Open sea OWC motions and mooring loads monitoring at BiMEP

Abstract

Despite the large number of wave energy converter concepts proposed over the past three decades, only a few field measurement datasets are available in the public domain. The sparse nature of device performance and reliability data coupled with a general lack of design convergence means that technological and economic progress within the sector is fragmented. Fundamental to ensuring device efficiency and survivability is the acquisition of long-term, open sea, device and mooring system response data, combined with comprehensive numerical modelling. With mooring systems representing approximately 10% of marine renewable energy device CAPEX, the evolution of shared mooring systems and the use of novel materials with load reduction capabilities represent clear strategies to achieve more favourable project finances. This paper will report on design of the mooring load monitoring system as well as preliminary analysis of several load cases identified from field data recorded during the winter of the first deployment. Comparisons are made to numerical simulations of the device and mooring system subjected to representative environmental conditions. The measured mooring line tensions also provide operational design criteria (i.e. load capacity and durability requirements) for two elastomeric tethers which will replace the polyester ropes currently used in the seaward catenary lines.