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Assessment of the Wave Energy Conversion Patterns in Various Coastal Environments
1  Dunarea de Jos University of Galati, Romania

Abstract: An important next stage in exploiting the ocean energy potential is to install several identical devices within an array, like doing in wind farms, to raise in this way their overall electricity production. The way in which the ocean energy devices will perform, as well as their economic viability, is critically linked to their design and moreover they depend directly on the specific environmental conditions characteristic of a certain area. Thus, due to the specific wave climate, one device can perform better than another in a particular coastal area while in another nearshore area the situation might be completely reversed. From this perspective, the main objective of the present work is to assess the performances of various WEC devices that would operate in different coastal environments. Three different groups of coastal environments were considered. They are: (I) the Iberian continental nearshore covering both Spanish and Portuguese coasts, (II) the Canaries Islands and the Archipelago of Madeira and (III) two enclosed seas (Black and Caspian seas). Various wave energy converters were evaluated covering the full range of the existing devices. Among these, the most representational devices considered are: Wave Dragon, Pelamis, Archimedes Wave Swing, Aqua Boy, Oyster, Langlee and Wave Bob. In order to evaluate the electric power expected in a certain location, the bivariate distributions of occurrences corresponding to the sea states defined by the significant wave height and the energy period were designed in each coastal area. The wave data were provided by hindcast studies covering extended time periods that were performed with numerical wave models based on the spectrum concept. The transformation efficiency of the wave energy in electricity was evaluated via the load factor and also through an index defined as the ratio between the electric power estimated to be produced by each specific WEC and the expected wave power corresponding to the location considered.The present work provides valuable information related to the effectiveness of various technologies for the wave energy extraction that would operate in different coastal environments. Moreover, the results can be easily extrapolated to some other nearshore areas.
Keywords: Wave power, WEC, electricity, efficiency, nearshore, wave models
Comments on this paper
Alejandro Mendez Guevara
Question about topic in paper
This was a very interesting paper. I wanted to ask you, when you mention in your conclusion that a future line of research in design converters with adjustable power matrices in order to fit better the environmental conditions would be convenient, since I'm not familiar with this topic, I'm curious to know if there has been work done in that line of research?

Eugen RUSU
Thank you for your nice comments and for your question. I have to admit that you have noticed indeed the most sensitive point.
Even from the beginning it has to be highlighted that, the direction I have mentioned is mainly from the point of view of a person who tries to evaluate the performances of various WEC devices in different coastal environments rather than from the point of view of an experienced WEC developer.
So, from this perspective, it would appear that if we could manage to adjust somehow the power matrix of the devices, function of location, season, etc., it would be indeed of great benefit for increasing the efficiency of these devices and adapt them better to the particular environmental conditions where they operate. On the other hand, it seems that the number one design consideration at this moment for WEC's is still related to the survival issues and from this perspective it is possible that a variable dynamics might increase both the costs and the risks of failures.

Thus, taking into account all these arguments, I mentioned however this issue at the conclusions of my work because in my opinion (based on the results presented in the paper) it would be worthwhile for the WEC developers to consider also a balance of all aspects (efficiency against survival issues). In order to give a straightforward answer to your question, I pointed these aspects especially because, as far as know, this direction it is not yet duly considered by the WEC developers.Finally, the point is that, the results of my study show without any doubt that if the power matrix of the device is well suited to the environmental conditions the efficiency of the WEC would be significantly enhanced.
I hope that I managed to give a reasonable explanation.