Monopile Foundations in Offshore Windfarms

Offshore wind turbines have a higher capacity factor averaging 45-60%, producing approximately 3.6-8 MW per turbine.

Approximately 40% of the global population lives within 60 miles of the ocean, highlighting the critical need for sustainable development and climate resilience in coastal areas to support nearly half of humanity (MIT Technology Review). The global shift towards renewable energy has propelled the development of offshore wind energy due to its higher efficiency and larger potential compared to onshore wind farms. Offshore wind farms present a significant opportunity to clean up the electricity supply globally. These farms play a crucial role in reducing reliance on fossil fuels and advancing sustainable energy solutions worldwide.

According to the Global Wind Energy Council (GWEC) and the International Renewable Energy Agency (IRENA), the world needs to achieve at least 380 GW of offshore wind capacity by 2030 to stay on track with climate goals. Long-term projections suggest that capacity could exceed 2,000 GW by 2050 if current growth trajectories and supportive policies continue. Currently, over 83.2 GW of offshore wind energy projects are installed across 18 countries, with China, UK, Germany, Netherlands and China leading the way.

Onshore and offshore wind turbines

Offshore wind turbines can be significantly larger than their onshore counterparts, leading to higher energy production. Additionally, the offshore environment provides access to steadier and stronger winds, which enhances the overall capacity factor of the wind turbines. Offshore wind turbines are sophisticated engineering structures designed to convert wind's kinetic energy into electrical power. Unlike onshore turbines, they face additional complexities due to hydrodynamic loads and extreme wind conditions. A critical component that ensures the stability and structural integrity of these turbines is the foundation, which anchors the turbine to the seabed. Designing and constructing this foundation requires meticulous attention and engineering excellence to withstand the harsh marine environment.

Foundation:

The foundation of a wind turbine is incredibly important but often not talked about much.  It supports the massive structure, which includes tower, transition piece and Wind Turbine Generator (WTG) to withstand the forces that rises from wind and wave action. The engineering behind these foundations is complex, which/as it requires precise and optimized solution and robust materials to handle dynamic loads and vibrations over its service life. An effective foundation keeps the turbine running smoothly, reduces repair costs, and helps produce more energy efficiently. Foundations account for 16% to 34% of the overall costs of a wind farm, with the exact percentage varying based on the location and size of the project (Bentley). The foundation isn’t just a support, it is the key to making sure the wind turbine does its job well.  

Monopile foundation:

The monopile foundation is one of the most popular and widely used offshore wind foundations over the past few decades. By the end of 2016, it accounted for 80.8% of all existing offshore installations in Europe. This foundation consists of a steel hollow cylinder with a varied diameter of 3-6 meters and a length of 20-50 meters, with 40-50% of the length embedded deep into the seabed to provide lateral resistance (Researchgate).

Monopiles are manufactured from high-strength steel, designed to withstand harsh marine conditions. They are typically fabricated in sections and welded together. Once manufactured, monopiles are transported to the installation site using specialized vessels. The installation process involves driving the monopile into the seabed using hydraulic hammers or vibration techniques, ensuring that the monopile is deeply embedded into the seabed and provides a robust foundation for the wind turbine.  

The suitable average water depth to install monopile foundations is upto 30-40 meters and beyond this, the material consumption and installation costs increase significantly (ScienceDirect).

Monopile foundations are preferred in offshore wind energy projects for several reasons:

Simplicity and Cost-Effectiveness: Due to its effective geometrical feature, monopile foundations are relatively straightforward to design, manufacture, and install compared to other types of foundations such as jackets or floating platforms. This simplicity translates into cost savings in both production and deployment.

Structural Integrity: The monopile are designed to carry both axial and lateral loads due to aerodynamic and hydrodynamic loading from the structure to the seabed. The embedded length of monopile into seabed ensures overturning stability and zero or negative pile toe displacement.

Versatility: Monopile foundations can be used in a range of water depths, typically up to 40 meters. This makes them suitable for many offshore wind farm locations. Beyond this depth, other foundation types, like floating structures, may be more appropriate.

Durability: Modern coatings and cathodic protection systems enhance the longevity of monopile foundations, ensuring they remain functional for the lifespan of the wind turbine, which is typically 20-25 years.

The design of a monopile is a complex process that requires expertise in structural engineering, geotechnical engineering, material science, and offshore construction.  

Monopiles are driving the offshore wind energy projects and NeXHS is at the forefront. With over 80% of offshore wind turbines anchored using monopile foundations, this solution has become the backbone of offshore energy infrastructure.

At NeXHS, we design and deliver foundation solutions that meet the challenges of the deep seas with precision, efficiency, and sustainability at their core.

Contact us to explore how our Optimised Monopile Foundation solutions can elevate your offshore projects.