Techno-Economic Analysis and Power Take-Off Optimization of a Wave Energy Converter Adjacent to a Vertical Seawall

Wave energy converters (WECs) that are installed in nearshore environments offer several practical advantages, including easier access, lower maintenance, reduced transmission costs, and potential integration with the existing coastal infrastructure, leading to cost savings and improved commercial viability. This study presents a techno-economic analysis and power take-off (PTO) optimization for a vertical cylindrical WEC positioned adjacent to a vertical seawall under irregular wave conditions. The PTO system is connected via frames and hinges, with one end connected to the vertical seawall and the other end to the arm extending to the oscillating WEC. Hydrodynamic parameters were obtained from WAMIT, incorporating the seawall effect via the image method using linear potential theory. This analysis considers variations in WEC diameter, the lengths of frame segments supporting the PTO system, and the PTO damping. First, the geometric configuration is optimized. The results show that placing the WEC closer to the seawall and positioning the hinge joint of the PTO frame at the midpoint of the actuating arm significantly enhances power extraction, due to intensified hydrodynamic interactions near the seawall. A techno-economic analysis is then conducted using two techno-economic metrics, with one representing device cost and the other a newly introduced metric for PTO cost, combined through the weighted sum model (WSM) within a multi-criteria decision analysis (MCDA) framework. Our findings indicate that a smaller-diameter WEC is more cost-effective within a narrow range of PTO damping, while larger WECs, although requiring higher PTO damping capacity, become more cost-effective at higher PTO damping values, due to increased power absorption. Optimal PTO damping values were identified for each diameter of the WEC, demonstrating the trade-off between power output and system cost. These findings provide practical guidance for optimizing nearshore WEC designs to achieve a balance between performance and cost.