Management of Tidal Turbine Biofouling Through Protective Biofilms

Abstract

Emissions from fossil fuel consumption have driven anthropogenic climate change, leading to an increased need for carbon-neutral, renewable energy sources. Tidal power offers a powerful and consistent means of energy generation, however, the maintenance demands of tidal turbines reduce their efficiency (and therefore viability) within the energy mix. Biofouling, the unwanted growth of micro- and macro-organisms on submerged surfaces, contributes to this obstacle. Focusing on the turbine’s nacelle, where the gearbox resides, we investigate whether a biofilm can serve as a natural protective coating, specifically analyzing the biofilm’s behavior under flow and heat transfer capabilities. Computational fluid dynamics (CFD) simulations of a turbine in flow were scaled up to real-world conditions and showed the gearbox experienced a near-wall shear stress of maximum 15 Pa and a turbulent kinetic energy of just over 0.1 m2/s2. Viscosity parameter sweeps showed that increasing thermal sensitivity Eµ (5×103–6×104 J/mol) produced the largest variations in biofilm viscosity, while average strain rates on the biofilm remained on the order of 400–600 s−1 in the quasi-steady regime. Additionally, a lab-grown biofilm model was able to adhere to a turbine-like surface and withstand applied shear forces, suggesting that certain biofilms may exhibit the properties required of a protective coating.