Abstract
The Blue Economy is the sustainable use of ocean resources to create economic growth while preserving the ocean environment. Opportunities are being explored to use marine energy resources to supply the power demands of key strategic areas, known as Powering Blue Economy (PBE) applications. A key challenge in this process is the effective co-location of marine energy conversion devices, specifically Wave Energy Converters (WECs) in this study, within PBE applications. To address this, it is crucial to understand the primary requirements of these key strategic areas, enabling the selection of the most suitable WECs and, subsequently, the appropriate Power Take-Off (PTO) system.
In this work, our goal is to present the main requirements for offshore aquaculture installations, a promising candidate within PBE applications, and identify the most suitable WEC and PTO systems to power them. The energy demand of the fish farms due to automatic fish feeders, instrumentation (sensors required for the farm), and lighting could be partially or fully supplied by WECs. The most obvious advantage is the presence of waves as a sustainable and reliable source of power in the ocean. This allows the farm to operate without the need for costly grid connections and the security concerns of its dependence to the grid or the logistical challenges of fuel transport, while avoiding the environmental concerns associated with diesel generators. Another unique opportunity in this co-location is utilization of the shared infrastructure adaptable to both devices, e.g., the mooring lines systems of the aquaculture platforms.
The first requirement is that the WEC should match the power needs of the aquaculture installation, emphasizing the importance of understanding both the power demand, the available wave energy resource, and the WEC's capacity to generate the necessary energy. Second, it is important to consider the water depth of offshore aquaculture farms and select a WEC that operates optimally at that depth. The safety of farmed species is also crucial, as the environmental conditions—such as salinity, current speeds, and temperature—must remain within specific ranges. Therefore, any system (such as WECs) that disrupts these conditions, pollutes the surrounding water, or generates excessive noise could negatively impact productivity. Finally, the mooring system should be carefully studied considering the shared use of them between WECs and farms. This dual-purpose application introduces additional cyclical forces, making it essential to conduct a comprehensive analysis of their impact on mooring performance and long-term reliability.
Finally, three types of WECs are compared, an oscillating water column (OWC), an oscillating surge converter (OSC), and a single-point absorber (SPA). Furthermore, the evaluated PTO systems include air turbines, direct mechanical drive, direct electrical drive and hydraulic motor based. The functional combinations of WECs and PTO systems are selected based on the previously outlined requirements, ensuring optimal performance, efficiency, and compatibility with offshore aquaculture energy demands. An example is SPA device with a hydraulic motor-based PTO, considering the adaptability to the ocean conditions for the first, and the easy maintenance and the scalability of the hydrodynamical coefficients related to its performance for the second.
The poster for this paper at OREC/UMERC 2025 can be found here.