Page 1 - Vannucchi_Cappietti_2016

sustainability

Article
Wave Energy Assessment and Performance

Estimation of State of the Art Wave Energy

Converters in Italian Hotspots

Valentina Vannucchi * and Lorenzo Cappietti
Department of Civil and Environmental Engineering, University of Florence, Via S. Marta 3, 50139 Florence,
Italy; cappietti@dicea.unifi.it
* Correspondence: valentina.vannucchi@dicea.unifi.it; Tel.: +39-338-1312152
Academic Editors: Diego Vicinanza and Mariano Buccino
Received: 29 September 2016; Accepted: 5 December 2016; Published: 10 December 2016
Abstract: This paper presents an assessment of offshore wave energy potential at the scale of the
whole Mediterranean Sea. The offshore wave data were propagated, by means of numerical modeling,
toward four Italian coastal areas, namely stretches of coast of Tuscany, Liguria, Sardinia and Sicily.
For each area, the wave power and the monthly, seasonal and annual variability at water depths of
50 m and 15 m were analyzed and hotspots were located. The results show strong variability of the
wave energy potential from point to point of the same area thus highlighting the need for spatially
detailed analysis. The higher values of wave energy potential are located in the hotspots of Sardinia
and Sicily, at 11.4 kW/m and 9.1 kW/m, respectively. The Tuscany and the Liguria hotspots are
characterized, respectively, by 4.7 kW/m and 2.0 kW/m. In order to point out which state of the art
WEC is best suited for the Italian areas, the performances of six different state of the art Wave Energy
Converters (WECs) were evaluated. Finally, a comparison of the performances of each WEC in the
selected Italian sites and in some European (EU) oceanic sites was conducted. The energy potential in
the most energetic EU oceanic site, among those here investigated, is up to 38-times greater than the
potentials in the studied Italian areas but the power output, of the best WEC technology, is no more
than nine times greater.

Keywords: wave energy; Mediterranean Sea; offshore wave energy assessment; coastal wave energy
assessment; wave energy hotspots; performances of wave energy converters

1. Introduction

Due to the depletion of fossil fuel energy resources and the environmental impacts related to their
use, the interest in the exploitation of renewable energy sources has been growing for many years and,
in this context, the energy of the sea waves is emerging. The wave energy is the renewable energy
source having the highest energy density and a global wave energy potential of 32,000 TWh/year is
estimated to reach the world coastlines, a value close to the yearly mean world energy consumption [1].
Various Wave Energy Converters (WEC) have been proposed so far but these technologies have not
yet reached the commercial level [2]. Among all the technical issues that impinge the development of
WECs, resistance to extreme wave loads is one of the most challenging. If, on the one hand, the sea
sites where the wave energy is relatively high offer higher energy potentials, on the other hand,
the presence of high waves leads to heavy loads on the WECs, thus increasing the failure probability
and so decreases the overall productivity. Seas with moderate wave climate, with respect to the oceanic
conditions, such as the Mediterranean Sea or the North Sea might offer a good compromise for the
exploitation of such kind of energy and act as test areas for prototypes in view of their development
for the more energetic oceanic sites.

Sustainability 2016, 8, 1300; doi:10.3390/su8121300 www.mdpi.com/journal/sustainability