Abstract
Hybrid wind-wave systems present a promising opportunity to enhance renewable energy generation by combining the strengths of offshore wind turbines and wave energy converters. This integration can lead to increased energy capture, improved system stability, and a reduction in the levelized cost of energy (LCOE). The complementary nature of wind and wave resources allows for shared infrastructure while optimizing power generation–wind turbines provide consistent power from wind resources, while wave energy converters peak during low-wind periods, reducing power variability and enhancing reliability.
Despite the LCOE being a critical metric for assessing offshore renewable energy systems, it does not fully capture the benefits of hybrid configurations. To address this, we propose the use of the power coefficient of variation as an additional metric to quantify the complementary relationship between wind and wave energy. Furthermore, we propose evaluating the symbiotic interactions within hybrid systems using an ecological framework: (1) mutualism, where both devices benefit; (2) commensalism, where one device benefits without affecting the other; and (3) parasitism, where one device benefits at the expense of the other. In this context, a hybrid system achieves mutualism if integration reduces the LCOE/power coefficient of variation of both the wind turbine and wave energy converter, commensalism if only one device experiences a cost reduction/power improvement, and parasitism if the integration increases the LCOE/power coefficient of variation of one system while decreasing it for the other.
This study evaluates two hybrid system designs integrating the National Renewable Energy Laboratory 5 MW and the International Energy Agency 15 MW wind turbines with two different and wave energy converters designs: Reference Model 3 (RM3) and Reference Model 5 (RM5). RM3 is a two-body point absorber consisting of a float that moves along a central spar, while RM5 is an oscillating surge wave energy converter with a flap that pivots in response to incident waves. Both configurations utilize spar mooring platforms to assess energy generation, power coefficient of variation, and cost-effectiveness.
The RM3-based system (Figure 1a) leverages the wind turbine tower as a shared structural foundation, significantly reducing capital and operational costs. The RM5-basedsystem (Figure 1b) features two oscillating surge wave energy converters mounted on a plate at the top of the spar platform, optimizing power production by aligning with wind and wave resources directionality at the deployment site. Both designs demonstrate a substantial reduction in the LCOE, particularly for the wave energy converters, and highlight cost advantages by distributing the capital and operational costs across two energy generation systems.
This study underscores the economic and operational viability of hybrid wind-wave systems, offering a practical pathway toward more cost-effective and reliable renewable energy solutions. By leveraging shared components and optimizing system designs, these hybrid configurations present a compelling case for the future deployment of integrated offshore energy technologies.