Beyond land-based installations, the pursuit of wind energy in the scope of the global transition to renewable energy has ventured into the marine domain. While fixed-bottom wind farms have been the mainstay, the emergence of floating offshore turbines is gaining momentum in response to evolving challenges. These two approaches diverge in location and foundation type, significantly impacting their technical feasibility, environmental footprint, and economic viability.
The main difference between offshore and floating wind farms
Wind energy, generated by windmills driving generators, stands as a prominent sustainable energy source. With steadier, stronger winds at sea, the ocean offers a consistent supply of clean electricity.
While offshore and floating wind turbines aim to harness wind power in marine environments, the key differences lie in their foundation types, installation and maintenance methods, suitable locations, costs, and environmental impacts. Let’s delve into the key differences between these two types of energy infrastructure.
Location defined by geographical characteristics
Conventional offshore wind turbines are typically situated near coastlines due to water depth constraints, often within 30 kilometers. These turbines harness robust and reliable wind conditions prevalent in shallow coastal waters.
According to June 2024 figures, China leads the global offshore wind industry with the highest number of operational offshore farms, followed closely behind by the United Kingdom with 39, Germany with 30, and Vietnam with 26. Europe and Asia also boast significant offshore wind installations, with notable contributions from Denmark, Belgium, the Netherlands, Norway, France, Taiwan, Japan, and South Korea.
In contrast, floating platforms are deployed at greater distances, ranging from 30 to 100 kilometers or beyond, in deeper oceanic regions. This strategic positioning grants access to more potent and consistent wind resources, resulting in increased energy production. Norway currently hosts the world’s largest operational floating wind farms, but the technology is rapidly gaining traction globally. Significant projects are underway or in production across diverse regions, including Scotland, Spain, Portugal, France, Japan, and the U.S. West Coast.
Foundation type
Fixed-bottom turbines are anchored directly to the seabed using monopiles, jackets, or gravity-based foundations. This type is suitable for shallow waters up to approximately 60 meters deep.
As for floating platforms, the turbines are mounted on floating platforms of different types.
- A spar-buoy is a structure that extends far below the water surface, providing stability through its deep draft and low center of gravity. The platform is anchored to the seabed with catenary mooring lines.
- A semi-submersible is composed of multiple columns and pontoons that distribute buoyancy and stability. This design is anchored using spread mooring lines that extend outward from the platform.
- A tension-leg platform (TLP) is anchored to the seabed with vertical tensioned mooring lines, providing high stability with minimal horizontal movement.
Such platforms are suitable for deep waters beyond 60 meters, often extending to depths of several hundred meters.
Distinct challenges in installation and maintenance
The establishment of offshore wind energy infrastructure demands specialized vessels and heavy lifting machinery to transport and install its large components. Construction is restricted to relatively calm sea conditions and shallow waters. By comparison, floating platforms can be assembled onshore before being towed to their designated location, mitigating the need for specialized vessels. Deployment is feasible in deeper and rougher waters.
Regarding maintenance, operations on fixed-bottom structures are relatively simpler due to their closer proximity to shore, offering easier access for crews. In contrast, servicing floating wind farms is considerably more demanding, given their remote and harsh operating conditions. However, some major repairs can be executed by towing these platforms back to shore.
Lower investment and operational costs for fixed-bottom structures
Using fixed structures for offshore wind power demands huge substantial upfront investments due to the complex nature of underwater construction and the specialized equipment required. Floating wind farms amplify these costs with the added complexities of advanced technology, sophisticated anchoring systems, and longer transmission distances.
Similarly, while traditional fixed-bottom structures generally incur lower operational expenses due to easier accessibility and established maintenance protocols, floating wind farms present unique challenges. Their remote locations and intricate designs necessitate specialized maintenance and logistics, driving up operational costs.
Limited ecological risk from floating wind farms
Floating platforms exert a gentler influence on marine ecosystems as they necessitate fewer and less invasive anchoring points compared to fixed-bottom turbines. The latter’s drilling and installation process on the ocean floor can endanger marine habitats and wildlife. Moreover, traditional wind farms can be visually intrusive from the shoreline and generate underwater noise that disrupts the marine fauna. Conversely, the offshore positioning of floating wind farms minimizes their impact on coastal landscapes and communities. Nevertheless, the environmental effects of mooring systems and underwater noise from these structures necessitate careful management.
The future of offshore wind: fixed or floating foundations?

To summarize, offshore wind energy with fixed-bottom turbines is limited to shallower waters and closer to shore, making it more established but potentially more disruptive to marine habitats and coastal views. Floating wind energy, on the other hand, offers the potential to exploit deeper and more remote waters with stronger wind resources, although it currently faces higher costs and technical complexities.
In the future, both offshore and floating wind farms will play vital roles in the global energy mix. Fixed-bottom offshore wind farms will continue to be privileged in shallow waters where they are most cost-effective and technologically mature. However, as floating wind technology advances and costs decrease, it will become increasingly privileged in deeper waters, allowing for improved ocean energy management.
Economic factors
The choice between offshore and floating wind farms will also depend on a combination of geographic and site-specific conditions, environmental impacts, and technological developments. However, a trend towards a balanced and complementary use of both approaches is likely to be favored to maximize clean energy generation. A thorough evaluation of these parameters is essential for optimizing the design and deployment of wind energy projects.
Geographic and site-specific conditions
When choosing between offshore and floating wind farms, several geographic and site-specific conditions must be taken into consideration. These factors influence the feasibility, efficiency, and cost-effectiveness of each type of wind farm. Here are the main conditions to consider:
- Water depth: fixed-bottom turbines are best suited for shallow waters, typically up to 60 meters deep. Shallow continental shelves, where the seabed gradually slopes away from the coast, are ideal. Floating is designed for deep waters beyond 60 meters and can be installed in areas where the seabed drops off sharply.
