Annual and seasonal variabilities in the performances of wave energy converters

Abstract

Locations of wave energy converters (WECs) are, most of the time, determined in areas with the highest density of mean wave power while ignoring the temporal variabilities of the resource. The most energetic regions are, however, characterised by strong interand intra-annual variations of wave power that may impact the energy production and performances of devices. We investigated these influences by focusing on the generated power from three well-known WECs that reached the stage of full-stage testing: Pelamis, AquaBuOY and Wave Dragon. This evaluation was conducted in western Brittany, one of the most energetic area along the coast of France. In comparison with the available resource, the generated technical power was characterised by reduced annual and seasonal variations. These effects were particularly noticeable for Pelamis that exhibited a reduced intermittency in the energy output between the winter and summer periods. The most energetic conditions had furthermore a restricted contribution to devices power output, mainly related to events with energy periods between 10.5 and 12.5 s, and significant wave heights between 2.75 and 4.25 m. WECs performances exhibited finally strong variabilities, in winter, with monthly-averaged values of the capacity factor up to 65% for Wave Dragon.

Wave Energy Resource Assessment for Exploitation—A Review

“…Indeed, wave energy converters (WEC) may potentially have a reduced lifespan with significant construction and maintenance costs as devices must withstand harsh environmental conditions, including severe storms, but also saltwater corrosive effects and biofouling [5]. WEC performances remain furthermore lower than other types of marine energy converters, and these performances are impacted by the high annual and seasonal variability of the wave resource [6]. A device may thus show yearly averaged high efficiency whereas it is designed for winter conditions, only.…”

“…The great part of wave power assessments were therefore conducted regardless of these specifications. Nevertheless, these resource assessments provided new features and methods to characterize the available resource and its exploitation by WEC [6,20], and an up-to-date review of associated analysis may promote new recommendations and specifications for advanced resource characterizations.…”

Wave Power Variation near the Romanian Coastal Waters

“…For the present work, three W ECs (Seabased, Pelamis and Wave Dragon) are considered, their power matrices being presented in Figure 2. By using these systems was possible to cover a fu ll range of rated powers, which start from 15 kW and reaching a maximu m of 7000 kW in the case of the Wave Dragon system [2,18,19]. The wave energy explo itation has many difficulties and it is possible that some wave project will no longer be operational.…”

Assessment of Offshore Wave Energy Potential in the Croatian Part of the Adriatic Sea and Comparison with Wind Energy Potential

“…where t is the number of hours in one year, i.e., 8760 h. WEC performance is usually defined through the capacity factor, which is defined as follows [36]:…”