Lowering the cost for offshore wind energy remains a major challenge. Increasing the accuracy of analysis tools used in the design and optimization process can strengthen the reliability and reduce conservatism, thereby leading to a more cost-efficient design. Although considerable development has been made on representing the interaction between wind, waves and structural aspects in integrated analyses of offshore wind turbines, the modelling of the foundation remains unrefined. The assumptions and shortcomings of the existing models are identified, and alternatives for a better representation of the foundation response are presented and discussed.
Offshore wind energy plays a central role in sustainability-focused international policies and shows one of the fastest growth rates of all renewable energy sources (E&Y, 2015). A higher energy production due to stronger and more frequent winds at the sea and fewer problems with noise production and visual impact are the main advantages over onshore wind turbines. However, the costs for offshore wind energy are around 80% higher compared to onshore wind (Fraunhofer, 2013) and are one of the highest among renewable energy sources. Lowering costs for offshore wind energy will be crucial for its further success (The Crown Estate, 2012). Up to date, costs for offshore wind energy were mainly reduced by improved supply chain integration and larger capacity turbines (ORE Catapult, 2015). A future key area for lowering costs is more cost-efficient designs for offshore wind turbines (OWTs). In particular, the support structure has high potential for cost reduction, since it contributes up to 20% of total capital costs (EWEA, 2015).