As the backbone of any structure, wind turbine foundations are critical to the longevity and effectiveness of a wind project. Wind turbines are exposed to the most challenging of weather, causing vibrations and stresses in the structure. A well-designed foundation helps to absorb these forces and prevent damage to the turbine over time. The design of wind turbine foundations involves soil mechanics and engineering principles.
The Soft-Spot® uses a soft layer of EPS under the central part of the foundation for a wind turbine in RWE’s “Rea unificado” wind farm in Spain.
Basic principles, but specialised engineering
Geotechnical engineers must consider the soil type, bearing capacity and subsurface conditions to determine the most appropriate foundation design. The foundation design itself must be reliable over the lifetime of the wind turbine, but not so large that the construction cost becomes prohibitive. While there are several types of wind turbine foundations, each with its own unique advantages and disadvantages, the foundation design ultimately depends on several factors, including soil conditions, water level, and turbine loads.
One company that has proven its expertise in foundation design is CTE Wind International. It has designed foundations for wind turbines in various regions of the world, from Australia to France, Spain to Latin America, Scandinavia to South Africa, and North America. Solutions range from standard gravity and deep foundations on piles to more innovative solutions that are difficult for the average structural engineer to calculate and design.
For the Mesa Morenos wind farm in Mexico CTE Wind designed a rock-anchored foundation with a shorter anchor cage.
Rock-anchored and other special foundations
CTE Wind International offers multiples special foundation designs. One of them is the rock anchor foundation. This solution is commonly used in Scandinavian countries, where it reduces the volume of concrete and steel tonnage by using rock as the primary foundation. Rock anchors provide the necessary hold in this solution. Either bolts or strands are used in rock anchor foundations. CTE Wind's engineers have designed rock-anchored foundations with bolts or strands, adapting the foundation with an interface between the towers and the rock anchors.
CTE Wind International's nearshore foundation is another proven solution, especially in intertidal areas. The nearshore area refers to the swash zone up to the position that marks the start of the offshore zone, with water depth of up to 20 metres. The foundation provides a circular conical structure on specially designed piles and is located on marine shorelines, including rocky shores and sandy beaches. The patented foundation design considers the challenging environmental criteria for geotechnics, tides, waves, and ship movements near the platforms, ensuring its feasibility and durability.
Another unique solution was recently introduced to the readers of WindPower Monthly: the Soft-Spot. The patented Soft-Spot® solution optimises the existing and well-functioning system of flat foundations by integrating well-known knowledge from structural engineering. A soft layer of expanded polystyrene (EPS) is simply placed under the centre of the foundation so that the forces from the wind turbine are dissipated radially into the ground rather than over the entire surface. The design of the Soft-Spot® optimises the use of all resources required for foundation construction. In figures, the solution helps save up to 15 per cent of concrete and 10 per cent of reinforcing steel, or even more depending on soil conditions. And it takes up less space than a standard shallow foundation.
The Nordex wind turbines in Dutch wind farm Heilbloem stands on a gravity Soft-Spot® foundation. In the Netherlands normally foundations stands on piles.
First choice for wind energy projects
CTE Wind's expertise in foundation design means it is frequently the first choice for Original Equipment Manufacturers (OEMs), wind farm developers and Engineering, Procurement and Construction/Balance of Plant (EPC/BoP) contractors. The business has designed foundations for various sizes and types of wind turbines, including the foundation on piles for a giant 12 MW offshore wind turbinein Rotterdam.
Thirty-five experienced senior civil, structural, and geotechnical engineers ensure that each project results in a foundation solution adapted to local soil conditions and the chosen wind turbine. Each wind farm site has its own specific geological challenges. CTE Wind's engineering team ensures the foundation design is reliable and cost-effective.
Wind turbine foundations are the backbone of any wind project, and CTE Wind International is a company that has proven its expertise in designing cost-effective, reliable, and efficient wind turbine foundations that can withstand the forces of nature. Its specialised foundation designs, such as the Soft-Spot Foundation, the Rock Anchor Foundation, and the Nearshore Foundation, ensure they can solve different geological challenges worldwide and for all types of wind turbines.
CTE Wind Civil Engineering is an international engineering consulting firm specialising in the analysis and design of onshore wind turbine foundations. CTE Wind has been active in the wind energy sector since 2003. As of 2023, CTE Wind has designed, value-engineered or peer-reviewed foundations for over 26,000 turbines in 75 countries. CTE Wind is headquartered in France and has offices in Brazil, Poland, Portugal, Spain, USA, Vietnam, and is represented in Australia.