52 JUNE 2024 • WORLD AQUACULTURE • WWW.WAS.ORG Aquaculture is growing exponentially worldwide, with anticipated production expected to increase 22 percent by 2030 (FAO 2022). As the competition for nearshore space grows, aquaculture developers are looking further offshore — but moving farther from land means higher energy and transportation costs, plus increased carbon emissions for an industry striving to go green. One solution that could make offshore aquaculture more sustainable? Marine energy. Marine energy is a renewable energy derived directly from the ocean — including the movement of waves, tides, and ocean currents, and even seawater temperature and salinity gradients. Covering over 70 percent of the planet’s surface, oceans hold massive amounts of this potential energy. U.S. waters alone are estimated to have a potential 3,300 terawatt hours of wave energy (Kilcher et al. 2023) — equivalent to roughly 78 percent of all the power generated in the US in 2022.1 Harnessing some of this energy to power aquaculture operations could be revolutionary for both sectors (Side Bar). Power from the Ocean In marine energy, motion equals energy (Figure 1). That can come directly from the motion of waves, tides, and currents moving a device or indirectly by leveraging large differences in seawater temperature or salinity to provide power. Because the ocean is constantly in motion, marine energy is a reliable, predictable energy source. Once captured, this clean energy can be used in a variety of ways to decrease reliance on fossil fuels and lower greenhouse gas emissions. Though the marine energy industry is still relatively young, there are many approaches and technologies available to capture and use ocean energy. Marine energy generation can rely on large-scale devices capable of delivering power to the electrical grid on land or smaller-scale devices suitable for providing power to islands, remote communities, or at-sea uses like aquaculture. Devices that can deliver high levels of consistent energy — like wave energy converters — may be best suited to finfish or integrated multi-trophic aquaculture operations that require more power to support various equipment and operations. Smaller-scale wave energy devices may be better suited to aquaculture operations with intermittent or lower power needs, like maintaining microalgae, crustaceans, and shellfish (Freeman et al. 2022). The variety of marine energy technologies can allow for identifying fit-for-purpose solutions for different aquaculture operations based on scale, location, and other factors (Figure 2). Opportunities and Challenges for Co-locating Marine Energy and Aquaculture Integrating marine energy technologies to power the growing aquaculture industry would enable more sustainable development while supporting the fledgling marine energy industry at the same time. It is part of a growing approach in sustainable ocean development called co-location, which purposefully integrates multiple compatible uses on shared infrastructure or within the same area for efficiency and sustainability — in this case, pairing marine energy production with aquaculture. Through co-location, Powering Sustainable Aquaculture with Marine Energy Mikaela Freeman and Alexandra Freibott FIGURE 1. The yearly average wave power around Puerto Rico identified during co-location suitability assessments. Data from Kilcher et al. 2023. FIGURE 2. Some of the various technologies designed to harness marine energy resources, including wave energy devices (top left: photo courtesy of CalWave Power Technologies, Inc., top right: photo courtesy of CorPower Ocean), tidal turbines (bottom left: photo courtesy of Verdant Power during turbine deployment), and ocean thermal energy converters (bottom right: photo courtesy of Makai Ocean Engineering).
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