METHOD OF OPERATING AN ELECTROLYZER

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 63/643,725 filed May 7, 2024, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

Electrolysis is process for converting electrical energy into chemical energy for large-scale applications and is a process in which an electric current forces a redox reaction. In water electrolysis, water is broken down into hydrogen at the cathode and oxygen at the anode of the electrolytic cell via the reaction: 2 H₂O (l/g)→2 H₂(g)+O₂(g).

Gas production during water electrolysis scales proportionally with current density. Heat generation within the cell scales with the square of the current density. Electrochemical cells work most reliably when the internal pressures and temperatures are maintained relatively constant. Large fluctuations in gas production can result in large pressure fluctuations within the cell. Large changes in heat generation can drive large temperature changes.

There is a need for methods and systems for managing the temperature of electrochemical cells and the pressure of gas generated during water electrolysis, especially in usage scenarios that include a variable power supply to the electrochemical cells.

SUMMARY OF THE INVENTION

Various aspects of the present invention provide a method of operating an electrolyzer including an electrochemical cell. The method includes detecting and/or causing a change in an electrical output of an electrolyzer power source electrically connected to an anode and a cathode of the electrochemical cell. The electrochemical cell includes the anode, the cathode, and a separator between the anode and cathode. The electrochemical cell includes an anode compartment that encloses the anode, a cathode compartment that encloses the cathode, a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment. The electrochemical cell also includes an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment. The method includes, responsive to the detected and/or caused change in the electrical output, feedforward controlling the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range.

Various aspects of the present invention provide a method of operating an electrolyzer including an electrochemical cell. The method includes detecting and/or causing a change in an electrical output of an electrolyzer power source electrically connected to an anode and a cathode of the electrochemical cell. The electrochemical cell includes the anode, the cathode, and a separator between the anode and cathode. The electrochemical cell includes an anode compartment that encloses the anode and a cathode compartment that encloses the cathode. The electrochemical cell includes a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment. The electrochemical cell also includes an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment. The method includes, responsive to the detected and/or caused change in the electrical output, feedforward controlling the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range. The method includes detecting a change in a pressure of the cathode electrolyte output stream gas collector, a pressure of the anode electrolyte output stream gas collector, or a combination thereof. The method also includes, responsive to the detected change in pressure, feedback controlling the electrolyzer to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range. The feedforward controlling the electrolyzer and the feedback controlling the electrolyzer include modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof.

Various aspects of the present invention provide a method of operating an electrolyzer including an electrochemical cell. The method includes detecting and/or causing a change in an electrical output of an electrolyzer power source electrically connected to an anode and a cathode of the electrochemical cell. The electrochemical cell includes the anode, the cathode, and a separator between the anode and cathode, wherein the anode and the cathode are electrically connected to the electrolyzer power source. The electrochemical cell includes an anode compartment that encloses the anode. The electrochemical cell includes a cathode compartment that encloses the cathode. The electrochemical cell includes a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment. The electrochemical cell also includes an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment. The method includes, responsive to the detected and/or caused change in the output, feedforward controlling the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range and/or to maintain a temperature of the separator of the electrochemical cell within a predetermined temperature range. The method includes detecting a change in a temperature of the anode electrolyte output stream, a temperature of the cathode electrolyte output stream, a pressure of the cathode electrolyte output stream gas collector, a pressure of the anode electrolyte output stream gas collector, or a combination thereof. The method also includes, responsive to the detected change in temperature and/or pressure, feedback controlling the electrolyzer to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range and/or to maintain the temperature of the separator of the electrochemical cell within the predetermined temperature range. In various aspects, the feedforward controlling the electrolyzer and the feedback controlling the electrolyzer include modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof.

Various aspects of the present invention provide an electrolyzer system. The electrolyzer system includes an electrochemical cell in an electrolyzer. The electrochemical cell includes an anode, a cathode, and a separator between the anode and cathode. The electrochemical cell includes an anode compartment that encloses the anode and a cathode compartment that encloses the cathode. The electrochemical cell includes a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment. The electrochemical cell also includes an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment. The electrolyzer system optionally includes a detector that is configured to detect a change in an electrical output of an electrolyzer power source that is electrically connected to the anode and the cathode of the electrochemical cell. The electrolyzer also includes a feedforward control system that, responsive to the detected change in output and/or a caused change in output, is configured to feedforward control the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range.

Various aspects of the present invention provide an electrolyzer system that includes an electrochemical cell in an electrolyzer. The electrochemical cell includes an anode, a cathode, and a separator between the anode and cathode. The electrochemical cell includes an anode compartment that encloses the anode and a cathode compartment that encloses the cathode. The electrochemical cell includes a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment. The electrochemical cell also includes an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment. The electrolyzer system optionally includes a detector that is configured to detect a change in an electrical output of an electrolyzer power source that is electrically connected to the anode and the cathode of the electrochemical cell. The electrolyzer system includes a feedforward control system that, responsive to the detected change in output and/or a caused change in output, is configured to feedforward control the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range. The electrolyzer system includes a detector that is configured to detect a change in a pressure of the cathode electrolyte output stream gas collector, a pressure of the anode electrolyte output stream gas collector, or a combination thereof. The electrolyzer system also includes a feedback control system that, responsive to the detected change in pressure, is configured to feedback control the electrolyzer to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range.

