Vanadium redox battery incorporating multiple electrolyte reservoirs

ES 2 397 101 T3

DESCRIPTION

Vanadium redox battery incorporating multiple electrolyte reservoirs.

Technical field

The present invention relates to systems and methods for providing a vanadium redox flow battery that can exhibit efficient operation and modular expandability, in accordance with the appended claims.

Representative prior art includes JP-9283169-A (Sumitomo et al.).

Brief description of the drawings

The various aspects and advantages of the invention are described by way of example in the following description of various embodiments and in the accompanying drawings. It should be understood that the accompanying drawings only show typical embodiments and, as such, should not be construed as limiting the scope of the claims. The embodiments will be described and explained with precision and detail with reference to the accompanying drawings, in which:

Figure 1 is a block diagram of an embodiment of a vanadium redox battery energy storage system in accordance with the teachings of the present invention;

Figure 2 is a block diagram of an embodiment of a vanadium redox battery energy storage system in accordance with the teachings of the present invention;

Figure 3 is a flow chart illustrating a processing method for modifying the capacity of a vanadium redox battery energy storage system in accordance with the teachings of the present invention;

Figure 4 is a representation of one embodiment of a vanadium redox flow battery energy storage system in accordance with the teachings of the present invention; and Figure 5 is an embodiment of a lid mechanism that could be used to allow the use of an intermediate container for bulk materials as a second electrolyte reservoir in the present invention.

Detailed description of the preferred embodiments

Energy storage systems such as rechargeable batteries are an important part of electrical energy systems, particularly electrical energy systems supplied by wind turbine generators, photovoltaic cells, or the like. Energy storage systems can also be used to: allow applications in energy arbitration, the purchase and sale of energy during off-peak hours; uninterruptible power supplies (UPS); provide backup power; or power quality applications in conjunction with a main power source.

Vanadium redox flow battery energy storage systems (hereinafter referred to as “VRB-ESS”) are ideal for use in these applications because they can respond quickly to changing loads (as required in UPS and in power quality applications), and can be configured for high capacity (as needed in main power source applications). In US Patent No. 4,786,567 to Skyllas-Kazacos et al. an all vanadium redox battery is described.

A VRB-ESS typically generates electrical energy by passing electrolyte solutions of anolyte and catholyte through one or more cells. A VRB-ESS can include any number and configuration of cells depending on the instantaneous power demands of the system. Similarly, a VRB-ESS can have various amounts of electrolyte solution available depending on the power capacity needs of the system. The number and cross-sectional area of ​​cells in the VRB-ESS can determine the amount of instantaneous energy that the VRB-ESS is capable of producing, and the volume of anolyte and catholyte electrolyte solutions available to the VRB-ESS can define its energy storage and production capacity. A VRB-ESS provided with a cell stack is described in US Patent No. 6,475,661 to Pellegrí et al.

When acting as a UPS, or any other low capacity application, it would be desirable to reduce the amount of electrolyte solution circulating through the VRB-ESS. This is to minimize energy losses in the electrolyte due to electrolyte self-discharge and to reduce energy loss to pump the electrolyte solution through the system. However, in high capacity applications (i.e. main power applications), it may be necessary to increase the energy storage capacity of the VRB-ESS by providing an additional electrolyte solution to the VRB-ESS through larger electrolyte reservoirs. Furthermore, even in a

ES 2 397 101 T3 low capacity UPS application, said VRB-ESS may require additional power capacity in the event of a failure in the main power source.

Even within these low-capacity and high-capacity modes, various VRB-ESS applications can have widely divergent capacity needs. For example, a VRB-ESS used as a UPS for a single floor of an office building may require significantly less capacity than a VRB-ESS used as a UPS for the entire building or group of buildings. Thus, it is difficult to produce a VRB-ESS provided with electrolyte reservoirs that can efficiently provide such highly variable capacity requirements. This is particularly true in UPS applications where it is more efficient to run the VRB-ESS using a limited electrolyte supply, but it may be necessary to provide a large amount of electrolyte due to the possibility of long-term failure of the power source. main energy.

The need to address varying capacity requirements can force customers to use a VRB-ESS that has significantly more capacity than necessary, resulting in low-efficiency operation. Similarly, a customer limited by restricted space may need to purchase custom-sized electrolyte reservoirs, which significantly increases the cost of the system. Furthermore, even in UPS applications with very high capacity, it is preferable to run the VRB-ESS with as little electrolyte as possible during standby operation, to improve efficiency and maintain the charge of unused electrolyte in case of failure. at the main power source.

The transportation and installation of a VRB-ESS can be time consuming and can be dangerous for the end user. Electrolyte solutions used in VRB-ESS systems have been classified by the United Nations (UN) and the United States Department of Transportation (DoT) as hazardous materials. As such, the anolyte and catholyte solutions used in VRB-ESS must be transported to the end user installation site in an approved container. These containers are generally referred to in the art as intermediate containers for bulk materials (hereinafter referred to as IBCs). Such containers generally must be certified for use with hazardous materials. IBCs must be certified for the transport of hazardous liquids in accordance with DoT and / or UN regulations. Certification procedures for IBCs can be rigorous, typically requiring many months of work and hundreds of hours of testing. All IBC containers must be tested and certified, including any lid mechanism on said IBC.

Because VRB-ESS electrolyte solutions can pose a substantial health risk to the end user, it would be desirable to minimize said end user's direct contact with the electrolyte. In most VRB-ESS systems, the anolyte and catholyte solutions must be transferred from the IBC used for transportation to the VRB-ESS reservoir. This transfer can be dangerous to the end user and pose the risk of allowing potentially hazardous material to spill into the environment. However, such a transfer may be necessary because the VRB-ESS may not be able to use electrolyte solutions housed in a standard IBC container. In addition, transfer may be necessary because the certified transport cap mechanism on the IBC cannot create an acceptable seal to allow the safe and reliable flow of electrolyte to and from the IBC.

The present invention provides a system and method for correcting many of these problems. A VRB-ESS is described capable of modularly incorporating additional electrolyte reservoirs to increase the energy capacity of the system. The VRB-ESS of the present invention operates efficiently using a first volume of electrolyte solution, while maintaining a second volume of electrolyte solution for the VRB-ESS when additional capacity is required. Furthermore, the VRB-ESS of the present invention can incorporate standard IBC industrial containers, obviating the need for transferring hazardous fluids, increasing the safety and flexibility of said VRB-ESS.

