Floating offshore wind is one of the most exciting opportunities in the energy transition, with the UK leading the way through a strong 52.2 GW project pipeline that brings both challenges and opportunities. The challenges related to floating wind made me wonder if there is another way we can develop a complementary technology? A technology I came across and found interesting is the hybrid concept which combines elements of fixed and floating designs, gaining benefits from both. This technology obviously comes with some challenges too and isn’t yet proven to be viable, but it has the potential to act as a stepping stone between fixed and floating offshore wind.
To get a sense of the opportunity for hybrid technology, I looked at the water depths of offshore wind sites around the UK — and the results were pretty striking. The UK’s seabed makes it well suited for hybrids, with the potential to replace around 77% of planned floating capacity. It also got me thinking: maybe “floating offshore wind” isn’t the best term after all. Perhaps “deep-water wind” would better capture the mix of technologies that could play a role to extend our build out into deeper waters with stronger more reliable wind.
The Floating Offshore Wind Landscape
In response to climate change, and to meet net zero targets, the UK Government has committed to doubling onshore wind (27-29 GW) and quadrupling offshore wind (43-50 GW) by 2030. Looking forward, it is estimated that by 2050, around 125 GW of offshore wind might be necessary to achieve net zero. [1]
Over 70% of the potential practical offshore wind resource is located in waters deeper than 60 metres, reaching the current upper limit for fixed offshore wind foundations, which is expected to be constrained to 60-80 metres [2,3,4]. Floating offshore wind (FOW) opens avenues that were previously closed for fixed bottom — utilising sites further from shore with higher wind speeds, or geographical locations where the continental shelf is narrow and falls off rapidly into ‘deep’ water. FOW is therefore expected to play a major role in decarbonising the grid, potentially accounting for one-third of total offshore wind capacity by 2050 (Figure 1).
Figure 1: The expected cumulative offshore wind capacity in the UK until 2050. Source: ORE Catapult Market Database (2025).
The FOW landscape in the UK is in the early development stage, with a huge pipeline totalling 52.2 GW at different stages of planning and development (Figure 2).
Figure 2: UK floating offshore wind pipeline. Source: 4C Offshore (2025).
Fixed and floating offshore wind at surface level may seem relatively similar; however, looking below the waterline, there are some major differences in design. Figure 3 highlights the four main categories of FOW substructures; barge, semi-submersible, spar and Tension Leg Platform (TLP). All technologies utilise some form of mooring arrangement consisting of a number of mooring lines or tendons and anchors to keep the system in place or, in the TLPs’ case particularly, provide stability. This differs from fixed offshore wind, which uses monopiles or jackets secured to the seabed—most commonly through piling. The differences lead to some economic and technical challenges, with the cost of floating wind expected to be double that of fixed offshore wind in the short term.
Figure 3: FOW foundation examples [5].
As an opportunity, floating offshore wind has strong government and industry support. The additional offshore wind capacity gained through opening up wind farms in sites with over 60 metres water depth has led to several initiatives to accelerate this new industry. Renewable energy Allocation Rounds have been updated to designate FOW a separate budget pot. There are also a number of schemes, like the Floating Offshore Wind Manufacturing Investment Scheme (FLOWMIS) investing in Cromarty Firth and Port Talbot, created to support port upgrades and aid deployment. Of the £300 million being earmarked by DESNZ for offshore wind (with a potential for more allocation in the future), floating is expected to be a key beneficiary. Finally, GB Energy is reportedly assessing floating offshore wind projects around the UK, with the plan to back up to six projects with public funds.
The UK Government has made it clear that floating is set to play a big part in our future energy mix. Yet this strong focus should not limit consideration of other deep-water solutions which could allow for opportunities to develop more standardised substructures across different site conditions.
In the development of floating offshore wind, the renewables sector has understandably drawn heavily from the Oil and Gas (O&G) industry, leveraging decades of proven engineering and technological expertise in deepwater conditions. While totally understandable, it should also be noted that there are unique challenges related to floating wind which do not easily carry over from one technology to another. While O&G platforms typically centre around a single, large-scale asset, FOW developments involve potentially hundreds of smaller units, each with distinct operational and structural demands. The physics are also fundamentally different: FOW systems experience significant thrust forces acting far from their centre of gravity, resulting in unique loading and weight distribution challenges.
In light of the technical and deployment challenges faced by floating offshore wind, and this mismatch between traditional O&G offshore practices and the needs of the wind industry, important questions arise about the suitability of some existing floating substructure designs. Are there alternative structural concepts that deserve equal attention?
The Alternative
An emerging technology which could sit alongside floating wind’s position in the offshore wind market is the hybrid concept, utilising lattice–like structures which extend to and are fixed to the seabed, further supported by a number of mooring lines (Figure 4). It is referred to as hybrid technology because it leans on both fixed and floating offshore wind concepts, combined into a new approach. The substructure is attached to the seabed as in fixed offshore wind yet, similarly to FOW, stability is provided through mooring lines or tendons. The expected operational range for hybrid concepts is intermediate water depths from 60-120 metres, covering off the transitional zone between fixed and floating, and extending into what has previously been deemed as floating territory.
