Control Systems and Methods for Monitoring Electrolyzer Cell Stack Conditions and Extending Operational Life

This nonprovisional application claims the benefit and priority, under 35 U.S.C. § 119(e) and any other applicable laws or statutes, to U.S. Provisional Application Ser. No. 63/346,640 filed on May 27, 2022, the entire disclosure of which is hereby expressly incorporated herein by reference.

The present disclosure generally relates to electrolysis systems, in particular control systems and methods for monitoring conditions of electrolyzer cell stacks in an electrolysis system.

In electrolysis systems, degradation of the electrolyzer cell stacks may occur, causing reduced potential lifespan of the stacks. For example, excessive amounts of voltage, current, temperature, pressure, fluid flow rate, fluid conductivity, and gas humidity may lead to damage of the electrolyzer cell stacks, thus reducing their lifespan. As such, monitoring of various operating parameters of the system is useful for maximizing the lifespan of the electrolyzer cell stacks. Typical monitoring of various operating parameters inside a cell stack as well as within the system as a whole remains difficult and invasive to confirm directly (e.g. without disassembly and inspection). Accordingly, it would be advantageous to provide a minimally invasive system of monitoring system performance, diagnosing system problems, and predicting a lifespan of electrolyzer cell stacks.

The present disclosure is directed to systems and methods for monitoring electrolysis system conditions and extending operational life of the electrolysis system. In particular, the present disclosure utilizes raw measurement sensors, soft sensors, and historical data to diagnosis abnormal behavior and predict life of the electrolysis system components. The use of soft sensors and historical data at various locations within the system for such diagnoses and predictions eliminates the need for additional sensors and measuring devices within the system, and also leverages existing reliable sensing technologies in obtaining empirical data for analysis. Thus, the systems and methods described herein allow for lifespan extension while minimizing invasiveness, as well as eliminating the need to disassemble and inspect certain components of the system.

According to the present disclosure, a method of monitoring at least one operating parameter in an electrolysis system for optimizing the operating lifespan of at least one component of the electrolysis system is disclosed. The method includes measuring the at least one operating parameter at a first location of the electrolysis system with a first sensor to obtain a first raw measurement of the at least one operating parameter, the first raw measurement including at least one of a first value of the at least one operating parameter or a first rate of change of the at least one operating parameter, and receiving, at a controller, the first raw measurement, the controller including at least one computer-readable storage medium.

In some embodiments, the method further includes comparing, via the controller, at least one of (i) the first value of the first raw measurement to a predetermined nominal measurement or (ii) the first rate of change of the first raw measurement to a predetermined nominal rate of change, diagnosing, via the controller, at least one abnormality of the at least one component of the system based on at least one of (i) the first value of the first raw measurement differing from the predetermined nominal measurement by a first amount or (ii) the first rate of change of the first raw measurement differing from the predetermined nominal rate of change by a first rate amount, and, in response to the diagnosis of the at least one abnormality, outputting a first message, via the controller, to an operator of the electrolysis system indicative of the at least one abnormality.

In some embodiments, the method further includes determining, via the controller, a predicted lifespan of the at least one component including a predicted length of lifespan based on the first raw measurement, comparing, via the controller, the predicted length of lifespan with a predetermined length of lifespan of the at least one component, and, in response to the predetermined length of lifespan being different than the predicted length of lifespan by a first amount of time, outputting a second message, via the controller, to the operator of the electrolysis system indicative of the predicted lifespan.

In some embodiments, the method further includes calculating, via the controller, a first calculated measurement of the at least one operating parameter at a second location of the electrolysis system different than the first location, the first calculated measurement including at least one of a first calculated value of the at least one operating parameter or a first calculated rate of change of the at least one operating parameter. The diagnosis of the at least one abnormality is further based on at least one of (i) the first calculated value of the first calculated measurement differing from a predetermined nominal calculated measurement by a first calculated amount or (ii) the first calculated rate of change of the first calculated measurement differing by a first calculated rate amount. The determining, via the controller, of the predicted lifespan of the at least one component including the predicted length of lifespan is based on at least one of the first raw measurement and the first calculated measurement.

