Can a breakwater protect the coast and generate renewable energy at the same time?
Oscillating Water Column devices capture wave energy by using the rise and fall of the water surface to compress and draw air through a turbine. Integrating these devices into breakwaters is particularly attractive because the same infrastructure can potentially provide both coastal protection and renewable electricity.
But the shape of the device matters enormously.
In this study, we built a highly adaptable physical model and systematically changed key aspects of its geometry, including the size and position of the energy-generating chamber, its opening, and the depth of the structure behind it. In total, 21 configurations were investigated across 378 laboratory tests. The aim was not simply to identify whether the concept works, but to understand why some configurations work substantially better than others.
The results showed that relatively small design decisions can produce major changes in performance. By progressively improving the geometry, the device's power output increased by as much as 164%, while the amount of wave energy transmitted beyond the structure was reduced by 55% compared with the initial configuration.
How design optimisation changes performance. The experiments progressively tested the opening, chamber size and position, and structural draft. At each stage, the better-performing configuration was carried forward, ultimately producing substantially greater energy capture while allowing less wave energy to pass through the structure.
Source: Almalki, Y.R., Swan, C. & Karmpadakis, I. (2025), Renewable Energy, 248, 122973, Fig. 23. Licensed under CC BY 4.0.
This highlights an important opportunity for future coastal infrastructure: rather than treating wave-energy generation and coastal protection as separate engineering problems, carefully designed structures could potentially perform both functions simultaneously.
Citation
Y.R. Almalki, C. Swan, I. Karmpadakis (2025). Experimental investigation of pile-supported Oscillating Water Column devices. Renewable Energy, 248, 122973.
Commentary
Can a breakwater protect the coast and generate renewable energy at the same time?
Oscillating Water Column devices capture wave energy by using the rise and fall of the water surface to compress and draw air through a turbine. Integrating these devices into breakwaters is particularly attractive because the same infrastructure can potentially provide both coastal protection and renewable electricity.
But the shape of the device matters enormously.
In this study, we built a highly adaptable physical model and systematically changed key aspects of its geometry, including the size and position of the energy-generating chamber, its opening, and the depth of the structure behind it. In total, 21 configurations were investigated across 378 laboratory tests. The aim was not simply to identify whether the concept works, but to understand why some configurations work substantially better than others.
The results showed that relatively small design decisions can produce major changes in performance. By progressively improving the geometry, the device's power output increased by as much as 164%, while the amount of wave energy transmitted beyond the structure was reduced by 55% compared with the initial configuration.
Source: Almalki, Y.R., Swan, C. & Karmpadakis, I. (2025), Renewable Energy, 248, 122973, Fig. 23. Licensed under CC BY 4.0.
This highlights an important opportunity for future coastal infrastructure: rather than treating wave-energy generation and coastal protection as separate engineering problems, carefully designed structures could potentially perform both functions simultaneously.