Method for energy storage with co-production of peaking power and liquefied natural gas
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Solution Overview
Problem
Current energy storage technologies, such as Liquid Air Energy Storage (LAES), face high energy consumption during the liquefaction process, and there is a lack of effective methods to convert waste energy from natural gas pressure reducing stations into liquid air for storage during off-peak hours.
Innovation Solution
The proposed method integrates LAES with city gate stations by using the kinetic energy of high-pressure natural gas and the cold thermal energy of the expanded low-pressure gas to reduce the power consumption during the liquefaction process, where the natural gas is depressurized to produce power and cool the air being compressed, thereby reducing the energy demand from the grid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If liquid air is produced using electrically-driven atmospheric and recirculating air compressors during off-peak hours, then energy storage is achieved, but a great deal of power is consumed from the grid
Solution Approach 1:
The patent combines the natural gas pressure reduction process with the air liquefaction process by integrating a turbo-expander from the gas station into the LAES system. The turbo-expander performs dual functions: driving the recirculating air compressor and pre-cooling the compressed air through heat exchange, thereby merging two separate processes into one synergistic system
Solution Approach 2:
The patent converts the waste high-pressure natural gas stream, which would normally be simply throttled through valves, into a useful energy source. The turbo-expander captures the kinetic energy and enthalpy drop of the high-pressure gas, transforming it into mechanical work to drive the compressor and cool the air, turning a waste stream into a beneficial resource
2Use of energy by moving object
If booster compressors are installed downstream of electrically-driven compressors, then power consumption is reduced, but the reduction does not provide a desirable cardinal increase in LAES round-trip efficiency
Solution Approach 1:
The system makes the compressor train self-sufficient by using the turbo-expander to drive the recirculating air compressor. The high-pressure natural gas stream serves the system's own compression needs without requiring external electrical power for this function, enabling the system to service itself
Solution Approach 2:
The turbo-expander serves multiple functions simultaneously: it acts as a prime mover for the recirculating air compressor, pre-cools the compressed air through heat exchange, and utilizes the pressure differential of the natural gas stream. This multi-functionality reduces the need for separate dedicated components
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
This integration significantly decreases the power consumption from the grid during charging, enhancing the round-trip efficiency of the LAES system and providing a more efficient method for energy storage by utilizing waste energy from natural gas stations.
Implementation Method 1
The proposed method integrates LAES with city gate stations by using the kinetic energy of high-pressure natural gas and the cold thermal energy of the expanded low-pressure gas
Implementation Method 2
using a cold thermal energy of the expanded low-pressure gas stream for cooling an air being compressed during said production of the liquid air
Implementation Method 3
reducing a pressure of a delivered natural gas at a co-located city gate station from a high pressure at the station inlet down to a low pressure at the station outlet with resulting production of a cooled low-pressure natural gas stream
Data Source
AI summary
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.