo-data to be acquired, which can lead to increased cost and timescale. For example, if it is assumed that cone penetration tests (CPTs) are required at each anchor location, then a geotechnical data acquisition scope could be three to four times larger than one for a monopile wind farm depending upon the anchor configuration.

However, recent developments in ground modelling and seismic inversion techniques - although still early in their development - provide innovative new ways to determine geotechnical parameters of a floating foundation without an excessive number of CPT’s and elevated risk levels. Integrated scoping of data acquisition and ground modelling requirements provides the opportunity to benefit from new technologies, whilst maintaining the flexibility to evaluate a wide range of anchoring patterns in parallel.

Collect high-quality soil samples

Optimised anchor designs satisfy installation requirements and provide sufficient holding capacity over the asset lifespan, whilst minimising cost and risk. It is estimated that to achieve the industry’s floating wind ambitions, approximately 3,400 floaters and around 10,000 anchors will need to be installed on a yearly basis throughout the 2030s. These ambitious targets require fast and accurate engineering solutions which provide flexibility to tailor designs for variable soil conditions.

Cyclic effects, complex loading patterns and trenching of mooring cables are examples of anchor-specific challenges that could influence holding capacity during a wind farm’s operational lifespan. To account for these effects in anchor designs, it is important to obtain a detailed understanding of the soil around each anchor via accurate and efficient laboratory testing programmes of high-quality samples from the site. We believe that any investment in the acquisition and analysis of representative soil samples will positively impact the LCOE of floating wind project by helping developers understand the seabed that their wind turbines are attached to.

Identify and investigate potential geohazards early

Geohazards exist at all offshore wind sites, and floating wind presents different types of geohazards to those recognised at fixed-bottom sites. This often adds complexity to site characterisation efforts and ultimately the design of wind farm infrastructure. Understanding a site’s geological conditions and potential geohazards at an early stage is crucial to reducing risk - to develop and construct the wind farm as planned and to ensure the integrity and performance of the asset throughout its lifetime.

In our experience, the best starting point to identify geohazards is a desktop study. Expertly assessing the potential for a wide range of factors using reliable data sources. The findings of a desktop study can then be applied to define the scope of a site investigation campaign, enabling the acquisition of sufficient data to perform site-specific geohazard analyses.

The techniques to acquire in-situ Geo-data for geohazard assessments have many similarities with those used for regular site investigations, such as CPTs, boreholes, piston cores and grab samples. Samples are despatched to geohazard core logging facilities to examine every millimetre of sediment and to determine how and when the soil laminae arrived in the core.  Experts can then model events to assess whether the risk and frequency of a particular factor are applicable to the lifespan of the offshore wind farm, with the results being used to refine wind farm designs.

Create partnerships to accelerate your innovation efforts

Today’s largest operational floating wind farm, Hywind Tampen, consists of 11 turbines and has a capacity of 88 MW. Wind farms planned beyond 2030 are up to 20 times larger and to make these large projects viable it is essential to reduce the LCOE by a significant margin (at least 50%). A large portion of this LCOE reduction can be achieved through standardisation and upscaling across the supply chain, but innovation is also expected to play a prominent role in growing capacity and scale.

Experts such as Fugro are always seeking to innovate – to optimise and improve performance, trial new technology and to deliver better, faster or smarter.  To identify the right opportunities for innovation and trial new technology in risk-managed ways, it is important to involve innovators early, so they can understand the challenges, share and explore ideas, and develop valuable solutions in good time.

The floating wind sector is young, and its future will depend upon collaborative efforts, shared goals and a collective desire to make it a success.  There are also huge opportunities for research and development, including academic research, joint industry projects, sponsorships and even a willingness to trial new technology or methods alongside more mature comparisons.    

Everyone in the floating wind sector - clients, counterparts, and colleagues - are encouraged to play their part in sparking and accelerating innovation by collaborating early with trusted advisors to explore this exciting future.

In conclusion

Much work remains to deliver on the Paris agreement goals. Although the floating wind sector is still young with many challenges yet to overcome, it is constantly evolving, growing and learning.

We are proud to be part of this voyage of discovery. With more than 55 years of offshore experience and expertise under our belt and having supported projects across the globe, we have the capability, capacity and desire to support the next phase of the floating wind sector’s evolution. We are also curious and keen to learn more from developers about the specific challenges they face, and we look forward to helping our clients achieve their floating wind ambitions.