In some embodiments, the method further includes, in response to the predetermined length of time differing from the predicted length of lifespan by a second amount of time that is greater than the first amount of time, shutting down the electrolysis system.

In some embodiments, the diagnosis of the at least one abnormality is further based on the at least one of a total age of the electrolysis system, a total amount of hydrogen already produced by the electrolysis system, or a present operating condition of the electrolysis system.

In some embodiments, the at least one operating parameter includes at least one of voltage, current, temperature, pressure, fluid flow rate, fluid conductivity, or gas humidity, and the at least one component includes at least one of an electrolyzer cell stack, a pump, a heat exchanger, a tank, or a valve of the electrolysis system.

In some embodiments, the method further includes receiving, at the controller, at least one historical measurement of the at least one operating parameter at the first location of the electrolysis system that was measured by the first sensor prior to the first raw measurement, and calculating, via the controller, a second calculated measurement of the at least one operating parameter at the second location based at least in part on the first raw measurement and the at least one historical measurement.

In some embodiments, the diagnosis of the at least one abnormality is further based on the at least one historical measurement differing from the predetermined nominal measurement by a third amount, and the determining of the predicted lifespan is further based on the first raw measurement, the first calculated measurement, the at least one historical measurement, and the second calculated measurement.

In some embodiments, the method further includes measuring the at least one operating parameter at a plurality of additional first locations of the electrolysis system different than the first location with a plurality of additional sensors to obtain an additional raw measurement of the at least one operating parameter at each additional location of the plurality of additional locations to establish a plurality of additional raw measurements, and receiving, at the controller, the plurality of additional raw measurements. The method may further include calculating, via the controller, a plurality of additional calculated measurements of the at least one operating parameter at respective additional second locations of the electrolysis system different than the first location, the plurality of additional first locations, and the additional second locations based at least in part on the plurality of additional raw measurements, and determining, via the controller, the predicted lifespan of the electrolyzer cell stack based on the first raw measurement, the first calculated measurement, the at least one historical measurement, the second calculated measurement, the plurality of additional raw measurements, and the plurality of additional calculated measurements.

An electrolysis system according to a further aspect of the present disclosure includes at least one component including at least one of a pump, a heat exchanger, a tank, or a valve, an electrolyzer cell stack configured to separate input water into hydrogen and oxygen, a controller including at least one computer-readable storage medium, and a first sensor. The first sensor is operably connected to the controller and configured to measure at least one operating parameter at a first location of the electrolysis system to obtain a first raw measurement of the at least one operating parameter, the first raw measurement including at least one of a first value of the at least one operating parameter or a first rate of change of the at least one operating parameter.

In some embodiments, the controller is configured to compare at least one of (i) the first value of the first raw measurement to a predetermined nominal measurement or (ii) the first rate of change of the first raw measurement to a predetermined nominal rate of change, diagnose at least one abnormality of the at least one component of the system based on at least one of (i) the first value of the first raw measurement differing from the predetermined nominal measurement by a first amount or (ii) the first rate of change of the first raw measurement differing from the predetermined nominal rate of change by a first rate amount, and, in response to the diagnosis of the at least one abnormality, output a first message, via the controller, to an operator of the electrolysis system indicative of the at least one abnormality.

In some embodiments, the controller is further configured to determine a predicted lifespan of the at least one component including a predicted length of lifespan based on the first raw measurement, compare, the predicted length of lifespan with a predetermined length of lifespan of the at least one component, and, in response to the predetermined length of lifespan being different than the predicted length of lifespan by a first amount of time, output a second message to the operator of the electrolysis system indicative of the predicted lifespan.

