High-efficiency energy-conversion based on fluid expansion and compression

• US 8,240,140 B2
• Filed: 08/30/2011
• Issued: 08/14/2012
• 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, Modderno, Jeffrey, Bollinger, Benjamin R.
• Primary Examiner(s): LESLIE, MICHAEL S
• Application Number:
  US13/221,559
• Publication Number:
  US 20120006013A1
• Time in Patent Office: 350 Days
• Field of Search: 603/27, 603/70, 603/71, 603/98, 604/08, 604/10, 604/13, 604/15
• US Class Current: 60/327
• 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 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

Abstract

In various embodiments, motor-pump efficiency is increased by limiting the fluid pressure communicated to the motor-pump to a range smaller than that communicated by other components of an energy storage and/or recovery system.

Claims

1. A method for energy recovery, the method comprising:

within a first cylinder assembly, expanding a gas to produce a pressure smoothly decreasing over a first pressure range;

producing, (i) from pressures within the first pressure range and in reaction to the gas expansion and (ii) within a second cylinder assembly mechanically coupled to the first cylinder assembly, a hydraulic pressure varying over a second pressure range smaller than the first pressure range; and

driving a motor via only the hydraulic pressure varying over the second pressure range,

wherein the second cylinder assembly comprises a cylinder having a discretely variable effective piston area.

2. The method of claim 1, further comprising generating electricity with the driven motor.

3. The method of claim 1, wherein the motor has an optimal operating pressure range (i) smaller than the first pressure range and (ii) at least partially overlapping the second pressure range.

4. The method of claim 1, further comprising expanding gas within a third cylinder assembly mechanically coupled to a fourth cylinder assembly, the expansion in the third cylinder assembly translating fluid from the fourth cylinder assembly to drive the motor in alternation with the expansion in the first cylinder assembly.

5. The method of claim 1, further comprising, prior to the expansion, receiving the gas from a fluid source.

6. The method of claim 5, wherein the fluid source comprises a compressed-gas reservoir.

7. The method of claim 1, further comprising venting the expanded gas to atmosphere after expansion.

8. The method of claim 1, wherein gas is expanded to supply energy when an intermittent source of renewable energy is nonfunctional.

9. The method of claim 1, further comprising thermally conditioning the gas during expansion.

10. The method of claim 9, wherein the thermal conditioning comprises maintaining the gas at a substantially constant temperature during the expansion.

11. The method of claim 1, further comprising, prior to expanding the gas, storing energy originating from an intermittent renewable energy source of wind or solar energy in the form of the gas, wherein the gas is expanded when the intermittent renewable energy source is nonfunctional.

12. The method of claim 1, wherein (i) the second cylinder assembly comprises first and second separated compartments and (ii) during the gas expansion, the second compartment of the second cylinder assembly is selectively fluidly connected to, in turn, (a) a volume of hydraulic fluid at a pressure lower than a minimum pressure of the second pressure range and (b) the first compartment of the second cylinder assembly, thereby reducing the hydraulic pressure range to the second pressure range.

13. The method of claim 1, wherein the second cylinder assembly comprises a plurality of separate compartments, at least one of the compartments being deactivated during the gas expansion to reduce the hydraulic pressure range to the second pressure range.

14. The method of claim 13, wherein deactivating the at least one compartment comprises disconnecting the at least one compartment from the motor and connecting the at least one compartment to a volume of hydraulic fluid having a pressure lower than a minimum pressure of the second pressure range.

15. A method for energy recovery, the method comprising:

expanding a gas to produce a pressure smoothly decreasing over a first pressure range;

producing, from pressures within the first pressure range and in reaction to the gas expansion, a hydraulic pressure varying over a second pressure range smaller than the first pressure range; and

driving a motor via only the hydraulic pressure varying over the second pressure range,

wherein the hydraulic pressure produced in reaction to the gas expansion oscillates over the second pressure range.

16. A method for energy recovery, the method comprising:

within a first cylinder assembly, expanding a gas to produce a pressure smoothly decreasing over a first pressure range;

producing, (i) from pressures within the first pressure range and in reaction to the gas expansion and (ii) within a second cylinder assembly mechanically coupled to the first cylinder assembly, a hydraulic pressure varying over a second pressure range smaller than the first pressure range; and

driving a motor via only the hydraulic pressure varying over the second pressure range,

wherein (i) the second cylinder assembly comprises first and second separated compartments and (ii) during the gas expansion, the second compartment of the second cylinder assembly is selectively fluidly connected to, in turn, (a) a volume of hydraulic fluid at a pressure lower than a minimum pressure of the second pressure range and (b) the first compartment of the second cylinder assembly, thereby reducing the hydraulic pressure range to the second pressure range.

17. The method of claim 16, further comprising thermally conditioning the gas during expansion.

18. The method of claim 17, wherein the thermal conditioning comprises maintaining the gas at a substantially constant temperature during the expansion.

19. A method for energy recovery, the method comprising:

within a first cylinder assembly, expanding a gas to produce a pressure smoothly decreasing over a first pressure range;

producing, (i) from pressures within the first pressure range and in reaction to the gas expansion and (ii) within a second cylinder assembly mechanically coupled to the first cylinder assembly, a hydraulic pressure varying over a second pressure range smaller than the first pressure range; and

driving a motor via only the hydraulic pressure varying over the second pressure range,

wherein the second cylinder assembly comprises a plurality of separate compartments, at least one of the compartments being deactivated during the gas expansion to reduce the hydraulic pressure range to the second pressure range.

20. The method of claim 19, wherein deactivating the at least one compartment comprises disconnecting the at least one compartment from the motor and connecting the at least one compartment to a volume of hydraulic fluid having a pressure lower than a minimum pressure of the second pressure range.