Method for liquid air energy storage with semi-closed CO<sub>2 </sub>bottoming cycle
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Solution Overview
Problem
Current Liquid Air Energy Storage (LAES) systems face challenges in increasing discharge power efficiency and reducing NOx and CO2 emissions, with existing methods being energy-intensive and lacking effective CO2 sequestration solutions, which hinders market adoption.
Innovation Solution
Implementing a semi-closed CO2 bottoming cycle that captures and recirculates CO2 emissions from the LAES facility's cryogenic cooling process, using the cold thermal energy to enhance power output and reduce NOx formation by replacing oxygen with recirculated CO2 at the engine inlet, thereby increasing power output and decreasing emissions without additional equipment costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If discharged air is used as combustion air at a co-located gas turbine plant, then power output is augmented, but specific air consumption increases excessively by a factor of 2-3, resulting in increased charging power requirements and larger liquid air tank volume
Solution Approach 1:
The patent changes the parameters of the combustion air by mixing recirculated CO2 with the discharged air from liquid air expansion. This modifies the composition and thermal properties of the combustion air, allowing for reduced air consumption while maintaining power output. The CO2 recirculation alters the specific heat capacity and density of the combustion atmosphere, enabling more efficient fuel combustion with less air intake.
Solution Approach 2:
The patent recovers CO2 that would otherwise be discarded from the liquid air expansion process and recirculates it back to the combustion chamber. This transforms a waste stream into a valuable resource that enhances combustion efficiency and reduces the need for additional air intake, thereby avoiding the need for larger storage tanks and charging power requirements.
2Object-generated harmful factors
If CO2 emissions are captured and liquefied through cryogenic cooling, then CO2 sequestration is achieved, but additional equipment and infrastructure for CO2 marketing or sequestration are required, creating market entry problems
Solution Approach 1:
The patent makes the CO2 capture and recirculation system self-serving by integrating it directly into the existing LAES facility operations. The CO2 is captured during the natural cryogenic cooling process of the liquid air expansion and is immediately recirculated to the combustion chamber, eliminating the need for separate CO2 storage, transport, or sequestration infrastructure. The system serves its own emission reduction needs internally.
Solution Approach 2:
The patent merges the CO2 capture function with the existing cryogenic cooling system of the LAES facility. Instead of adding separate CO2 sequestration equipment, the system combines the CO2 liquefaction that naturally occurs during air cooling with a recirculation mechanism that feeds the CO2 back into the combustion process, creating an integrated emission reduction solution.
3Power
If a supercharged reciprocating engine is used for fueled augmentation, then discharge power is increased by more than 45%, but NOx emissions increase due to higher combustion temperatures and pressures
Solution Approach 1:
The patent introduces recirculated CO2 into the combustion chamber to create a more inert combustion atmosphere. The CO2 acts as a diluent that reduces the concentration of oxygen and lowers the peak combustion temperature, thereby suppressing thermal NOx formation. This allows the supercharged reciprocating engine to operate at high power output while maintaining lower NOx emissions through the modified combustion environment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The semi-closed CO2 bottoming cycle enhances LAES discharge power output by 10% and significantly reduces NOx emissions, achieving a marked decrease in CAPEX and emissions levels, while providing an alternative to CO2 sequestration, thus improving market viability and operational efficiency.
Implementation Method 1
recovering the cold thermal energy of discharged liquid air being regasified for cryogenic cooling the LAES facility exhaust
Implementation Method 2
recovering the cold thermal energy of discharged liquid air being regasified
Implementation Method 3
combustion of fuel in the said LAES facility
Implementation Method 4
replacing oxygen with recirculated CO2 at the engine inlet, thereby increasing power output and decreasing emissions
Implementation Method 5
capturing and liquefying at least a part of CO2 emissions formed by combustion of fuel
Implementation Method 6
cryogenic cooling the LAES facility exhaust with capturing and liquefying at least a part of CO2 emissions
Data Source
AI summary
A proposed method provides a highly efficient fueled power output augmentation of the liquid air energy storage (LAES) through its integration with the semi-closed CO2 bottoming cycle. It combines the production of liquid air in air liquefier during LAES charge using excessive power from the grid and an effective recovery of stored air for production of on-demand power in the fueled supercharged reciprocating internal combustion engine (ICE) and associated expanders of the power block during LAES discharge. A cold thermal energy of liquid air being re-gasified is recovered for cryogenic capturing most of CO2 emissions from the facility exhaust with following use of the captured CO2 in the semi-closed bottoming cycle, resulting in enhancement of total LAES facility discharge power output and suppressing the thermal NOx formation in the ICE.