Germany-based company Enercon has built two LCC140 self-climbing cranes, each of which can install turbine models of its latest EP3 and EP5 platforms – including the latest E-160 EP5 E2 and the upcoming flagship E-160 EP5 E3 with the new E-nacelle which will be the company’s most powerful offering at 5.56 MW (see Section E-160 EP5 below).

Conceptual evidence

Each LCC140 crane has a lifting capacity of 140 tons “under the hook” – without the weight of the hook and cables of the unit. On a project in Eemshaven, the Netherlands, an LCC140 crane was used to install the first of three E-136 EP5 turbines.

This initial installation test process also served as a proof of concept test for the new LCC140, explains crane specialist and lead engineer Henk Hendriksen, a senior member of Enercon’s Dutch research and development (R&D) team in Barneveld, central Netherlands.

“After this complete test installation process with all the tower segments, the nacelle stern, generator, hub and rotor blades, the same crane was used again to install the second turbine, while the other LCC140 installed the third turbine for this project,” says Henriksen. “All three come with a hub height of 132 meters and in a standard combination with our self-developed, bolted modular steel towers (MSTs), which is an essential feature of this fully integrated concept.”

The next job for the self-climbing LCC140 cranes is a 21-turbine wind farm with E-136 turbines in the same coastal region of Eemshaven. 16 of the systems – all with a hub height of 155 meters – will be assembled with LCC140 cranes, the rest with conventional crawler cranes.

The first conceptual ideas for this clever, innovative self-climbing crane concept come from the former Dutch wind pioneer Lagerwey and resulted in the first LCC60 product development in 2015/16. The crane was developed by Lagerwey with the 2-2.6 MW LP2 series in mind, in particular the volume model L100-2.5 MW. As with the LCC140, the number in the name refers to the maximum lifting capacity of 60 tons under the hook.

Standard combination

“Our small core team developed the LCC60 together with three external companies, including a specialist company for mechanical construction,” explains Hendriksen. “A key system feature is that this self-climbing crane is supplied in a standard combination with the bolted modular steel tower (MST).

“To demonstrate both the main principle and the concept, we installed a complete LP2 turbine, including all tower segments, nacelle stern, generator, hub and blades,” he adds.

The Dutch supplier carried out a second proof-of-concept installation attempt in spring 2017, this time with the latest 4.0-4.5 MW LP4 prototype in Eemshaven. However, since the mass of the direct drive generator LP4 far exceeded the maximum lifting capacity of the LCC60, this essential part of the prototype installation had to be carried out with a conventional crawler crane.

Enercon acquired Lagerwey and all of its intellectual property, including the patented LCC60 concept, in late 2017. Development of the refined LCC140 (see “Perfect Harmony”, below) began in 2019 under the auspices of the new owner, more new comprehensive resources.

Most of the other LP2 turbines, now a discontinued platform, were destined for Russia and were erected on standard tubular steel towers. These more than 100 turbines were produced in Enercon plants and only installed in the last few years.

The next planned use of the LCC60 crane is a spatially limited three-turbine project in Eemshaven with 2.5 MW L100-2.5 MW turbines, which will be installed on the Oostpolderdijk flood protection system across from the Ems in the German-Dutch border area become.

Complex websites

“We have also found that LCC technology offers particular advantages in complex locations,” says Hendriksen. “One of the three E-136 Eemshaven locations had limited installation space and was, for example, near a roundabout and access roads. If we had used a conventional crawler crane, the roundabout and the access roads would have had to be closed to traffic for the entire duration of the installation. “

According to Hendriksen, lifting the buckets is the most critical operation of any crane as it requires the longest lifting distance, measured from the center of the tower. In addition, a blade always creates lift, which naturally imbalances the aerodynamic load center of gravity with the center of gravity of the blade. This causes the shield to move up and down continuously while it hangs under the jib.

Enercon sees the lifting capabilities of the LCC (left) as one of its strengths in reducing installation time and costs compared to conventional cranes (right) (Photos: Klaas Eissens)

“The most important lesson from turbine installations using the LCC60 and LCC140 models is to find the right balance between the lowest additional cost for crane attachment points (see the“ Perfect Harmony ”section below) and the maximum benefits of the self-ascending crane that must be installed in the tower walls reinforced on both sides with steel plates in order to restore the original strength and to preserve the certified (fatigue) life of the tower. For example, the additional investment for crane points on the MSTs of the LP2 series turned out to be too high.

