A NORTH-East subsea contractor is using an autonomous underwater vehicle to reduce how much time it takes to survey a challenging off-sea windfarm, while reducing its carbon footprint.
Darlington-based Modus Seabed Intervention, which provides subsea services, has just completed a high speed, bathymetric and depth of burial survey of the inter array cable routes on the Gwynt-y-Môr offshore wind farm, about eight miles of the North Wales coast, utilising the Modus HAUV-2 (Hybrid Autonomous Underwater Vehicle).
The site, which generates enough renewable electricity to meet the equivalent needs of about 400,000 average UK homes, is known for high subsea currents and water depths ranging between 12m and 28m.
The HAUV-2, which has the power and stability to work in high currents, was able to reach survey speeds about four times faster than remotely operated vehicles.
Nigel Ward, chief commercial officer for Modus said; “The HAUV’s capability has now been proven across the energy sector since 2018.
"The ability to perform high speed depth of burial in high current areas has been an ongoing requirement of the offshore wind industry.
"With HAUV, we were able to significantly reduce overall survey time at this important offshore wind farm for the UK energy industry. As well as cost savings, use of this vehicle significantly decreases the carbon footprint of a survey of this nature.
"Going forward, the flexibility of payload enables this vehicle to combine various types of survey and inspection to improve efficiency and further reduce vessel days offshore, setting new standards for subsea operations.
"The next phase of development is to remove the need for a dedicated support vessel and to use the autonomous features of the HAUV to perform scopes from vessels or structures already in field.”
The Gwynt-y-Môr offshore wind farm comprises 160 Siemens 3.6MW turbines, which are connected by 161 inter array cables with a total length of about 147km.
Having already performed numerous oil and gas scopes, Gwynt-y-Môr was the first complete offshore wind farm inter array survey performed by HAUV-2.
As well as the high current capability, the HAUV, unlike incumbent systems, can hover and can interchange sensors on the vehicle, which ensures system flexibility to change tasks. For example the HAUV can combine depth of burial survey with structure inspection activities to offer further synergy savings in these challenging environments.
Graham Thorpe, asset integrity engineer for Innogy Renewables UK Limited, which runs the wind farm, said: "At innogy we are always striving to enhance our operations at the Gwynt-y-Môr offshore Wind Farm. Being in the long-term operation and management phase of the project, cost saving is a significant driver and we have a continued effort to deliver operational performance.
"Part of this is the ongoing inspection and maintenance of our assets through periodic surveys in order to ensure a continued reliable supply of renewable power to the UK. The HAUV’s performance capability was proven and the system delivered high speed data acquisition without compromising quality."