Reducing the costs of marine renewables via advanced structural materials (ReC-ASM)

For marine renewable energy conversion to achieve a much needed step change in cost reduction, whilst proving to be cost effective and a reliable source for electricity supply, a number of major engineering challenges need to be addressed. The biggest challenge relates to the scaling up of the power capture interface (device level) and new approaches to the station keeping system (physical environment) which in turn is governed by the characteristics of the resource. In order to achieve technology cost reduction, it is envisaged that the development of marine renewable will emulate the development practices adopted in the early days of the wind energy industry and embark on building and deploying larger diameter rotors to increase device capacity and through this deliver lower unit costs. The challenge however relates to managing the resulting consequences on structural loadings. These increase with the square of the diameter of rotors/ power capture interface. As such, this approach will result in the materials used in the power capture interface operating under very high loading conditions. Evidence to date indicates that all large horizontal axis rotor systems greater than 15m diameter, which have been deployed in full scale tidal environments, have succumbed to catastrophic rotor blade failure. Hence, there is a serious Materials challenge in developing more robust materials for the operating environment. By combining expertise in Tidal Energy and Materials Science, this project aims to tackle this issue, through a combination of laboratory testing and modelling.

The synergy between wear (erosion, fatigue and cavitation) and sea water in polymer based composites and metallic materials. Crack propagation is accelerated by salt migration to grain boundaries. These results have important implications in development of more robust tidal turbines and in rolling out this technology to make it commercially viable and is set to change the momentum in the subject internationally where already there is very significant interest in this EPSRC flagship project. For metallic materials, the levels of synergistic interactions between cavitation erosion and corrosion for cast nickel aluminium bronze in saline solutions were found to be 30% of the total erosion-corrosion loss rate and represent enhanced corrosion activity under cavitation erosion-corrosion.