In our previous blog post, we mentioned the advantage of mooring vessels offshore to reduce emissions.
The mooring function of our Oasis Power Buoy (OPB) is an integral part of the system, aligning with the charging aspect to bring a host of technical and decarbonisation advantages. Certainly not to be considered a secondary purpose, the benefits of mooring offshore deserve their own acclaim.
Safety
The OPB has purposely been designed as a separate piece of infrastructure to wind turbines. Safety to personnel, vessels and wind structures is always paramount. Our analysis demonstrated that to eliminate risk for both vessel and turbine, vessels should remain a safe distance away from fixed structures and have no physical connection. Instead, the OPB is installed ~100m from the turbines and anchored to the seabed, rather than any load on the structures. Electric power generated from the turbines is supplied via subsea cables to the power buoy. Any collision is eliminated simply by not having two valuable assets in close proximity to one another.
This separation and anchorage give the OPB the unique advantage as both an offshore charging and mooring station. Connection between vessel and buoy is always maintained through a 87t (BL) mooring line operational in sea-states in excess of 2m Hs.
Without a mooring, crew have to manually maintain a vessel’s position using constant engine power. With a varying sea state, even experienced crew are liable to misjudgements and human errors, which can have dangerous and costly consequences. A stable mooring eliminates this danger.
When connected to an OPB, crew transfer vessel’s (CTVs) propulsion systems can be switched off to maximise safety and recharge time, and reduce fuel consumption and CO2 emissions. The OPB and vessel simply move with the sea.
Robust telemetry and hardwire communication are established between the vessel, buoy and turbine which include system health checks before any power transfer can be made, as well as security protocols that ensure only certified vessels can use the system.
Advantages to crew
Further to the safety improvements for personnel, with a dual-function station, their workload is also reduced. Upon approach to the buoy, the crew makes the connection using a winch system and they are not exposed to mechanical loads. The bespoke mooring houses both the charging and mooring lines, meaning only one connection is required. No strain is placed on the electric cables as the load strain is fully absorbed by the mooring system.
With the mooring system maintaining position, time in-field can actually be used as rest time for the crew.
There is no need for the CTV to disconnect from the buoy when fully charged. The OPB can continue to be used as a mooring buoy until the vessel is ready to depart.
Decarbonisation
The development of the Oasis Power Buoy was motivated by the ambition to reach Net Zero. The OPB provides the ability to charge hybrid and electric vessels offshore which is imperative for the decarbonisation of the maritime sector. Considerable CO2 savings are generated by increasing the duration vessels can operate on electric power, especially when from a green, zero-emission energy source such as wind energy.
However, charging is not the only way OPB aids decarbonisation. Further to the dual charging and mooring function, the OPB can also be used as just a standalone mooring system for fuel-operated vessels. As the mooring function permits engines to be switched off, CTVs – electric, hybrid or those using fuel – do not need to idle. Using the OPB as a mooring will reduce fuel-operated vessels emitting unnecessary CO2. CTVs are the primary vessels used for the maintenance of offshore wind farms, carrying personnel and equipment for routine maintenance. As such research found that 88% of a CTV’s usage is spent waiting in-field. For one small wind farm, this equates to 3,780 hours annually. Currently, wind farms do not have mooring points in place, so engine power must be used. This requires significant fuel – 130 litres per hour, equating to 406kg CO2e produced every hour. Installing an OPB would eradicate this idling fuel consumption.
The development of innovative new technologies is imperative to achieve Net Zero, however, it is important that safety or ease of use is not compromised. Instead, it should be seen as an opportunity to enhance operations with smart engineering. By designing the Oasis Power Buoy with dual functions, benefits are optimised to their maximum potential for decarbonisation, safety, and operator satisfaction.