Figure 1 is a block diagram of one embodiment of a VRB-ESS 100 incorporating the teachings of the present invention. The VRB-ESS according to embodiment 100 may include one or more cells 10. Each cell 10 may comprise a negative electrode 12 arranged in negative compartment 14 and a positive electrode 20 arranged in positive compartment 22. Suitable electrodes include any number of components known in the art and can include electrodes made in accordance with the teachings of US Patent No. 5,665,212 to Zhong et al.

The negative compartment 14 can include an anolyte solution 16 in electrical communication with the negative electrode 12. Said anolyte solution 16 can be an electrolyte, containing redox ions in a reduced state and which are oxidized during the discharge process of the cell 10 , or in an oxidized state and which are reduced during the charging process of the cell 10, or which are a mixture of reduced ions and ions for their reduction.

As an example, in VRB-ESS 100 the charge-discharge redox reaction that takes place at the negative electrode 12 in an anolyte solution 16 can be represented by equation 1.1:

ES 2 397 101 T3

V²⁺ «V³⁺+ e Eq. 1.1

Positive compartment 22 may contain a catholyte solution 24 in electrical communication with positive electrode 20. Said catholyte solution 24 can be an electrolyte that contains specific redox ions that are in an oxidized state and that must be reduced during the discharge process of a cell 10, or that are in a reduced state and will be oxidized during the cell 10 charging process, or that they are a mixture of said oxidized ions and ions to be oxidized. As an example, the charge-discharge redox reaction that occurs at positive electrode 20 in catholyte solution 24 can be represented by Equation 1.2:

V⁴⁺ «V ⁵⁺+ e ~ Eq. 1.2

The anolyte solution 16 and the catholyte solution 24 can be prepared according to the teachings of US Patents No. 4,786,567, No. 6,143,443, No. 6,468,688 and No. 6,562,514 or by other procedures known in the art. technique.

Each cell 10 may include an ionically conductive membrane 11 disposed between the positive compartment 22 and the negative compartment 14 of cell 10. Said membrane 11 may be in fluid contact with the catholyte solution 24 and the anolyte solution 16, to provide ionic communication. between them. The membrane 11 can serve as a proton exchange membrane. Said membrane 11 can be formed as an anion membrane or a cation membrane and can include a carbon material that can be perfluorinated.

Anolyte solution 16 may be housed in a first anolyte reservoir 52. Said anolyte reservoir 52 may be embodied as a tank, chamber, IBC, or other container that can house an anolyte solution known in the art. The first anolyte reservoir 52 may be in fluid communication with the negative compartment 14 through an anolyte supply connection 30 and the first anolyte return connection 32. In embodiment 100, the anolyte solution housed in the first anolyte reservoir 52 can flow into the negative compartment 14 of cell 10 through the first anolyte supply connection 30, and can flow out of the negative compartment. 14 from cell 10 to the first anolyte reservoir 52 through the first anolyte return connection 32. The first anolyte supply connection 30 and the first anolyte return connection 32 may comprise any type of fluid conduit known in the art capable of containing an anolyte solution.

The catholyte solution 24 may be housed in a first catholyte reservoir 62. Said catholyte reservoir 62 may be embodied as a tank, chamber, IBC, or other container that can house a catholyte solution known in the art. The first catholyte reservoir 62 may be in fluid communication with the positive compartment 22 through a first catholyte supply connection 34 and the first catholyte return connection 36. In embodiment 100, the catholyte solution housed in the first catholyte reservoir 62 can flow into the positive compartment 22 of cell 10 through the first catholyte supply connection 34, and can flow out of the positive compartment 22 from cell 10 to first catholyte reservoir 62 via first catholyte return connection 36. The first anolyte supply connection 30 and the first anolyte return connection 32 may comprise any type of fluid conduit known in the art capable of containing an anolyte solution.

In embodiment 100, the first anolyte supply connection 30 may be in fluid communication with the anolyte pump 50. Said anolyte pump 50 may regulate and allow the flow of the anolyte solution in the first anolyte reservoir. anolyte 52 through the anolyte supply connection 30 in negative compartment 14. The anolyte pump 50 can also regulate and allow the anolyte 16 to flow from the negative compartment 14 through the first anolyte return connection 32 into an anolyte reservoir 52. The anolyte pump 50 can be a flow rate pump. variable flow, in which the flow rate of the anolyte pump 50 determines the flow rate of anolyte 16 through the negative compartment 14. The anolyte pump 50 may be communicatively coupled to the system controller 80. In embodiment 100, the system controller 80 may regulate the flow of anolyte through the negative compartment 14 by controlling the flow rate of the anolyte pump 50.

In embodiment 100, the first catholyte supply connection 34 may be in fluid communication with the catholyte pump 60. Said catholyte pump 60 may regulate and allow the flow fluid of the catholyte solution in the first catholyte reservoir. catholyte 62 through catholyte supply connection 34 in positive compartment 22. The catholyte pump 60 can also regulate and allow the catholyte 24 to flow from the positive compartment 22 through the first catholyte return connection 36 into a first catholyte reservoir 62. The catholyte pump 60 can be a flow pump. variable flow rate, in which the flow rate of the catholyte pump 60 determines the flow rate of catholyte 24 through the positive compartment 22. The catholyte pump 60 may be communicatively coupled to the system controller 80. In embodiment 100, the system controller 80 can regulate the flow of catholyte through the positive compartment 22

ES 2 397 101 T3 by controlling the flow rate of the catholyte pump 60.

Embodiment 100 may comprise a second anolyte reservoir 54. Said second anolyte reservoir 54 may be embodied as a tank, chamber, IBC, or other container known in the art that can house an anolyte solution. The second anolyte reservoir 54 may be in fluid communication with the first anolyte reservoir 52 through a second anolyte supply line connection 31. The second anolyte reservoir 54 may also be in fluid communication with the negative compartment 14 through a second anolyte return line connection 33.

