In future windfarms, robots deployed by autonomous units could inspect offshore wind turbines and apply repairs
Robotics is increasingly seen as a potential solution to manpower-intensive O&M jobs, particularly those that involve rope access, but could also be applied to many operations currently carried out by personnel deployed from vessels.
In its ‘Stay Ashore!’ programme, GE Renewable Energy is focusing on the use of new digital and robotic technology that can reduce risk, reduce manual work offshore and reduce the levelised cost of energy. The projects it is working on leverage expertise from the broader GE Renewable Energy businesses – onshore, offshore, digital and services – and by collaborating with the Offshore Renewable Energy Catapult and SMEs.
At the heart of the Stay Ashore! programme is a challenge. That challenge is the size and revenue-generating potential of its new offshore wind turbine, the Haliade-X.
Currently the world’s most powerful offshore wind turbine, the Haliade-X is rated at 12 MW. It has a gross annual energy production of 67 GWh, 63% capacity factor, a 220-m diameter rotor, 107-m long blades, is 248 m high and has a swept area of 38,000 m2. Its ability to generate green electricity puts it in a class of its own, but one of the potential challenges the huge turbine poses is the potential for lost revenue if it needs to be taken out of service for maintenance or develops a fault.
With this in mind, the ‘Stay Ashore!’ programme is built on three pillars, all designed to reduce risk, reduce costs and maximise revenue.
The first pillar is reliability by design, which is primarily focused on validating key wind turbine components. The second is enabling full remote operability and troubleshooting of the turbine through advanced digital functionality, to reduce the need to go offshore for unplanned events. This remote operability will be enhanced using digital twins and life models, and through adopting smart O&M strategies. The third is using robotics for planned maintenance events, specifically for repetitive tasks, inspection and activities in areas that are difficult to access. Together they aim to further reduce the operating costs of offshore wind.
As GE Renewable Energy programme manager Anthony Gordon told the Offshore Wind Scotland: Robotics conference held earlier this year, to maximise uptime and reduce downtime, the company wants to drive visibility, insights and action. To do this, it is focusing on ‘connecting,’ ‘analysing’ and ‘fixing.’
To analyse, GE Renewable Energy envisages using ‘analytics orchestration’ and case management; and to fix it envisages an integrated system that would provide planning and dispatch for site managers, with a ‘digital plan of the day’ with scheduling, inventory management, tooling and dispatch.
Robotics will play an important role once the turbines are in service, not least when it comes to reducing the need for rope access. Currently, rope access is used to undertake inspection and maintenance (preventive or corrective) on turbine blades. Mr Gordon said the periodic interval for doing so is usually 12 or 24 months for inspections, and 36 months for some major maintenance items.
“If possible, our objective is to develop a semi or fully autonomous device that is capable of undertaking wind turbine blade maintenance of all types,” Mr Gordon told the event. This removes the associated risks surrounding rope access, and work on turbine blades. It would also lead to a reduction in downtime of wind turbine generators, and an improvement in the operating window for inspection and maintenance work.
The second major challenge GE is working on for which it anticipates a potential role for robotics is that the generator pole shoe bolt connection on the Haliade-X needs to be inspected 36 months after commissioning. A rope access team would usually be deployed to carry out the job, but before the torqueing can be done, a cap and silicon seal must be removed and subsequently replaced, using a 500-nM manual torque wrench to inspect the bolts.
“What we would like to do in the Stay Ashore! project is to develop a semi or fully autonomous device capable of performing the inspection and retightening,” Mr Gordon explained. “Developing such a device would eliminate the risks associated with rope access and lead to reduced downtime for the wind turbine generator and an improvement in the operating window for inspection and retightening work.”
To overcome these challenges associated with rope access, the company is seeking applications from established businesses, startups and SMEs who are based in the UK or intend to set up a UK base. Any technology proposed would need to be suitable for the UK market and meet regulations and certification.
Robots of the type GE and other turbine OEMs are seeking are already being developed, among them the BladeBUG, for which the latest round of testing was recently completed at the Offshore Renewable Energy (ORE) Catapult’s National Renewable Energy Centre in Blyth in the UK.
In trials in March 2020, the six-legged blade crawler reached a major milestone in its development when the lightweight robot ‘walked’ up and down blade surfaces, proving the stability of its vacuum adhesion technology and its dexterity in adapting its gait to the varying curves of a blade. Ancillary tethers, which would allow the robot to operate for extended periods offshore and enable rapid deployment to and from blades, were also proven.
With these capabilities now firmly under its belt, BladeBUG will begin integration into the UK MIMRee (Multi-Platform Inspection Maintenance and Repair in Extreme Environments) project, where it will operate alongside other robotic and autonomous systems.
As highlighted previously by OWJ, MIMRee foresees the use of fully autonomous inspection and repair systems for offshore windfarms. The scenario being examined for BladeBUG sees an autonomous vessel act as a launch platform for it, deploying teams of drones and BladeBUG robots to inspect, test and repair blade surfaces. During the project, BladeBUG will be integrated with a robotic repair arm for resurfacing damaged blades.
As attendees at the Offshore Wind Scotland: Robotics conference heard, robotics is also being applied to many other aspects of windfarm operation. One such application is the concept of ‘resident’ remotely operated vehicles (ROVs) that live at sea, in a windfarm, rather than on a vessel.
The concept has already been applied in the offshore oil and gas industry, but resident ROVs or resident autonomous underwater vehicles (AUVs) could be equally beneficial in the offshore wind industry according to Modus Seabed Intervention and Osbit. In the Avision project, the companies developed a vehicle recharging system for a resident AUV. They also developed technology that would enable an AUV to upload data it had acquired and download new mission plans.
In the RadBlad project, another British company, Innvotek, developed a robot capable of climbing a wind turbine tower using magnetic adhesion. While there is nothing new in radiographic scanning of turbine blades, the technique currently requires turbines blades to be dismantled and transported to a workshop onshore to be inspected. Radblad would undertake radiographic inspection in situ, on an offshore windfarm, conducting inspections in a few hours instead of several days, thus reducing turbine downtime.
Rovco commercial manager Joe Tidball told the event his company foresees using platforms running collaborative robotics to control, collect and analyse live data from offshore windfarms. This could include live 3D data streaming using advanced vision systems, and AUVs with integrated artificial intelligence (AI).
Riviera will host a week of free to attend 45-minute webinars focused on offshore wind commencing 8 June. Register your interest now