Systems and methods for reducing dead volume in compressed-gas energy storage systems

• US 8,479,505 B2
• Filed: 04/06/2011
• Issued: 07/09/2013
• Est. Priority Date: 04/09/2008
• Status: Expired due to Fees

• Current Assignee: SustainX, Inc. (General Compression, Inc.)
• Original Assignee: SustainX, Inc. (General Compression, Inc.)
• Inventors: McBride, Troy O., Scott, Michael Neil, Bollinger, Benjamin, Shang, Andrew, Cook, Robert, Doyle, Lee
• Primary Examiner(s): Bomberg, Kenneth
• Assistant Examiner(s): JETTON, CHRISTOPHER M
• Application Number:
  US13/080,910
• Publication Number:
  US 20120000557A1
• Time in Patent Office: 825 Days
• Field of Search: 60325-594, 606/59, 911/60, 911/66, 912/74, 912/85, 417434-571, 137/253
• US Class Current: 60/508
• CPC Class Codes: F15B 1/024 used as a supplementary power source, e.g. to store energy in idle periods to balance pump load
• CPC Class Codes: F15B 11/032 by means of fluid-pressure converters
• CPC Class Codes: F15B 15/00 Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
• CPC Class Codes: F15B 21/08 Servomotor systems incorporating electrically operated control means F15B21/02, F15B21/065 take precedence
• CPC Class Codes: F15B 2211/20569 capable of working as pump and motor
• CPC Class Codes: F15B 2211/212 the pressure sources being accumulators
• CPC Class Codes: F15B 2211/214 the pressure sources being hydrotransformers
• CPC Class Codes: F15B 2211/216 the pressure sources being pneumatic-to-hydraulic converters
• CPC Class Codes: F15B 2211/30505 Non-return valves, i.e. check valves
• CPC Class Codes: F15B 2211/3057 having two valves, one for each port of a double-acting output member
• CPC Class Codes: F15B 2211/30575 in a Wheatstone Bridge arrangement (also half bridges)
• CPC Class Codes: F15B 2211/3058 having additional valves for interconnecting the fluid chambers of a double-acting actuator, e.g. for regeneration mode or for floating mode
• CPC Class Codes: F15B 2211/3111 the pump port being closed in the centre position, e.g. so-called closed centre
• CPC Class Codes: F15B 2211/31594 having multiple pressure sources and multiple output members
• CPC Class Codes: F15B 2211/327 electrically or electronically
• CPC Class Codes: F15B 2211/40515 with variable throttles or orifices
• CPC Class Codes: F15B 2211/41509 being connected to a pressure source and a directional control valve
• CPC Class Codes: F15B 2211/41554 being connected to a return line and a directional control valve
• CPC Class Codes: F15B 2211/426 electrically or electronically
• CPC Class Codes: F15B 2211/45 Control of bleed-off flow, e.g. control of bypass flow to the return line
• CPC Class Codes: F15B 2211/50581 : using counterbalance valves
• CPC Class Codes: F15B 2211/5153 : being connected to an output member and a directional control valve
• CPC Class Codes: F15B 2211/62 : Cooling or heating means
• CPC Class Codes: F15B 2211/6309 : the pressure being a pressure source supply pressure
• CPC Class Codes: F15B 2211/7058 : Rotary output members
• CPC Class Codes: H02J 15/006 : in the form of pneumatic energy, e.g. compressed air energy storage [CAES] accumulators for supplying fluid under pressure F15B1/04
• CPC Class Codes: Y10T 137/86051 : Compressed air supply unit

Abstract

In various embodiments, dead space and associated coupling losses are reduced in energy storage and recovery systems employing compressed air.

Claims

1. An energy storage and recovery system comprising:

a cylinder assembly for compressing gas to store energy and expanding gas to recover energy, the cylinder assembly comprising (i) first and second chambers and (ii) a movable mechanical boundary mechanism separating the first and second chambers, at least one of the chambers being a pneumatic chamber, whereby the cylinder assembly includes dead space when the boundary mechanism is disposed at a limit of travel within the cylinder assembly;

a first mechanism for removably introducing a substantially incompressible fluid into a pneumatic chamber to substantially fill the dead space prior to or during gas compression or expansion;

a second mechanism for (i) introducing a gas into the pneumatic chamber and (ii) removing the gas and at least a portion of the substantially incompressible fluid from the pneumatic chamber;

a second cylinder assembly comprising (i) first and second chambers and (ii) a movable mechanical boundary mechanism separating the first and second chambers, at least one of the chambers being a pneumatic chamber;

a conduit for fluidly connecting the pneumatic chamber of the cylinder assembly with a pneumatic chamber of the second cylinder assembly, at least a portion of the conduit constituting dead space during compression or expansion of gas in the cylinder assembly and the second cylinder assembly; and

a third mechanism for introducing substantially incompressible fluid into the conduit to substantially fill the dead space therein.

