Abstract
Open ocean currents provide energy dense resources along the western boundaries of the word’s ocean basins. These resources contain average energy densities that can exceed 3 kW/m2 in select areas with total extractable energy levels of several GW. Nearly all areas where ocean currents exceed 0.5 kW/m2 in energy density are located within the top 100 m of the water column, where the total water depth exceeds 250 m. For this reason, moored ocean current turbine (OCT) solutions are being pursued to enable the extraction of this resource with variable buoyancy, lifting surfaces, or a combination of the two being considered from altitude control. Dual-rotor designs enable net torque cancelation through counter-rotation, minimizing roll motions and misalignment with the current. In this paper, the numerical modeling and simulation-based performance evaluation for a dual-rotor OCT design that uses coupled variable-buoyancy and lifting surface control (i.e., dual-control) is presented. A rigid body approach is utilized where the OCT is modeled as having 8-degrees of freedom (6 for the main body plus the relative rotation speed of each rotor), in addition to the 3-degrees of freedom assigned to each node within the finite-element, lumped-mass cable model.
The presentation for this paper at UMERC+ METS 2024 can be found here.