In some embodiments, the electrolysis system further includes a first soft sensor configured to calculate a first calculated measurement of the at least one operating parameter at a second location of the electrolysis system different than the first location, the first calculated measurement including at least one of a first calculated value of the at least one operating parameter or a first calculated rate of change of the at least one operating parameter. The diagnosis of the at least one abnormality via the controller is further based on at least one of (i) the first calculated value of the first calculated measurement differing from a predetermined nominal calculated measurement by a first calculated amount or (ii) the first calculated rate of change of the first calculated measurement differing by a first calculated rate amount. The determining of the predicted lifespan of the at least one component via the controller including the predicted length of lifespan is based on at least one of the first raw measurement and the first calculated measurement.

In some embodiments, the at least one operating parameter includes an amount of conductivity of water flowing through the electrolysis system, and the amount of conductivity of the water is inversely proportional to the predicted lifespan of the electrolyzer cell stack.

In some embodiments, the amount of conductivity of the water is determined based on an ion concentration of the water.

In some embodiments, the ion concentration of the water includes measurements of a concentration of at least one of fluorine, platinum, iron, calcium, chromium, and nickel.

In some embodiments, the first location of the electrolysis system is located downstream of the electrolyzer stack and the second location of the electrolysis system is located downstream of the first location in the electrolyzer system.

In some embodiments, the electrolysis system further includes a hydrogen separator located downstream of and fluidically connected to the electrolyzer stack of the electrolysis system, a polishing loop fluidically connected to the hydrogen separator and configured to treat drain flow from the hydrogen separator for recirculation into an oxygen separator, the oxygen separator located downstream of and fluidically connected to the electrolyzer stack and downstream of and fluidically connected to the polishing loop, and a water circulation pump located downstream of and fluidically connected to the oxygen separator and configured to direct water from the oxygen separator to an input of the electrolyzer stack.

In some embodiments, the first location of the electrolysis system is located along a first fluidic line that extends between and interconnects the polishing loop and the oxygen separator, and the second location of the electrolysis system is located along a second fluidic line that extends between and interconnects the water circulation pump and the input of the electrolyzer.

In some embodiments, the electrolysis system further includes a second, third, and fourth sensor arranged within the polishing loop and each operably connected to the controller, each of the second, third, and fourth sensors being configured to measure the water conductivity at a third, fourth, and fifth location within the polishing loop, respectively, the second, third, and fourth sensors being configured to obtain second, third, and fourth raw measurements of the water conductivity, respectively, and send the second, third, and fourth raw measurements to the controller.

The electrolysis system may further include a second soft sensor configured for calculations regarding a sixth location directly downstream of the hydrogen separator, a third soft sensor configured for calculations regarding a seventh location directly upstream of the oxygen separator, and a fourth soft sensor configured for calculations regarding an eighth location along a third fluidic line that extends from the water circulation pump to the polishing loop, each of the second, third, and fourth soft sensors being configured to calculate second, third, and fourth calculated measurements of the water conductivity at the sixth, seventh, and eighth locations, respectively, based at least in part on the first, second, third, and fourth raw measurements. The controller is further configured to determine the predicted lifespan of the at least one component including the predicted length of lifespan based on the first, second, third, and fourth raw measurements and the first, second, third, and fourth calculated measurements.

In some embodiments, the diagnosis of the at least one abnormality is further based on the at least one of a total age of the electrolysis system, a total amount of hydrogen already produced by the electrolysis system, or a present operating condition of the electrolysis system.

Electrochemical cells and electrolytic cells provide chemical reactions that include electricity. For example, a fuel cell uses hydrogen and oxygen to produce electricity. An electrolyzer uses water and electricity to produce hydrogen and oxygen.

An electrolyzer comprises one or more electrolytic cells that utilize electricity to chemically produce substantially pure hydrogen and oxygen from water. Often the electrical source for the electrolyzer is produced from power or energy generation systems, including renewable energy systems such as wind, solar, hydroelectric, and geothermal sources for the production of green hydrogen. In turn, the pure hydrogen produced by the electrolyzer is often utilized as a fuel or energy source for those same power generation systems, such as fuel cell systems.