Embodiment 100 may comprise a second catholyte reservoir 64. Said second catholyte reservoir 64 may be embodied as a tank, chamber, IBC, or other container known in the art that can house a catholyte solution. The second catholyte reservoir 64 may be in fluid communication with the first catholyte reservoir 62 through a second catholyte supply line connection 35. The second catholyte reservoir 64 may also be in fluid communication with the positive compartment 22 through a second catholyte return line connection 37.

The negative electrodes 12 and the positive electrodes 20 may be in direct communication with a switch module 70. Said switch module 70 may be capable of electrically coupling the negative electrode 12 and the positive electrode 20 to the power source 72 (which does not shown) or load 74 (not shown). Switch module 70 may be arranged in series between power source 72 and each negative electrode 12. Switch module 70 can also be arranged in series between load 74 and each negative electrode 12. This circuit arrangement allows switch module 70 to selectively connect VRB-ESS 100 to power source 72 or load. 74. In one embodiment 100, switch module 70 is communicatively coupled to system controller 80, allowing system controller 80 to selectively connect cell 10 to power source 72 or load 74. A skilled person It will be appreciated in the art that alternative circuit arrangements and configurations can be made, therefore, the embodiment of Figure 1 is provided for illustrative purposes only.

Embodiment 100 can be configured to circulate only electrolyte solutions housed in the first anolyte reservoir 52 and the first catholyte reservoir 62. When configured in this way, the VRB-ESS can be said to be in the form of Embodiment 100 operates in "low volume" mode. Alternatively, embodiment 100 may be configured to circulate electrolyte solutions housed in both the first and second anolyte reservoirs 52, 54 and the first and second catholyte reservoirs 62, 64. When configured as In this mode, the VRB-ESS of embodiment 100 can be said to operate in a "full volume" mode.

As used herein, said second anolytic supply line connection 31, second anolytic return line connection 33, second catholyte supply line connection 35, and second catholyte return line connection 37, or a fluid such as anolyte supply connection 30, anolyte return connection 32, the catholyte supply connection 34 and the catholyte return connection 36 may be formed in any fluid conduit capable of accommodating an electrolyte solution. Said fluid conduit may comprise: plastic pipes reinforced with a mesh; fiber reinforced rubber pipes; a multilayer composite hose; polyethylene pipes; reinforced rubber pipes; or similar. Those skilled in the art will understand that any number of different fluid conduit materials can be used without departing from the teachings of the present invention.

In order to configure embodiment 100 in the "full volume" mode, a first anolyte return valve 59 and a first catholyte return valve 69 may be provided in a closed state. This could prevent the anolyte flowing from the negative compartment 14 of cell 10 through connection 32 from flowing into the first anolyte reservoir 52; Rather, in this configuration, the anolyte flowing through the first anolyte return connection 32 flows into the second anolyte reservoir 54 through the second anolyte return line connection 33. When the anolyte flows into the second anolyte reservoir 54, said second anolyte reservoir 54 can be filled, creating an overflow condition in said second anolyte reservoir 54. This overflow condition can cause the anolyte to flow out of the second reservoir. of anolyte 54 into the first anolyte reservoir 52 through a second anolyte supply line connection 31. In an alternative embodiment, the VRB-ESS can be configured in the "full volume" mode by opening an anolyte supply valve (not shown) at fluid connection 31 and arranging fluid connection 31 next to the part. bottom of the reservoir 54 so that it is always in contact with the anolyte regardless of how full the reservoir is.

In the "full volume" mode, closing the first catholyte return valve 69 can prevent catholyte flowing from the positive compartment 22 of cell 10 through connection 36 from flowing into the first catholyte reservoir 62; conversely, in this configuration, the catholyte flowing through the first catholyte return connection 36 may flow into the second catholyte reservoir 64 through the second catholyte return line connection 37. When the catholyte flows into the second catholyte reservoir 64, said second catholyte reservoir 64 can be filled, creating an overflow condition in said second catholyte reservoir 64. This

ES 2 397 101 T3 overflow condition can cause the catholyte to flow out of the second catholyte reservoir 64 into the first catholyte reservoir 62 through a second catholyte supply line connection 35. Thus, in the "volume" mode. "Complete" the anolyte in the second anolyte reservoir 54 can flow serially through the first anolyte reservoir 52 and the catholyte in the second catholyte reservoir 64 can flow serially through the first catholyte reservoir 62. Thus, in the "full volume" mode, all of the electrolyte contained in the reservoirs 52, 54, 62, 64 can circulate through the VRB-ESS 100.

In order to configure embodiment 100 in the "low volume" mode, the first anolyte return valve 59 and the first catholyte return valve 69 can be opened. In this configuration, the anolyte flowing from the negative compartment 14 from cell 10 through the anolyte return connection 32 can flow into the first anolyte reservoir 52. In one embodiment, the second anolyte return pipe connection 33 can be raised relative to the first anolyte return connection 32 or cell 10. This differential can prevent anolyte from flowing from the negative compartment 14 through from the first anolyte return connection will flow into the second anolyte reservoir 54 when the first anolyte return valve 59 is in an open position. In an alternative embodiment, the second anolyte return line connection may comprise a second anolyte return valve (not shown), to prevent anolyte from flowing into the second anolyte reservoir 54 in the "volume" mode. under". Accordingly, in the "low volume" mode the overflow condition cannot be created in the second anolyte reservoir 54. Thus, in the "low volume" mode, the anolyte may not flow from the second anolyte reservoir 54 to the first anolyte reservoir 52 through the second anolyte supply line connection 31.

In the "low volume" mode, the catholyte flowing from the positive compartment 22 of the cell 10 through the catholyte return connection 36 can flow into the first catholyte reservoir 62. In one embodiment, the second connection of catholyte return tubing 37 can be raised relative to the first catholyte return connection 36 or cell 10. This differential can prevent the catholyte flowing from the positive compartment 22 through the first catholyte return connection 64 from flowing into the second catholyte reservoir 36 when the first catholyte return valve 69 is in an open position. In an alternate embodiment, the second catholyte return line connection 33 may comprise a second catholyte return valve (not shown), to prevent catholyte from flowing into the second catholyte reservoir 64 in the " Low volume". Accordingly, in the "low volume" mode the overflow condition cannot be created in the second catholyte reservoir 64. Thus, in the "low volume" mode, the catholyte may not flow from the second catholyte reservoir 64 to the first catholyte reservoir 62 through the second catholyte supply line connection 35. Thus, in the volume mode Low, the electrolyte solution contained in the second anolyte reservoir 54 and in the second catholyte reservoir 54 can be substantially isolated from the VRBESS 100.