- Wind speed and consistency: both types of wind farms need areas with high and consistent wind speeds. Floating wind farms, however, can access stronger and more consistent winds found further offshore in deep waters.
- Seabed conditions: the type of seabed (rocky, sandy, muddy) affects the installation of fixed-bottom foundations. Floating wind farms are less dependent on seabed composition since they are anchored rather than fixed. Additionally, areas with high seismic activity may pose challenges for fixed-bottom turbines, making floating turbines a better choice.
- Weather and ocean conditions: regions with extreme wave and storm conditions require robust engineering solutions. Floating platforms need to be particularly resilient to harsh marine environments. In colder regions, ice buildup can pose additional challenges for both types of wind farms.
- Proximity to from shore: being closer to land, fixed offshore wind installations require shorter and less expansive transmission lines. Floating wind farms, often located further offshore, necessitate more extensive undersea cabling and grid infrastructure. Another key aspect is the availability of local supply chain resources, ports, and construction infrastructure, since it may affect the project feasibility and cost.
- Ecological impact: areas with sensitive marine habitats may benefit from floating wind farms, which have a lower seabed footprint compared to fixed-bottom turbines. In this regard, analysis of birds and marine mammal migratory paths is crucial to minimize environmental disruptions.
Areas with deep coastal waters, as well as strong and consistent winds, such as the West Coast of the United States, parts of Europe, and Japan, are ideal for floating wind farms. In Japan, the lack of extensive shallow continental shelf limits fixed-bottom installations.
Conversely, regions characterized by extensive shallow continental shelves, and strong wind resources, will continue to favor fixed-bottom offshore wind farms. The North Sea is a cost-effective location for fixed-bottom offshore wind farms.
In the Mediterranean Sea, mixed conditions with both shallow and deep waters make it suitable for a combination of fixed-bottom and floating wind turbines, with the latter being more advantageous in areas with greater depths.
Environmental and regulatory factors
Local regulations and permitting processes can vary significantly by region, affecting the feasibility of both offshore and floating wind projects. For instance, government policies and incentives will play a crucial role in the development of both technologies. Regions with supportive regulatory frameworks for renewable energy will likely see more investment in both offshore and floating wind projects.
Besides, compliance with environmental protection laws and regulations can influence the choice of technology. Floating wind farms may be favored in countries where seabed disturbance is a significant concern or where marine ecosystems are particularly sensitive.
The International Energy Agency (IEA), an intergovernmental organization established in 1974 after the 1973 oil crisis, aims to ensure a secure and sustainable energy future for its member countries. It collaborates with national authorities. For example, in the United States, a government agency known as the Bureau of Ocean Energy Management (BOEM) is responsible for managing the development of energy and mineral resources on the Outer Continental Shelf (OCS). Among its missions are assessing the potential of offshore areas for energy and mineral resources, and overseeing safety standards for offshore operations.
Technological advancements
Innovations in floating platform design, materials, and installation techniques will likely reduce costs, making floating wind farms more competitive with fixed-bottom installations. R&D will focus on some aspects:
- More efficient and stable structures that can withstand harsh marine conditions are key. This will require advanced materials that enhance durability and reduce floating platform weight. Modular designs should be favored for easier transport and assembly, simplifying the construction process and reducing costs. Additionally, using eco-friendly materials and coatings can help reduce the impact on marine ecosystems.
- The same principles apply to anchoring and mooring systems, which must provide greater stability and flexibility, enabling deployment in deeper and more turbulent waters. These systems should be combined with enhanced dynamic positioning technologies to allow floating turbines to maintain optimal orientation and stability in changing sea conditions.
- Developing larger and more powerful turbines is strategic for generating more electricity, making both fixed-bottom and floating wind farms more cost-effective. Using lightweight and durable materials for turbine components will improve performance and reduce the load on floating structures. Additionally, incorporating noise reduction technologies will minimize the impact of the turbine operation on marine life.
- Energy storage solutions, such as batteries and hydrogen storage, are unavoidable for better integrating intermittent wind energy into the grid. Smart grid technologies will facilitate the efficient transmission and distribution of electricity from remote offshore and floating wind farms.
- Researchers need to develop high-voltage direct current (HVDC) cables that can transmit electricity over long distances with minimal losses, making it feasible to connect remote floating wind farms to the onshore grid. These undersea cables must exhibit improved durability and flexibility to withstand deep-water pressures and the dynamic movements of floating structures.
- Robotic and automated systems for installation and maintenance tasks will reduce the need for human intervention in harsh and remote offshore environments. Advanced monitoring systems using AI and machine learning will predict maintenance needs and optimize performance, thereby reducing downtime and operational costs.
As floating wind technology matures, it will become easier to scale up projects, leading to economies of scale and further cost reductions in construction, installation, operation, and maintenance.
FAQ about floating wind
Offshore energy infrastructure typically refers to fixed installations on the seabed, such as offshore wind farms or oil rigs. In contrast, floating energy infrastructure includes platforms that float on the water’s surface, like floating wind turbines or solar panels.
Floating energy systems can be installed in deeper waters where fixed structures are impractical. They often have lower installation and maintenance costs and can be moved to optimal locations for energy production.
Floating energy infrastructures face challenges such as stability in harsh weather conditions, higher initial costs, and the need for advanced technology to anchor and maintain these systems securely.
Both systems can have environmental impacts, including potential disruption to marine life and ecosystems. However, floating systems generally have a lower seabed impact, making them potentially less disruptive to marine habitats compared to fixed offshore installations.