This study, firstly, provides an up-to-date global review of the potential, technologies, prototypes, installed capacities, and projects related to ocean renewable energy including wave, tidal, and thermal, and salinity gradient sources. Secondly, as a case study, we present a preliminary assessment of the wave, ocean current, and thermal gradient sources along the Brazilian coastline. The global status of the technological maturity of the projects, their different stages of development, and the current global installed capacity for different sources indicate the most promising technologies considering the trend of global interest. In Brazil, despite the extensive coastline and the fact that almost 82% of the Brazilian electricity matrix is renewable, ocean renewable energy resources are still unexplored. The results, using oceanographic fields produced by numerical models, show the significant potential of ocean thermal and wave energy sources in the northern and southern regions of the Brazilian coast, which could contribute as complementary supply sources in the national electricity matrix.

This paper addresses the current status and future research and development perspectives associated with technologies to harness offshore renewable energy, including offshore wind, waves, tides, ocean currents, and thermal and salinity gradient, in South America (SA). It focuses on five countries: Argentina, Brazil, Chile, Colombia and Uruguay. At first, a comprehensive survey presents the number of scientific papers classified based on the resource to show the tendency and importance of such subjects in the academic community. Each country’s electricity matrix and grid connection are shown to understand the region’s renewable source participation situation. The potential of offshore renewable resources is addressed by considering the published technical papers in scientific journals. The main conflicts and synergies associated with ocean space utilization are presented by considering the exclusive economic zone of each country. The status of the regulatory frameworks to promote and development of offshore renewable energies is presented. Two sections are dedicated to presenting the active, decommissioned and planned projects, research groups and laboratory infrastructures to develop the technologies. The last section discusses the future perspectives on the development of this sector in SA. It is observed that SA, with more than 25,000 km of coastline, has a great potential for offshore renewable energy; however, so far, these resources have not been explored commercially. Larger investment in the sector, establishing an adequate legal framework and deploying full-scale demonstration projects at sea are necessary for the commercialization of such technologies in SA.

The offshore harnessing of oil and gas resources is made possible by massive infrastructures installed at sea. At the end-of-life stage, in the absence of new uses for offshore installations, decommissioning proceedings usually take place, requiring the removal and final disposal of all materials. In Brazilian waters, decommissioning is hampered by high costs. The offshore wind-power sector has arisen as a new clean power source, in line with worldwide de-carbonization initiatives. In this context, we propose an innovative approach suggesting offshore wind power projects as an alternative to the removal and final disposal of infrastructures, a potential solution to Brazilian offshore decommissioning. In this article we report on the assessment of structures at the end of their lifecycle along with decommissioning cost estimation. Then, we explore wind turbine installation viability along the Brazilian coast and estimate the levelized cost of energy for each wind turbine. Finally, the results allow us to conduct a critical analysis of customary decommissioning versus the repurposing of infrastructures as offshore wind power project sites in two scenarios involving site repurposing. Our main results indicate that the CapEx discount rate of wind power projects offsetting decommissioning is considerable, as are the benefits of delaying decommissioning in terms of reduced carbon emissions and the social effects of increased local employment rates, through the repurposing of offshore oil and gas infrastructures.