Figure 4: Schematic illustrating an offshore wind hybrid concept.
Figure 5 shows a bathymetric map of the UK offshore, and highlights through the rainbow areas coloured red through blue, the proportion of the UK offshore that is under 120 metres water depth. The figure suggests that a significant portion of the UK’s Exclusive Economic Zone (EEZ) has a water depth below 120 metres and can be considered in the range of hybrid offshore wind concepts.
Figure 5: Bathymetric map of UK offshore, with a grey mask covering areas over 120m water depth. Rainbow colours from dark red to light blue highlight the portion of the seabed with 60-120m water depths. Image source: Global Wind Atlas.
To determine the hybrid opportunity in the UK, data from 4C Offshore was used to find the range of water depths for each of the proposed floating wind farms around the UK. By plotting the pipeline of floating offshore wind projects against the water depth range of their proposed sites, it can be seen that many of the projects are located in sites with water depths below 120 metres, and that all have a proportion of their sites below that water depth (Figure 6).
Figure 6: Water depth range and capacity of floating wind farms around the UK (CEP: Concept/Early Planning, CAS: Consent Application Submitted, CA: Consent Authorised, DZ: Development Zone and FC: Fully Commissioned).
The information from 4C Offshore was then used in combination with the expected water depth ranges for each technology (Table 1) to determine if the site could use floating, hybrid, a combination of both technologies, or if the site was not suitable for either and would be more suited to fixed, or a combination of fixed/hybrid or floating. The minimum water depth was set to 60 metres, as this is expected to be the cut off for current proven fixed bottom substructures [6]. Similarly, 1000 metres was assumed to be the maximum depth for FOW, since this is greater than the maximum depths presented in the data [7].
| Substructure Type | Water depth minimum (m) | Water depth maximum (m) |
| Hybrid | 60 | 120 |
| Floating | 60 | 1000 |
Table 1: Water depth limits for each technology.
Figure 7 shows the results of the analysis by the break down of capacity suitable for different technologies, or technology combinations. The results can be summarised as follows:
- According to 4C Offshore, the total current pipeline of FOW capacity in the UK is 52.2 GW. When considering the water depth of the sites, 1.4 GW of the pipeline lies at water depths shallower than 60 metres; these projects would be more suited to fixed substructures. This leaves 50.8 GW capacity in sites deeper than 60 metres.
- Of this 50.8 GW, around 17 GW is in sites each with a range of water depths from 60 metres to 120 metres. These sites could feasibly use either floating or hybrid technology. Within this subset, approximately 1.96 GW also have water depths suited to fixed offshore wind support structures, leaving 15.04 GW that could employ a mix of hybrid and floating solutions. For the 15.04 GW of sites assessed, 66% of the seabed area falls within the 60–120 metre depth range. Using a simple calculation (without considering the exact locations of these depths within each site), this suggests that around 12 GW could be met by hybrid technology instead of floating.
- Of the remaining 33.8 GW of sites, 28.1 GW have water depths within the 60-120 metre range applicable to hybrid technology. This leaves only 5.7 GW of the current FOW pipeline situated in sites where the water depth is over 120 metres.
Figure 7: Breakdown of current floating offshore wind pipeline capacity, by applicability to different technologies, and by water depth.
Assuming that hybrid technology would be suitable for 66% of the combination sites, the analysis suggests that 77% of the current floating wind pipeline of projects are located in areas where a hybrid technology could be deployed. In addition to that, of the remaining sites, only around 5.7 GW are in water depths where pure floating substructures will be the only option.
But what are the advantages of hybrid substructures over floating? Would the offshore wind industry be exchanging one innovative and fledgling technology for another?
One of the most critical challenges facing the FOW sector is the availability of suitable turbines. At present, there does not seem to be an appetite from Western original equipment manufacturers (OEMs) to actively pursue the development of turbines specifically designed for floating applications. This absence risks slowing progress and could even stall the industry’s momentum altogether. This is where hybrid could have the edge, although it should be noted that the appetite of OEMs from other parts of the world, such as China, may be different.
Hybrid technology offers a practical bridge between fixed and floating systems, particularly when purpose-built floating turbines are in short supply. By adapting existing fixed-bottom turbine designs, hybrid platforms could provide a more cost-effective and readily deployable solution, creating a strategic opportunity for OEMs willing to innovate in this space. Due to the major component of capital expenditure that turbine supply contributes to offshore wind projects, leveraging current fixed bottom turbine design could considerably reduce the CAPEX of projects.
One limiting factor of hybrid technology is the lack of demonstrator projects. Unlike FOW, hybrid technology is yet to be proven and installed in an offshore site. Cierco Energy and Marine Power Systems (MPS) have recently signed a Memorandum of Understanding, deploying MPS PelaFlex technology at one of the Llŷr demonstration project sites in the Celtic Sea. It is yet unknown which technology will be used at this site. However, MPS have recently demonstrated at the FloWave Ocean Energy Research facility, their PelaFlex TS (TLP) and GS (hybrid concept), against a semi-submersible. This demonstration exhibited exceptional motion response from PelaFlex GS (Table 2).
| PelaFlex TS | PelaFlex GS | Semi-submersible | |
| Mass (tons) | 2750 | 2250 | 5000 |
| Turbine tilt downwind (°) | <2 | <1 | >6 |
| Vertical displacement– heave (m) | <1 | 0 | >10 |
| forward displacement -surge (m) | <10 | <2 | >20 |
Table 2: PelaFlex TS, PelaFlex GS and Semi-submersible performance comparison.
