The Fundamentals and Challenges of Offshore Wind Farm Construction

By Samudrapom DamReviewed by Laura ThomsonUpdated on Jun 19 2025

Offshore wind farms refer to the construction of wind turbines in bodies of water that generate electricity from the wind. Greater wind speeds are available offshore compared to onshore, and hence, offshore wind turbines can supply more electricity than onshore ones. Offshore wind turbine technology has developed quickly over the last few years, with some of the world’s largest companies involved in several offshore wind energy projects.¹

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With the potential to reduce carbon dioxide emissions by up to hundreds of millions of tons annually, offshore wind farm installations offer a cleaner alternative to conventional fossil fuel-based power sources, which contribute nearly two-thirds of all greenhouse gas (GHG) emissions. In the face of rising energy demands and changing climate patterns, developing efficient offshore wind infrastructure is essential to ensure a stable, sustainable energy future.^2-4

According to the Global Wind Energy Council (GWEC), total global wind capacity is expected to exceed 2 terawatts (TW) by 2030 under current policies, with 224 GW of new offshore wind additions projected over the next seven years.⁶

Offshore wind has become highly cost-competitive, especially when deployed at scale. In late 2023, the average levelized cost of energy (LCOE) for offshore wind was 114 USD/MWh and 95 USD/MWh in the United Kingdom (UK) and Germany, respectively, significantly lower than combined-cycle gas turbines (CCGT), which averaged 144 USD/MWh and 149 USD/MWh, respectively. This downward LCOE trend applies globally, including in emerging markets.⁶

Construction of Ocean Wind Farms

A typical ocean wind farm consists of many wind turbines located in seawater, linked together by a series of cables to an offshore transformer station. An underwater cable connects the station to an onshore transformer station linked to a power grid.

Wind turbines are usually laterally spaced at a distance several times their rotor diameter and staggered to reduce wake effects. Installing turbines closer to each other increases turbulence and wake effects, thereby minimizing power generation.

Each wind turbine system in an ocean wind farm will include a foundation, support structure, transition piece, tower, rotor blades, and nacelle. Numerous foundation structures exist, including a monopole base, gravity base structures, tripod piled structures, conventional steel jacket structures, and floating bases. Support structures are used to connect the transition piece or tower to the foundation. In certain cases, foundations act as support structures as well. The nacelles include the electro-mechanical components of wind turbines, such as generators and gearboxes. The power cable for each turbine is placed within a plastic tube, and it runs to the cable trench located in the seabed.

Construction Considerations of Offshore Wind Farms

Considerations include collisions with ships, marine growth, and corrosion protection. Efficient construction can achieve significant cost and schedule savings. Since sea conditions are irregular and extreme, maintaining offshore wind farms is much more challenging than onshore operations. Ocean wind farms require a strict maintenance schedule at intervals of four to six months.

Transportation

Foundations such as suction caissons, braced frames, tripods, and monopiles must be transported to the sites using barges. In some cases, like monopiles with a large diameter, the ends are capped, sealed, and floated to the site. The turbine is generally transported as one piece.

Assembly

A jack-up rig acts as a stable platform for operation, including rotor, nacelle, tower, and pile installation. However, it lacks maneuverability during tower installation. Hence, ship-shaped vessels with rotating cranes are usually preferred in construction work.

Offshore electric cabling

Undersea power transmission cables are employed through a hydro-plowing process in which cables are buried a few meters below the seabed.

Floating offshore wind platforms

Offshore wind turbines use fixed foundations up to 60 meters deep, but floating structures called floaters are used in deeper waters or steep continental shelves.

Floating offshore wind turbines (FOWTs) are mounted on platforms anchored to the seabed with mooring lines. These systems are essential for deeper sites and offer significantly greater potential than fixed offshore wind power due to their adaptability to various seabed conditions.^2,7

Floating offshore wind turbine (FOWT) platforms are mainly categorized as semi-submersible, spar-buoy, and tension-leg platforms (TLPs). The OC3-Hywind concept uses a spar-buoy platform moored with three anchor piles. Designed for deep waters (over 100 m), spar buoy platforms feature a small plane area and a large cylindrical mass submerged below the water surface.⁷

