• Energy Research

To date the estimation of long-term wave energy production at a given deployment site has commonlybeen limited to a consideration of the significant wave height H s and mean energy period T e . This paperaddresses the sensitivity of power production from wave energy converters to the wave groupiness andspectral bandwidth of sea states. Linear and non-linear systems are implemented to simulate theresponse of converters equipped with realistic power take-off devices in real sea states. It is shown inparticular that, when the converters are not much sensitive to wave directionality, the bandwidthcharacteristic is appropriate to complete the set of overall wave parameters describing the sea state forthe purpose of estimating wave energy production.

In this article, an original Markov-switching autoregressive model is proposed to describe the space-time evolution of wind fields. At first, a non-observable process is introduced in order to model the motion of the meteorological structures. Then, conditionally to this process, the evolution of the wind fields is described using autoregressive models with time-varying coefficients. The proposed model is calibrated and validated on data ill the North Atlantic.

This paper presents a refined description of the wave climate observed in a Portuguese location for marine energy projects. The data used in this case study were derived from 3-month in situ measurements carried out using three directional buoys that have been deployed simultaneously – yet independently (various buoy types and water depths) – on the Atlantic coast in the neighbourhood of Figueira da Foz. Two ways of reporting the statistics were adopted. In the first one, each recorded sea state was summarized as a set of global parameters accounting for energy, mean frequency and direction, spectral bandwidth and directional spreading related to the main ongoing wave field considered as unimodal. In the second one, each sea state has been decomposed into its own wave components – swells and wind-sea – which are characterised separately and individually by the same set of parameters as previously. Besides the adopted data processing techniques and the illustration of such thorough wave climate description modes, the paper also addresses the advantages and limits of each adopted parameterization in the frame of simultaneous and independent in situ wave measurements.Highlights► Wave statistics produced considering unimodal and multimodal sea-state descriptions. ► Spectral bandwidth and directional spreading are included in both descriptions. ► Spectral bandwidth is significantly correlated to wave energy/peak period. ► Wave directional spreading is difficult to estimate in absolute terms. ► Directional artefacts are obtained with Maximum Entropy Methods in some cases.