The anolyte and catholyte electrolyte solutions of the VRB-ESS 100 can be charged by configuring switch module 70 to connect power source 72 (not shown) to negative electrode 12 and positive electrode 20 of cell 10. Power The electrical power supplied through the negative electrode 12 can produce divalent vanadium ions in the anolyte solution 16, as represented by Equation 1.3:

V³⁺e ~ ® V²⁺ Eq. 1.3

Electrical energy supplied through positive electrode 20 can produce pentavalent vanadium ions in catholyte solution 24, as represented by Equation 1.4:

V⁵⁺e ~ ® V⁴⁴ Eq. 1.4

When charged, each of the cells can provide an open circuit voltage of approximately 1.41V at 25 ° C.

Switch module 70 can be configured to draw electrical power from cell 10 by connecting cell 10 to load 74 (not shown). This causes the charge 72 (not shown) to draw electrical energy from the anolyte solution 16 in the negative compartment 14 and from the catholyte solution 24 in the positive compartment 22. This extraction of electrical energy can produce trivalent vanadium ions in the anolyte solution 16, as represented by Equation 1.5, and can produce tetravalent vanadium ions in the catholyte solution 24 in the positive compartment 22, as represented by Equation 1.6:

V²⁺ ® V ³⁺+ e ~ Eq. 1.5

V⁴⁺ ® V⁵ + e ~ Eq. 1.6

When the electrical energy is withdrawn from cell 10, the anolyte solution 16 in the negative compartment 14 and the catholyte solution 24 in the positive compartment 22 can be discharged. Thus, you could use the pump

ES 2 397 101 T3 anolyte 50 for circulating additional anolyte in negative compartment 14 through anolyte supply connection 30, expelling anolyte 16 from inside negative compartment 14 through first anolyte return connection 32. The catholyte pump 60 could be used to pump catholyte through the catholyte supply connection 34 into the positive compartment 22, forcing the catholyte 24 from the positive compartment 22 to flow out of the positive compartment 22 through the first catholyte return connection 36.

FIG. 2 shows another embodiment 200 of the present invention in which the first anolyte reservoir 52 of FIG. 1 is located in reservoir 52a and 52b. In this embodiment 200, the first anolyte reservoir 52a may contain substantially charged anolyte, and the first anolyte reservoir 52b may contain substantially discharged anolyte. Similarly, reservoir 62 of FIG. 1 may be comprised of two reservoirs 62a and 62b. In this embodiment, the first catholyte reservoir 62a may contain substantially charged catholyte and the first catholyte reservoir 62b may contain substantially discharged catholyte.

Similarly, the second anolyte reservoir 54 of FIG. 1 may be composed of reservoirs 54a and 54b, said second anolyte reservoir 54a may contain substantially charged anolyte, and the second anolyte reservoir 54b may contain substantially discharged anolyte. Similarly, the second catholyte reservoir 64 of FIG. 1 may be comprised of reservoirs 64a and 64b, said second catholyte reservoir 64a may contain substantially discharged catholyte and second catholyte reservoir 64b may contain substantially discharged catholyte.

As in embodiment 100, the VRB-ESS of embodiment 200 can operate in a "low volume" mode, in which only the electrolyte solutions contained in the first anolyte reservoir 52a, 52b and the First catholyte reservoir 62a, 62b can flow through cell 10. Alternatively, the VRB-ESS of embodiment 200 can be operated in a "full volume" mode, in which the electrolyte solutions housed in the first anolyte reservoir 52a, 52b, the second anolyte reservoir 54a , 54b, the first catholyte 62a, 62b, and the second catholyte reservoir 64a, 64b can circulate through cell 10.

Electrical energy can be stored in the VRB-ESS of embodiment 200 by having switch module 70 connect cell 10 to power source 72 (not shown), creating an electrical connection between the power source. energy 72 and negative electrode 12 and positive electrode 20 of cell 10. In this configuration, the anolyte 16 within the negative compartment 14 and the catholyte 24 within the positive compartment 22 can be charged as previously described in conjunction with FIG. 1. In order to charge the additional electrolyte, a reversible anolyte pump 51 can be used to circulate the anolyte in the negative compartment 14 of cell 10, and a reversible catholyte pump 61 can be used to circulate the catholyte in the cell 10. positive compartment 22 of cell 10. The movement of fluid caused by the reversible anolyte pump 51 can cause the anolyte solution from the first substantially discharged anolyte reservoirs 52b, 54b to transfer to the first substantially charged anolyte reservoirs 52a, 54a. Similarly, the movement of the catholyte fluid caused by the reversible catholyte pump 61 can cause the catholyte solution within the first substantially discharged catholyte reservoirs 62b, 64b to transfer to the first substantially charged anolyte reservoirs 62a, 64a. In one embodiment the flow created by the reversible anolyte pump 51 and the reversible catholyte pump 61 can return depending on whether the VRB-ESS 200 is charging or discharging.

Electrical power can be drawn from the VRB-ESS of embodiment 200 by having switch module 70 connect cell 10 to load 74 (not shown), creating an electrical connection between load 74 and the negative electrode. 12 and the positive electrode 20 of cell 10. In this configuration, energy is drawn from anolyte 16 from negative compartment 14 and from catholyte 24 from positive compartment 22, as previously described in conjunction with Figure 1. After removal of electrical energy from anolyte 16 and the catholyte 24, additional electrical power may be required. In order to provide such electrical energy, additional electrolyte can be circulated through the system. The reversible anolyte pump 51 can be used to circulate said anolyte in the negative compartment 14 of cell 10, and the reversible catholyte pump 61 can be used to circulate the catholyte in the positive compartment 22 of cell 10. Movement of fluid caused by reversible anolyte pump 51 can cause anolyte within the first substantially charged anolyte reservoirs 52a, 62a to flow through anolyte supply connection 30 to negative compartment 14 of cell 10; this flow can also cause anolyte 16 from negative compartment 14 to flow out of cell 10 through anolyte return connection 32. Fluid movement caused by reversible catholyte pump 61 can cause catholyte from the first substantially charged catholyte reservoirs 62a, 64a to flow through catholyte supply connection 34 to positive compartment 22 of cell 10; this flow can also cause catholyte 24 within positive compartment 22 to flow out of cell 10 through catholyte return connection 36.

