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 system for storing and transporting compressed natural gas includes source and destination facilities and a vehicle, each of which includes pressure vessels. The pressure vessels and gas therein may be maintained in a cold state by a carbon-dioxide-based refrigeration unit. Hydraulic fluid (and/or nitrogen) ballast may be used to fill the pressure vessels as the pressure vessels are emptied so as to maintain the pressure vessels in a substantially isobaric state that reduces vessel fatigue and lengthens vessel life. The pressure vessels may be hybrid vessels with carbon fiber and fiber glass wrappings. Dip tubes may extend into the pressure vessels to selectively expel/inject gas from/into the top of the vessels or hydraulic fluid from/into the bottom of the vessels. Impingement deflectors are disposed adjacent to the dip tubes inside the vessels to discourage fluid-induced erosion of vessel walls.

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.

This invention provides a means of loading, processing and conditioning raw production gas, production of CGL, storage, transport, and delivery of pipeline quality natural gas or fractionated products to market. The CGL transport vessel utilizes a pipe based containment system to hold more densely packed constituents of natural gas held within a light hydrocarbon solvent than it is possible to attain for natural gas alone under such conditions. The containment system is supported by process systems for loading and transporting the natural gas as a liquid and unloading the CGL from the containment system and then offloading it in the gaseous state. The system can also be utilized for the selective storage and transport of NGLs to provide a total service package for the movement of natural gas and associated gas production. The mode of storage is suited for both marine and land transportation and configured in modular form to suit a particular application and/or scale of operation.

A system for storing and transporting compressed natural gas includes source and destination facilities and a vehicle, each of which includes pressure vessels. The pressure vessels and gas therein may be maintained in a cold state by a carbon-dioxide-based refrigeration unit. Hydraulic fluid (and/or nitrogen) ballast may be used to fill the pressure vessels as the pressure vessels are emptied so as to maintain the pressure vessels in a substantially isobaric state that reduces vessel fatigue and lengthens vessel life. The pressure vessels may be hybrid vessels with carbon fiber and fiber glass wrappings. Dip tubes may extend into the pressure vessels to selectively expel/inject gas from/into the top of the vessels or hydraulic fluid from/into the bottom of the vessels. Impingement deflectors are disposed adjacent to the dip tubes inside the vessels to discourage fluid-induced erosion of vessel walls.

A system for transporting natural gas. The system may include a loading facility, a first storage system, a second storage system, and a CNG carrier. The loading facility may be operable to receive, compress, and chill natural gas while maintaining the natural gas in a gaseous state, and further operable to transfer the chilled CNG at a constant flowrate. The first storage system may be operable to receive chilled CNG from the loading facility at the constant flowrate, store the chilled CNG, and transfer the chilled CNG. The second storage system may be operable to receive and store the chilled CNG. The CNG carrier may be operable to receive chilled CNG from the first storage system, transport the chilled CNG, and transfer the chilled CNG to the second storage system. The system may be sized such that the constant flowrate of the chilled CNG is maintained without interruption.

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 compressed air energy storage system may have an accumulator and a thermal storage subsystem having a cold storage chamber for containing a supply of granular heat transfer, a hot storage chamber and at least a first mixing chamber in the gas flow path and having an interior in which the compressed gas contacts the granular heat transfer particles at a mixing pressure that is greater than the cold storage pressure and the hot storage pressure and a conveying system operable to selectably move the granular heat transfer particles from the cold storage chamber, through the first mixing chamber and into the hot storage chamber, and vice versa.

A method of increasing the glass transition point of a cured epoxy comprising a bisphenol A diglycidyl ether and a polyetheramine includes the step of including 1,8-diamino-p-menthane as an additional hardener for curing the epoxy. An epoxy formulation includes bisphenol A diglycidyl ether and a hardener including a polyetheramine and 1,8-diamino-p-menthane.

A portable subsea storage tank for the storage of gas products under pressure or oil products consisting of pipeline sections in an array which can be coated in specialist coatings and recovered for inspection and re-use. A method of self-installing the subsea storage tank is also described.