Another purpose-built vessel that will play a key role in Dutch projects, the cablelay vessel Nexus, is approaching completion
contract structure with reduced risk, a fixed price, guaranteed schedule and performance. Another issue is weather delays, which have plagued some projects, so for Gemini ‘weather allowances’ have been built into the fixed price contracts, along with a healthy project contingency. The use of purpose-built installation vessels, as recently introduced into service by Van Oord, should also help. Permitting delays have also been an issue, noted Northland in a recent investor presentation, but all of the permits for Gemini are already in hand and, it hopes, the use of modern purpose-built installation vessels and fixed-price contracts under warranty and long-term maintenance contracts, should reduce any potential problems with equipment failure. Execution of the project recently got under way and is due to be completed by 2016. The offshore site, which is 55km north of Schiermonnikoog and 120km sailing distance from Eemshaven, will see 150 Siemens 4 MW turbines installed on monopile foundations. The project will call for a significant amount of scour protection to the turbine foundations to be installed, along with around 140km of infield cables, two high voltage sub-stations and 208km of export cables plus an onshore high voltage station. The project will also require 8 million m3
of material to be dredged. Production of the cabling started in the spring of 2014; April 2014 saw work start on the onshore sub-station, and installation of the foundations got under way this summer. Installation of the infield cables is due to start in August 2015, with the installation of the export cables starting in March 2015 (installation of the HDD export cable will get under way this year). The monopiles for the project will vary in length from 59-73m and in diameter from 5.5-7.0m. They will weight 670-916 tonnes. With a length of 21m and diameter of 5.5m, the transition pieces will weigh 192 tonnes. All of the foundations and transition pieces will be installed by Van Oord’s recently completed installation vessel Aeolus; another purpose-built Van Oord vessel, Nexus, will be responsible for cable lay. In late July, the logistics operation for Gemini at BOW Terminal got under way. The terminal will handle the storage and transfer of 75 pile
Near-shore project under way
Westermeerwind BV reached financial close on 25 July 2014 for the turnkey construction of the Westermeerwind wind farm in IJsselmeer. Work can now start on building the 48 wind turbines, which are 3MW units which will be installed in water 500-1,100m from the dikes of the Noordoostpolder. Installation work is scheduled to start in March 2015. The first turbines are expected to start delivering power to the grid at the end of 2015. Siemens concluded a contract in March 2013 for the turbines. The windfarm is to be constructed by a consortium consisting of Ballast Nedam and Mammoet. Ballast Nedam is to design, deliver and install
www.owjonline.com
the foundations. Mammoet will then transport and install the 48 turbines. The foundations will be installed in water between 3m and 7m deep. The monopiles for the foundations are 5m in diameter, have an average length of 40m, and weigh 250-300 tonnes. The wind turbine towers have a direct flange connection with the monopiles with no transition piece. Pile driving will be performed on the flange. When the driving work is complete a concrete maintenance platform will be attached and the wind turbines installed. The monopiles will be produced by SIF Group in Roermond, and the pile driver will be supplied by IHC Hydrohammer in Kinderdijk.
foundations for the project. In June, Avantha Group Company CG, along with the consortium partners Fabricom and Iemants, announced that they had been selected by Van Oord to design, deliver and install the high voltage offshore substations and high voltage onshore substation for the project. CG will design and engineer the overall electrical high voltage system, manufacture and supply all key equipment and connect the onshore substation to TenneT’s 400 kV high voltage grid. Van Oord begun engineering
and procurement for Eneco’s Luchterduinen windfarm in 2013 and is also balance of plant contractor for this project. Eneco and Mitsubishi Corporation each own 50 per cent of the windfarm. Joulz will supply and install the 8km long underground cable that will run from the beach to the TenneT onshore switching station in Sassenheim, the Netherlands. The project is being constructed
23km off the coast of Zandvoort and will consist of 43 Vestas V112 wind turbines. With a capacity of 129 MW, it will start supplying green energy to 150,000 households in 2015. Construction of the windfarm started in spring of 2014. Like the Gemini project, Luchterduinen is also being constructed under an EPC contract with Van Oord once again responsible for the engineering, procurement, and construction of the foundations and electrical infrastructure. As highlighted elsewhere in this
issue of OWJ, the foundations will be uniquely engineered because the monopile and the transition piece, which are usually built as two separate components, will be built as a single structure. 2013 saw a start made on engineering and manufacturing the electrical components, such as the offshore high voltage sub-station and cables. Production of the foundation piles began in November 2013 and the construction phase is due to run from mid-2014 to mid-2015. OWJ
Offshore Wind Journal I 3rd Quarter 2014 I 15
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70