2. The system of claim 1, further comprising, (i) selectively fluidly connected to the pneumatic chamber of the cylinder assembly, a compressed-gas reservoir for storage of gas after compression and supply of compressed gas for expansion thereof, and (ii) selectively fluidly connected to the pneumatic chamber of the second cylinder assembly, a vent for exhausting expanded gas to atmosphere and supply of gas for compression thereof.

3. The system of claim 1, further comprising, connected to the cylinder assembly, an intermittent renewable energy source of wind or solar energy, wherein (i) energy stored during compression of the gas originates from the intermittent renewable energy source, and (ii) energy is recovered via expansion of the gas when the intermittent renewable energy source is nonfunctional.

4. The system of claim 1, further comprising a heat-transfer subsystem in fluid communication with the pneumatic chamber of the cylinder assembly for enabling substantially isothermal expansion and compression of gas, thereby increasing efficiency of the energy recovery and storage.

5. The system of claim 4, wherein the heat-transfer subsystem comprises a circulation apparatus for circulating a heat-transfer fluid through the pneumatic chamber of the cylinder assembly.

6. The system of claim 5, wherein the heat-transfer subsystem comprises a mechanism disposed within the pneumatic chamber of the cylinder assembly for introducing the heat-transfer fluid.

7. The system of claim 6, wherein the mechanism for introducing the heat-transfer fluid comprises at least one of a spray head or a spray rod.

8. The system of claim 4, wherein the heat-transfer subsystem comprises a heat exchanger and a circulation apparatus for circulating gas from the pneumatic chamber of the cylinder assembly through the heat exchanger and back to the pneumatic chamber of the cylinder assembly.

9. The system of claim 1, wherein the first mechanism comprises:

a check valve for allowing flow of the substantially incompressible fluid in only one direction; and

a flow control valve for metering a rate of introduction of the substantially incompressible fluid.

10. The system of claim 9, further comprising (i) a sensor for measuring at least one of a flow rate or a pressure of the substantially incompressible fluid, and (ii) a controller for controlling the flow control valve based on data from the sensor.

11. The system of claim 1, wherein the second mechanism comprises:

a first shut-off valve for controlling the introduction of the gas into the pneumatic chamber of the cylinder assembly; and

a second shut-off valve for controlling the removal of the substantially incompressible fluid and the gas from the pneumatic chamber of the cylinder assembly.

12. The system of claim 1, wherein the first chamber of the cylinder assembly is the pneumatic chamber of the cylinder assembly, and the second chamber of the cylinder assembly is a hydraulic chamber.

13. The system of claim 1, wherein both the first and second chambers of the cylinder assembly are pneumatic chambers.

14. The system of claim 1, further comprising a crankshaft (i) mechanically coupled to the boundary mechanism of the cylinder assembly, and (ii) for converting reciprocal motion of the boundary mechanism of the cylinder assembly into rotary motion.

15. The system of claim 14, further comprising a motor/generator coupled to the crankshaft.

16. The system of claim 1, wherein the second mechanism is configured to direct gas from the pneumatic chamber of the cylinder assembly to the pneumatic chamber of the second cylinder assembly.

17. The system of claim 1, wherein the first mechanism and the third mechanism are the same mechanism.

18. The system of claim 1, wherein the third mechanism is connected to the conduit, and the first mechanism is connected to the pneumatic chamber of the cylinder assembly.

19. An energy storage and recovery system comprising:

a first cylinder assembly for compressing gas to store energy and expanding gas to recover energy, the cylinder assembly comprising (i) first and second chambers and (ii) a movable mechanical boundary mechanism separating the first and second chambers, at least one of the chambers being a pneumatic chamber;

a first mechanism for (i) introducing a gas into the pneumatic chamber and (ii) removing at least one of gas or a substantially incompressible fluid from the pneumatic chamber;

a second cylinder assembly comprising (i) first and second chambers and (ii) a movable mechanical boundary mechanism separating the first and second chambers, at least one of the chambers being a pneumatic chamber;

a conduit for fluidly connecting the pneumatic chamber of the first cylinder assembly with a pneumatic chamber of the second cylinder assembly, at least a portion of the conduit constituting dead space during compression or expansion of gas in at least one of the first cylinder assembly or the second cylinder assembly; and

a second mechanism for introducing substantially incompressible fluid into the conduit to substantially fill the dead space therein.

20. The system of claim 19, wherein:

the second mechanism comprises (i) a check valve for allowing flow of the substantially incompressible fluid in only one direction, and (ii) a flow control valve for metering a rate of introduction of the substantially incompressible fluid, and

the system further comprises (i) a sensor for measuring at least one of a flow rate or a pressure of the substantially incompressible fluid, and (ii) a controller for controlling the flow control valve based on data from the sensor.