An energy storage apparatus for storing energy transmitted by a power transmission line includes an elastically deformable component and an actuator-generator. The actuator-generator is coupled to the elastically deformable component such that electrical actuation of the actuator-generator generates tension in the elastically deformable component. The actuator-generator is further coupled to the elastically deformable component such that mechanical actuation of the actuator-generator via a release of tension in the elastically deformable component causes a generation of electrical energy by the actuator-generator.