In a significant stride towards enhancing wave energy capture, a team of researchers led by Ruben J. Paredes from ESPOL Polytechnic University and Stevens Institute of Technology has developed a novel, passive approach to tuning wave energy converters (WECs). The study, published in ‘Energy Conversion and Management: X’ (which translates to ‘Energy Conversion and Management: Cross-Disciplinary Approaches and Technologies’), introduces a design that could potentially revolutionize the wave energy sector.
So, what’s the big deal? Well, traditionally, WECs have struggled with a mismatch between their natural oscillation frequencies and the dominant frequencies of ocean waves. This mismatch limits their energy capture efficiency. Conventional designs often rely on complex active control systems to address this issue, but these can be costly and prone to mechanical wear and tear.
Paredes and his team have proposed a passive alternative that uses inverted cone-shaped submerged structures. Here’s how it works: as the WEC moves upwards, seawater is trapped within these cones, increasing the effective added mass of the device. This, in turn, lowers the natural frequency of the WEC, enabling it to resonate with the waves more effectively.
The team tested a 1:40-scale model of their design in both regular and irregular waves. They evaluated five different configurations, each with varying cone sizes and suspension distances. The top-performing configuration achieved a maximum Capture Width Ratio (CWR) of 52%, a notable improvement over the typical 20%–40% range of conventional WECs.
But how does it fare in real-world conditions? To test this, the team subjected their best-performing configuration to irregular wave spectra representative of swell-dominated seas. Even under these random conditions, the tuned device maintained efficiencies above 20%, demonstrating its robustness against spectral variability.
Paredes explained, “Our experimental results show close agreement with predictions from a linear analytical model. This confirms that passive tuning via cone-shaped structures effectively broadens the resonance bandwidth of roll-harvesting WECs.”
So, what does this mean for the maritime industry? For one, it presents a low-cost, scalable solution that addresses a long-standing limitation of WECs. The design’s structural simplicity and high efficiency make it an attractive prospect for full-scale deployment. Moreover, its adaptability to diverse wave climates opens up opportunities for wave energy projects in various maritime sectors.
As Paredes put it, “By combining high efficiency, robustness, and structural simplicity, this approach provides a viable pathway toward full-scale deployment with integrated power take-off damping and adaptation to diverse wave climates.”
In essence, this research brings us one step closer to harnessing the vast potential of wave energy, offering a promising solution that could reshape the future of renewable energy in the maritime sector.