Harnessing tidal energy with breakwater-integrated marine turbines for coastal protection

Abstract

This study presents the design and evaluation of a vertical axis tidal micro-turbine system integrated into an improved wave breakwater, based on the Wave Breakwater and Coral Restorer (WABCORE) structure, which was developed through a collaborative project between UTM and NAHRIM. The aim is to develop a structurally viable and hydrodynamically efficient solution for renewable energy extraction in shallow coastal environments with low tidal velocities. The research addresses the dual challenge of combining shoreline protection with localized energy harvesting, responding to the limitations of conventional breakwaters, which typically serve a single purpose and previous turbine integrations that lacked optimization for shallow and low-speed tidal currents. The methodology integrates finite element analysis (FEA) to assess structural integrity under hydrostatic loading and computational fluid dynamics (CFD) simulations using the validated k-ω SST turbulence model to analyze flow behaviour and power extraction. Structural results confirm the design’s robustness, with a maximum first principal stress of 0.366 MPa and compressive stress of −0.226 MPa, both well within the limits for Grade 30 concrete. The structure exhibited a negligible displacement of 0.00489 mm and a high factor of safety of 8.01, ensuring long-term durability under marine conditions. Fluid flow analysis demonstrated that the ducted vertical axis turbine provided the most accurate flow alignment and fastest wake recovery, achieving downstream velocity prediction errors as low as 0.38% at 12D. The breakwater-integrated duct outperformed the standalone turbine, which showed greater turbulence and flow dispersion. The inline row configuration produced the highest average power output (3.85 W), followed by the vertical stack (2.61 W) and single breakwater model (2.51 W). However, rear-tier shadowing in the vertical stack caused local power drops to as low as 0.12 W, underscoring the importance of spatial turbine placement. In conclusion, the study demonstrates the feasibility of integrating micro-turbines into wave breakwaters for dual-purpose coastal protection and renewable energy generation. The validated design offers a structurally robust and hydrodynamically efficient solution for shallow, low-velocity tidal environments.