The typical electrolytic cell, also referred to as an “electrolyzer cell,” is comprised of many assemblies compressed and bound into a stack. An electrolytic cell includes a multi-component membrane electrode assembly (MEA) that has an anode, a cathode, and an electrolyte. Typically, the anode, cathode, and electrolyte of the membrane electrode assembly (MEA) are configured in a multi-layer arrangement that enables the electrochemical reaction to produce hydrogen via contact with one or more gas diffusion layers. A gas diffusion layer (GDL) and/or a porous transport layer (PTL) is typically located on one or both sides of the MEA. Bipolar plates (BPP) often reside on either side of the GDLs and separate the individual electrolytic cells of the stack from one another.

The present disclosure is directed to systems, assemblies, and methods used to predict and optimize the lifespan of electrolyzer cells and/or stacks in an electrolysis system. The present systems and methods include utilizing raw measurements, soft sensors, and historical data to predict the lifespans of the electrolyzer cells and/or stacks. According to a first aspect of the present disclosure as shown in, a control systemfor monitoring (“a control system”) at least one operating parameterin an electrolysis systemis shown. The at least one operating parameter may be for forecasting a lifespan of an electrolyzer cell stack,of the electrolysis system(see). A person skilled in the art will understand that the electrolysis systemof the first aspect of the present disclosure, as shown in, may be configured similarly to the exemplary electrolysis systemshown inand described below, or may include additional or fewer components as necessitated by the design requirements of the electrolysis system.

As shown in, electrolysis systemsare typically configured to utilize water and electricity to produce hydrogen and oxygen. An electrolysis systemstypically includes one or more electrolyzer cellsthat utilize electricity to chemically produce substantially pure hydrogenand oxygenfrom deionized water. Often the electrical source for the electrolysis systemsis produced from power or energy generation systems, including renewable energy systems such as wind, solar, hydroelectric, and geothermal sources for the production of green hydrogen. In turn, the pure hydrogen produced by the electrolysis systemsis often utilized as a fuel or energy source for those same power generation systems, such as fuel cell systems. Alternatively, the pure hydrogen produced by the electrolysis systemsmay be stored for later use.

The typical electrolyzer cell, or electrolytic cell, is comprised of multiple assemblies compressed and bound into a single assembly, and multiple electrolyzer cellsmay be stacked relative to each other, along with bipolar plates (BPP),therebetween, to form an electrolyzer cell stack (for example, electrolyzer cell stacks,in). Each electrolyzer cell stack,may house a plurality of electrolyzer cellsconnected together in series and/or in parallel. The number of electrolyzer cell stack,in the electrolysis systemscan vary depending on the amount of power required to meet the power need of any load (e.g., fuel cell stack). The number of electrolyzer cellsin an electrolyzer cell stack,can vary depending on the amount of power required to operate the electrolysis systemsincluding the electrolyzer cell stack,.

An electrolyzer cellincludes a multi-component membrane electrode assembly (MEA)that has an electrolyteE, an anodeA, and a cathodeC. Typically, the anodeA, cathodeC, and electrolyteE of the membrane electrode assembly (MEA)are configured in a multi-layer arrangement that enables the electrochemical reaction to produce hydrogen and/or oxygen via contact of the water with one or more gas diffusion layers,. The gas diffusion layers (GDL),, which may also be referred to as porous transport layers (PTL), are typically located on one or both sides of the MEA. Bipolar plates (BPP),often reside on either side of the GDLs and separate the individual electrolyzer cellsof the electrolyzer cell stack,from one another. One bipolar plateand the adjacent gas diffusion layers,and MEAcan form a repeating unit.