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Static stability is maintained by positioning heavy ballast low within the buoy, which keeps the center of gravity below the center of buoyancy and provides strong resistance to pitch and roll movements. Typically made from steel/concrete with the ballast of water or solid materials, these platforms are stabilized by mooring lines made of fiber ropes, steel cables, or chains with embedded anchors to the seabed.⁷

A semi-submersible platform consists of multiple partially submerged columns, with the wind turbine mounted on one. Its hydrostatic stability is achieved through large spacing between columns, which provides the second moments of the waterplane area around its principal axes.⁸

TLPs achieve stability through highly tensioned mooring lines enabled by the platform’s positive buoyancy. TLP FOWTs offer advantages in motion dynamics and lightweight structures compared to spar-buoy and semi-submersible platforms, potentially improving power performance. Large-scale deployment is possible due to their small footprints.⁸

However, TLP development lags due to challenges like a lack of inherent hydrostatic stability, which increases installation costs for turbines and cables. The complex design and stability concerns during installation and under accidental limit states also further impact feasibility and cost-effectiveness, making careful evaluation essential in TLP FOWT development decisions.⁸

Artificial intelligence (AI)-enabled maintenance and condition monitoring

This AI-based approach for offshore wind turbines enables automated early fault detection in wind turbine systems and subsystems, allowing timely diagnosis, condition-based maintenance, and efficient repair planning. This reduces downtime, prevents damage, and extends the turbine's lifespan. Frequent, remote predictive maintenance also lowers capital expenditures by minimizing costly on-site visits, making it especially beneficial for offshore wind farms.⁹

Modular offshore substations

Offshore substations are vital for submarine electric power transmission in wind farms. Recent innovations include modular designs to reduce weight, ease maintenance, and lower costs. For instance, Siemens has developed the offshore transformer module for alternating current systems within 80 km of shore, which fits on existing turbine foundations and eliminates the need for extra platforms.

For wind farms beyond 80 km, Siemens introduced a smaller high-voltage direct current substation, offering greater efficiency over long distances and for larger projects.¹⁰

Robotic installation or repair systems

These systems are revolutionizing offshore wind farm operations by enhancing safety and reducing human intervention in hazardous environments. These advanced technologies enable precise, efficient maintenance and construction, ensuring higher uptime and lower operational costs.¹¹

Maintenance technologies for offshore wind turbines now include robots for blade cleaning using controllable motion and water-jet systems. Prototype unmanned aerial vehicles (UAVs) and remotely operated vehicles (ROVs) have also been tested for inspections. The Multiplatform Inspection, Maintenance & Repair in Extreme Environments (MIMRee) project introduced a fully autonomous multi-robot system combining aerial, surface, and crawling robots to detect and repair blade defects efficiently.¹¹

Video Credit: Siemens Gamesa/YouTube.com

Environmental and Regulatory Challenges of Offshore Wind Farms

Offshore wind energy has great potential to help nations achieve a clean, independent energy source for the future. Yet, offshore wind farms face environmental and regulatory challenges that can impact their development and operation. These include ecological concerns, permitting complexities, and compliance with evolving marine and energy regulations.

The impact of noise generated during wind farm construction on marine populations is currently one of the major concerns of offshore wind turbines. Several studies evaluating the noise impacts suggest that the regulators must make efforts to meet both climate change targets and existing environmental policies on conserving marine species.¹²

Bubble curtains reduce pile-driving noise during offshore wind farm construction, protecting marine species such as porpoises from hearing loss.

A study found that single and double bubble curtains reduced noise by 7-10 dB and 12 dB, respectively, with the greatest attenuation at frequencies above 1 kHz, making pile driving noise at longer distances comparable to ambient noise.¹³

Ecological impacts of offshore wind farms primarily occur during construction and operation phases, affecting marine species and ecosystems around installations. Construction activities can cause endogenous pollutants release, sediment-water interface destruction, and water stratification mixing, leading to habitat disturbance, altered biomass and species composition, and disrupted communication and migration patterns. Epibenthic, benthic organisms, and plankton are particularly vulnerable to these changes.¹⁴

In the United States (US), the Bureau of Ocean Energy Management (BOEM) oversees permitting and operation of offshore wind facilities. In January 2023, the bureau issued a proposed rulemaking to establish a leasing system for offshore renewable projects similar to offshore oil and gas. Multiple federal agencies are involved in permitting, while states regulate projects within state waters, including transmission cables. The Coastal Zone Management Act (CZMA) outlines three frameworks for state-level coastal regulation, which vary significantly by state.¹⁵

