Cable, cable installation and grid connection consumes approximately 27 percent of an offshore wind farm’s capital expenditure, according to Wind Energy Update’s latest report.

Capital investment of €72 million ($ 96 million) is required on export cables, and €24 million ($ 32 million) on inter-array conductors for a generic park size of 500MW.

The Wind Energy Update Offshore Operations and Maintenance report says that around €840,000 ($1.1214 million approx) is needed for J-tube seals, bend restrictors, stiffeners and cable mats to minimize premature deterioration and failure.

The report said that a number of variables can affect the lifecycle and reliability of subsea cabling.

Facts such as seabed conditions, wave action and tidal effects, ship transit and fishing activity affect submarine conductors. Activities around the offshore wind park will likely lead to considerable seabed disruption, according to the authors of the Wind Energy Update Offshore O&M report.

Developers and operators should account disruption in order to accurately assess the impact of maritime activities on cable faults. Bottom fishing is widespread on most continental shelves and adjacent continental slopes, and can be expected to have a significant impact on export cable integrity.

The report suggests that the offshore wind industry is at a nascent stage. The Wind Energy Update’s latest report offers cable integrity monitoring, spare cable, and joint availability, cable re-laying, joint/splicing expertise availability.

Offering a comprehensive overview of an offshore wind farm’s cable fault landscape, the report also lists important incidents where invaluable lessons learned can help shape cable O&M plans. The key is to avoid repeating events such as that incurred during the construction phase of Horns Rev I.

In this particular incident, a construction vessel’s anchor hit an export cable that lay bared on the seabed, resulting in an unforeseen cost of €2 million ($2.7 million approx).