Systems and Methods for Improving Drivetrain Efficiency for Compressed Gas Energy Storage and Recovery Systems

Abstract

The invention relates to power generation and energy storage and recovery. In particular, the invention relates to compressed gas energy storage and recovery systems using staged pneumatic conversion systems for providing narrow pressure ranges to a hydraulic motor.

1 . A compressed gas-based energy storage and recovery system utilizing substantially isothermal expansion and compression of a gas, the system comprising:
 at least one cylinder assembly including a first chamber and a second chamber separated by a movable mechanical boundary mechanism that transfers energy therebetween;   a hydraulic motor; and   a staging subsystem coupling the hydraulic motor to the at least one cylinder assembly, wherein the staging subsystem is configured to convert a pneumatic pressure range within the at least one cylinder assembly into a smaller hydraulic pressure range at the hydraulic motor.   
     
     
         2 . The system of  claim 1 , wherein the first chamber is a pneumatic chamber and the second chamber is a hydraulic chamber. 
     
     
         3 . The system of  claim 2 , wherein the staging subsystem comprises a double-acting hydraulic-hydraulic intensifier in fluid communication with the second chamber of the at least one cylinder assembly and the hydraulic motor. 
     
     
         4 . The system of  claim 1 , wherein the staging subsystem comprises:
 a plurality of pneumatic-hydraulic intensifiers, each having a first chamber and a second chamber separated by a movable mechanical boundary mechanism that transfers energy therebetween; and   at least one valve arrangement configured to provide fluid communication between the hydraulic motor and each second chamber of the plurality of pneumatic-hydraulic intensifiers.   
     
     
         5 . The system of  claim 4 , wherein the movable mechanical boundary mechanisms of each pneumatic-hydraulic intensifier transfer energy at different pressure ratios. 
     
     
         6 . The system of  claim 1 , wherein the staging subsystem comprises:
 a second hydraulic motor in fluid communication with the at least one cylinder assembly and the hydraulic motor; and   a valve arrangement for selectively connecting the second chamber of the at least one cylinder assembly to at least one of the hydraulic motors.   
     
     
         7 . The system of  claim 6 , wherein the second hydraulic motor has a first port configured for communication with a first port of the hydraulic motor and a second port configured for communication with at least one of the first port of the hydraulic motor and a second port of the hydraulic motor and the valve arrangement is configured for selectively connecting the two hydraulic motors in series or parallel relative to the second chamber of the at least one cylinder assembly. 
     
     
         8 . The system of  claim 6 , wherein the second hydraulic motor is a low-pressure turbine and the valve arrangement is configured to direct hydraulic fluid from the second chamber of the at least one cylinder assembly to the turbine during a low-pressure operation and to the hydraulic motor during a high pressure operation. 
     
     
         9 . The system of  claim 1 , wherein the at least one cylinder assembly is a pneumatic cylinder assembly and the staging subsystem comprises:
 at least one hydraulic cylinder assembly having a first chamber and a second chamber separated by a movable mechanical boundary mechanism that transfers energy therebetween;   a mechanical linkage coupling the movable mechanical boundary mechanism of the pneumatic cylinder assembly with the movable mechanical boundary mechanism of the hydraulic cylinder assembly; and   a valve arrangement configured to fluidly couple at least one of the first chamber and the second chamber of the hydraulic cylinder assembly to the hydraulic motor.   
     
     
         10 . The system of  claim 9  further comprising:
 a second hydraulic cylinder assembly having a first chamber and a second chamber separated by a movable mechanical boundary mechanism that transfers energy therebetween, the second hydraulic cylinder assembly mechanically coupled to at least one the pneumatic cylinder assembly and the hydraulic cylinder assembly via the mechanical linkage;   a second valve arrangement configured to fluidly couple the first chamber of the second hydraulic cylinder assembly with the first chamber of the hydraulic cylinder assembly;   a third valve arrangement configured to fluidly couple the second chamber of the second hydraulic cylinder assembly to the second chamber of the hydraulic cylinder assembly; and   a fourth valve arrangement configured to fluidly couple the first and second chambers of the second hydraulic cylinder assembly.   
     
     
         11 . The system of  claim 10  further comprising a control system for operating the valve arrangements and cylinder assemblies in a staged manner to provide a predetermined pressure profile to the hydraulic motor. 
     
     
         12 . The system of  claim 9 , wherein the at least one cylinder assembly comprises a plurality of pneumatic cylinder assemblies, each having a first chamber and a second chamber separated by a movable mechanical boundary mechanism that transfers energy therebetween, wherein the pneumatic cylinder assemblies are fluidly coupled in series. 
     
     
         13 . The system of  claim 10 , wherein the hydraulic cylinder assemblies are different sizes. 
     
     
         14 . The system of  claim 1 , wherein the hydraulic motor is a variable displacement hydraulic motor. 
     
     
         15 . The system of  claim 1  further comprising a compressed gas storage system, wherein the at least one cylinder assembly is in fluid communication with the compressed gas storage system. 
     
