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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - NEXUS (Towards Game-changer Service Operation Vessels for Offshore Windfarms)

Teaser

Summary

Context
Operation and Maintenance (O&M) accounts for 20-30% of life cycle cost for a typical offshore wind farm, and this is forecast to increase as sites move further out to sea. This requires longer more difficult travel, increasing the associated O&M costs. NEXUS will systematically analyse the farms, providing better understanding and tools to improve efficiency and thus offset this trend.
As the carrying of technicians, equipment and spare parts is mostly done using service vessels, the efficiency of these vessels and their operation is the target for improvement by NEXUS. The demand for SOVs will continue to grow as the windfarms move further offshore and increase in size and number, and estimates are that the SOV fleet will have to quadruple to meet demand over the next decade.
To create significant cost savings, NEXUS is pursuing new vessel and O&M innovations and is also carrying out a business analysis of the current O&M services across the supply chain. NEXUS is also analysing a list of innovations to determine potential game changers, including removing barriers caused by current safety regulations.
Objectives
The NEXUS objectives are to:
- Reduce lifecycle O&M expenditure by 20% and lower CO2 emission by 30% associated with windfarm operation.
- Enable robust decision-making resulting in reduced costs and effective management of business risk for the service vessel.
- Capture the robust design requirements for a new windfarm service vessel for operation in the North Sea.
- Develop a new vessel concept for servicing offshore windfarms to robust design requirements captured during the feasibility study.
- Develop specialised safety regulations for windfarm service vessels to improve cost effectiveness and operational flexibility, which are potentially undermined by the current, generic safety rules.
- Compile an evidenced business case for a new windfarm service vessel, of which development will be exemplified in the project.

Work performed

This includes the NEXUS requirements, the assessment of new and emerging efficient technologies along with a vessel concepts development, the analytical assessment of the key business drivers behind windfarm maintenance allowing effective decision analysis and the development of safety requirements and hazard scenarios. In relation to the project objectives, this covers:
Towards Objective 1: Efficient, safe and secure technologies
WP1 has defined the project requirements by assessing the global and EU energy and labour markets, including a review of the regulations and guidelines that affect the offshore wind. The influence of climate, maintenance strategies and fleet logistics on cost of energy for offshore wind have been assessed, along with opportunities and issues facing the offshore wind industry. WP2 has assessed the hydrodynamic performance of the baseline state-of-the-art reference vessel, and established methods for use on the new concept being developed in WP5, and subsequently to be transferred into WP7. WP3 has carried out a safety assessment of the critical elements of the safety systems baseline design and will address the emerging technologies. WP4 developed a graphical model regarding the variables that drive the key KPIs such as CAPEX, OPEX and emissions, which will allow comparisons of potential service operations (vessel) solutions against the KPIs.
Towards Objective 2: Systemic business risk and robust decision-making
This objective is key to enabling reduced windfarm maintenance costs and allowing effective business risk management. In Period 1 WP4 has developed an advanced probability model based on the qualitative graphical model mentioned in objective 1. This model captures the interdependencies between the decisions, uncertainty and KPIs associated with a game-changer service operational solution, and will be capable of being interrogated in different ways to support analysis and hence decision-making.
Towards Objective 3: Feasibility study & design requirements
WP3 has developed a assessment process defining the safety design requirements and will be used to support evaluation of the most appropriate vessel concepts. WP5 has collected input from numerous sources which has supported the definition of the design requirements and the operational scenarios. 4 distinct windfarms have been assessed showing a spread of conditions, with locations including farms close to shore and further offshore, and those with differing national regulations and with different environmental conditions.
Towards Objective 4: Vessel concept development, testing and validation
2 WPs have contributed to this objective in Period 1. The safety requirements defined in WP3 have been used to develop the safety test cases in WP8 which will be used for the final validation tests on the NEXUS concept in WP8 in Period 2.
Towards Objective 5: Specialised safety regulations
The main activity for Objective 5 starts in Period 2. However, the set of safety requirements and hazard scenarios developed in Period 1 by WP3 will be used as an input to the development of the specialised safety regulations to be implemented in Period 2.

Final results

Novel Beyond State-of-Art Vessel Technologies
NEXUS is assessing the use of novel technologies in the vessel design which will improve the vessel efficiency. 15 technologies have been assessed in Period 1 and, from the assessment the most appropriate novel technologies on the vessel have been identified as:
- Solar Energy: potential for ~3% fuel reduction.
- Hydrogen â€“ Zero emission, still a huge challenge cost and logistics.
- DC-grid/Variable Speed, very beneficial for SOV-operations.
- Wind Power for Floatel.
New Vessel Concept
This assesses the potential advantages and disadvantages of novel concept designs for windfarm application. This includes:
- Novel hull concepts, including advanced mono-hull and multi-hull designs.
- The use of different transfer systems including SOV, SOV with daughter craft and Floatel.
- Beyond SoA technologies potential in the vessel, including: (Part) autonomy, alternative energy sources and energy efficiency measures, advanced propulsion, manoeuvring and mooring systems, advanced transfer systems.
Operational Planner
The development of optimisation code for the operational planning for various vessel configurations of maintenance fleet within an offshore wind farm. This will provide, both on-board and onshore, the capability to plan and assess operations in advance, based on route planning, positioning, weather and environmental conditions as well as expected fuel consumption and cost.
The Operational Planner has been developed for a number of case studies and operational scenarios including:
- Single and combination of vessels.
- Optimal routing and inspection/maintenance effort assigned.
- Use of multiple inputs/outputs.
Business risk modelling for Windfarm Maintenance and Operation
The creation of an advanced model to support decision-making under the uncertainty about the risk of service operation over its lifetime. The business risk model will provide a first-order representation of the system in which a service operations solution will operate to allow different questions about the associated risks at different stages of the overall NEXUS solution development. This modelling will provide a predictive assessment of uncertain elements of future market and operational needs, and will be used to optimise the design of the vessel and the Q&M requirements.