Spectral and Entropy-based Wave Energy resource assessment: A global view, and point analysis at the Galapagos Islands

Abstract

An apparent paradox emerges when assessing the wave energy resources at global scale because a typical map displaying the mean annual wave power will bias our preference towards the most energetic places on earth, which are the extra-tropical storm zones. In turn, tropical areas that appear to be less energetic may be actually more convenient. We evaluate three main aspects: seasonal variability, extreme conditions, and spectral energy dispersion. Lower seasonal variability implies a more regular input of energy along the year, while the absence of extremes is related to lower investment costs and reduced exposure to risk. In turn, the energy distribution within the spectrum is associated to the facility to convert wave energy, being unidirectional and monochromatic waves the most attractive conditions. Naturally, such pristine conditions do not exist on earth, but places characterized by low frequency swells are close to that. For a map overview we evaluate the statistical entropy of the system, which provides insight into the spectral energy dispersion. In order to locally assess these apparent counter-intuitive results we look at the spectral characteristics at a specific point in the Galapagos Islands, where other constraints of the natural environment must be put also in consideration.