Reliability assessment of wave Energy devices

Energy from waves may play a key role in sustainable electricity production in the future. Optimal reliability levels for components used for Wave Energy Devices (WEDs) need to be defined to be able to decrease their cost of electricity. Optimal reliability levels can be found using probabilistic methods. Extreme loads during normal operation, but also extreme loads simultaneous with failure of mechanical and electrical components as well as the control system, are of importance for WEDs. Furthermore, fatigue loading needs to be assessed. This paper focus on the Wavestar prototype which is located near Hanstholm (DK). In the present paper, a generic example for an extreme limit state is considered. The extreme limit state case considers important failure modes of the system which are determined by a Fault Tree Analysis (FTA) and Failure Mode and Effects Analysis (FMEA). The resulting reliability indices are then compared with related industries like offshore wind turbines.