Hollandse Kust Zuid inspection

Challenge

Maintaining the health and efficiency for a large-scale offshore wind farm demands constant attention. For Vattenfall's Hollandse Kust Zuid (HKZ) project, ensuring the resilience of underwater infrastructure and the protection of key power cables was crucial for optimising clean energy output while minimising environmental impact. However, traditional inspection methods presented notable challenges:

• Limited visibility: Southern North Sea environments make visual inspections difficult and time-consuming

• Environmental impact: Operations involving large vessels risk disturbing marine habitats and ecosystems

• Health and safety: Personnel in the hazardous offshore environment

Vattenfall sought an integrated, sustainable, and cost-efficient solution to assess 140 wind turbine generators, 2 offshore substations, and 260 cable protection systems, ensuring the project's long-term success and environmental integrity.

Solution

We used our Blue Essence® to conduct a remote inspection which comprised of multibeam echosounder surveys and ROV based visual inspections around the wind turbine generator transition pieces, stone berms and inter array cable protection systems. Equipped with our Blue Volta® eROV, the USV commenced operations in Q3 2023, controlled from our remote operations centre (ROC) in Aberdeen on the other side of the North Sea. Our team of experts worked to assess the integrity of Vattenfall’s assets in real time. Over the course of the two month project, the USV covered 142 km2 and operated more than 179 hours of diving with the eROV, all while reducing carbon emissions by 95 %. Following the inspection, no significant anomalies were detected with 17 minor issues identified, showing the resilience and quality of Vattenfall’s assets.

Innovative Highlight

Blue Essence® USV and Blue Volta® eROV were used to carry out the inspection work in place of a traditional inspection vessel. Blue Volta® is equipped with a mounted multibeam Norbit sonar and high-definition cameras used for both close and general visual inspection surveys. With the acquired Geo-data accessed in real time, the eROV can be deployed at any stage to investigate points of interest picked up during the multibeam echosounder (MBES) conducted from the USV hull mounted survey.

Impact

Throughout the project, the USV reduced CO2 emissions by 95 % compared to a traditional survey vessel and consumed only 5 % of the fuel. By eliminating the need for a traditional vessel and offshore personnel, we saved 35,000 offshore work hours, reducing risk to people and the environment, as well as improving the efficiency of the team with a more productive working environment.

The utilisation of the USV and eROV reduced disruptions to marine life, aligning seamlessly with Vattenfall's commitment to biodiversity and our own net-zero carbon emission operations (scope 1 and scope 2) by 2035 ambitions. Our commitment to transitioning to more sustainable survey methods is evidenced by the innovative techniques implemented throughout the HKZ project, all of which were designed to minimise disturbance to local marine ecosystems.

The ROC provided real-time data analysis which enables quick decision-making and facilitated a tailored scope for Vattenfall. 

Our innovative approach to inspection sets a new benchmark for the future of sustainable offshore wind farm maintenance. By partnering with Fugro, Vattenfall achieved a sustainable and cost-effective inspection, guaranteeing the continued success of their HKZ wind farm and contributing to a safer and more liveable world.