Site report: How these cranes delivered key work at the Fécamp offshore wind farm
03 February 2022
A total of 16 rail-mounted luffing jib tower cranes are key to the construction of 71 concrete gravity bases for an offshore wind farm in France. Alex Dahm reports
The 500 MW Fécamp offshore wind farm will consist of 71 wind turbines planted in the sea between 13 and 22 km from the coast of northwest France.
The €2 billion (US$2.3 billion) wind farm will provide electricity for 770,000 people, or more than 60 per cent of the population in the local Seine-Maritime department.
It is under construction with the help of 16 large Potain luffing jib tower cranes supplied by global tower crane specialist NFT.
The Fécamp project is jointly owned through Éolien Maritime France SAS by EDF Renouvelables and Enbridge Inc, each with 35 per cent, while WPD Offshore has the remaining 30 %. Main contractor for the construction is Bouygues Travaux Publics.
Siemens Gamesa Renewable Energy (SGRE) will supply the wind turbines while Bouygues Construction with Saipem and Boskalis are responsible for the foundations. Chantiers de l’Atlantique, GE Grid Solutions and SDI will do the offshore substation.
SGRE has a new turbine factory in Le Havre in which to build the turbines. Manufacturing the turbines’ reinforced concrete gravity foundations started last summer at the Grand Port Maritime site on the Quai de Bougainville in Le Havre. This is where all the tower cranes are working, alongside around 600 people.
The hollow concrete foundations are gravity bases being cast on land then floated out to the offshore wind farm site, sunk to the seabed and filled with aggregate before the turbine is mounted on top.
The bases are being built 16 at a time, each station with its own dedicated crane. Four tracks each carry four rail mounted cranes which pick and carry under load.
What tower cranes were used for Fécamp offshore wind farm?
Tower cranes were chosen as the best choice for the job following a study of the various methods with their cycle times and also with the weights of the various packages to be lifted. The heaviest loads on this job are 24 tonnes. More typical lifts, however, for the bulk of the work, vary between 10 and 16 tonnes. These are for internal platforms, reinforcement cages, formwork and so on.
All 16 of the Potain MR 608 luffing jib tower cranes were supplied at the end of 2020 by NFT, one of the largest tower crane-owning companies in the world. The MR 608 lifts 32 tonnes with a 40 metre or shorter jib. In this application, however, they all had 50 metre jibs so capacity was 24 tonnes.
Abu Dhabi-based NFT already had 14 units of this model in its fleet. Of these, 12 were from 2018 and two were from 2019, but unused. Two more brand new upper parts were bought to complete the supply. The 12 units had previously been used in Korea helping to build computer chip factories for Samsung and LG.
“NFT also invested in six new 10 x 10 metre reinforced chassis and 11 brand new travelling systems, which was the majority of the investment for this job. The strong chassis and bogies were necessary to ensure the cranes could not only freestand at 57 metres in a very windy area, but also travel while lifting heavy loads,” explained Nawar Al Zahlawi, NFT business development director.
Bouygues, Uperio and Mediaco
NFT supplied the MR 608s to Bouygues Materiel, which in turn is renting them to site. Belgium-headquartered tower crane specialist Uperio erected all the tower cranes and is maintaining them. It will also dismantle them – they are due to have finished and be off site by June 2022. Uperio engaged Mediaco, France’s largest mobile crane rental company, for the tower crane assembly.
In conjunction with the above partners NFT co-ordinated the shipping of cranes on an almost weekly basis from the UAE. Three-quarters of the cranes and components were delivered from there. Shipments from the Manitowoc Potain factories in Moulins and Charlieu also had to reach the site at the appropriate time. This was to ensure timely delivery without overwhelming the Uperio team on site who had to unload the containers from UAE, unload trailers from France and Belgium, as well as assemble the cranes on the ground. Uperio invested two teams to work in parallel and to meet the site schedule. One of the teams was to unload while the other was on assembly and erection.
“Despite numerous obstacles – delayed shipping vessels, bad weather conditions and some other surprises – we managed to install all the cranes on schedule, if not ahead of schedule,” commented Al Zahlawi.
Investments in the Fécamp offshore wind farm
Another considerable investment for this project is the spare parts holding on site for the tower cranes which is worth more than €300,000 ($340,000). NFT provided it to avoid long breakdowns on site and prevent interruptions to the project schedule. “We provide our own recommended list based on our site experience and expertise. We have rented them for many years so we have site feedback and know what parts are needed to avoid long breakdowns,” Al Zahlawi explained.
The parts are stored on site in a 40HC shipping container. Included are major components such as motors, inverters, hoist rope and luffing rope. Fast moving parts like encoders and relays are also kept in stock there.
Following removal of the tower cranes in June 2022, and then the completion of construction, project commissioning is scheduled for 2023 when the Fécamp wind farm will be handed over to the client.