Prediction of vortex-induced vibration effects on a subsea gravity energy storage module

Abstract

Subsea buoyancy gravity energy storage systems (SBGESS) could take advantage of large water depth to store energy in the form of potential energy. In the proposed system, drum hoists mounted on a semisubmerged support structure simultaneously lift concrete cylinders with hundreds of tonnes and lower floaters with equivalent buoyancy force, which can be released with high round trip efficiencies by inverting the motor operation. The present study addresses the potential effect of the vortex-induced vibration (VIV) produced by current velocities on the behaviour of the energy storage modules. In order to analyse the system response, a state-of-the-art VIV model was integrated with a spherical pendulum and tuned with experimental results from the literature. The numerical model allows estimating amplitudes and frequencies of oscillation for a single module in both in-line and cross-flow directions. Results are used to assess the risk between modules of collisions on a previously designed SBGESS.