A thermal storage subsystem may include at least a first storage reservoir configured to contain a thermal storage liquid at a storage pressure that is greater than atmospheric pressure. A liquid passage may have an inlet connectable to a thermal storage liquid source and configured to convey the thermal storage liquid to the liquid reservoir. A first heat exchanger may be provided in the liquid inlet passage and may be in fluid communication between the first compression stage and the accumulator, whereby thermal energy can be transferred from a compressed gas stream exiting a gas compressor/expander subsystem to the thermal storage liquid.

A method of storing hydrogen involves forming an excavation in the earth and constructing a storage tank therein comprised of integrated primary and secondary containment structures. The primary containment structure composed of a plurality of joinable cylindrical segments, or pre-fabricated sections joined to form a cylinder within the excavation. The secondary containment structure formed by pumping a curable, flowable composition into the cylinder, allowing it to flow out the bottom and up the second annulus to the earth's surface, and then hardening; thereby encasing the primary containment structure. The bottom of the cylinder is sealed with the bottom assembly. The top assembly is attached to the cylinder and tubing and packer are run into the cylinder creating a first annulus between the cylinder and tubing. Top assembly is sealed, fluids circulated out, and the tank dried. Thereafter, the tank is capable of safely storing hydrogen gas.

Storage vessel, system and method for storing compressed gas are provided. A storage vessel for storing compressed gas comprises a wellbore provided in the subsurface; a casing placed within the wellbore and cemented to the formation, the casing defining a volumetric space within the wellbore for storing the compressed gas; and at least one flow regulator sealed at a top end of the casing for selectively injecting the compressed gas into the space or discharging the compressed gas from the space, wherein the wellbore has a volumetric capacity of at least 20 m3, and wherein the compressed gas has a pressure of at least 5 MPa.

Embodiments of the inventive concept include a manufactured pressure vessel including pressure cells having an impermeable layer containing porous material in which air can permeate, and a big mass layer disposed atop the pressure vessel to pressurize the air within the pressure vessel. The impermeable layer can include rubber from recycled vehicle tires. The big mass layer can have a total weight of between one (1) million and one (1) billion tonnes, or more. The big mass layer can include a remediated upper surface. The pressure vessel can include an interface section through which the air can enter and exit the pressure vessel. Pressure lines can be coupled to the interface section. A turbine center can be coupled to the pressure lines to generate electricity in response to pressurized air received through the pressure lines, or to pump air through the pressure lines into the pressure vessel to pressurize the pressure vessel.

A thermal storage subsystem may include at least a first storage reservoir disposed at least partially under ground configured to contain a thermal storage liquid at a storage pressure that is greater than atmospheric pressure. A liquid passage may have an inlet connectable to a thermal storage liquid source and configured to convey the thermal storage liquid to the liquid reservoir. A first heat exchanger may be provided in the liquid inlet passage and may be in fluid communication between the first compression stage and the accumulator, whereby thermal energy can be transferred from a compressed gas stream exiting a gas compressor/expander subsystem to the thermal storage liquid.

A thermal storage subsystem may include at least a first storage reservoir configured to contain a thermal storage liquid at a storage pressure that is greater than atmospheric pressure. A liquid passage may have an inlet connectable to a thermal storage liquid source and configured to convey the thermal storage liquid to the liquid reservoir. A first heat exchanger may be provided in the liquid inlet passage and may be in fluid communication between the first compression stage and the accumulator, whereby thermal energy can be transferred from a compressed gas stream exiting a gas compressor/expander subsystem to the thermal storage liquid.

Systems and methods for recovery, storing and utilizing heat energy during compressed gas energy storage are disclosed. In an example, a system for storing energy in a form of compressed gas, comprising: one or more energy storage vessels for storing compressed gas, said energy storage vessels each comprising: a wellbore provided in a subsurface; and a casing placed within the wellbore and cemented to a surrounding geological medium, the casing defining a volumetric space for storing the compressed gas; and a geothermal reservoir formed at the surrounding geological medium of the one or more energy storage vessels for underground thermal energy storage, wherein a portion of thermal energy of the compressed gas stored in the one or more storage vessels is conductively transferred to, via the one or more storage vessels, the surrounding geological medium, and stored in the surrounding geological medium.

The invention relates to a compressed air energy storage system comprising a pressure accumulator (2) for gas to be stored under pressure, and a heat accumulator (27) for storing the compression heat that has accumulated during charging of the pressure accumulator (2), wherein the heat accumulator (27) is arranged ready for use in an overpressure zone (31). Said arrangement enables a structurally simple heat accumulator to be provided, since said heat accumulator is not loaded by the pressure of the gas passing therethrough.

Apparatus comprising a source of a first fluid (204), a fluid displacement device (210) for moving the first fluid from the source to a sealed storage chamber (214), means for introducing a second fluid (207), different from the first fluid into the first fluid prior to reaching the storage chamber, the arrangement being such that the sealed storage chamber receives a mixture of the first and second fluids under a pressure greater than the pressure at the point at which the second fluid is introduced into the first fluid and includes a first fluid outlet (220) for directing the first fluid separated from the second fluid in the storage chamber externally of the storage chamber.

A subterranean tank can consist of at least a casing string that has a containment section disposed between first and second end regions. The containment section may have a first width while each of the first and second end regions have a second width. The first width can be greater than the second width of the respective first or second end regions. The entire casing string may be sealed to maintain a gas at 5,000 psi or more until a gas delivery assembly attached to the first end region releases gas stored in the casing string.