Impacts of soft marine fouling on the hydrokinetic energy harvesting from one-degree-of-freedom vortex-induced vibrations

•This is the first study on marine fouling effects on hydrokinetic VIV energy conversion from cylindrical oscillators.•Towing tank VIV tests included artificially marine fouled cylinders of different densities.•The soft fouling significantly reduced the VIV mechanical power generation and the transfer ratio.•The results showed the smooth oscillator as the best VIV-based energy harvesting alternative.•The results showed marine fouled oscillators as non-ideal VIV-based energy harvesting alternatives. Most previous studies on marine hydrokinetic energy harvesters focussed on clean cylindrical oscillators. The current paper presents the results of the first investigation on the vortex-induced vibrations (VIV) hydrokinetic energy conversion from cylindrical oscillators covered with soft marine fouling. The one-degree-of-freedom system oscillates in the cross-flow direction. The Reynolds number ranges from 5.5 × 103 to 5.5 × 104. A hydroid-type of soft marine fouling is modelled with three different compaction ratios. On average, under a variety of electromechanical coupling and flow velocities examined, the marine fouling reduces the power harnessed and the energy transfer ratio by around 59 % and 62 %, respectively, relative to the clean oscillator.