Patent ID: 11916508
Assignee: nan
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  F  B | IPC B  F  H

Claim 12:
13. An energy or fluid storage system comprising:
a bag comprising a deformable boundary defining a bag interior that can be filled with said fluid and emptied of said fluid as desired, said bag being capable of occupying a less-filled configuration and a more-filled configuration; and
a mass of overburden overlying said bag, said overburden being able to be raised and lowered as a function of a degree of filling of said bag interior,
wherein said overburden has a variation in composition or particle size or particle size distribution from one location in said overburden to another location in said overburden,
wherein said overburden comprises a coarser layer and a finer layer, said coarser layer being located above said finer layer, wherein said system is located in a geographic location having a frost depth that characterizes a maximum depth of freezing of soil during winter, and wherein said coarser layer has a thickness that is greater than said frost depth.