The systems and methods described herein integrate a supercritical fluid power generation system with a LNG production/NGL separation system. A heat exchanger thermally couples the supercritical fluid power generation system with the LNG production/NGL separation system. A relatively cool heat transfer medium, such as carbon dioxide, passes through the heat exchanger and cools a first portion of extracted natural gas. The relatively warm heat transfer medium returns to the supercritical fluid power generation system where a compressor and a thermal input device, such as a combustor, are used to increase the pressure and temperature of the heat transfer medium above its critical point to provide a supercritical heat transfer medium. A second portion of the extracted natural gas may be used as fuel for the thermal input device.

A cooling system includes a compressor configured to pressurize carbon dioxide to form pressurized carbon dioxide, a mixer configured to generate mixed refrigerant in which the pressurized carbon dioxide and solvent in a liquid state, a depressurization apparatus provided downstream from the mixer and configured to depressurize the mixed refrigerant, a separator configured to separate carbon dioxide in a gas state from the mixed refrigerant, a heat exchanger configured to exchange heat between the mixed refrigerant cooled through depressurization and a fluid to be cooled, and a second heat exchanger configured to cool the carbon dioxide or the mixed refrigerant using vaporized carbon dioxide or the mixed refrigerant.

In a method for liquefying a gas rich in carbon dioxide, the gas is compressed to a first pressure greater than its critical pressure in a compressor to form a compressed gas, the compressed gas is cooled through heat exchange with a refrigerant to a variable temperature to form a cooled compressed gas with a density between 370 and 900 kg/m.sup.3, the cooled compressed gas is cooled at supercritical pressure in a first heat exchanger to a temperature below the critical temperature, the gas cooled below the critical temperature is expanded to a second pressure between 45 and 60 bara to form a diphasic fluid which is separated in a phase separator to form a liquid and a gas, and a liquid portion originating from the phase separator provides cold to the first heat exchanger.

A CO.sub.2 energy storage system includes a storage tank that stores a CO.sub.2 slurry, including dry ice and liquid CO.sub.2, at CO.sub.2 triple point temperature and pressure conditions. The storage system also includes a first pump coupled in flow communication with the storage tank. The first pump is configured to receive the CO.sub.2 slurry from the storage tank and to increase a pressure of the CO.sub.2 slurry to a pressure above the CO.sub.2 triple point pressure. The energy storage system further includes a contactor coupled in flow communication with the first pump. The contactor is configured to receive the high pressure CO.sub.2 slurry from the pump and to receive a first flow of gaseous CO.sub.2 at a pressure above the CO.sub.2 triple point pressure. The gaseous CO.sub.2 is contacted and then condensed by the melting dry ice in the slurry to generate liquid CO.sub.2.

A process for liquefying a natural gas comprising a mixture of hydrocarbons predominating in methane, the process comprising a first semi-open refrigerant cycle with natural gas in which any natural gas liquids that have condensed are separated from the natural gas feed stream, which stream then passes through a main cryogenic heat exchanger (4) in order to contribute by heat exchange to pre-cooling a main natural gas stream (F-P) and to cooling an initial refrigerant gas stream (G-0), a second semi-open refrigerant cycle with natural gas for contributing to pre-cooling the natural gas and the refrigerant and also to liquefying the natural gas, and a closed refrigerant cycle with refrigerant gas for subcooling the liquefied natural gas and for delivering refrigeration power in addition to the other two cycles. The invention also provides a natural gas liquefaction installation for performing such a process.

A system and method for increasing the efficiency of natural gas liquefaction processes by using a hybrid cooling system and method. More specifically, a system and method for converting a transcritical precooling refrigeration process to a subcritical process. In one embodiment, the refrigerant is cooled to sub-critical temperature using an economizer. In another embodiment, the refrigerant is cooled to a sub-critical temperature using an auxiliary heat exchanger. Optionally, the economizer or auxiliary heat exchanger can be bypassed when ambient temperatures are sufficiently low to cool the refrigerant to a sub-critical temperature. In another embodiment, the refrigerant is isentropically expanded.

A system and method for increasing the efficiency of natural gas liquefaction processes by using a hybrid cooling system and method. More specifically, a system and method for converting a transcritical precooling refrigeration process to a subcritical process. In one embodiment, the refrigerant is cooled to sub-critical temperature using an economizer. In another embodiment, the refrigerant is cooled to a sub-critical temperature using an auxiliary heat exchanger. Optionally, the economizer or auxiliary heat exchanger can be bypassed when ambient temperatures are sufficiently low to cool the refrigerant to a sub-critical temperature. In another embodiment, the refrigerant is isentropically expanded.

The present invention relates to a method for liquefying hydrogen, the method comprises the steps of: cooling a feed gas stream comprising hydrogen with a pressure of at least 15 bar(a) to a temperature below the critical temperature of hydrogen in a first cooling step yielding a liquid product stream. According to the invention, the feed gas stream is cooled by a closed first cooling cycle with a high pressure first refrigerant stream comprising hydrogen, wherein the high pressure first refrigerant stream is separated into at least two partial streams, a first partial stream is expanded to low pressure, thereby producing cold to cool the precooled feed gas below the critical pressure of hydrogen, and compressed to a medium pressure, and wherein a second partial stream is expanded at least close to the medium pressure and guided into the medium pressure first partial stream.

The present invention relates to a refrigerant composition. According to the invention it is envisioned that the composition comprises comprising an inert gas selected from nitrogen, argon, neon and a mixture thereof, and a mixture of at least two C.sub.1-C.sub.5 hydrocarbons. The present invention further relates to the use of the refrigerant composition in a method for liquefying a gaseous substance, particularly hydrogen or helium.

The present invention relates to a refrigerant composition comprising neon and hydrogen. The present invention further relates to the use of the refrigerant composition in liquefying gaseous substances such as hydrogen or helium.