Compressed gas energy storage system
View Patent ↗Embodiments relate generally to energy storage systems, and in particular to energy storage systems using compressed gas as an energy storage medium. In various embodiments, a compressed gas storage system may include a plurality of stages to convert energy into compressed gas for storage, and then to recover that stored energy by gas expansion. In certain embodiments, a stage may comprise a reversible compressor/expander having a reciprocating piston. Pump designs for introducing liquid for heat exchange with the gas, are described. Gas flow valves featuring shroud and/or curtain portions, are also described.
1. An apparatus comprising:
a chamber defined within a plurality of liquid sprayers;
a plunger piston having a first end moveable in response to gas expanding within the cylinder in an absence of combustion, the plunger piston having a second end in communication with a crank;
a dedicated active high pressure valve comprising a poppet moveable relative to a port of the cylinder;
a channel between the dedicated high pressure valve and the chamber to substantially balance a pressure during valve actuation; and
a piston seal located on a chamber wall rather than on the plunger piston.
2. An apparatus as in claim 1 wherein the plurality of liquid sprayers are arranged in at least one liquid spray ring.
3. An apparatus as in claim 1 wherein the channel comprises a vent through the poppet, and the valve further comprises a curtain portion.
4. An apparatus as in claim 1 wherein the valve further comprises a shroud.
5. An apparatus as in claim 1 further comprising a passive high pressure valve in communication with the chamber.
6. An apparatus as in claim 1 further comprising a cam assembly configured to operate the dedicated high pressure valve via a physical connection to the crank.
7. An apparatus as in claim 6 wherein the physical connection comprises a planetary gear.
8. An apparatus as in claim 6 wherein the cam assembly comprises a first cam pair and a second cam pair.
9. An apparatus as in claim 1 further comprising a dedicated low pressure valve comprising a second poppet moveable relative to a second port of the cylinder.
10. An apparatus as in claim 9 wherein the dedicated low pressure valve is spring actuated.
11. An apparatus as in claim 1 further comprising a liquid pump in fluid communication with a liquid sprayer, the liquid pump comprising opposing plungers in communication with a rotating cam via a carrier cam follower.
12. An apparatus as in claim 1 wherein the plunger piston is in communication with the crank through a mechanical linkage.
13. An apparatus as in claim 12 wherein the mechanical linkage comprises a crosshead having a central portion connected to an eccentric in order to move relative to end portions of the crosshead.
14. An apparatus as in claim 1 wherein the plurality of liquid sprayers are supplied with liquid only when they are not covered by the plunger piston.
15. A method comprising:
actively controlling a dedicated high pressure valve via a rotating cam assembly to flow compressed gas into a chamber from a high pressure side;
allowing the compressed gas to expand against a plunger piston in an absence of combustion within the chamber in order to drive a mechanical linkage;
causing a liquid pump to flow liquid into the chamber through a plurality of sprayers for heat exchange;
generating electricity from movement of the mechanical linkage; and
a piston seal located on a chamber wall rather than on the plunger piston.
16. A method as in claim 15 wherein the plurality of sprayers are arranged in at least one liquid spray ring.
17. A method as in claim 15 wherein actively controlling the dedicated high pressure valve comprises changing a position of a first cam pair and a second cam pair.
18. A method as in claim 17 wherein the position is changed utilizing a stepper motor.
19. A method as in claim 15 wherein the dedicated high pressure valve is controlled via desmodromic actuation.
20. A method as in claim 15 wherein the liquid pump comprises a carrier type cam follower with opening and closing cams, and opposed plungers.
21. A method as in claim 15 wherein a pressure across the dedicated high pressure valve is balanced by a channel between the dedicated high pressure valve and the chamber.
22. A method as in claim 21 wherein the dedicated high pressure valve comprises a poppet and a curtain portion, and the channel comprises a vent through the poppet.
23. A method as in claim 15 wherein the dedicated high pressure valve comprises a shroud.
24. A method as in claim 15 wherein the plurality of liquid sprayers are supplied with liquid only when they are not covered by the plunger piston.