“Less waiting times for blade lifts are the greatest time savings when using the LCC140, but there are many other variables that have to be taken into account depending on the project-specific circumstances,” he explains.

The aim of the LCC design has never been to compete with conventional cranes under all circumstances, adds Hendriksen. Rather, the team worked with two specific key development drivers. The first is to get the maximum benefit from locations that are not suitable for normal cranes. The second is to actively anticipate future trends, as the hub heights – now already in the range of 150 to 160 meters and more – continue to rise and drive up the operating costs for conventional cranes. Hendriksen believes that the LCC concept could be further scaled up.

System integration

“Another major challenge is to work towards an even higher level of system integration throughout the entire construction process of wind projects. Another is to further optimize the cost-critical connection between crane and tower and to continuously evaluate the price for the additional benefit as part of this process, “he concludes.

Perfect harmony – this is how the modular steel tower and LCC60 / LCC140 work together

All Enercon modular steel towers (MSTs) with a wide base are made of pre-bent conical steel sheets, each 2.8 by 12 meters, about 20 mm thick and already containing precisely pre-cut holes for the vertical and horizontal bolt connections. The assembly process begins by screwing these individual elements together in tapering full-circle sections, with the section diameter decreasing with height.

An essential feature of the combined tower-crane system is that all individual MST profiles have three levels with large pre-punched holes in the shell floor area for the LCC60 / LCC140 assembly.
At each level, these holes are -90 degrees, neutral, and +90 degrees around the perimeter. The position relative to the central axis of the main body is neutral.

A total of six holes – three at each height – serve as climbing crane attachment points and are therefore statically reinforced on both sides by steel plates. Two additional stiffening beams connect the central (neutral) hole, with holes two and three together forming a V-shape that provides additional structural strength and optimal load transfer between tower and crane.

At the beginning of each complete turbine installation process, a small crane installs the first three MST bases, creating a “start” assembly platform for the self-climbing crane.

To bring all the components of a complete LCC140 crane system to a construction site, 11 road transports are required, including one with a total load of 80 tons. Like the smaller LCC60, the LCC140 is also designed according to European standards.

The approximately 30 meter long central main body comprises four hydraulically operated side “gripper arms” on two separate vertical levels with a spacing of around 24 meters, a distance that spans the distance of two full MST sections but is divided into three sections.

Gripping arms

With each lifting process, all four gripper arms and central attachment points between the crane body and tower are closed and locked. When the crane is moved to the next installation position, the side gripping arms are released before the central body, activated by another hydraulic system, moves a tower section upwards.

The rotation of the “split” lattice-like crane boom on the upper crane body is made possible by several slewing motors. New for the LCC140 is an integrated horizontal traverse for single blade assembly, which is mounted above the crane hook and can actively rotate around its central axis.

The lifting processes of the LCC60 and LCC140 are controlled remotely from the ground with the help of cameras that are attached to important points on the crane. Many built-in safety functions determine when a lifting process can begin.

The prototype of the E-160 EP5 marks the progress towards rapid commercialization

The E-160 prototype was upgraded to the 5.5 MW E2 model with a conventional crane, but the LCC140 could also be used in the future (Photo: Klaas Eissens)

On April 23, Enercon completed the upgrade of its existing 4.6 MW E-160-EP5-E1 prototype to the more powerful 5.5 MW E2 with the same rotor size, and commissioning is now in progress.

The process included the replacement of the permanent magnet generator (PMG) and the hub as well as the expansion of the E-module located at the base of the tower, which contains the entire power electronics. The foundation, tower and engine house of the E-160 E1 remained untouched. The E2 is already a fully instrumented existing turbine, with, for example, sensors and / or strain gauges attached to critical components. This makes commissioning much faster, so that trial operation can begin earlier.

At similar locations with an average wind speed of 7.5 m / s, the E-160 E2 will produce over 21,534 MWh annually – around 9% more than the original E1 (19,615 MWh).

The cumulative EP5 order intake with the majority of the flagship model E-160 is already “well over 2 GW”, according to the company. Several large projects in Vietnam, Canada and Chile are about to start, as well as many small and medium-sized projects with the E-160 in Germany.

The existing 4.6MW E-160 EP5 E-1 prototype was upgraded to the 5.5MW E-160 E2 with a new generator and hub plus an improved E-module (Image: Klaas Eissens)