A comprehensive evaluation of wave energy conversion to power desalination plants: The Portuguese case-study

Abstract

The geographical position of Portugal and its wave climate explain the strategic potential for harnessing wave energy. This renewable source can significantly contribute towards achieving the established goals for renewable energies in the national energy mix, as well as drive the development of a “blue” and sustainable economy. In parallel, the increasing frequency and severity of droughts and water scarcity in the country, particularly in the Southern regions, have sparked interest in constructing reverse osmosis desalination plants to address this challenge. As an energy-intensive process, decarbonizing seawater desalination through co-location with wave energy parks appears as a promising solution. This paper provides an exploratory, yet realistic evaluation of scenarios with two wave energy devices for three Portuguese sites with ongoing/upcoming desalination plant projects. Marine space conflicts, park efficiency, survivability and operational restrictions, and economies of scale/learning rate gains were considered to assess energy costs and number of units needed to meet water demands at an annual and seasonal level (Summer). It was found that each site exhibits unique features, opportunities and challenges, from stoppages inherent to the local wave climate to cost metrics. Overall, the CorPower device tended to yield better cost results, with annual levelized values as low as 1.5 €/m³ (Albufeira and Odemira, in Algarve) and 1.0 €/m³ (Porto Santo, in Madeira), respectively. Nevertheless, the Summer season proved to be quite challenging, as energy expenditures were several times greater than the annual ones, which reflected upon the total water costs. Also, even with very beneficial economies of scale/learning rates, current costs are not yet competitive with existing references, though future developments may alter this outcome. Nevertheless, this work's findings and data sources can be repurposed for other case studies of co-located seawater desalination with wave energy, given the distinct and encompassing features of each evaluated scenario.