The VRB-ESS of embodiment 200 can operate using only the first anolyte reservoir 52a, 52b and the first catholyte reservoir 62a, 62b. This configuration may be referred to as a "low volume" mode of embodiment 200. Alternatively, embodiment 200 may operate using the first and second anolyte reservoirs 52a, 52b, 64a, 64b and the first and the second catholyte deposits 62a, 62b,

ES 2 397 101 T3

64a, 64b. This configuration may be referred to as a "full volume" mucus of embodiment 200. In one embodiment 200, the volume of the second anolyte reservoir 54a, 54b may be substantially greater than the volume of the first anolyte reservoir 52a. , 52b, and the volume of the second catholyte reservoir 64a, 64b may be substantially greater than the volume of the first catholyte reservoir 62a, 62b. In this configuration, the VRB-ESS 200 can efficiently operate in the "low volume" mode, minimizing losses due to electrolyte self-discharge and pumping energy, while maintaining a substantially larger volume of electrolyte for use as needed.

Embodiment 200 may be arranged in a "low volume" mode by providing the second anolyte supply valve 56, the second anolyte return valve 58, the second catholyte supply valve 66, and the second anolyte return valve. catholyte 68 in a closed position and disposing the first anolyte return valve 59 and the first catholyte return valve 69 in an open position. In this configuration, the anolyte contained in the second substantially charged anolyte reservoir 54a is prevented from flowing into the first substantially charged anolyte reservoir 52a or negative compartment 14 of cell 10, and the catholyte contained in the second catholyte reservoir is prevented substantially charged 64a flows into the substantially charged catholyte reservoir 62a or positive compartment 22 of cell 10. Additionally, in this configuration, the anolyte flowing from the negative compartment 14 of cell 10 is prevented from flowing into the second substantially discharged anolyte reservoir 54b and the catholyte flowing from the positive compartment 22 of cell 10 is prevented from flowing. in the second substantially discharged catholyte reservoir 64b.

Embodiment 200 may be arranged in a "full volume" mode by arranging the second anolyte supply valve 56, the second anolyte return valve 58, the second catholyte supply valve 66, and the second catholyte return valve. catholyte 68 in an open position. In this configuration, the anolyte contained in the second substantially charged anolyte reservoir 54a can flow into the first substantially charged anolyte reservoir 52a and the negative compartment 14 of cell 10, and the catholyte contained in the second substantially charged catholyte reservoir 64a can flow to the first substantially charged catholyte reservoir 62a and positive compartment 22 of cell 10. Additionally, in this configuration, the first anolyte return valve 59 and the first catholyte return valve 69 can be arranged in a closed position, and the second anolyte return valve 58 and the second catholyte return valve 68 are can be arranged in an open position. In this configuration, the anolyte flowing from the negative compartment 14 of cell 10 flows into the second substantially discharged anolyte reservoir 54b and the catholyte flowing from the positive compartment 22 of cell 10 flows into the second substantially discharged catholyte reservoir. 64b.

In embodiment 200, the first anolyte reservoir 52a, 52b, the second anolyte reservoir 54a, 54b, the first catholyte reservoir 62a, 62b, and the second catholyte reservoir 64a, 64b may be coupled to communicate. with the system controller 80, so that the system controller 80 can control the volume level of each of the reservoirs 52, 54, 62, 54. In this embodiment, the system controller 80 can determine the volume of electrolyte contained in the first anolyte reservoir 52a, 52b, the first catholyte reservoir 62a, 62b, the second anolyte reservoir 54a, 54b, and the second anolyte reservoir. Catholic 64a, 64b.

In this embodiment, while the VRB-ESS 200 is charged in the "full volume" mode, the system controller 80 can cause the first anolyte return valve 59 to be in an open state and the second non-return valve. anolyte return 58 is placed in a closed state until substantially all of the anolyte housed in the first substantially discharged anolyte reservoir 52b has circulated through the negative compartment 14 of cell 10. After detecting this condition, the system controller 80 can cause the first anolyte return valve 59 to be in a closed position and the second anolyte return valve 58 to be in an open position, allowing the anolyte from the second. substantially discharged anolyte deposit 54b flows through negative compartment 14 of cell 10. Similarly, during charging in the "full volume" mode, the system controller 80 can cause the first catholyte return valve 69 to go into an open state and the second catholyte return valve 68 to go into an open state. closed state until substantially all of the catholyte housed within the first substantially discharged catholyte reservoir 62b has circulated through the positive compartment 22 of cell 10. After detecting this condition, the system controller 80 can set the first catholyte return valve 69 to a closed position and the second anolyte return valve 58 to an open position, allowing the catholyte from the second. substantially discharged catholyte reservoir 64b flows through positive compartment 22 of cell 10.

In Embodiment 200, while the VRB-ESS 200 is discharging in the "full volume" mode, the system controller 80 can cause the first anolyte return valve 59 to be in an open position and the second anolyte return valve 58 to be in a closed position until the substantially discharged first anolyte reservoir 52b contains a volume of anolyte substantially equivalent to that originally contained in the first substantially charged reservoir 52a. After detecting this condition, the system controller 80 can set the first anolyte return valve 59 to a closed position and the second anolyte return valve 58 to an open position, allowing the anolyte to flow in. the interior of the second substantially discharged anolyte reservoir 54b. Similarly,

ES 2 397 101 T3 the system controller 80 can cause the first catholyte return valve 69 to be set to an open position and the second anolyte return valve 58 to be set to a closed position until the first catholyte reservoir substantially discharged 62b contains a volume of catholyte substantially equivalent to that originally contained in the first substantially charged catholyte reservoir 62a. After detecting this condition, the system controller 80 can set the first catholyte return valve 69 to a closed position and the second anolyte return valve 58 to an open position, allowing catholyte to flow into the open position. interior of the second substantially discharged catholyte reservoir 64b.

