This study is set to shape how the industry approaches solving T2P challenges. The findings will help developers and the supply chain to inform their project financial planning and floating array infrastructure design.
The problem
As the industry prepares for the growth in Floating Offshore Wind (FOW) deployments around the UK, there is a need for guidance on good practice. One critical area is the disconnection of the FOW turbine (FOWT) from the array and its removal to port for Major Component Exchange (MCE).
There is a high level of uncertainty around the need to tow to port. Whilst in-field MCE solutions are being developed, tow to port remains the base case approach to intervention and maintenance on many planned floating offshore wind farms. The study aims to inform the wider industry of key T2P challenges and solutions, so that operating cost escalation can be avoided.
The background
The work was performed by Apollo and Global Energy Group on behalf of the ORE Catapult’s Floating Offshore Wind Centre of Excellence.
The findings draw on 22 stakeholder consultation interviews, which validated the assumptions and ensured the right focus areas were captured.
The process
A focused case study has been defined involving a 900MW floating wind array, whilst also considering the evolving population of floating wind deployed across the East Coast of Scotland.
Following a review of the conventional methods, constraints, and challenges for tow to port operations at scale, opportunities to do things better are identified.
Innovative methodologies and technology to reduce the cost, risk and schedule associated with tow to port operations are explored.
Hrishikesh Atitkar, T&I Engineer at Global Energy Group said: “The industrialisation of Floating Offshore Wind is set to revolutionise Scotland’s energy landscape, with enhanced port infrastructure essential to unlocking this technology. Global Energy Group are delighted to have collaborated in this critical T2P study, focused on optimised O&M strategies to ensure the competitiveness and long-term success of floating wind.
As part of the study, we have been able to utilise our expertise from the extensive offshore wind track record developed at the Port of Nigg. Our facility has grown into a renewables superhub, having managed over 3.5GW of offshore wind assets and we continue to develop our capabilities to support future developments in the North Sea and beyond.”
The details
Bottom-fixed turbine failures and floating wind deployment rates are used to project the frequency of T2P operations. Between 10 to 30 turbines are expected to require T2P per year between 2035 and 2040. The higher figure represents the emergence of serial defects for large floating wind turbines. Taking a proactive and preventative approach to design, operation and maintenance for long-term reliability could conceivably control the headline MCE rate. Active investment, incentivization and open collaboration will be required across the floating wind industry to make this a reality.
Offshore and in-port operation durations for T2P are provided in the report. The headline cost per T2P at the array scale can make T2P costs more important than offshore installation and routine O&M costs combined.
A major bottleneck for T2P operation planning is the availability of suitable vessels, berths and cranage at acceptable day rates. Concurrent construction activities may put T2P operations on hold for a full season. If the T2P requirement is due to a serial defect then the array may be facing several years of unplanned downtime, due to the challenge of obtaining T2P logistics at the required scale. Any serial defects could represent an existential risk to floating wind, and as such must be addressed as a priority.
Jason Wise, Senior Project Manager for Floating Offshore Wind at ORE Catapult, said: “This project is extremely valuable to the industry as it highlights the need to better understand the operation and maintenance challenges associated with tow-to-port at gigawatt scale. The insights and outcomes presented in this report demonstrate the methodologies proposed for use in floating offshore wind while also highlighting some of the challenges to be overcome”.
The solution
The report presents options to ease these bottlenecks and secure long-term availability. New vessels and cranage solutions will be required to bridge the gap between demand and supply.
Pre-planning, pre-contracting, and operator collaboration is recommended to ensure that vessels, berths, anchorage and cranage are available to support peak T2P demand. A shared facility, supported by multiple developers, may circumvent the berth availability bottleneck. Similarly for vessels and cranes, long term charter clubs supported by multiple wind farms owners could secure capacity at favourable rates, whilst minimising mobilisation and transit costs.
T2P considerations – specifically focussed on offshore vessel costs – must be built into FOWT design. Otherwise, overall system lifecycle costs will not be optimised.
“Understanding the challenges of T2P early helps developers to make better decisions”, commented Apollo’s Lead Naval Architect, Will Brindley. “T2P cost and frequency can be significantly reduced with better planning to ensure the availability of essential resources at competitive rates. Innovative technology must also play a part by enabling more efficient offshore operations. Active investment, incentivisation and open collaboration across the floating wind industry are essential to make this a reality.”
The outcome
Understanding the challenges of T2P early helps developers to make better decisions. The findings of this study will help developers and the supply chain to inform their project financial planning and floating array infrastructure design.
A public report distills the study into its main findings: https://fowcoe.co.uk/industry-insights/reports/tow-to-port-offstation-management/
Contact us at renewables@apollo.engineer