Are we, as an industry, getting closer to eliminating the need for mobile cranes entirely? The market for the installation, operation and maintenance of wind turbines continues to grow globally. So does installed wind energy generation capacity, and the need to rethink processes and technologies across the industry persists if we are to continually optimise operations.
By Thomas Lamberth Sandbjerg, Liftra, Denmark
While the fields of preventive maintenance and small corrections are where we find many new developments and still see improving competencies, it is in the areas of installation and major corrections that the greatest challenges continue to be present.
More than ever, we are seeing solutions out there that aim to remove mobile cranes from the equation altogether to provide operators with options that have major economic and environmental advantages. It is nothing new that crane rental fees can be hefty. Less known, yet just as relevant, are the many indirect costs that frequently follow. For instance, bridges and roads may require reinforcement to allow passage of the trucks carrying the crane, the site itself may need elaborate preparation to provide a level area big enough for the large crane structure, and special permits may need to be obtained.
Turbine height is another factor that inflates crane costs. With current turbine development nearing 10MW capacity, the systems require increasingly taller towers, which already reach above 150 metres, only adding to the headaches facing the corrective maintenance field.
Finally, availability presents a separate challenge. Until the crane reaches the wind farm and performs the necessary operation, turbine downtime and the resulting loss of production may last for days or weeks, depending on the number of cranes needed and the distance to the site.
With all this in mind, the industry has potential for huge savings on mobilisation, installation and maintenance. If with smarter solutions we managed to eliminate the need to use mobile cranes, it would have a major impact on both the economic and environmental cost of energy, ultimately reducing the bill for the end-consumer while sustaining our natural resources.
The advance of craneless systems is unmistakable, and the examples are numerous:
Esteyco, an engineering company based in Spain, has been recognised as a benchmark in the construction of concrete tower sections and foundations worldwide. The company has been refining solutions for self-elevating tower sections since 2014 and has received support from the Eurostars Programme.
Nabrawind is a relative newcomer to the industry that has won several patents, including for its ‘Nabralift’ technology for self-erecting towers based on a lattice structure. The solution promises to save 30% of total tower costs while reducing the assembly time by up to 50% – because no large cranes are needed. Nabrawind has won support from the European ERDF fund.
Lagerwey is a Dutch manufacturer of direct-drive wind turbines that has developed a ‘Climbing Crane’ for installing its turbines. The Climbing Crane scales from the base to the top of the turbine by means of a series of steps that are installed in each tower section. This set-up allows the crane to install the full tower, section by section, climbing upwards in the process. It can even be used to install the rotor without incurring the costs of mobilising a large crane.
Liftra, based in Denmark, is also active in the field of independent craneless technologies. In 2013, the company introduced the ‘Self-Hoisting Crane’, for replacing gearboxes and generators, and just recently unveiled the new ‘Blade Way’ technology for replacing single blades and pitch bearings. The two technologies require just a single or two 40-foot containers to mobilise, and rely on a set of hoists installed up-tower to perform corrective operations with no mobile cranes involved.
The Danish Energy Technology and Demonstration Program (EUDP) has supported both solutions, and the Self-Hoisting Crane has received funding support from Horizon 2020 as well, while Blade Way has been backed by the Market Development Fund.
More craneless innovations exist,* and it is going to be an exciting trend to watch in 2018 and in years to come. The future is very promising, as more solutions address key challenges faced by operators industry-wide. All technologies highlighted here represent more environmentally responsible solutions to common problems. After all, everyone wants to reduce emissions, while encouraging the installation of renewables in hard-to-access areas and further reducing the cost of energy.