Returning to Figure 3, as described above, embodiments 100 and 200 can be configured to operate in a "low volume" mode or in a "full volume" mode. In one embodiment, the volume of the anolyte and catholyte reservoirs 52 and 62 can be relatively small compared to the volume of the second anolyte and catholyte reservoirs 54 and 64. In this configuration, the VRB-ESS of the present invention can function efficiently using a relatively small volume mode of electrolyte solution ("low volume"), while maintaining a larger volume of electrolyte as needed. Operating the VRB-ESS 100 “low volume” can minimize losses due to electrolyte self-discharge and pumping. In addition, "low volume" operation can allow an electrolyte solution contained in the second electrolyte reservoirs 54, 64 to be held at a high level of charge for use as needed.

As described above, system controller 80 of embodiment 100, 200 can be communicatively coupled with cell 10. In this configuration, system controller 80 can control the electrochemical status of cell 10. This control may comprise: measuring a voltage generated by cell 10; measuring an electrical current flowing to or from cell 10; measuring the temperature of cell 10 and / or measuring the charge level of the electrolyte in cell 10. During operation, the system controller 80 can control cell 10 and change the setting of the VRB-ESS 100, 200 in response to conditions in cell 10. Additionally, the system controller 80 can change the configuration of the VRB-ESS 100, 200 in accordance with an externally generated control signal. Flow chart 300 provides a flow chart of a VRB-ESS configuration and control procedure incorporating the teachings of the present invention.

In step 310, the system controller can control one or more electrochemical properties of each cell 10 in a VRB-ESS. The measurement performed at 310 may be periodic, such that the measurement 310 may take place at regularly set intervals. In one embodiment, this control period may change depending on the VRB-ESS operating mode, or it may change in response to an externally generated control signal. In step 320, the flow can be divided depending on the current operating mode of the VRB-ESS. In one embodiment, step 320 can be divided depending on whether the VRBESS is currently operating in "low volume" mode, or in "full volume" mode. In step 320, if the URB-ESS is operating in the "low volume" mode, the flow continues to 330, if the VRB-ESS is operating in the "full volume" mode, the flow continues to 340.

At 330, the "low volume" comparison 332 can be performed. Such "low volume" comparison 332 can compare the electrochemical state of the cell 10 measured at 310 in a threshold condition. For example, in one embodiment, during the discharge of the VRB-ESS said comparison could comprise comparing the voltage generated by the cell 10 with respect to a threshold voltage. In this embodiment, if comparison 332 determines that the cell voltage measured at 310 is above the threshold voltage at 332, the flow can continue at 310. However, in this embodiment, if the comparison 332 determines that the cell voltage measured at 310 is below the threshold voltage 332, the flow can proceed up to 334. In another embodiment, the "low volume" comparison 332 may compare the current flowing from cell 10 or the state of charge of the electrolyte in cell 10 against a threshold value. In this embodiment, if the current flowing from cell 10 is above a threshold value, or the state of charge of the electrolyte in cell 10 has dropped below a threshold value, the flow can continue until 334. In one embodiment, comparison 332 may comprise a time component, such that flow only proceeds to 334 if the electrochemical state of cell 10 measured at 310 has been maintained for a specified period of time. Additionally, comparison 332 may respond to an externally generated control signal, said signal causing flow to proceed to 334. At 334, the system controller can configure the VRB-ESS to operate in "full volume" mode. After doing the 334 setting, the flow can continue up to 310.

At 340, the "full volume" comparison 342 can be performed. The "full volume" comparison 342 can compare the electrochemical state of cell 10 measured at 310 against a threshold condition. For example, in one embodiment, during charging of the VRB-ESS this comparison could comprise comparing the voltage generated by the cell 10 with respect to a threshold voltage. In this embodiment, if comparison 342 determines that the cell voltage measured at 310 is below the threshold voltage of 342, the flow can continue at 310, and if comparison 342 determines that the cell voltage cell measured at 310 is above the threshold voltage of 342, the flow proceeds to 344. At another

In an embodiment, the "full volume" comparison 342 may compare the current flowing in cell 10 or the state of charge of the electrolyte in cell 10 against a threshold value. In this embodiment, if the current flowing into cell 10 is below a threshold value, or the state of charge of the electrolyte inside cell 10 has risen above a threshold value , the flow can continue up to 344. In one embodiment, comparison 342 may also comprise a time component, such that flow only proceeds to 344 if the electrochemical state of cell 10 measured at 310 has been maintained for a specified period of time. Additionally, comparison 342 may respond to an externally generated control signal, said signal causing flow to proceed to 344. At 344, the system controller can configure the VRB-ESS to operate in "full volume" mode. After doing the 344 setup, the flow can continue up to 310.

Figure 4 shows another embodiment of a VRB-ESS 400 according to the teachings of the present invention. In embodiment 400, the system module 405 may be comprised of a cell stack 410, an anolyte pump 50, a catholyte pump 60, a first anolyte reservoir 52, a first catholyte reservoir 62, a catholyte module switch 70 and a controller system 80. Said system module 405 may be arranged in a housing 406.

In embodiment 400, the second anolyte reservoir 54 may be disposed on the outside of the housing 406. The second anolyte reservoir 54 may be in fluid communication with the first anolyte reservoir 52 in the housing 406 through the second anolyte supply line connection 431. The second anolyte reservoir 54 may be in fluid communication with the cell stack 410 through the second anolyte supply line connection 433. The second anolyte supply line connection 431 and the second anolyte return line connection 433 may be comprised of flexible tubes that allow the second anolyte reservoir 54 to be disposed separately from the housing 406.

In the embodiment of Figure 4, the fluid connection between cell 410 and first anolyte reservoir 52 comprises a first anolyte return valve 59 (not shown). In addition, in the embodiment of Figure 4, the fluid connection between cell 410 and first catholyte reservoir 62 may comprise a first catholyte return valve 69 (not shown). The first anolyte return valve 59 and the first catholyte return valve 69 may be disposed within the housing 406 and can be communicatively coupled with the system controller 80.

