Novel mooring design options for high-intensity typhoon conditions - An investigation for wave energy in China

The industrialised and densely populated coastal regions in China are in search of local energy supplies in order to avoid expensive energy transmission from the West of China. Wave energy technology is considered as one of the possible solutions with a potential installed capacity of 13GW around China. However, typhoons are a major meteorological threat for China's coastal regions with estimated damages of over 20bnRMB. Prediction, prevention and mitigation of typhoons have greatly improved and coastal regions at risk are readily identified. This paper will outline the environmental load conditions that are faced by floating installations in the Chinese Sea. The paper assesses the feasibility of novel mooring solutions that aim to absorb energy during the most severe load conditions in order to reduce peak and fatigue loads. Their suitability for wave energy converters in high-intensity typhoon conditions is assessed by a fully-coupled hydrodynamic analysis. Initial modelling has been conducted in the time-domain employing a moored cylindrical buoy with six degrees of freedom. The mooring line properties have been chosen to be characteristic of the strongly nonlinear behaviour of novel mooring designs. The results show a reduction in peak loads along the entire length of the mooring line in comparison to standard rope mooring, whilst crucially not restricting the heave motion of the buoy. These initial results will inform the refinement and optimisation of the mooring design of floating installations for high-intensity typhoon conditions.