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The most common foundation scenario for concrete towers features a cellar. Since 2010, CTE Wind has provided foundation solutions for concrete towers in different variants. One such foundation solution is the hollow foundation solution.

One critical factor to be considered in a wind farm project is the type of wind turbine tower.  There are primarily two categories of wind turbine towers available in the market: tubular steel and concrete tower. The mix of both types is a hybrid tower. Independent from the selected tower system, the increased prevalence of higher hub heights leads to larger tower bases which challenges the tower manufacturers to develop new solutions or systems.

In addition to the various pros and cons of tubular steel versus concrete to be considered, the choice of the tower has an impact on the foundation. A steel tower nowadays almost always comes with an anchor cage. On the other hand, concrete towers need a tensioning system usually using cables anchored in the foundation. CTE Wind Civil Engineering has provided solutions for concrete towers in different variants for the last 11 years and counting.

Let us take a closer look at the different parts of the concrete tower foundation:

Foundation design of the outer shape

Like the toes and the ball of your feet, the outer shape prevents the wind turbine from tipping over. The foundation for concrete towers can be designed as standard gravity or deep foundation with piles. To save resources, CTE Winds Soft-Spot® solution (patent pending) or a ribbed (star) foundation could also be applied. Moreover, working with different tower manufacturers requires consideration for further variable construction criteria. CTE Wind is specialized in its knowledge and experience in factoring in said variables, such as the pre-stressed or post-tensioned cable system.

The foundation from inside

The most common concrete tower foundation scenario from the inside point of view features a cellar where cables are anchored and cable tensioning tools are placed. This kind of solution is often referred to as a “Hollow Foundation Solution” as shown in the picture. This design has a cellar to allow for access into the foundation and to tension the anchor cables of the tower. The reinforcement design for the hollow foundation solution is also substantially different from that of standard gravity foundations. Besides the customized interior formwork, special attention has to be paid to the design of the anchoring bulkheads where concentrated loads are applied to the concrete in very limited spaces.

Another option to anchor the tower to the foundation is to install protruding bolts out of the pedestal and into the tower where the cables can be connected. In this solution, the cellar is not necessary. The bolts are easy to access for tensioning. Lastly, and more seldomly used, is the combination of the concrete tower and foundation into a monolithic structure where only classic reinforcements are used but no tensioning elements are needed.  This type of solution can unfortunately lead to concrete cracks at the bottom tower section.

If you want to learn more about CTE Wind International and CTE Winds CONCRETE TOWER FOUNDATIONS SOLUTION please visite OUR-PROJECTS & OUR-NEWS – sections. For more Information about OUR-SERVICES please CONTACT US.

CTE Wind’s engineering team is working on different wind projects in Ethiopia, Egypt, South Africa and Saudi-Arabia. And not for the first time ! The WTG foundation experts can look back on 15 years of project history in these regions.

La Richardais FRA – Wind projects all over Africa and Middle East are ramping up. The Global Wind Energy Council foresees wind energy capacity reaching over 3GW by the end of 2023 in South Africa, but according to the IEA, Sub-Saharan Africa alone offers a wind energy potential of 1,300 GW.

Foundation Expertise

As a matter of fact, CTE Wind has been requested to support different European and Arabian customers for their wind projects in Africa and the Middle East. Projects in South-Africa, Ethiopia, Egypt and Saudi-Arabia are currently in CTE Wind’s pipeline. The engineering office provided many times its wind turbine foundation expertise over the last 15 years in North and South Africa. As of 2021, CTE Wind designed, value-engineered or peer-reviewed foundations of 2700 wind turbines within 76 projects. The services vary from geotechnical consulting, to preliminary and detailed foundation design, as well as forensic engineering for existing wind farms, without forgetting the third-party verification (CAT3) task.

First African Project

CTE Wind has worked regularly in Morocco but also in other countries of Africa and the Middle East.

In 2008 CTE Wind had its first wind project for a project in North-Africa. The expert in foundation design for wind turbine foundations designed gravity bases for 131 Siemens machines in the Tarfaya wind park, located in Southern Morocco. Then came the Ashegoda wind farm in Ethiopia, the Kabertene wind park project in Algeria, the Balikesir wind farm in Turkey and the Nojoli wind park in South Africa

Bigger Wind Parks

In 2016 CTE Wind has been awarded the wind park in Ras Ghareb, Egypt, with 125 wind turbines.

