This research project introduces a novel hydrokinetic turbine system called a direct-drive parallel-stream counter-rotating darrieus turbine (DD-PS-CRDT). Two darrieus rotors are arranged horizontally across the water stream, one directly driving an armature coil rotor and the other a permanent magnet rotor of a generator. The proposed system improves on other counter-rotating turbine systems because each rotor utilizes a separate stream, direct-drive eliminates friction losses in the gearbox and the generator's rotational speed is doubled. This study emulated the DD-PS-CRDT by writing a simulation program using Visual Basic and Matlab codes. Turbine system configurations had different numbers of blades and lag angles between the rotors. Torque coefficient (C-T) profiles and ripples were investigated in the interest of torque output smoothing. The system with the lowest ripple was found and a table of prescribed lag angles presented. It is noted that both the magnitude of the minimum ripple and the corresponding lag angle change with rotational speed (n(i)). Moreover, the C-T output profile varies greatly with n(i) and a few curves contain irregular spikes. However, the evidence suggests that it is possible to maintain smooth curves, especially at the rated speed (n(s)). (C) 2019 Elsevier Ltd. All rights reserved.