Tall wind turbines require a lot of innovation. Joost Cornelli, team leader of the construction team and construction manager Tijs Boorsma saw the wind turbines take to the skies and construction change as a result. They outline trends in construction.   

Cranes
Those good old days of small wind turbines for which you needed almost no space to lift them. A crane staging area for the telescopic crane was enough. The crane mast was hydraulically extended. Those days have been over for several years. Wind turbines are getting bigger and bigger: shaft heights of up to 160m and rotor diameters of almost 200 meters. Today, a lattice crane is the standard, looking like the one you make with Mecano. Depending on the height of the mill, between 40 and 70 trucks drive to deliver the mast sections of about 12 meters and other parts. These mast sections are fastened together on the ground with a hydraulic press to the desired height. Then the crane pulls itself up and, if necessary, can move with its tracks. This is in contrast to a telescopic crane that is outriggered.



Crane emplacement and subsoil
The lattice crane is not only more labor-intensive, it also places increasingly stringent demands on the ground.  Because the crane is so high, a small unevenness makes a big difference.The crane siding for a latticework crane therefore requires space and load-bearing capacity. What is the load-bearing capacity of the subgrade? Should there be a pile mattress, for example, or is reinforcing the ground with geotextile and rubble sufficient for the wind turbine? These are dilemmas that Joost and Tijs increasingly face and must coordinate with the wind turbine manufacturer and civil design firms.  

Transportation
Blades used to fit whole on one trailer of a truck, albeit with a long overhang.  With a red flag and an escort car, it was settled. A two-part trailer with co-steering axles for cornering was not necessary.Let alone a dolly or trailer in a trailer extendable with co-steering axles. Let alone a special permit from RDW because with a 75-meter blade you are not actually allowed on the road. And if you have that permit, the height of the overpasses is another road blocker. Taller mills also have larger diameter tower sections so Tijs and Joost monitor the transport route from start to finish to make sure trucks don't have to pass under a viaduct that is only 4.3 meters high. Fortunately, the ingenious trucks the wind turbine parts arrive with have self-unloading trailers so there is no need for a crane to unload the load. 

Safety
Over the years, safety has become an important issue for all parties involved in the creation of a wind farm.  A Health, Safety & Environment (HSE) officer oversees site safety and all workers. He makes rounds on the job and reviews work plans and regularly coordinates with Joost and Tijs. Anyone new to the project must report to the HSE officer.Any worker active on the construction site is also required to take an HSE site introduction before entering the site.  
To keep safety in the spotlight in a positive way, every month the HSE officer hands out an HSE award to the employee who sets a good example. An idea of our Marlous Nooi during the construction of Windpark Krammer that Joost and Tijs emulate.  Just like rewarding milestones by, for example, arranging a French fry shop or barbecue when the foundation is laid. These extras ensure more involvement in the project, which raises the quality of the work.
Through various apps, Joost and Tijs log and monitor any risks and unsafe situations to be able to intervene and guarantee safety as much as possible. Additional safety measures have also been taken within the wind turbine such as an Evacuator system, which allows people to descend in a secured manner in the event of a fire in the turbine.  

GWO
The entire construction team is GWO certified to climb a windmill. GWO stands for Global Wind Organization, a training course taught worldwide and wind energy-wide on working at height in addition to working safely in and around wind turbines. Without a GWO certificate, you are not allowed to get to the top of a wind turbine to do the final inspection, for example. Joost and Tijs would rather not miss this inspection.It is easier to talk through the remaining points with an inspector on the spot than to receive a list. It also gives them an impression of how the work was done.

ICT
Cameras, bird detection, ice detection, aviation detection: these are additional systems on a wind turbine that can no longer be ignored.  All those systems need an internet connection because they have to interact with the turbine and the environment. Joost and Tijs take care of that integration during construction. That is a challenge because they are on the cutting edge of ICT and construction. Who is responsible if systems don't work properly?Is it the supplier of the detection system, the builder or the wind turbine manufacturer? What about cyber security? Those questions are becoming a bigger and bigger chunk of Joost and Tijs' work. 

Innovations a decade from now
Reducing CO2 emissions during construction will become increasingly important. Joost and Tijs predict various means of transportation (think boat or special trailers), divisible blades or divisible towers to facilitate transport. There will be innovative solutions for lifting. The climbing crane that Henk Lagerweij devised for his turbines will be more widely imitated. Or cranes will become part of the turbine as it becomes more technically challenging to hoist even higher. Electric excavators, electric trucks, electric cranes and other electric equipment will make their appearance.Joost and Tijs are ready and looking forward to it already  Joost and Tijs are ready and looking forward to it.