Norwegian subsea solutions bring down floating wind costs

An offshore wind farm is so much more than majestic turbines on the water’s surface, blades rotating in the wind. In fact, Norway’s offshore wind expertise lies well beyond the wind turbine itself. Take substations, for instance. Typically located topside, they collect and export the electricity generated by the wind turbine generators.

Now, Norwegian companies are developing substations to be placed on the seabed to improve efficiency and cut costs.

One of these is Aker Solutions, which recently signed a contract to design the underwater substations for Med Wind, the first large-scale floating offshore wind farm in the Mediterranean Sea. The agreement with Renexia involves the design of eight modules, two for each section of the Med Wind park, to be laid on the seabed of the Strait of Sicily at a depth of 520 to 660 metres.

Aker Solutions’ module was chosen for its technological efficiency and low impact on the marine ecosystem. Moreover, the components will not require major maintenance work for the 25 years of Med Wind's concession, resulting in significant cost savings.

Aker Solutions will work in close cooperation with its partner ABB, with whom it is also developing a subsea power distribution system for floating offshore wind at the METCentre in Haugesund, Norway.

ABB is developing a complete electrical system that brings a topside solution underwater. The technology includes a subsea transformer, subsea switchgear and a subsea control module.

Studies have shown that collecting wind power to feed subsea substations could reduce costs by 30 to 40 per cent compared to a topside solution at water depths greater than 60 to 70 metres. The cost savings could be even higher in water depths exceeding 100 metres.

Groundbreaking robotics solutions are emerging from Norwegian offshore technology companies. Global offshore wind relies on advanced robotics for subsea inspection, maintenance and repair (IMR). These solutions reduce risk in terms of costs as well as human safety and will have an even more crucial role as wind farms are placed farther offshore, in deeper seas and harsher environments.

Many offshore wind robots are uncrewed underwater vehicles. Some are autonomous underwater vehicles (AUVs), which conduct independent, pre-programmed missions without operator intervention, while remotely operated vehicles (ROVs) are connected to a vessel by a series of cables that transmit command and control signals between the operator and the ROV.

AUVs are a main focus of Argeo, a pioneering robotics company in survey and inspection. “We use a suite of vehicles, advanced robotics and digital solutions to provide insight from seabed mapping,” states Thorbjorn Rekdal, CTO of Argeo.

In recent developments, Argeo has secured six patents in the field of subsea electromagnetic and acoustic sensor technology, and been awarded a contract to carry out the initial site investigation survey for an offshore wind project in Northern California.

Another innovator, SubC3D has designed an ROV for deep sea inspection and is now developing a specialised subsea monitoring system for floating offshore wind. Data from the ROV is transferred to a 3D model and can be used to monitor subsea cables, structures, anchoring and wildlife at wind farms.

“The benefit of having a resident unit at each turbine lets operators conduct subsea surveys every day as opposed to as needed. The data can be used to resolve an issue before it becomes a serious one,” explains Einar Magnus Mjåtvedt-Fiskaaen, CTO of SubC3D.

While all wind energy production requires sensors, floating offshore wind presents special challenges. Unlike bottom-fixed turbines, floating turbines are prone to six degrees of platform motion, which can affect the power generation, structural life, operation and maintenance of the turbine.

To address this challenge, Norwegian Subsea delivers small, high-accuracy motion sensors that measure real time attitude (roll, pitch and yaw) and linear motions (surge, sway and heave), including the corresponding velocities and accelerations. Data from the sensors is processed with a novel sensor fusion algorithm, providing crucial decision support for floating wind operations.

Another notable company is 4Subsea, whose sensors monitor both floating and bottom-fixed offshore wind substructures to detect anomalies. Complementary software interprets data from the sensors, and digital twins of the real-life offshore structures are used to predict potential problems, which can then be addressed.

This may mean setting maintenance and repair work in motion. Kongsberg Ferrotech has come far in developing a family of subsea robots for in-situ IMR of underwater assets. In offshore wind, this includes turbine substructures, subsea power cables and the like.

“Our robots conduct these operations in a completely new way, with less risk, in less time and with fewer resources. We bring the workshop to the damage, not the damage to the workshop,” says Christopher Carlsen, CEO of Kongsberg Ferrotech.

Good subsurface risk management lowers offshore wind costs while boosting safety for humans and the environment. One company doing precisely this is GeoProvider, a pioneer in data processing for offshore wind. The company’s solutions reduce subsurface risk during a wind project’s life cycle – from site selection to full-scale operation to end-of-life restoration.

“What sets GeoProvider apart is our groundbreaking technology,” states Wim Lekens, CTO of GeoProvider. “We provide wind farm developers with detailed information on ground conditions using advanced data mining and seismic processing. This ensures the best site selection and design decisions.”

The company does this without the use of intrusive data acquisition methods such as shooting seismic. It also identifies sensitive habitats such as coral reefs, preventing biodiversity loss from project start-up.

“Better control of data gives developers deeper knowledge of the site. Through data-based decision making, they can minimise risks, optimise installations and thus reduce installation and operational costs.”