Any offshore wind energy activity on federal or federally controlled lands, such as the outer continental shelf, requires permissions like rights-of-way or licenses. Offshore wind development was formally regulated under the Energy Policy Act (EPAct) of 2005, which mandated federal oversight to ensure environmental protection, safety, national security, and respect for other lawful uses of offshore areas. These regulatory layers create complex challenges for offshore wind project approval and development.¹⁵

Similarly, under a European Union directive, countries with territorial waters have implemented maritime spatial planning to identify areas with high potential for offshore wind energy. MSP is a planning tool that balances sectoral interests with environmental protection needs, playing a critical role in offshore wind farm siting. However, conflicts arise with fisheries, shipping routes, marine protected areas, species protection, flight safety, and existing infrastructure.

To minimize these conflicts, countries apply specific siting criteria, including ecological buffer zones, safety zones for shipping, and activity restrictions. The precautionary principle must guide MSP by avoiding sensitive areas and busy shipping routes, with detailed rules and conditions to reduce sectoral conflicts.^16,17

Offshore foundations are subjected to additional load impacts such as ice loads, ocean currents, potential ship impact, and storm wave loading. Another significant barrier is the high cost of construction and maintenance of offshore wind turbines. Despite all these significant challenges, increasing installations of offshore wind turbines worldwide emphasize the need for significant improvements in offshore wind farm construction processes to achieve more innovative and cost-effective foundations in the future.

Industrial and Commercial Context

Ørsted, Siemens Gamesa, Vestas, and Equinor are key players in the offshore wind energy market.

Over 75 GW offshore wind energy projects have been installed across 18 countries by December 2023, with the UK, China, Germany, Denmark, and the Netherlands being the leading countries.

Wind Catching Systems is developing the Windcatcher, a scalable floating wind solution that reduces the LCOE through standardization, improved operations, and efficient acreage use. Its design features multiple small, locally produced turbines with accessible maintenance via an integrated elevator system.¹⁸

Active projects such as Hornsea 3 Offshore Wind Farm and Dogger Bank Wind Farm are set to significantly boost the UK’s renewable energy capacity.

Hornsea 3, a £8.5 billion project with a 2.9 GW capacity, will power over 3 million UK homes. Located 160 km off the Yorkshire coast, it will be managed from Grimsby and will join Hornsea 1 (1.2 GW) and Hornsea 2 (1.3 GW), which together supply green electricity to 2.5 million homes.

Hornsea 4, with a potential capacity of 2.6 GW, is also in development. Similarly, Dogger Bank Wind Farm, located 130–190 km off the North East coast of England, will become the world’s largest offshore wind farm. Developed in three phases—Dogger Bank A, B, and C—each with 1.2 GW capacity, it will collectively generate 3.6 GW, enough to power up to 6 million homes annually. These projects significantly contribute to UK energy security and economic growth.^19,20

Future Developments in Offshore Wind Technology

Ocean wind farms are transforming global energy landscapes with their vast potential for clean power generation. Emerging trends such as offshore hydrogen production, integration with battery storage systems, and the decarbonization of heavy industries are expanding their impact.

Offshore-generated electricity can be used to produce green hydrogen at sea, supporting zero-emission fuels. Coupled with energy storage, these advancements enhance grid reliability and flexibility, positioning offshore wind as a cornerstone of the global transition to a low-carbon, sustainable energy future.

