A gravitational energy storage system is provided that includes one or more tracks extending from a lower storage yard to an upper storage yard, a plurality of mass cars moveable along the track, a conveyance system comprising at least a first tether, and a first power module associated with the first tether to drive a respective one of the first tethers to move the plurality of mass cars from the lower storage yard to the upper storage yard, and to dispatch energy when the plurality of mass cars are moved from the upper storage yard to the lower storage yard.

An electric energy storage and recovery system is provided to store electric energy from a generator when it is not required for the electric power grid. The system employs a controller to switch a generator between operating as an electric motor in power storage mode and operating as a generator in a power generation mode. A weight engaged to a distal end of a cable may be wound upon a reel by the generator when operating as an electric motor. The weight, in an elevated position, will pull the cable from the reel to rotate the generator and produce electric power when operating in power generation mode.

An energy storage system is for at least one electrical consumer in an electrical system of a watercraft. The at least one consumer is preferably a stabilizing device of the watercraft or a steering system for influencing the course of the watercraft. The energy storage system includes at least one converter connected to the electrical system for the supplying of the consumer. An energy storage is associated with the at least one converter.

An energy storage system stores power received from a power grid as potential energy in compressed earth materials. The energy storage system includes a motor-generator coupled to an anchor via a tensile member. The motor-generator is configured to apply a tensile force to the tensile member. The tensile force causes the motor-generator and the anchor to apply a compression force to the earth materials in the ground, and causes the anchor to displace, thereby storing the received power as potential energy. The energy storage system provides power to the power grid by relieving some of the tensile force on the tensile member and thereby relieving some of the compression force on the earth materials. The anchor displaces towards its original position, and thereby causes the motor-generator to generate electrical power from the stored potential energy.

A gravitational energy storage system is provided that includes one or more tracks extending from a lower storage yard to an upper storage yard, a plurality of mass cars moveable along the track, a conveyance system comprising at least a first tether, and a first power module associated with the first tether to drive a respective one of the first tethers to move the plurality of mass cars from the lower storage yard to the upper storage yard, and to dispatch energy when the plurality of mass cars are moved from the upper storage yard to the lower storage yard.

Microgrids and methods for controlling a microgrid. In one example, a microgrid includes a microgrid controller, a primary junction, a high-voltage supply line, a high-voltage output line, one or more switchgear connecting the primary junction to at least one other component of the microgrid, a plurality of photovoltaic (PV) panels, a breaker connected to the plurality of PV panel inverters, a first load connected to the breaker, and one or more battery banks. In some instances, the microgrid includes a ground bank transformer configured to provide a ground current path. Each of the plurality of PV panels is connected to one of a plurality of PV panel inverters. Each of the battery banks may include a plurality of battery cells.

A passive energy-storage exoskeleton for assisting elbow joint is provided, which includes an upper arm unit, a lower arm unit, and an elbow joint unit located therebetween, the upper arm unit is rotatably connected with the lower arm unit. The elbow joint unit includes an anti-gravity mechanism, a coil spring mechanism, and a lower-arm-unit self-locking mechanism. The anti-gravity mechanism generates an equilibrant moment to eliminate the influence of the weight of the arm of the user and the weight of the device on the elbow joint. The lower-arm-unit self-locking mechanism is configured for locking/releasing the lower arm unit at any specified angle of rotation. The coil spring mechanism is configured for capturing and storing kinetic energy generated by rotation and swing of the arm of the user and releasing the energy as required.

A system may include a flywheel including one or more plates and coupled at a central axis of rotation to a flywheel bearing, the flywheel being adapted to rotate about the central axis. A system may include a flywheel housing providing vertical support to the flywheel bearing. A system may include the flywheel bearing coupling the flywheel to the flywheel housing. A system may include a motor assembly including a motor adapted to convert an input electrical current to rotational momentum by spinning up the flywheel, the motor further being adapted to convert the rotational momentum of the flywheel into an output electrical current. A system may include a flywheel coupling adapted to couple the motor assembly with the flywheel and impart rotational force between the motor and the flywheel.

A frequency support system arranged for providing frequency support to an AC grid. The system includes an ES arrangement, and a bi-directional DC/AC power electronic converter interface configured for connecting the ES arrangement with the grid. The ES arrangement includes a plurality of series connected ES groups, each ES group including a plurality of parallel connected ES modules, each ES module including an energy storage interfaced by a bi-directional power electronic ES converter configured for connecting the ES with a DC side of the converter interface.

This disclosure describes novel hybrid energy storage systems for providing short-term and long-term storage and delivery of electricity generated by any energy source including renewable energy sources such as solar energy and wind energy. The hybrid energy storage systems described herein have a higher overall real-world efficiency than energy storage systems currently available.