Abstract: An energy extraction device for extracting energy from a flow of fluid is provided. The energy extraction device comprises a rotating member for rotatably mounting to a support structure, at least one rotatable bank of blades connected to the rotating member through a connection disposed radially from the main axis of rotation of the rotating member, and, a pitch control system for controlling the angular position of the at least one rotatable bank of blades relative to a direction of the flow of fluid. The rotating member has a main axis of rotation and the at least one bank of blades comprises an array of spaced-apart blades secured together. Each of the at least one bank of blades has a bank axis of rotation.