The present disclosure is directed at a method and system for harnessing wind energy using a tethered airfoil. During a traction phase, wind is allowed to extend a kite tether. Wind energy that is harnessed through extension of the kite tether is mechanically stored prior to using the wind energy that is stored to generate electricity. During a retraction phase, the wind energy that is mechanically stored during the traction phase is used to retract the kite tether. Beneficially, the mechanical storage allows the kite tether to be retracted without relying on electricity from an electrical grid.