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.

A system for storing air at high pressure underground or underwater includes a plurality of arrays of air tanks, each tank configured to store compressed air at a pressure of at least 40 bar. A piping system connects between an outlet of each air tank, the piping system further including at least one central port for delivering compressed air to and from a respective array. A storage receptacle surrounds the arrays and piping system, protecting the arrays and piping system from an external environment, and thermally insulating the arrays and piping system. A liquid bath is arranged within the storage receptacle. A heat exchanger is configured to maintain a temperature of the liquid bath substantially constant. The storage receptacle may be comprised of plastic pieces welded together in a modular fashion. Each piece may be a cylindrical tube configured to receive therein one or more of the arrays.

Disclosed herein is a system for storing gas at almost constant pressure, which involves the injection and withdrawal of a liquid in a process known as hydraulic compensation. This disclosure teaches a way to minimize that dissolution by ensuring that, as the gas containment is charged up, the hydraulic compensation liquid emerges from the containment at the gas storage pressure and the pressure of that liquid is caused to fall in a number of discrete steps with settling volumes present at the nodes between these steps. These settling volumes enable some gas to come out of solution at each node having lost relatively small amounts of pressure. The gas is compressed back up to storage pressure and re-injected into the main storage containment without significant use of energy.

A subsea vessel includes an outer layer of non-corrosive material and an inner layer of high-strength material that both corroborate in a subsea environment to withstand external pressure and prevent corrosion. The subsea vessel further includes a cavity surrounded by the inner layer and outer layer for providing storage in and protection from the subsea environment. The cavity is accessible via an opening that extends through the inner layer and the outer layer. The opening can be opened and closed with a cooperating cap that impermeably seals the cavity. The cap may include a number or connection mechanisms for being selectively secured to the opening. In addition, the cap may include a portion formed of a high-strength material and a portion formed of a non-corrosive material.

The invention relates to a submersible system (1) comprising at least a first frame structure (2) for horizontal storage of tanks (3) with a positive buoyancy in water therein, wherein the first frame structure (1) has a negative buoyancy in water and comprises at least two storage positions (4) for supporting at least two tanks (3), wherein the storage positions (4) are arranged side by side in one level and each storage position comprises at least one cradle (4) for supporting a tank (3) from below, and wherein the system (1) comprises a fastening device (6,11) having a first and a second state, wherein: i. when in the first state, the fastening device (6,11) is configured to permit positioning of a tank (3) from above into the at least one cradle (4) and; ii. when in the second state, the fastening device (6,11) is configured to secure a tank (3) positioned in the at least one cradle (4) in a radial direction of the tank (3) preventing movement of the tank (3) in a vertical upward direction; and wherein a total buoyancy of the system (1) when submerged in water, when tanks (3) are positioned in each of the storage positions, is negative. The invention also relates to an associated method of storing tanks on a seabed using the submersible system (1).

A modular subsea fluid storage unit comprises a variable-volume inner tank having a rigid top panel and a peripheral wall that is flexible by virtue of concertina formations. The peripheral wall is extensible and retractable vertically while the horizontal width of the tank remains substantially unchanged. A side wall of a lower housing part surrounds and is spaced horizontally from the peripheral wall of the inner tank to define a floodable gap between the peripheral wall and the side wall that surrounds the tank. An upper housing part extends over and is vertically spaced from the top panel of the inner tank and overlaps the side wall to enclose the inner tank. The floodable gap and the upper housing part enhance thermal insulation and trap any fluids that may leak from the inner tank.

A compressed fluid energy storage system includes a submersible fluid containment subsystem charged with a compressed working fluid and submerged and ballasted in a body of water, with the fluid containment subsystem having a substantially flat portion closing a domed portion. The system also includes a compressor and an expander disposed to compress and expand the working fluid. The fluid containment subsystem is at least in part flexible, and includes an upper portion for storing compressed energy fluid and a lower portion for ballast material. The lower portion may be tapered proximate the flat portion to prevent it from being collapsed by ballast materials. The region between the fluid and the ballast has exchange ports to communicate water between the inside and outside of the containment subsystem. In other embodiments, an open-bottomed fluid containment system is held in position underneath a ballast system by a tensegrity structure.

A method and apparatus for storing at least one fluid, and a flexible fluid storage pipe are disclosed. The method comprises: via a production device, providing a desired quantity of at least one fluid to be stored; transporting the quantity of fluid from the production device into at least one flexible pipe member via at least one fluid import region of the flexible pipe member, the flexible pipe member being windable around a spool element and comprising an inner fluid retaining layer that defines a bore region of the flexible pipe member, an outer sheath disposed over and coaxial with the inner fluid retaining layer and at least one composite reinforcement layer comprising helically wound fibre reinforced thermoplastic tapes that is disposed between the inner fluid retaining layer and the outer sheath; closing the fluid import region of the flexible pipe member to thereby retain the quantity of fluid in the bore region of the flexible pipe member; and storing the quantity of fluid at a first pressure in the bore region.

A system for storing air at high pressure underground or underwater includes a plurality of arrays of air tanks, each tank configured to store compressed air at a pressure of at least 40 bar. A piping system connects between an outlet of each air tank, the piping system further including at least one central port for delivering compressed air to and from a respective array. A storage receptacle surrounds the arrays and piping system, protecting the arrays and piping system from an external environment, and thermally insulating the arrays and piping system. A liquid bath is arranged within the storage receptacle. A heat exchanger is configured to maintain a temperature of the liquid bath substantially constant. The storage receptacle may be comprised of plastic pieces welded together in a modular fashion. Each piece may be a cylindrical tube configured to receive therein one or more of the arrays.

The present invention relates to a subsea storage system for storing a water miscible storage fluid and methods related thereto.