The problem:
The mooring system of a floating offshore wind turbines (FOWT) is composed by several lines anchored to the seabed that keep the platform in the desired location. Mooring systems are critical components due to their impact in the stability, structural design and dynamics of the platform and the associated risk of collapse of the whole system in case of failure. Oil&Gas (O&G) has a long track record and experience in mooring systems design and operation. However, despite mooring components are designed for a typical lifetime of 20 years, high safety factors are applied and integrity management plans are implemented (including monitoring and inspection) failure do happen. Between 2000 and 2013, at least 42 mooring failures occurred in permanent Floating Production Units in the UK, resulting in partial or total replacements, or pre-emptive remedial interventions.
Mooring systems’ design principles and integrity management plans used in FOW so far have been based on O&G recommended practices. Since a Floating Offshore Wind (FOW) farm of 500MW is assumed to have more than 150 mooring lines, the situation suggests that FOW industry will need to take action to mitigate the probability of failure in a much more efficient way.
Consequently, there is a need to develop a more efficient integrity management approach based on accurate and reliable monitoring technologies and appropriate risk-based inspection approaches specific to FOW to reduce operational costs and increase annual energy production (reduce losses).
The need:
Wind energy development will contribute with a 40% reduction of the CO2 emissions in the European Union by 2030, the decarbonisation of the economy being part of the Energy Union Strategy. The SET-Plan Declaration on Strategic Targets in the Context of an Initiative for Global Leadership in Offshore Wind states: “Wind energy is the renewable energy technology expected to provide the largest contribution to the targets for 2020 and beyond.” It is expected that by 2030 21-24% of electricity supply will come from wind. In this context, “Offshore wind (OW) represents a significant future opportunity”. However, floating offshore costs are still substantially above grid parity, and significant innovation is needed. In particular, the SET-Plan Declaration targets for offshore floating wind energy an objective for Levelised Cost of Energy (LCOE) of 12 ct€/kWh by 2025 and 9ct€/kWh by 2030, while these values are far away from the LCOE achieved for prototype (20.1ct€/kWh) and pre-commercial (16.6ct€/kWh) projects like Hywind Scotland.
Objectives:
MooringSense aims at reducing FOW operational costs by 10-15% and increasing operational efficiency by means of an increase of Annual Energy Production by 2-3%, through the development of more efficient strategies and tools for mooring system integrity management and control. MooringSense will take advantage of mooring systems’ updated condition information, provided by a Digital Twin (DT) and innovative monitoring technologies, to allow the implementation risk-based integrity management plans and more holistic control strategies to reduce OPEX and increase energy production of FOW farms.
