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TRENCHING


FEATURE SPONSOR


NEW INSTALLATION CHALLENGES


The new generation of larger and more remote offshore wind farms represent new challenges for installation.


Harsh subsea environments, uneven topography and variable soil conditions all increase risk and negatively impact schedules.


REDUCING COSTS


As the industry looks to lower the Levelised Cost Of Electricity (LCOE), the efficiency and effectiveness of cable installation must be thoroughly examined, especially when taking the increasingly complex conditions faced by contractors into consideration.


RESEARCH AND DEVELOPMENT IHC Engineering Business, part of Royal IHC (IHC) has undertaken extensive research and development, utilising lessons learned from previously delayed and over-budget projects across the industry, to develop the Hi-Traq; a four-track trencher dedicated to offshore renewables cable burial.


SUBSEA CONDITIONS


Operational weather windows are key drivers for installation schedules and as we move into more challenging subsea environments, with the presence of stronger currents and wave action, it will be the subsea conditions that will dictate burial schedules.


Openly available European Union data suggests that new projects such as Dogger Bank are in areas of significant wave energy and given the shallow water depth, this can lead to turbulent and harsh subsea environments. A heavy vehicle is required in this environment to maximise operational windows by enabling the vehicle to stay on-station without being adversely affected by the strong currents and wave action. Consequently, the Hi-Traq has been designed to be heavy on the seabed in order to extend the operational window in the challenging conditions.


REMOTE LOCATIONS


As the location of wind farms move further offshore, the costs of installation operations can increase because of the requirement to transit further to refuel and resupply. Accordingly, any advantage that can be made on the performance of installation tools can generate significant overall project savings as it is ultimately the vessel time that represents the largest opportunity to reduce costs.


The Hi-Traq has been designed to operate in the widest possible window in order to accomplish cable burial operations within a smaller timescale. This is born out of the heavy vehicle format as well as the application of a high sea state launch and recovery system. By reducing down-time for both bad weather as well as poor subsea conditions, the application of a Hi-Traq can lead to project schedule reductions and thus decreased installation costs.


CABLE INSURANCE CLAIMS


The majority of offshore wind farm insurance claims relate to the cable; this can be due to inherent faults or damage occurring during storage, transportation, installation, burial or in situ damage. Although there has been a reduction in the number of cable claims over the last couple of years, it still represents a significant cost.


The level of installation experience in the industry has continued to grow and this has been the main driver for reducing cable faults by employing lessons learned to mitigate operational damage to the product. The Hi- Traq has been designed to eliminate damage to cables through safe cable handling and also by ensuring adequate burial protection to reduce the likelihood of damage occurring. Superior product grading capability and reduced shock loading due to the smooth traction generated by the four track system also offer superior focus on the cable.


EARLY PROJECT BENEFITS


Early offshore wind projects benefitted from taking advantage of optimum locations with ideal environment conditions, whereas the next generation of wind farms face more difficult locations in areas which represent substantial challenges such as seabed topography. Locations prone to sand waves and mega-ripples will be the norm for new wind farm location which presents a new collection of problems for cable burial.


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www.windenergynetwork.co.uk


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