Gravitational potential energy storage systems and methods
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.
1 . A method of storing energy comprising:
providing a track extending from a lower storage yard to an upper storage yard, the track having an inclined area between the lower storage yard and the upper storage yard;
coupling a plurality of mass cars to a conveyance system comprising at least a first tether that is an endless loop, wherein each mass car includes at least one coupling member configured to releasably engage with the first tether;
engaging the plurality of mass cars with the first tether and driving a first power module associated with the first tether to drive the conveyance system and transport the plurality of mass cars along the inclined area from the lower storage yard to the upper storage yard to store energy;
disengaging at least some of the plurality of mass cars from the first tether after the mass car is moved to the upper storage yard;
engaging the plurality of mass cars with the first tether and transporting the plurality of mass cars along the inclined area from the upper storage yard to the lower storage yard to dispatch energy with the first power modules; and
transferring the energy dispatched by the first power modules to a power grid.
2 . The method of claim 1 , further comprising controlling the first power module and conveyance system by sending one or more signals that direct a position of each mass car, and a speed, acceleration, and direction of transport of the mass cars.
3 . The method of claim 1 , further comprising releasing the plurality of mass cars from the conveyance system after the mass car is moved to the upper storage yard and/or after the mass car is lowered to the lower storage yard.
4 . The method of claim 3 , wherein each of the mass cars comprises at least one coupling member that engages with a corresponding member of one or more tether links of the first tether, the coupling members and corresponding members being configured to be releasably engaged.
5 . The method of claim 1 , wherein inclined area has a grade that ranges from 35% to 215%.
6 . The method of claim 1 , further comprising disengaging at least some of the plurality of mass cars after the mass car is transported to the lower storage yard.
7 . The method of claim 1 , wherein the first tether comprises a metal chain.
8 . The method of claim 7 , wherein the metal chain comprises aluminum and/or steel.
9 . The method of claim 1 , further comprising controlling the first power module and the conveyance system by sending one or more signals that direct a position of each mass car, and a speed, acceleration, and direction of transport of the mass cars.
10 . The method of claim 1 , wherein the at least one coupling member is configured such that at least some of the plurality of mass cars remain stationary in the upper storage yard after being disengaged from the first tether while the first tether continues to travel as the endless loop.
11 . A method of storing energy comprising:
providing a plurality of tracks extending from a lower storage yard to an upper storage yard, each track having an inclined area between the lower storage yard and the upper storage yard;
coupling a plurality of mass cars to a plurality of conveyance systems that each comprise a first tether and a coupling system disposed on the endless first tether, the first tether being an endless loop, wherein each mass car includes at least one coupling member configured to releasably engage with a corresponding member of the coupling system;
engaging, for each conveyance system, selected ones of the plurality of mass cars with the coupling system on the first tether by actuating the coupling members to releasably engage;
driving a plurality of power modules associated with the first tethers to drive the conveyance systems and transport the plurality of mass cars along the inclined area from the lower storage yard to the upper storage yard to store energy;
transporting the plurality of mass cars along the inclined area from the upper storage yard to the lower storage yard to dispatch energy with the plurality power modules;
disengaging at least some of the plurality of mass cars from the coupling system on the first tether by releasing the releasable engagement after a mass car is moved to the upper storage yard and/or after the mass car is lowered to the lower storage yard; and
transferring the energy dispatched by the plurality power modules to a power grid.
12 . The method of claim 11 , wherein the number of tracks ranges from two to twenty.
13 . The method of claim 11 , wherein the first tethers comprise a metal chain.
14 . The method of claim 11 , wherein the first tethers comprise an aluminum and/or steel chain.
15 . The method of claim 11 , wherein the coupling system comprises corresponding coupling fixtures on one or more links of the first tether, the corresponding members being configured to be releasably engaged by the coupling members of the mass cars.