Systems and methods for integrated energy storage and cryogenic carbon capture
The systems and methods integrate energy storage with cryogenic carbon capture, providing effective grid management and energy-efficient carbon capture capabilities to power plants. The systems store energy during off-peak demand by using off-peak energy to compress natural gas to form liquefied natural gas (LNG) and storing the LNG for use as a refrigerant. The systems use the stored LNG as a refrigerant in a cryogenic carbon capture (CCC) process to isolate carbon dioxide from light gases in a flue gas. The systems supply energy during peak demand by burning the natural gas warmed by the CCC process to generate power.
1. A method for storing electrical or mechanical energy and separating condensable vapors from light gases or liquids, comprising:
(i) liquefying at least one gaseous refrigerant using electricity or mechanical energy during off-peak demand;
(ii) storing the liquefied refrigerant in a liquefied refrigerant storage vessel for later use as a refrigerant;
(iii) generating electricity by burning fuel in a fuel-based boiler, the fuel-based boiler outputting a mixed process stream;
(iv) using the liquefied refrigerant as the refrigerant in a traditional heat exchanger (THE) or desublimating heat exchanger (DHE) during peak demand of energy to cool the mixed process stream, the mixed process stream comprising at least one condensable vapor and at least one light gas, thereby causing the condensable vapor to condense or desublimate to form a liquid or solid stream;
(v) separating the liquid or solid stream from the light gas; and
(vi) burning the refrigerant as a spent refrigerant to generate additional electricity during the peak demand.
2. The method as in claim 1 , wherein the gaseous refrigerant comprises natural gas (NG), and the liquefied refrigerant comprises liquefied natural gas (LNG).
3. The method as in claim 2 , further comprising, after liquefying the NG, pressurizing the LNG so that the LNG's boiling point is in the range of 0-20° C. below the lowest design desublimation temperature of the condensable vapor.
4. The method as in claim 2 , further comprising, after liquefying the natural gas, pressurizing the LNG to 2-6 bars.
5. The method as in claim 1 , wherein the at least one condensable vapor comprises CO 2 , and the at least one light gas, or the liquid or solid stream comprises N 2 .
6. The method as in claim 1 , wherein the spent refrigerant is combusted in a gas turbine to generate the additional electricity during the peak demand.
7. The method as in claim 6 , wherein the effluent of the gas turbine passes into the fuel-based boiler.
8. The method as in claim 6 , wherein a portion of a turbine inlet stream comprises CO 2 -laden boiler flue gas output from the fuel-based boiler, thereby increasing CO 2 content of a turbine outlet stream of the gas turbine as compared to the CO 2 content of the turbine outlet stream when air alone is used as the turbine inlet stream for the gas turbine.
9. The method as in claim 1 , wherein the step of cooling the mixed process stream by transferring heat to the liquefied refrigerant occurs during both peak and off-peak demands.
10. The method as in claim 9 , wherein the gaseous refrigerant comprises natural gas (NG), and the liquefied refrigerant comprises liquefied natural gas (LNG), and
the method further comprises recycling spent but not combusted refrigerant by liquefying and returning a portion of the NG that is spent but not combusted natural gas to the LNG storage vessel during off-peak demand.
11. The method as in claim 1 , wherein the step of cooling the mixed process stream by transferring heat to the liquefied refrigerant occurs during peak demand, and the method further comprising cooling the mixed process stream using a refrigerant other than liquid natural gas (LNG) during off-peak demand.
12. The method as in claim 1 , further comprising, before liquefying the refrigerant, cooling the refrigerant in a recuperative heat exchanger (RHE).
13. The method as in claim 1 , further comprising, before liquefying the refrigerant, cooling the refrigerant in a recuperative heat exchanger (RHE) by transferring heat from the refrigerant to the separated light gas.
14. The method as in claim 1 , further comprising, prior to cooling the mixed process stream in the DHE, cooling the mixed process stream in a self-recuperative heat exchanger (SRHE) by warming the separated condensable vapor.
15. The method as in claim 1 , further comprising, prior to cooling the mixed process stream in the DHE, cooling the mixed process stream in a self-recuperative heat exchanger (SRHE) by warming the separated light gas.
16. A system for storing energy and separating condensable vapors from light gases or liquids, comprising:
(i) a gaseous refrigerant liquefaction apparatus configured to use electricity or shaft work during off-peak demand to produce liquefied natural gas (LNG);
(ii) a liquefied refrigerant storage vessel configured to store the LNG for later use as a refrigerant;
(iii) at least one traditional heat exchanger (THE) or desublimating heat exchanger (DHE) comprising: (a) an inlet for a mixed process stream, the mixed process stream being output from a fuel-based boiler configured to generate electricity, the mixed process stream comprising at least one condensable vapor and at least one light gas or liquid, (b) the refrigerant comprising the liquefied refrigerant from the liquefied refrigerant storage vessel, supplied during peak demand, and (c) a heat exchange area configured to allow heat to transfer from the mixed process stream to the refrigerant, thereby causing the condensable vapor in the mixed process stream to desublimate;
(iv) a solid separator configured to separate the desublimated condensable vapor as a solid stream from the light gas or liquid; and
(v) a natural gas (NG) power generator configured to burn at least a portion of the refrigerant downstream from the THE or DHE as spent refrigerant to generate additional electricity during the peak demand.
17. A system as in claim 16 , wherein the natural gas power generator includes a gas turbine.
18. A system as in claim 16 , wherein the system comprises at least two DHEs.