Mammoet suggests clever crane ideas for wind turbine assembly and maintenance

Innovations eliminate current physical boundaries of turbines and make wind turbine construction and
maintenance safer and more efficient.

The WTA 250 ready to lift the 2nd
tower section.

Heavy lifting and transport company Mammoet introduces the WTM 100 and the WTA 250 – two cranes that are intended to conduct wind turbine construction and maintenance projects, making them safer and more efficiently. Both cranes use the turbine’s tower as a point of support, letting them lift and lower components to greater heights than equipment currently in use. This lets wind turbine manufacturers further increase the capacity of their turbines with greater height and scale.

The wind energy industry is continuously increasing economies of scale to make the wind a more cost-effective alternative to other energy sources. For that purpose, wind turbines are getting bigger and higher – reaching physical limits as they become higher than conventional cranes can reach. This also affects the efficiency of

A WTA 250 install a nacelle.

wind turbine maintenance activities. Mammoet recognized these developments and the limits that current cranes pose on the height and scale of wind turbines. Therefore, the company set out to develop two new cranes: one for wind turbine assembly and one for wind turbine maintenance.

The Wind Turbine Assembly Crane 250 (WTA 250) has a capacity of 250 metric tons. The WTA 250 crane will be developed in close cooperation with the engineering firm MECAL which will provide the wind turbine tower design. It is installed on a guiderail that runs along the bottom turbine section and can lift the next section using the turbine’s tower as support.

Once the next section is installed and equipped with a guiderail as well, the crane can push itself up along the rail and repeat the process for all of the subsequent turbine sections. Once construction has been completed, the guiderail can either be removed or remain in place to facilitate easy access for future maintenance operations. Because the crane uses the turbine’s tower for support, the maximum lifting height of the crane is virtually limitless.

Installation of a turbine blade using the WTA 250.

The Wind Turbine Maintenance Crane 100 (WTM 100) works according to a similar principle. The crane has a capacity of 100 metric tons. It is attached to two pre-installed hoisting eyes and can pull itself and the load up along the turbine using the tower for support. The WTM 100 has been equipped with claws that wrap around the tower to keep itself steady. The use of this crane requires minimal modification. It can be used on turbines that have been equipped with pre-fitted hoisting eyes and, in some cases, it can also be used on existing turbines.

“Both cranes are compact – the WTM can easily fit into two standard-sized containers – and the WTA only needs two transport trailers to be moved on site. This makes them easy to mobilize and relocate, and much more efficient than conventional alternatives.” explains Wessel Helmens, Mammoet’s Innovations Director. “More importantly, both cranes eliminate the height restrictions for turbines and render both the assembly and
replacement process faster and more cost-effective.”

In a maintenance operation, the WTM 100 would ascend to an elevation just below the turbine.

In addition, the cranes offer safety benefits, says Helmens, “Because the cranes are attached to the tower, they have no footprint, making the need for additional ground reinforcements virtually redundant. The tower-based design also puts the crane and the operator closer to the work area, rendering assembly and maintenance both
safer and easier.”

Mammoet is currently discussing the first applications of this new technology with their customers. They are also exploring other versions. “Depending on the input from our customers, we may introduce more additions to the WT-series,” says Helmens.

Replacing a generator with the WTM 100.

WTM 100 at elevation is ready to start turbine service.

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