     
         16 . A method of providing a narrow pressure range to a hydraulic motor in a compressed gas-based energy storage and recovery system utilizing substantially isothermal expansion and compression of a gas, the method comprising the steps of:
 providing a compressed gas storage system;   providing at least one cylinder assembly including a first chamber and a second chamber separated by a movable mechanical boundary mechanism that transfers energy therebetween;   fluidly coupling the at least one cylinder assembly to the compressed gas storage system;   providing a hydraulic motor;   providing a staging subsystem to couple the hydraulic motor to the at least one cylinder assembly; and   converting a pneumatic pressure range within the at least one cylinder assembly into a smaller hydraulic pressure range at the hydraulic motor.   
     
     
         17 . The method of  claim 16 , wherein the step of providing a staging subsystem comprises the steps of:
 providing a double-acting hydraulic-hydraulic intensifier;   fluidly coupling the first chamber of the at least one cylinder assembly to the compressed gas storage system;   fluidly coupling the second chamber of the at least one cylinder assembly to the double-acting hydraulic-hydraulic intensifier; and   fluidly coupling the double-acting hydraulic-hydraulic intensifier to the hydraulic motor.   
     
     
         18 . The method of  claim 17 , wherein the step of converting the pneumatic pressure range to a smaller hydraulic pressure range comprises the steps of:
 expanding gas from the compressed gas storage system in the first chamber of the at least one cylinder assembly;   driving hydraulic fluid from the second chamber of the at least one cylinder assembly to push a piston in the double-acting hydraulic-hydraulic intensifier; and   driving the hydraulic motor with fluid from one hydraulic side of the double-acting hydraulic-hydraulic intensifier.   
     
     
         19 . The method of  claim 16 , wherein the step of providing a staging subsystem comprises the steps of:
 providing a plurality of pneumatic-hydraulic intensifiers, each having a first chamber and a second chamber separated by a movable mechanical boundary mechanism that transfers energy therebetween;   coupling each first chamber of the plurality of pneumatic-hydraulic intensifiers to at least one of the at least one cylinder assembly and the compressed gas storage system; and   coupling each second chamber of the plurality of pneumatic-hydraulic intensifiers to the hydraulic motor via at least one valve arrangement.   
     
     
         20 . The method of  claim 19 , wherein the step of converting the pneumatic pressure range to a smaller hydraulic pressure range comprises the steps of:
 configuring each of the movable mechanical boundary mechanisms of the plurality of pneumatic-hydraulic intensifiers to transfer energy at different pressure ratios; and   operating the at least one valve arrangement to selectively couple each second chamber of the plurality of pneumatic-hydraulic intensifiers to the hydraulic motor.   
     
     
         21 . The method of  claim 16 , wherein the step of providing a staging subsystem comprises the steps of:
 providing a second hydraulic motor in fluid communication with the at least one cylinder assembly and the hydraulic motor; and   providing at least one valve arrangement for selectively connecting the second chamber of the at least one cylinder assembly to at least one of the hydraulic motors.   
     
     
         22 . The method of  claim 21 , wherein the step of converting the pneumatic pressure range to a smaller hydraulic pressure range comprises the steps of:
 coupling a first port of the second hydraulic motor to a first port of the hydraulic motor;   coupling a second port of the second hydraulic motor to the first port of the hydraulic motor and a second port of the hydraulic motor via the at least one valve arrangement; and   operating the at least one valve arrangement to selectively connect the two hydraulic motors in series or parallel relative to the second chamber of the at least one cylinder assembly.   
     
     
         23 . The method of  claim 21 , wherein the second hydraulic motor is a low-pressure turbine and the step of converting the pneumatic pressure range to a smaller hydraulic pressure range comprises the step of directing hydraulic fluid from the second chamber of the at least one cylinder assembly to the turbine during a low-pressure operation and to the hydraulic motor during a high pressure operation. 
     
     
         24 . The method of  claim 16 , wherein the at least one cylinder assembly is a pneumatic cylinder assembly and the step of providing a staging subsystem comprises the steps of:
 providing a hydraulic cylinder assembly having a first chamber and a second chamber separated by a movable mechanical boundary mechanism that transfers energy therebetween;   mechanically coupling the movable mechanical boundary mechanism of the pneumatic cylinder assembly with the movable mechanical boundary mechanism of the hydraulic cylinder assembly via a linkage; and   fluidly coupling at least one of the first chamber and the second chamber of the hydraulic cylinder assembly to the hydraulic motor via at least one valve arrangement.   
     
     
         25 . The method of  claim 24 , wherein the step of providing a staging subsystem further comprises the steps of:
 providing a second hydraulic cylinder assembly having a first chamber and a second chamber separated by a movable mechanical boundary mechanism that transfers energy therebetween;   mechanically coupling the second hydraulic cylinder to at least one of the pneumatic cylinder assembly and the hydraulic cylinder assembly via the linkage;   fluidly coupling the first chamber of the second hydraulic cylinder assembly with the first chamber of the hydraulic cylinder assembly via a second valve arrangement;   fluidly coupling the second chamber of the second hydraulic cylinder assembly to the second chamber of the hydraulic cylinder assembly via a third valve arrangement; and   fluidly coupling the first and second chambers of the second hydraulic cylinder assembly via a fourth valve arrangement.   
     
     
         26 . The method of  claim 25 , wherein the step of converting the pneumatic pressure range to a smaller hydraulic pressure range comprises the step of operating the valve arrangements and cylinder assemblies in a staged manner to provide a predetermined pressure profile to the hydraulic motor.