Navigating the Future of Floating Offshore Wind Turbine Energy

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.

Introduction to the importance of offshore wind power

Offshore wind power is a remarkable form of renewable energy that harnesses the power of wind to generate electricity in the ocean. As of 2023, offshore wind power contributes around 11.2% to the electricity mix in the UK, showcasing its growing importance in the energy sector. In the United States, the offshore wind energy pipeline is estimated to have a staggering 52,687 MW of capacity. According to the National Renewable Energy Laboratory, the technical resource potential for US offshore wind is more than 4,200 GW of capacity, translating to an impressive 13,500 terawatt-hours per year of generation. This immense potential underscores the critical role offshore wind power can play in meeting global energy demands and reducing reliance on fossil fuels.

What is offshore wind power?

Offshore wind power is a form of renewable energy that utilises wind turbines installed in the ocean to generate electricity. These turbines capture the kinetic energy of the wind and convert it into electrical power, which is then transmitted to the grid. The technology behind offshore wind power is sophisticated and involves advanced engineering to ensure the turbines can withstand harsh marine environments. According to recent energy trend figures from the Department for Business, Energy and Industrial Strategy (BEIS), the share of electricity generated from offshore wind increased from 8.5% in the second quarter of 2021 to 11.2% in the second quarter of 2022. This growth highlights the expanding role of offshore wind turbines in the global energy mix.

Benefits of offshore wind power

Offshore wind power offers numerous benefits that make it an attractive option for renewable energy generation:

• Reduced greenhouse gas emissions: As a renewable energy source, offshore wind power significantly reduces greenhouse gas emissions, contributing to the fight against climate change.

• Increased energy production: Offshore wind farms can be installed in various water depths, from shallow to deep waters, maximising the potential for energy production. This flexibility allows for the exploitation of high wind speeds found further offshore.

• Job creation: The development and operation of offshore wind farms create substantial employment opportunities. For instance, a modern 1 GW fixed wind farm can generate more than 18,400 direct and indirect jobs, boosting local economies.

• Biodiversity: Offshore wind farms can positively impact marine biodiversity. The structures can attract marine life, providing habitats and foraging grounds for various species, thus enhancing the local ecosystem.

How do floating wind turbines work?

Floating wind turbines represent a cutting-edge advancement in the field of offshore wind energy. Unlike traditional fixed-bottom turbines, floating wind turbines are designed to operate in deep waters where the seabed is too deep for fixed foundations. The technology behind these turbines involves a floating structure that supports the turbine, which can be a spar buoy, a tension leg platform (TLP), or a semi-submersible. These innovative designs allow for the deployment of wind turbines in areas with higher wind speeds, further offshore, where traditional turbines cannot be installed.

Floating wind turbines operate by using a floating structure to support the turbine, which is anchored to the seabed using mooring lines. The turbine itself is designed to rotate with the wind, capturing its energy and converting it into electricity. This electricity is then transmitted to the grid through underwater cables. The floating structure is engineered to withstand extreme weather conditions, including high winds and waves, ensuring the turbine’s stability and efficiency. Although the technology behind floating wind turbines is still in its early stages, it holds immense potential to revolutionise the offshore wind industry by enabling the exploitation of wind resources in deeper waters, thus significantly expanding the areas available for wind energy generation.

Tips for floating offshore wind farm development

Embrace new offshore wind 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.

Recent advancements in floating offshore wind farm technology have enabled the deployment of turbines in deeper waters, utilising innovative anchoring and stability systems.

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.

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 wind turbine 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 turbine 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.

Floating wind farms, such as the Hywind Tampen, demonstrate the potential benefits of deploying turbines in deeper waters, including increased capacity and stronger winds.

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.