Like MPS, OSI Renewables have also presented a hybrid type solutions FTLP and FTLP+, showing there is clearly consensus from different companies that the hybrid solution has a number of benefits.
A major anticipated benefit of adopting hybrid technologies is the limitation of motion. Lower motions in general should reduce the fatigue on the structure and put less stress on control systems, which could have the impact of bringing down operational costs and improving power production.
As well as impacting upfront asset costs and OPEX, hybrid systems may also benefit from lower installation costs. Fixed offshore wind installation processes are well known and practiced, along with the required vessels. It is anticipated that fixed bottom installation would be more comparable to hybrid installation than FOW, and therefore pass on experience benefits to the hybrid installation processes. However, as the water depth of sites edges closer to 100m, traditional jack up vessels used for turbine integration are no longer an option. As large capacity turbines (>15 MW) are expected to be utilised as standard in all future offshore wind developments, specialised vessels are already required for fixed bottom installation, and would be required for hybrid also. Innovation in installation technique is already a requirement for FOW developments, so except for the utilisation of jack-up vessels in water depths less than 100 metres, hybrid concepts do not appear to have a clear advantage over floating regarding installation.
Transportation could potentially be made cheaper for hybrid solutions given their modular designs. It is expected that hybrid substructures could be 100% manufactured locally in the UK, and components shipped by road. Mooring line footprint is also expected to be considerably smaller compared to FOW, which is expected to benefit layout optimisation.
The last major consideration for hybrid concepts over current floating design is the mass of the support structures. The examples given in Table 2 suggest that the total substructure mass for a hybrid option could be significantly lower compared to that of a semi-submersible. Lower substructure mass makes for much easier handling in ports, and potentially requires fewer upgrades to existing infrastructure. The need for more upgrades to existing infrastructure is currently a major barrier/bottleneck for FOW development. Lower substructure mass often also accompanies a lower substructure cost, adding another advantage to hybrid concepts for deeper water offshore wind.
Hybrid vs Floating: Market Impact
The hybrid offshore wind concept offers significant potential benefits to the industry, not only in project cost savings but from the added value of increased local content. Given the UK’s geographical advantages, it presents a major opportunity, potentially matching or even surpassing fixed-bottom offshore wind in terms of installed capacity.
Figure 8: FOW market size in the UK as a function of hybrid technology applicability to water depth.
Expanding the role of hybrid technology will inevitably influence the scale of opportunity for floating offshore wind (FOW) in the UK. Figure 8 illustrates how the FOW market would shrink if hybrid concepts were to replace projects in the current pipeline, depending on how deep hybrid projects could be installed. At present, FOW projects are considered viable for all sites deeper than 60 metres. However, as hybrid designs extend the depth threshold further offshore, they could increasingly substitute floating projects, thereby reducing the overall share of FOW capacity within the UK EEZ.
Although hybrid concepts have the potential to influence local FOW deployment, the UK’s ambition to lead globally in FOW development remains well-founded. Unlike hybrid designs, FOW has already been demonstrated at scale and is potentially more suitable across a wider range of seabed types and metocean conditions. This versatility ensures that FOW will continue to play a central role in the UK’s offshore energy mix. Moreover, as international demand for FOW grows, the UK has a unique opportunity to establish itself as a key exporter of technology and expertise. Continued investment in FOW is therefore justified, regardless of how hybrid concepts progress, as both technologies can contribute to a balanced and resilient offshore wind portfolio.
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Footnotes
[1] Wind power monthly (2020). UK needs up to 125GW offshore wind by 2050 to achieve net zero. Available online at: https://www.windpowermonthly.com/article/1702388/uk-needs-125gw-offshore-wind-2050-achieve-net-zero
[2] Empire Engineering (2020). The frontier between fixed and floating foundations in offshore wind. Available online at: https://www.empireengineering.co.uk/the-frontier-between-fixed-and-floating-foundations-in-offshore-wind/
[3] ORE Catapult (2016). Cost Modelling Analysis of Floating Wind Technologies: Assessing the Potentail for TLPWIND.
[4] OffshoreWIND.biz (2022). World’s Deepest Fixed-Bottom Offshore Wind Farm Reaches Construction Milestone. Available online at: https://www.offshorewind.biz/2022/09/23/worlds-deepest-fixed-bottom-offshore-wind-farm-reaches-construction-milestone/
[5] COWI (2023). The floating wind forecast: mostly sunny with a chance of showers. Available online at: https://www.cowi.com/insights/the-floating-wind-forecast-mostly-sunny-with-a-chance-of-showers/
[6] It is acknowledged that fixed bottom is expected to potentially extend to 80m.
[7] It is noted that floating wind could be deployed in water depths >1000m, although technical feasibility is still in question.