The VRB-ESS 400 can be configured to operate in "full volume" mode by closing the first anolyte return valve 59 (not shown) and the first catholyte return valve 69 (not shown). As mentioned above in conjunction with FIG. 1, in this configuration, the anolyte flowing from cell 10 can be prevented from flowing into the first anolyte reservoir 52 and can instead flow into the second anolyte reservoir. anolyte 54 through the second anolyte return line connection 433. As the anolyte flows into the second anolyte reservoir 54, it can fill, creating an overflow condition within the second anolyte reservoir 54. This overflow condition in the second anolyte reservoir 54 can cause the anolyte to flow out of the second anolyte reservoir 54 in the first anolyte reservoir 52 through the second anolyte supply line connection 431. Similarly, in this configuration, the catholyte flowing from cell 10 can be prevented from flowing into the first catholyte reservoir 62 and can instead flow into the second catholyte reservoir 64 through the second catholyte connection. catholyte return line 437. As catholyte flows into second catholyte reservoir 64, it can fill, creating an overflow condition within second catholyte reservoir 64. This overflow condition in the second catholyte reservoir 64 can cause the catholyte to flow out of the second catholyte reservoir 64 in the first catholyte reservoir 62 through the second catholyte supply line connection 435. Accordingly, in a "full volume" mode the anolyte can flow in series through the first anolyte tank 52 and the second catholyte tank 54, and the catholyte can flow in series through the first catholyte tank 62 and of the second catholyte deposit 64.

The VRB-ESS 400 can be configured to operate in "low volume" mode by opening the first anolyte return valve 59 (not shown) and the first catholyte return valve 69 (not shown). As mentioned above in conjunction with FIG. 1, in this configuration, the anolyte flowing from cell 10 can flow into the first anolyte reservoir 52 and the catholyte flowing from cell 10 can flow into the first catholyte reservoir 62. . In embodiment 400, the second anolyte return line connection 433 may be disposed over a fluid level of the cell 10 and the first anolyte reservoir 52. Thus, when the first anolyte return valve 59 is located In an open position, the anolyte may not flow into the second anolyte reservoir 54. Similarly, in embodiment 400, the second catholyte return line connection 437 may be disposed over a fluid level of cell 10 and the first catholyte reservoir 62. Thus, when the first catholyte return valve catholyte 69 is in an open position, the catholyte may not flow into the second catholyte reservoir 64. Accordingly, in the low volume mode, the electrolyte solution in the second anolyte reservoir 54 and in the second catholyte reservoir 64 is substantially isolated from the system module 405. In an alternative embodiment of the VRB-ESS 400, the second anolyte return line connection 433 may comprise a second anolyte return valve 58 (not shown) and the second catholyte return line connection 437 may comprise a second catholyte return valve 68 (not shown). In this embodiment, in the "low volume" mode, the electrolyte can be prevented from flowing into

ES 2 397 101 T3 the second anolyte reservoir 54 and in the second catholyte reservoir 64 via valves 58, 69.

In one embodiment, the second anolyte supply line connection 431 and the second anolyte return line connection 433 may be comprised of flexible tubing, which can allow the second anolyte reservoir 54 to be arranged separately from the system module 405 and chassis 406. Similarly, the second catholyte supply line connection 435 and the second catholyte return line connection 437 may be comprised of flexible tubing, which can allow the second catholyte reservoir 64 to be arranged separately from the catholyte module. 405 system and 406 housing.

In one embodiment, the tubing connections 431, 433, 435, 437 can be comprised of any fluid conduit that can fluidly transport an electrolyte solution. Said fluid conduit may comprise: mesh-reinforced braided plastic pipes; fiber reinforced rubber pipes; multilayer composite hose; polyethylene pipes; reinforced rubber pipes, or the like. Those skilled in the art will understand that any number of different conducting materials can be used without departing from the teachings of the present invention. Additionally, in one embodiment, the tubing connections 431, 437, 435, 437, the second anolyte reservoir 54, and the second catholyte reservoir 64 can be self-ventilated in accordance with the teachings of US Patent Application No. 11 / 701,573.

In one embodiment, the pipe connections 431, 433 to the second anolyte tank 54 and the pipe connections 435, 437 to the second catholyte tank 64 can be arranged on top of said tanks 54, 64. In this configuration, electrolytic fluid is circulated through reservoirs 54, 64 by displacing fluid from a top-mounted connection, improving safety by ensuring that electrolyte solution cannot be pumped out into the environment at case of a leak in the pipe connection 431, 433, 435, 437, a failure of the system controller 80, a failure of the pumps 50, 60, or a leak at any of the internal fluid connections such as 30, 32, 34, 36 of Figures 1, 2.

In one embodiment, the tubing connections 431 and 433 can be connected to the second anolyte reservoir 54 above the normal liquid level 424 in the anolyte reservoir and the tubing connections 435, 437 can be connected to the second catholyte reservoir. 64 above the normal liquid level 434 in the second catholyte reservoir. In this configuration, the pipe connections 431, 433, 435, 437 are self-draining and remain empty when the secondary tanks 54, 64 are not used. Furthermore, this configuration ensures that electrolytes do not need to be handled nor can they spill when connecting or disconnecting tubing connections 431, 433, 435, 437 at secondary electrolyte reservoirs 54, 64.

In embodiment 400, secondary anolyte reservoir 54 and secondary catholyte reservoir 64 can be disposed separately from housing 406 via tubing connections 431, 433, 435, 437. Such a flexible arrangement can allow the embodiment 400 is located in a plurality of different configurations, allowing the VRB-ESS 400 to be arranged in locations with limited or irregular space restrictions.

Additionally, the VRB-ESS 400 housing 406 can be connected to any 54, 64 secondary electrolyte reservoir of almost any size via pipe connections 431, 433, 435, 437. Thus, the VRB-ESS 400 can be customized in modular form for a wide variety of different capacity needs. For example, Figure 4 shows two smaller tanks 454, 464 that have a capacity of approximately 135 gallons each. Accordingly, tanks 454, 464 can store approximately 10kWh of energy when used with the VRB-ESS 400. Alternatively, Figure 3 shows tanks 454, 464 (the tanks connected through the pipe connections). 431, 433, 435, 437). Each of the reservoirs 454, 464 can hold approximately 275 gallons of electrolyte, providing 20 kWh of energy storage to the VRB-ESS 400. Finally, the 470 tank can be used in conjunction with the VRB-ESS 400. The 470 tank can hold 550 gallons of electrolyte, providing the VRB-EsS 400 with 40 kWh of energy storage capacity.

