A method of operating a hydrostatically compensated compressed air energy storage system in a first charging mode including conveying the compressed air at a nearly constant first operating pressure which displaces a corresponding volume of compensation liquid from the layer of compensation liquid out of the accumulator, and a second charging mode including conveying additional compressed air into the accumulator while compensation liquid is not displaced from within the accumulator so that the pressure of the layer of compressed air increases to a second operating pressure that is greater than the first operating pressure.

A hydrostatically compensated compressed air energy storage system may include an accumulator disposed underground and a compressor/expander subsystem in fluid communication. A compensation shaft may extend between an upper and a lower end and define a shaft depth. An upper end wall can cover the upper end of the shaft. A compensation liquid reservoir can be offset above the upper end wall by a reservoir elevation that is at least about 15% of the shaft depth. A compensation liquid flow path may extend between the compensation liquid reservoir and the accumulator and can include the compensation shaft and a liquid supply conduit extending between the compensation liquid reservoir and the upper end of the compensation shaft whereby a total hydrostatic pressure at the lower end of the shaft is greater than a hydrostatic pressure at a depth that is equal to the shaft depth.

A method of temporarily storing thermal energy via a thermal storage subsystem in a compressed air energy storage system comprising an accumulator disposed at least 300 m underground and having an interior configured to contain compressed air at an accumulator pressure that is at least 20 bar and a gas compressor/expander subsystem in communication with the accumulator via an air flow path for conveying compressed air to the accumulator when in a charging mode and from the accumulator when in a discharging mode.

A method of storing hydrogen gas in a subsurface formation may include compressing hydrogen gas by utilizing a compressor. This may create pressurized hydrogen gas that may be introduced into a subsurface formation through a wellhead to store as reserved hydrogen gas. The reserved hydrogen gas may be stored and maintained in the subsurface formations for a period. Another method in accordance with one or more embodiments of the present disclosure relates to recovering previously stored hydrogen gas from a subsurface storage for energy production. The method may include extracting reserved hydrogen gas from a subsurface formation. The extracted hydrogen gas may be purified by using at least a dehydrator, a pressure swing adsorption unit (PSA) and at least a temperature swing adsorption unit (TSA). The purified hydrogen gas may then be pressurized and used as a fuel for combustion in a turbine-generator unit.

A compressed gas energy storage system may include an accumulator for containing a layer of compressed gas atop a layer of liquid. A gas conduit may have an upper end in communication with a gas compressor/expander subsystem and a lower end in communication with accumulator interior for conveying compressed gas into the compressed gas layer of the accumulator when in use. A shaft may have an interior for containing a quantity of a liquid and may be fluidly connectable to a liquid source/sink via a liquid supply conduit. A partition may cover may separate the accumulator interior from the shaft interior. An internal accumulator force may act on the inner surface of the partition and the liquid within the shaft may exert an external counter force on the outer surface of the partition, whereby a net force acting on the partition is less than the accumulator force.

The present disclosure is directed toward a method for storing methane. The method for storing methane comprises several steps. A dissolving fluid comprising water is injected into a salt formation to produce a brine and a salt cavern within the salt formation. The brine is then removed from the salt cavern. A sorbent is then placed within the salt cavern before methane is injected into the salt cavern.

A system and method for creating a subterranean storage facility at a location where there is underlying bedrock. A storage tank is provided that is formed from a cylindrical casing that is sealed with a top closure and a bottom closure. A first hole is excavated through the overburden. At the bottom of the first hole, a second hole is excavated into the bedrock. The storage tank is placed in the second hole with the top closure of the storage tank facing upward. The storage tank is set into the bedrock with a cement mixture. Pipe risers are extended into the storage tank through the first closure. The pipe risers extend up through the first hole and provide access to the storage tank.

An integral side slope structure of a soil-covered tank, includes a tank body, connecting pieces, and reinforcing frameworks. The exterior of the tank body is completely covered with soil, and a side slope is formed after the tank body is covered with the soil; each connecting piece is composed of ribs which are in cross connection to each other; the connecting pieces are connected to the outer wall of the tank body and are laid inside the side slope in the horizontal direction; a single-layer connecting net is formed after a single layer of the connecting pieces is connected to the tank body; a plurality of layers of the connecting pieces are arranged at intervals in the vertical direction; the tank body and the side slope are connected by the multi-layer connecting net to form an integral structure; the reinforcing frameworks are arranged along the side slope.

An underwater compressed air storage device with at least one underwater compressed air tank, positioned on the floor (7) of a body of water and provided with at least one water outlet opening and at least one inlet opening (11, 13) for a mixture of water and air. A tank which has at least one compressed air storage volume provided with two connecting ducts (9, 11) between said volume and a collection chamber (5) for the water and air mixture, a first duct (9) located in the upper part of the volume ensuring the passage of compressed air in the volume and a second duct (11), at an altitude lower than the first duct (9), ensuring the passage of the water and air mixture in the volume, said tank also having at least one opening for discharging the degassed water into the body of water.

The present disclosure is directed toward a method for storing carbon dioxide. The method for storing carbon dioxide comprises several steps. A dissolving fluid comprising water is injected into a salt formation to produce a brine and a salt cavern within the salt formation. The brine is then removed from the salt cavern. A sorbent is then placed within the salt cavern before carbon dioxide is injected into the salt cavern.