Power recovery sub-systems, cryogenic energy storage systems, and methods of capturing, storing, and re-using thermal energy are disclosed.

A method for liquid air and gas energy storage (LAGES) which integrates the processes of liquid air energy storage (LAES) and regasification of liquefied natural gas (LNG) at the import terminal through the exchange of thermal energy between the streams of air and natural gas (NG) in their gaseous and liquid states and includes harnessing the LNG as an intermediate heat carrier between the air streams being regasified and liquefied, recovering a compression heat from air liquefier for LNG regasification and utilizing a cold thermal energy of liquid air being regasified for reliquefaction of a part of send-out NG stream with its return to LNG terminal.

The invention relates to a facility for producing liquid helium from a source gas mixture substantially comprising nitrogen and helium. The facility includes a cryogenic purifier including a system for separating the nitrogen from the source gas mixture with a view to producing helium at a temperature lower than the temperature of the source gas. The facility also includes a helium liquefier that subjects the helium to a work cycle including, in series: compressing the helium, cooling and decompressing the compressed helium, and reheating the cooled, decompressed helium. The facility includes a helium transfer pipe connecting an outlet of the purifier to an inlet of the liquefier in order to transfer helium produced by the purifier into the work cycle of the liquefier. The facility is characterized in that the cryogenic purifier includes a decompression system that includes an inlet to be connected to a source of pressurized nitrogen gas. Said system for decompressing the nitrogen gas exchanges heat with the separation system in order to transfer cold from the decompressed nitrogen gas to said separation system.

A method for loading liquefied nitrogen (LIN) into a cryogenic storage tank initially containing liquid natural gas (LNG) and a vapor space above the LNG. First and second nitrogen gas streams are provided. The first nitrogen stream has a lower temperature than the second nitrogen gas stream. While the LNG is offloaded from the storage tank, the first nitrogen gas stream is injected into the vapor space. The storage tank is then purged by injecting the second nitrogen gas stream into the storage tank to thereby reduce a natural gas content of the vapor space to less than 5 mol %. After purging the storage tank, the storage tank is loaded with LIN.

A method for liquid air and gas energy storage (LAGES) which integrates the processes of liquid air energy storage (LAES) and regasification of liquefied natural gas (LNG) at the Floating Storage, Regasification and Power (FSRP) facilities through the exchange of thermal energy between the streams of air and natural gas (NG) in their gaseous and liquid states and includes recovering a compression heat from air liquefier and low-grade waste heat of power train for LNG regasification with use of an intermediate heat carrier between the air and LNG streams and utilizing a cold thermal energy of liquid air being regasified for increase in LAGES operation efficiency through using a semi-closed CO.sub.2 bottoming cycle.

A reliquefaction system and process for innovative reliquefaction of LNG boil-off gas (BOG), where the reliquefaction is propelled by LNG gas fuel. The reliquefaction system is preferably installed on shipboard including LNG carrier or harbor tug, where the LNG carrier and harbor tug use a gas fuel engine.

A method for loading liquefied nitrogen (LIN) into a cryogenic storage tank initially containing liquid natural gas (LNG) and a vapor space above the LNG. First and second nitrogen gas streams are provided. The first nitrogen stream has a lower temperature than the second nitrogen gas stream. While the LNG is offloaded from the storage tank, the first nitrogen gas stream is injected into the vapor space. The storage tank is then purged by injecting the second nitrogen gas stream into the storage tank to thereby reduce a natural gas content of the vapor space to less than 5 mol %. After purging the storage tank, the storage tank is loaded with LIN.

A method for energy storage which integrates charging a liquid in an energy storage facility through consumption of a power from the grid with reduction pressure of natural gas through expander at the co-located city gate station and includes recovery of mechanical power of the natural gas expander and cold thermal energy of the expanded natural gas for an increase in production of liquid air per each kW of low-demand power consumed from the grid during off-peak hours.

A method of liquefying hydrogen, including dividing a hydrogen stream into at least a first fraction and a second fraction, introducing the first fraction into a refrigeration cycle of a hydrogen liquefaction unit, thereby liquefying a product hydrogen stream, withdrawing one or more warm hydrogen stream(s) from the hydrogen liquefaction unit, and returning the one or more warm hydrogen stream to the hydrogen stream, wherein the second fraction is combined with a high-pressure nitrogen stream to form an ammonia synthesis gas stream.

A method for separating air by cryogenic distillation in a system of columns comprising a first column and a second column operating at a lower pressure than the first column, comprising the steps of compressing all of the feed air in a first compressor to a first output pressure of at least 1 bar greater than the pressure of the first column, sending a first portion of the air under the first output pressure to the second compressor, and compressing the air to a second output pressure, cooling and condensing at least a portion of the air under the second output pressure in a heat exchanger, withdrawal of a liquid from a column of the system of columns, pressurising the liquid and evaporating the liquid by heat exchange in the heat exchanger, and pressure reduction of a portion of the compressed air to a second output pressure, at least partially evaporating said air in the heat exchanger, optionally additional heating of said air in the heat exchanger, and sending at least a portion of this air to the second compressor.