Turning now to Figure 5, the electrolyte used with VRB-ESS systems is generally classified by the United Nations (UN) and the United States Department of Transportation (DoT) as hazardous material. Therefore, VRB-ESS electrolyte solutions must be transported in an intermediate bulk container (“IBC”) that has been tested and approved for use in the transportation of hazardous materials. IBCs may be certified for the shipment of hazardous materials in accordance with DoT and / or UN regulations. Certification procedures for such IBCs can be rigorous, typically requiring many months of work and hundreds of hours of testing. The entire IBC must be tested and certified, including any cap mechanisms on the IBC.

In one embodiment, the secondary electrolyte reservoirs of the VRB-ESS of the present invention may comprise an IBC. For example, in the embodiment of Figure 4, any of the reservoirs 54, 64, 454, 464, 470 can be an IBC container. In one embodiment, the IBC used in the VRB-ESS can be the same IBC used to transport the electrolyte to the installation site. In such a configuration, the end user of the VRB-ESS does not need to transfer the electrolyte solution from the transport IBC to a VRB tank.

ES 2 397 101 T3

ESS separate. This would be desirable as it minimizes the contact that the end user of the VRB-ESS must have with potentially hazardous electrolyte solutions. The use of transport in IBC as a secondary electrolyte reservoir is also advantageous and eliminates the possibility of any hazardous electrolyte solution being spilled into the environment during transfer from a transport IBC to a secondary electrolyte reservoir. In addition, the use of a transport IBC as an electrolyte reservoir obviates the need to ship a separate reservoir component, which can significantly reduce the overall transportation tracking of the VRB-ESS.

IBCs used for transportation must incorporate a lid mechanism to allow liquids to transfer in and out of the IBC. As mentioned above, the IBC cap must be certified for use in the transportation of hazardous material, and this certification can be a lengthy and expensive procedure. However, the battery cover included in the IBC shipment may not allow a secure coupling to the tubing connections used in the VRB-ESS of the present invention. For example, many IBC caps include one or more threaded ports in accordance with the National Pipe Thread (“NPT”) threading regulations. The use of NTPs is problematic because they are generally formed as part of the IBC cap and thus turning the IBC cap changes the turning orientation of the ports. Also, the turning orientation of the cap and ports may not be known until the IBC is installed. The twist interdependence between the cap and the nPt ports can pose problems for the installer, as the tightening of the IBC cap can affect the VRB-ESS plumbing. This independence reduces the location flexibility of the VRB-ESS by restricting the possible orientations of its piping connections, which can restrict the possible locations of the secondary tanks with respect to the system module. Additionally, NTP ports require a high degree of skill to install and it has been observed that their tightness cannot be guaranteed, which presents a risk of dangerous electrolyte leakage into the environment.

Turning now to Figure 5, Figure 5 shows an embodiment of a cap mechanism 500 that can be used in conjunction with a standard IBC. The cap mechanism 500 can allow a certified hazardous material IBC 510 to be used as a secondary electrolyte reservoir in a URB-ESS. The cap mechanism 500 can be used in place of a certified shipping cap (not shown) on the IBC 510 once the IBC 510 reaches its destination. Thus, the lid mechanism 500 does not need to be certified for the transport of hazardous materials like the standard IBC 510 lid, obviating the need for an expensive and time-consuming process for the lid mechanism 500.

Cap mechanism 500 can be attached to IBC 510 using a cap receptacle 512 on IBC 510. In embodiment 500, the inside diameter and thread pattern 522 of compression ring 520 are configured to be compatible with the threads 514 disposed in the lid socket 512 of the IBC 510. The compression ring 520 may include a lip 524 for compression fitting the sealing plate 530. In embodiment 500, the sealing plate 530 may comprise a slotted portion 532 along its outer diameter. Said grooved portion 532 can be adapted to receive the O-ring 534. In this embodiment, said O-ring 534 can create a seal between the seal plate 530 and the IBC cap receptacle 512 when the compression ring is tightened. 520 into the thread of the IBC 514.

The seal plate 530 may also comprise fluid outlet ports 540 and 550. Said fluid outlet ports 540, 550 may be tightly coupled to the seal plate 530 or may be integrally formed therewith. The outlet bag 540 may comprise a bag extension 544 for extension into the IBC 510 when the lid is installed thereon. In embodiment 500, the length of bag extension 544 may be sufficient to allow bag 540 to be in fluid communication with an electrolyte solution housed within IBC 510. Accordingly, the extension of bag 544 may extend below normal liquid level 516 of IBC 510 when lid mechanism 500 is installed therein.

Cap mechanism 500 may also comprise fluid connectors 560 and 570. Such fluid connectors 560, 570 may comprise a seal mechanism 562, 572 for tightly engaging outlet ports 540, 550. In embodiment 500 , outlet bag 540 may comprise indentation 542 and outlet bag 550 may comprise indentation 552. In this embodiment, the sealing mechanism 562, 572 can be adapted to tightly engage the outlet ports 540, 550 in the indentation 542, 552. It should be understood by those skilled in the art that any number of mechanisms can be used. seal 562, 572 to create a seal between bag 540, 550 and fluid connectors 560, 570.

In embodiment 500, fluid connectors 560, 570 may comprise a tubing coupling 564, 574. Such tubing couplings 564, 574 may comprise flanges 566, 576 for engaging an inner portion of a mated tubing connection. In some embodiments, such ribs 566, 576 can be used in conjunction with a compression sleeve (not shown) to hermetically couple the tubing to the tubing coupling 564, 574.

In embodiment 500, all of the components of the cap mechanism 500 can be arranged

ES 2 397 101 T3 above the normal liquid level 516 of the IBC 510. Thus, the lid mechanism 500 can be installed in the receptacle 512 of the IBC 510 without requiring the installer to touch or otherwise come into contact with the liquid in the inside said IBC 510. This provides a significant safety advantage, since the electrolyte contained in the IBC 510 can be dangerous.

In embodiment 500, the sealing plate 530, with the outlet ports 540 and 550 attached, can be rotated independently of the compression ring 520. In this embodiment, the installer can determine the rotation orientation of the outlet ports 540, 550 and fluid connectors 560, 570 insulated, regardless of the rotation of compression ring 520. Thus, embodiment 500 can allow for flexible installation arrangements of the IBC 510.

It is obvious to those skilled in the art that many changes can be made to the details of the embodiments described above without departing from the underlying principles of the invention. Thus, the scope of the present invention should be determined only by the following claims.