A liquid storage tank comprising an outer container wherein the outer container is rigid and has at least one inner container disposed within the outer container. The at least one inner container contains at least one stored liquid which may be refilled from a surface vessel or host facility. The at least one inner container is flexible and pressure balanced while the volume of the outer container remains fixed, and the volume of the at least one inner containers is variable. Disposed on the outer container is a balance assembly containing an isolation valve, a check valve, and a flexible bladder. The balance assembly allows for the hydrostatic pressure to be maintained during chemical dosing and tank raising operations.

Apparatus for use with fluid-processing plant configured to generate and store pressurized fluid. Fluid-processing plant is spaced apart from body of water. Apparatus includes variable-buoyancy assembly positioned in body of water in such way that buoyancy force urges variable-buoyancy assembly to move toward surface of body of water. Apparatus also includes non-collapsible fluid-line assembly positionally anchored, at least in part, underground in such way that non-collapsible fluid-line assembly extends, at least in part, into body of water. Non-collapsible fluid-line assembly fluidly connects fluid-processing plant and variable-buoyancy assembly together in such way that non-collapsible fluid-line assembly conveys pressurized fluid between fluid-processing plant and variable-buoyancy assembly. Non-collapsible fluid-line assembly transmits an anchoring force from ground to variable-buoyancy assembly; this is done in such way that anchoring force substantially counteracts, buoyancy force acting on non-collapsible fluid-line assembly. Anchoring force substantially urges variable-buoyancy assembly to remain below surface of body of water.

The present invention provides a carbon dioxide ocean liquid balloon storage method. The method comprises: suspending an uncharged liquid balloon device in seawater at a depth of not less than 600 m in advance; conveying liquid carbon dioxide to an inside of the liquid balloon device through a conveying pipe; when the liquid carbon dioxide charging volume reaches the rated charging volume of a carbon dioxide submarine storage device, stopping charging; closing a stop valve of a liquid balloon inlet pipe and disconnecting the carbon dioxide conveying pipe from the liquid balloon inlet pipe; and controlling the liquid balloon device to enable the liquid balloon device to be placed in a seabed at the appropriate depth, with the depth of the seabed of not less than 3,000 m. The whole liquid balloon device is of a frame liquid balloon structure, and comprises a frame structure and a liquid balloon structure.

A gas storage system is provided comprising a surface facility for gas production, and a storage vessel for storing pressurised gas from the surface facility, the gas being transferred from the storage vessel to the surface facility and/or a carrier vessel without substantial change in pressure, wherein the transfer is substantially driven by liquid displacement or elastomeric force.

A hydraulic compressed air energy storage system includes air and liquid tanks, each of which includes interdependent volumes of liquid and air. Each tank includes dedicated passages through which incoming air may be fed, forcing outflow of liquid, or incoming liquid may be fed, forcing outflow of air. Compressed air tanks are connected to a first group of the air and liquid tanks. The system further includes a pump and a liquid turbine, the liquid turbine being electrically connected to a generator for generating electric power. During charging of the system, liquid is pumped through the first group of air and liquid tanks, and air is expelled from the first group of air and liquid tanks and compressed in the compressed air tanks. During discharging of the system, compressed air is released from the compressed air tanks, and said compressed air pumps liquid through the liquid turbine, thereby generating electricity.

A liquid storage tank comprising an outer container wherein the outer container is rigid and has at least one inner container disposed within the outer container. The at least one inner container contains at least one stored liquid which may be refilled from a surface vessel or host facility. The at least one inner container is flexible and pressure balanced while the volume of the outer container remains fixed, and the volume of the at least one inner containers is variable. Disposed on the outer container is a balance assembly containing an isolation valve, a check valve, and a flexible bladder. The balance assembly allows for the hydrostatic pressure to be maintained during chemical dosing and tank raising operations.

A liquid storage tank comprising an outer container wherein the outer container is rigid and has at least one inner container disposed within the outer container. The at least one inner container contains at least one stored liquid which may be refilled from a surface vessel or host facility. The at least one inner container is flexible and pressure balanced while the volume of the outer container remains fixed, and the volume of the at least one inner containers is variable. Disposed on the outer container is a balance assembly containing an isolation valve, a check valve, and a flexible bladder. The balance assembly allows for the hydrostatic pressure to be maintained during chemical dosing and tank raising operations.

A hydrostatically compensated compressed air energy storage system may include an accumulator disposed underground, a gas compressor/expander subsystem in fluid communication with the accumulator interior via an air flow path; a compensation liquid reservoir spaced apart from the accumulator and in fluid communication with the layer of compensation liquid within the accumulator via a compensation liquid flow path; and a first construction shaft extending from the surface of the ground to the accumulator and being sized and configured to i) accommodate the passage of a construction apparatus therethrough when the hydrostatically compensated compressed air energy storage system is being constructed, and ii) to provide at least a portion of one of the air flow path and the compensation liquid flow path when the hydrostatically compensated compressed air energy storage system is in use.

The present invention relates to a system for CO.sub.2 storage, comprising a subsea CO.sub.2 storage unit having at least one inlet for receiving liquid CO.sub.2 and at least one outlet connected to at least one injection well in a subterranean reservoir, the subsea storage unit comprising at least one pipeline, the subsea storage unit being configured to contain and store CO.sub.2 and to transfer heat from the surrounding seawater to the contained CO.sub.2. The invention also relates to a method for CO.sub.2 storage.

A wind-turbine apparatus uses turbine-generated electrical energy to convert water to hydrogen in an electrolysis process, and stores the hydrogen in a subsea vessel. The submerged vessel is configured to contain and transport compressed hydrogen. By monitoring the vessel's hoop tension, ballast may be controlled to vary the buoyancy of the vessel. Electrical generating apparatus may use a wind turbine, water turbine or photovoltaic array, or combination thereof. The apparatus may employ an offshore fluid-turbine array or an onshore-turbine array combined with a photovoltaic array with associated fuel-synthesis hardware.