Construction of wind power

We perform all phases from soil investigations to the contruction of wind parks. In our contact network, we make local selection of partners with solid experience and skills in the area. Our experienced site managers monitor and adjust the production to ensure compliance with quality and budget.

Choice of foundations – rock-anchored foundations or gravitation foundations: A wind turbine with a rotor mounted on a steel column between 75 and 200 metres into the air requires stability for the entire structure to be able to withstand weather and wind. Therefore, a solid foundation of steel and concrete is needed.

Skarta offers two types of foundation for wind power on land, gravitation foundations and rock-anchored foundations, of which the gravitation foundations are most common. Both types of foundation are large concrete structures acting as a counterweight to the wind forces. The mounting of the wind turbine tower in the foundation is made through a large quantity of steel cast into the middle of the foundation.

A rock-anchored foundation is cast directly on the rock and is anchored with rock bolts, whereas the gravitation foundation is adapted so that the soil depth is greater, and the foundation itself becomes a counterweight to the wind forces. When the geotechnical basis is poor, we also offer pile gravitation foundations.

The method selected and the structure of the foundation depend on the soil conditions, but also on the type of wind turbine. For obvious reasons, different wind turbines need different types od of anchoring, but also the transition from the tower itself to the soil anchoring varies according to the type of wind turbine and the soil conditions.

Through carrying out of geotechnical examination, which means performing a test drilling to obtain knowledge of the actual conditions, the most appropriate method can be selected, and the foundations are dimensioned in the proper way.

Self-developed gravitation foundations for wind turbines: Skarta offers a gravitation foundation developed by our parent company in Finland, where during recent years, the investments in wind power have been higher than in Sweden. Skarta is part of the Skarta Group, which is one of Finland’s largest suppliers of wind turbine foundations, which provides us with an excellent basis for finalising our construction. Thanks to construction optimisation, our foundations thus are very cost-effective.

The gravitation foundation is the most advanced foundation to construct, and it is used when there is a long distance to the rock, or if the geotechnical conditions are challenging. A gravitation foundation comprises a reinforced sub-soil concrete foundation. Steel reinforcement is mounted in the lower bottom of the pit, and in the middle a column is formed to the turbine which functions as a base. When the casting is ready, the foundations are covered with soil, and the only thing visible is the cylindrical base on which the tower is fastened.

Rock-anchored wind turbine foundations: Rock-anchoring foundations are substantially smaller than gravitation foundations, and they are used when the wind turbine is placed on rock, usually rock of a poorer quality. For rock-anchoring, we blast a pit of about two metres in the rock. However, the diameter is smaller than in the case of gravitation foundations. The foundation itself is reinforced and then cast in about the same way as with the gravitation foundation. Deep holes are drilled in the rock to anchor the foundations with long bolts. By filling the hole with a type of concrete that expands, the bolts are fastened. On top of the bolts, a base is cast on which the tower is mounted. To let the concrete cure, the foundation is completed about a month before the wind turbine is put into place.

Road construction: There are many issues that need to be solved in placing wind turbines. In addition to the foundations, roads must be constructed. Digging must also be made for the foundations, and power lines that can connect the wind turbine to the grid. Depending on the transportation requirements, roads may need to be reinforced, aligned or made broader.

Construction of complete wind energy parks:  In the group, we have made a strategic decision to expand our services in the wind power sector. We can participate in wind power projects, both as specialists in concrete structures, or we can offer complete construction of wind farms. As a turn-key contractor, we undertake responsibility for the entire project including earthworks, road construction, steelwork, the turbine foundations etc.

 

Do you want advice or a cost estimate?

Mikael Sidér, CEO
+46 705 567 620