As shown in, an exemplary electrolysis systemcan include two electrolyzer cell stacks,and a fluidic circuitFC including the various fluidic pathways shown inthat is configured to circulate, inject, and purge fluid and other components to and from the electrolysis systems. A person skilled in the art would understand that one or a variety of a number of components within the fluidic circuitFC, as well as more or less than two electrolyzer cell stacks,, may be utilized in the electrolysis systems. For example, the electrolysis systemsmay include one electrolyzer cell stack, and in other examples, the electrolysis systemsmay include three or more electrolyzer cell stacks.

The electrolysis systemsmay include one or more types of electrolyzer cell stacks,therein. In an illustrative illustrated embodiment, a polymer electrolyte membrane (PEM) electrolyzer cellmay be utilized in the stacks,. A PEM electrolyzer celltypically operates at about 4° C. to about 150° C., including any specific or range of temperatures comprised therein. A PEM electrolyzer cellalso typically functions at about 100 bar or less, but can go up to about 1000 bar (including any specific or range of pressures comprised therein), which reduces the total energy demand of the system. A standard electrochemical reaction that occurs in a PEM electrolyzer cellto produce hydrogen is as follows.

Anode: 2HO→O+4H4

Cathode: 4H4→2H

Overall: 2HO (liquid)→2H+O

Additionally, a solid oxide electrolyzer cellmay be utilized in the electrolysis systems. A solid oxide electrolyzer cellwill function at about 500° C. to about 1000° C., including any specific or range of temperatures comprised therein. A standard electrochemical reaction that occurs in a solid oxide electrolyzer cellto produce hydrogen is as follows.

Anode: 2O→O4

Cathode: 2HO→4+2H+2O

Overall: 2HO (liquid)→2H+O

Moreover, an AEM electrolyzer cellmay utilized, which uses an alkaline media. An exemplary AEM electrolyzer cellis an alkaline electrolyzer cell. Alkaline electrolyzer cellscomprise aqueous solutions, such as potassium hydroxide (KOH) and/or sodium hydroxide (NaOH), as the electrolyte. Alkaline electrolyzer cellstypically perform at operating temperatures ranging from about 0° C. to about 150° C., including any specific or range of temperatures comprised therein. Alkaline electrolyzer cellgenerally operate at pressures ranging from about 1 bar to about 100 bar, including any specific or range of pressures comprised therein. A typical hydrogen-generating electrochemical reaction that occurs in an alkaline electrolyzer cellis as follows.

Anode: 4OH→O+2HO+4

Cathode: 4HO+4→2H+4OH

Overall: 2HO2H+O

As shown in, the electrolyzer cell stacks,include one or more electrolyzer cellsthat utilize electricity to chemically produce substantially pure hydrogen and oxygen from water. In turn, the pure hydrogen produced by the electrolyzer may be utilized as a fuel or energy source. As shown in, the electrolyzer cell stack,outputs the produced hydrogen along a fluidic connecting lineto a hydrogen separator, and also outputs the produced oxygen along a fluidic connecting lineto an oxygen separator.

The hydrogen separatormay be configured to output pure hydrogen gas and also send additional output fluid to a hydrogen drain tank, which then outputs fluid to a deionized water drain. The oxygen separatormay output fluid to an oxygen drain tank, which in turn outputs fluid to a deionized water drain. A person skilled in the art would understand that certain inputs and outputs of fluid may be pure water or other fluids such as coolant or byproducts of the chemical reactions of the electrolyzer cell stacks,. For example, oxygen and hydrogen may flow away from the cell stacks,to the respective separators,. The systemmay further include a rectifierconfigured to convert electricityflowing to the cell stacks,from alternating current (AC) to direct current (DC).

The deionized water drains,each output to a deionized water tank, which is part of a polishing loopof the fluidic circuitFC, as shown in. Water with ion content can damage electrolyzer cell stacks,when the ionized water interacts with internal components of the electrolyzer cell stacks,. The polishing loop, shown in greater detail in, is configured to deionize the water such that it may be utilized in the cell stacks,and not damage the cell stacks,.