References and Further Reading

1. Ocean Energy Council. Offshore Wind Energy. [Online] Available at: https://www.oceanenergycouncil.com/ocean-energy/offshore-wind-energy/
2. Nikitas, G., Bhattacharya, S., Vimalan, N., Demirci, H. E., Nikitas, N., & Kumar, P. (2019). Wind power: A sustainable way to limit climate change. Managing Global Warming, 333-364. DOI: 10.1016/B978-0-12-814104-5.00010-7, https://www.sciencedirect.com/science/article/abs/pii/B9780128141045000107
3. Nagababu, G., Srinivas, B. A., Kachhwaha, S. S., Puppala, H., & Kumar, S. V. (2023). Can offshore wind energy help to attain carbon neutrality amid climate change? A GIS-MCDM based analysis to unravel the facts using CORDEX-SA. Renewable Energy, 219, 119400. DOI: 10.1016/j.renene.2023.119400, https://www.sciencedirect.com/science/article/abs/pii/S0960148123013150
4. Climate change mitigation: reducing emissions [Online] Available at https://www.eea.europa.eu/en/topics/in-depth/climate-change-mitigation-reducing-emissions (Accessed on 11 April 2025)
5. Wind [Online] Available at https://www.iea.org/energy-system/renewables/wind (Accessed on 11 April 2025)
6. Global Offshore Wind Report 2024 [Online] Available at https://www.connaissancedesenergies.org/sites/connaissancedesenergies.org/files/pdf-actualites/GOWR-2024_digital_final_2.pdf (Accessed on 11 April 2025)
7. Shafiee, M. (2023). Failure analysis of spar buoy floating offshore wind turbine systems. Innovative Infrastructure Solutions, 8(1), 28. DOI: 10.1007/s41062-022-00982-x, https://link.springer.com/article/10.1007/s41062-022-00982-x
8. Wang, Y., Yao, T., Zhao, Y., & Jiang, Z. (2025). Review of tension leg platform floating wind turbines: Concepts, design methods, and future development trends. Ocean Engineering, 324, 120587. DOI: 10.1016/j.oceaneng.2025.120587, https://www.sciencedirect.com/science/article/abs/pii/S0029801825003026
9. Maron, J., Anagnostos, D., Brodbeck, B., & Meyer, A. (2022). Artificial intelligence-based condition monitoring and predictive maintenance framework for wind turbines. Journal of Physics: Conference Series, 2151, 1, 012007. DOI: 10.1088/1742-6596/2151/1/012007, https://iopscience.iop.org/article/10.1088/1742-6596/2151/1/012007/meta
10. JRC Wind Energy Status Report 2016 Edition [Online] Available at https://static.smartgridsinfo.es/media/2017/03/informe-jrc-energia-eolica-mercado-2016.pdf  (Accessed on 11 April 2025)
11. Khalid, O., Hao, G., Desmond, C., Macdonald, H., McAuliffe, F. D., Dooly, G., & Hu, W. (2022). Applications of robotics in floating offshore wind farm operations and maintenance: Literature review and trends. Wind Energy, 25(11), 1880-1899. DOI: 10.1002/we.2773, https://onlinelibrary.wiley.com/doi/full/10.1002/we.2773
12. Foley, J. A. (2013) Noise from Offshore Wind Farm Construction Could Harm Marine Mammal Life [Online] Available at https://www.natureworldnews.com/articles/4751/20131104/noise-offshore-wind-farm-construction-harm-marine-mammal-life.htm
13. Jongbloed, R. H. et al. (2021). Efficient and effective use of bubble curtains for noise mitigation in offshore installation projects: WP1: Defining the starting conditions. DOI: 10.18174/629724, https://research.wur.nl/en/publications/efficient-and-effective-use-of-bubble-curtains-for-noise-mitigati
14. Wang, L. et al. (2024). Ecological impacts of the expansion of offshore wind farms on trophic level species of marine food chain. Journal of Environmental Sciences, 139, 226-244. DOI: 10.1016/j.jes.2023.05.002, https://www.sciencedirect.com/science/article/abs/pii/S100107422300205X
15. Offshore Wind Energy Development: Legal Framework [Online] Available at https://sgp.fas.org/crs/misc/R40175.pdf (Accessed on 11 April 2025)
16. Martín-Betancor, M., Osorio, J., Ruiz-García, A., & Nuez, I. (2024). Evaluation of maritime spatial planning for offshore wind energy in the Canary Islands: A comparative analysis. Marine Policy, 161, 106046. DOI: 10.1016/j.marpol.2024.106046, https://www.sciencedirect.com/science/article/pii/S0308597X24000447
17. Planning Criteria for Offshore Wind Energy [Online] Available at https://maritime-spatial-planning.ec.europa.eu/media/document/12529 (Accessed on 11 April 2025)
18. Unleashing The Power of Offshore Wind [Online] Available at https://www.windcatching.com/ (Accessed on 11 April 2025)
19. Hornsea 3[Online] Available at https://hornseaproject3.co.uk/  (Accessed on 11 April 2025)
20. Building the world’s largest offshore wind farm [Online] Available at https://doggerbank.com/ (Accessed on 11 April 2025)

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