Systems and methods for liquefying a gaseous hydrogen that include a first refrigeration stage and a second refrigeration stage. The first refrigeration stage includes a first heat exchanger configured to flow a first refrigerant to pre-cool the gaseous hydrogen. The second refrigeration stage includes a second heat exchanger configured to flow a second refrigerant to liquefy and sub-cool the hydrogen. The second refrigerant is split into two streams that flow through two compressor-expanders and multiple passes through the second heat exchanger before being recombined to repeat the second refrigeration stage circuit.

A system and method for power generation and CO.sub.2 sequestration include a fuel cell system configured to generate power using natural gas (NG), a container configured to store liquid natural gas (LNG), and a fluid processor configured to convert LNG received from the container into NG and to convert exhaust output from the fuel cell system to dry ice by transferring heat between and the LNG and the exhaust.

Described herein are systems and processes for precooling hydrogen or helium gas streams for liquefaction using liquid nitrogen having reduced energy consumption and amount of liquid nitrogen usage. The systems include a stream of pressurized liquid nitrogen, at least one turboexpander, and at least one heat exchanger.

A system for an aircraft includes an engine bleed source of a gas turbine engine. The system also includes a means for chilling an engine bleed air flow from the engine bleed source to produce a chilled working fluid. The system further includes a means for providing the chilled working fluid for an aircraft use.

A process that includes pre-cooling a H.sub.2 gas feedstock with a compressed liquid natural gas via a heat exchanger, introducing the pre-cooled H.sub.2 gas feedstock into an active magnetic regenerative refrigerator H.sub.2 liquefier module, and delivering liquid H.sub.2 from the active magnetic regenerative refrigerator H.sub.2 liquefier module to a liquid H.sub.2 vehicle dispenser.

A propulsion system includes an electric fan propulsion motor with a plurality of propulsion motor windings. The propulsion system also includes a means for controlling a flow rate of a working fluid through a cryogenic working fluid flow control assembly to the propulsion motor windings. The propulsion system further includes a controller operable to control supplying a pre-cooling flow of the working fluid from a cryogenic liquid reservoir through the cryogenic working fluid flow control assembly to the propulsion motor windings.

A system for an aircraft includes an engine bleed source of a gas turbine engine. The system also includes a means for chilling an engine bleed air flow from the engine bleed source to produce a chilled working fluid. The system further includes a means for providing the chilled working fluid for an aircraft use.

A method for converting excess liquid oxygen into liquid nitrogen, including introducing a gaseous nitrogen stream into a main heat exchanger, therein exchanging heat with a vaporized oxygen stream, a vapor phase nitrogen steam, and a waste liquid nitrogen stream; thereby producing a cold gaseous nitrogen stream, an oxygen vent stream, a nitrogen vent steam, and a gaseous nitrogen waste stream, introducing the cold gaseous nitrogen stream into a secondary heat exchanger, therein exchanging heat with a liquid oxygen stream; thereby producing the vaporized oxygen stream and a cold liquid nitrogen stream, introducing the cold liquid nitrogen stream into a nitrogen pressure reduction valve thereby producing a two-phase nitrogen stream, introducing the two-phase nitrogen stream into a nitrogen flash vessel thereby producing a liquid phase nitrogen stream and the vapor phase nitrogen stream, wherein the method is performed in the absence of refrigerant turbo-expanders, refrigerant expansion turbines, or refrigerant compressors.

An apparatus for converting excess liquid oxygen into liquid nitrogen, including a main heat exchanger to exchange heat between a gaseous nitrogen stream, a vaporized oxygen stream, a vapor phase nitrogen steam, and a waste liquid nitrogen stream; thereby producing a cold gaseous nitrogen stream, an oxygen vent stream, a nitrogen vent steam, and a gaseous nitrogen waste stream, a secondary heat exchanger to exchange heat between a liquid oxygen stream and the cold gaseous nitrogen stream; thereby producing the vaporized oxygen stream and a cold liquid nitrogen stream, a nitrogen pressure reduction valve to reduce the pressure of the cold liquid nitrogen stream; thereby producing a two-phase nitrogen stream, a nitrogen flash vessel to receive the two-phase nitrogen stream, and to generate a liquid phase nitrogen stream and a vapor phase nitrogen stream, wherein the apparatus does not include any refrigerant turbo-expanders, refrigerant expansion turbines, or refrigerant compressors.

A method for operating the liquid air energy storage (LAES) includes production of the storable liquid air through consumption of a low-demand power and recovery the liquid air for co-production of an on-demand power and a high-grade saleable cold thermal energy which may be used, say, for liquefaction of the delivered natural gas; in so doing zero carbon footprint is provided both for fueled augmentation of the LAES power output and for LNG co-production at the LAES facility.