The present disclosure relates to systems and methods that provide a low pressure liquid CO.sub.2 stream. In particular, the present disclosure provides systems and methods wherein a high pressure CO.sub.2 stream, such as a recycle CO.sub.2 stream from a power production process using predominately CO.sub.2 as a working fluid, can be divided such that a portion thereof can be expanded and used as a cooling stream in a heat exchanger to cool the remaining portion of the high pressure CO.sub.2 stream, which can then be expanded to form a low pressure CO.sub.2 stream, which may be in a mixed form with CO.sub.2 vapor. The systems and methods can be utilized to provide net CO.sub.2 from combustion in a liquid form that is easily transportable.

A method including entraining carbon dioxide (CO.sub.2) in a cement slurry composition and subjecting the cement slurry composition to conditions under which the CO.sub.2 achieves and maintains a supercritical state; and allowing the cement slurry composition to harden to form a hardened cement having CO.sub.2 sequestered therein.

An integrated system for generating power and vaporizing liquefied natural gas with reduced CO.sub.2 emissions into the atmosphere is provided.

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 device includes a heat exchanger connected to an air line through which air flows and to a hydrogen line through which liquid-state hydrogen flows. The heat exchanger is configured to produce liquid-state air as the air and the liquid-state hydrogen exchange heat with each other. The device also includes a carbon dioxide separator connected to the heat exchanger via the air line and the hydrogen line. The carbon dioxide separator is configured to separate at least a portion of carbon dioxide from the air. The device also includes an air storage container connected to the heat exchanger via the air line. The air storage container is configured to store the liquid-state air discharged from the heat exchanger. The carbon dioxide separator is configured such that the air and the hydrogen exchange heat with each other inside the carbon dioxide separator.

A system for storing or producing electricity, which allows stabilization of a power network under conditions of excess availability of electricity or lack thereof and for producing liquefied natural gas is provided.

Liquefaction of industrial gases or gas mixtures (hydrocarbon and/or non-hydrocarbon) uses a modified aqua-ammonia absorption refrigeration system (ARP) to chill the gas or gas mixture during the liquefaction process. The gas is compressed to above its critical point, and the heat of compression energy may be recovered to provide some or all of the thermal energy required to drive the ARP. A Joule Thomson (JT) adiabatic expansion process results in no requirement for specialty cryogenic rotating equipment. The aqua-ammonia absorption refrigeration system includes a vapour absorber tower (VAT) that permits the recovery of some or all of the heat of solution and heat of condensation energy in the system when anhydrous ammonia vapour is absorbed into a subcooled lean aqua-ammonia solution. The modified ARP with VAT may operate at pressures as low as 10 kPa, and the ammonia gas chiller may operate at temperatures as low as 71 C.

An autonomous airborne carbon dioxide capturing assembly for carbon dioxide sequestration includes a plurality of airships each including a propulsion and navigation system, a sensor, and a carbon dioxide (CO.sub.2) capture and liquefaction module. The sensor measures CO.sub.2 concentrations. A computer is operationally engaged to the propulsion and navigation system, the sensor, the CO.sub.2 capture and liquefaction module, a positioning transceiver, and a communications transceiver. The computer automates decision-making and selectively actuates the propulsion and navigation system for controlled flight to a target area, to selectively actuate the CO.sub.2 capture and liquefaction module to capture and to liquefy CO.sub.2 from air at the target area, and to selectively actuate the propulsion and navigation system for controlled flight to a CO.sub.2 storage facility for offloading of the CO.sub.2.

The present invention is directed to a method, device and system to efficiently liquefy and isolate a gas from a gaseous mixture. In an embodiment of the present invention, separation of gasses from the atmosphere can be carried out using a cooled surface to separate the gasses from the atmosphere. In an alternative embodiment of the present invention, removal of CO.sub.2 from the atmosphere can be carried out by using the method, device and system to efficiently cryogenically separate CO.sub.2 from air and capture the CO.sub.2 from a gaseous mixture using a surface and release the CO.sub.2 lean air into the atmosphere and store the captured liquefied CO.sub.2.

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.