The Ombepo wind farm in Namibia came later. In Saudi Arabia, the trouble shooting work was done successfully for the Dumat Al Jandal wind park with 99 positions. A new project in the country has just been awarded to CTE Wind.

This short list gives a quick overview as to where CTE Wind’s expertise in wind turbine foundation in Africa and the Middle East has been requested.

CTE wind is more confident than ever to work on any wind projects from South-Africa to the Middle East region. Get in touch if you need further information about foundation expertise and services.

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About CTE Wind

About CTE Wind – Experts in Foundation Design World Wide:We serve since 2003 the wind industry as civil / structural engineers for wind park owner, developers and EPC/BoP-contractors. Often also directly for the OEMs. 25000 wind turbines in 73 countries. We provide geotechnical services, preliminary and final designs for wind turbine foundations, repowering and life time extension services.

CTE Wind R&D and Consulting services are the first choice when it comes to foundation design regardless of the WTG-manufacturer, model, size, power or soil conditions. Thanks to internal R&D-Team with senior engineers, holding over 100 years of cumulated experience in the design of wind turbine foundations, nothing is impossible.

La Richardais (FRA) – In 2019 Developers worldwide have globally commissioned a little over 45GW of onshore wind turbines. According to Bloomberg New Energy Finance, the Danish firm Vestas remained this way the world’s leading wind turbine supplier, with Spanish-German wind engineering company Siemens Gamesa a strong second. Chinas manufacturer number one Goldwind was third in the rankings, while US-Leader GE Renewable Energy’s secured its fourth place. Together the top four manufacturers accounted for 55 percent of the market share.

100 years of cumulated experience

This statement applies more or less also to CTE Wind, which calculated, designed and evaluated about 5000 WTG-foundations in 2019 around the globe. Thanks to CTE Wind’s internal R&D, with senior engineers holding over 100 years of cumulated experience in the design of wind turbine foundations worldwide, new turbine models from the top manufacturers as well as less common WTG-models from smaller or local manufacturers are only a little challenge. CTE Wind engineering services lead to state-of-the-art foundation solutions for wind turbines. Regardless of whether it is a prototype, such as GE’s giant 12 MW Haliade X or smaller 1 MW machine, from German ENO or Dutch EWT.

Wooden tower

Also worth mentioning: the different types of towers for wind turbines. Concrete (hollow foundation) and steel towers are well known to CTE Wind. Both tower systems are suitable to be used alone or in combination. Even foundations with wooden towers were calculated and designed by CTE Wind in the past. The sum of all experiences made during the projects since 2003 is the reason why their engineering services in foundation design are the first choice for wind turbine manufacturers, wind park developers and EPC contractors worldwide.

A pile foundation transfers the WTG loads to the lower-lying ground, thereby providing an overall support to the structure. Geotechnical experience is a must for designing wind turbine foundation pile. CTE Wind designed piles with length varying from 10 to 70 meters.

Foundation piles transfer loads from the wind turbine foundation to lower-lying ground, thereby providing overall support to the structure. These piles carry concentrated loads and are subject to fatigue. As such, careful assessment of geotechnical conditions and proper interpretation of the soil reports’ drilling logs and laboratory data are critical, which is why CTE Wind has senior geotechnical engineers working on wind farm projects worldwide.

CTE Wind’s pile foundation designs solutions consider driven, bored and drilled piles as well as vibro piles and Franki piles. Once the pile solution has been chosen, the length and diameters, as well as the stiffness of the pile and the loads on top of it have to be determined. The compression, the tensile and the fatigue loads are taken into account to establish the calculation report and the final drawings stating the rebars and concrete volumes.

Piles for intertidal nearshore foundations

In current projects CTE Wind has designed pile foundations with lengths varying from 10 to 70 meters which is exceptional. The latter was designed and built in Asia in different nearshore projects on an intertidal sea-zone. CTE Wind also provided pile designs in Belgium, France, Germany, The Netherlands, Brazil, Serbia, Ukraine, Russia, and Finland to name a few.

If you want to learn more about CTE Wind International and CTE Winds PILE FOUNDATIONS please visite OUR-PROJECTS & OUR-NEWS – sections. For more Information about OUR-SERVICES please CONTACT US.