Various aspects of the present invention provide an electrolyzer system including an electrochemical cell in an electrolyzer. The electrochemical cell includes an anode, a cathode, and a separator between the anode and cathode, wherein the anode and the cathode are electrically connected to an electrolyzer power source. The electrochemical cell includes an anode compartment that encloses the anode. The electrochemical cell includes a cathode compartment that encloses the cathode. The electrochemical cell includes a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment. The electrochemical cell also includes an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment. The electrolyzer system optionally includes a detector that is configured to detect a change in an electrical output of an electrolyzer power source that is electrically connected to the anode and the cathode of the electrochemical cell. The electrolyzer system includes a feedforward control system that, responsive to the detected change in output and/or a caused change in output, is configured to feedforward control the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range and/or to maintain a temperature of the separator of the electrochemical cell within a predetermined temperature range. The electrolyzer system includes a detector that is configured to detect a change in a temperature of the anode electrolyte output stream, a temperature of the cathode electrolyte output stream, a pressure of the cathode electrolyte output stream gas collector, a pressure of the anode electrolyte output stream gas collector, or a combination thereof. The electrolyzer system also includes a feedback control system that, responsive to the detected change in temperature and/or pressure, is configured to feedback control the electrolyzer to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range and/or to maintain the temperature of the separator within the predetermined temperature range.

Various aspects of the present invention provide a tangible non-transitory computer readable medium, the computer readable medium storing one or more computer applications that, when executed by one or more processors, causes the one or more processors to perform a method including determining whether a change is detected and/or caused in an electrical output of an electrolyzer power source electrically connected to an anode and a cathode of an electrochemical cell. The electrochemical cell includes the anode, the cathode, and a separator between the anode and cathode. The electrochemical cell includes an anode compartment that encloses the anode and a cathode compartment that encloses the cathode. The electrochemical cell includes a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment. The electrochemical cell also includes an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment. The method also includes, responsive to determining that a change is detected and/or caused in the electrical output of the electrolyzer power source, feedforward controlling the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range.

Various aspects of the present invention provide a tangible non-transitory computer readable medium, the computer readable medium storing one or more computer applications that, when executed by one or more processors, causes the one or more processors to perform a method including determining whether a change is detected and/or caused in an electrical output of an electrolyzer power source electrically connected to an anode and a cathode of an electrochemical cell. The electrochemical cell includes the anode, the cathode, and a separator between the anode and cathode. The electrochemical cell includes an anode compartment that encloses the anode and a cathode compartment that encloses the cathode. The electrochemical cell includes a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment. The electrochemical cell also includes an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment. The method includes, responsive to determining that a change is detected and/or caused in the electrical output of the electrolyzer power source, feedforward controlling the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range. The method includes determining whether a change in a pressure of the cathode electrolyte output stream gas collector, a pressure of the anode electrolyte output stream gas collector, or a combination thereof, is detected. The method also includes, responsive to determining that a change is detected in the pressure, feedback controlling the electrolyzer to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range.

Various aspects of the present invention provide a tangible non-transitory computer readable medium, the computer readable medium storing one or more computer applications that, when executed by one or more processors, causes the one or more processors to perform a method including determining whether a change is detected and/or caused in an electrical output of an electrolyzer power source electrically connected to an anode and a cathode of an electrochemical cell. The electrochemical cell includes the anode, the cathode, and a separator between the anode and cathode, wherein the anode and the cathode are electrically connected to the electrolyzer power source. The electrochemical cell includes an anode compartment that encloses the anode. The electrochemical cell includes a cathode compartment that encloses the cathode. The electrochemical cell includes a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment. The electrochemical cell also includes an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment. The method includes, responsive to determining that a change is detected and/or caused in the electrical output of the electrolyzer power source, feedforward controlling the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range and/or to maintain a temperature of the separator of the electrochemical cell within a predetermined temperature range. The method includes determining whether a change in a temperature of the anode electrolyte output stream, a temperature of the cathode electrolyte output stream, a pressure of the cathode electrolyte output stream gas collector, a pressure of the anode electrolyte output stream gas collector, or a combination thereof, is detected. The method also includes, responsive to determining that a change is detected in the temperature and/or pressure, feedback controlling the electrolyzer to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range and/or to maintain the temperature of the separator within the predetermined temperature range.

Various aspects of the presently disclosed method of operating an electrolyzer have certain advantages over other electrolyzer operation methods. For example, in various aspects, the presently disclosed method can maintain produced gas pressures at a more consistent pressure and/or can maintain the temperature of the electrochemical cell at a more consistent temperature, as compared to other methods. In various aspects, the presently disclosed method can respond more quickly to abrupt variation in the power source of the electrolyzer, enabling the electrolyzer to be used with environmentally-friendly but variable power sources such as solar power or wind power, with electricity supplied from a battery (e.g., lithium-ion, sodium-ion, flow battery, and the like), or to be used with power sources that are varied based on the price of electricity. In various aspects of the presently disclosed method, the combination of feedforward and feedback control can provide a combination of fast responses to changes in the power source as well as continuous fine-tuning of the produced gas pressures and/or the temperature of the electrochemical cell.

In various aspects of the presently disclosed method, by maintaining the produced gas pressure and/or electrochemical cell temperature within narrower ranges, the method can enable a longer lifetime of the separator of the electrochemical cell and/or can enable more consistently efficient operation of the electrochemical cell. In various aspects, by maintaining the produced gas pressure and/or electrochemical cell temperature within narrower ranges, gas sampling and real-time analysis is simplified. In various aspects, by maintaining the produced gas pressure and/or electrochemical cell temperature within narrower ranges, downstream compressors and/or other downstream units can operate more efficiently and for a longer duration before mechanical failures or needed maintenance. In various aspects, maintaining the produced gas pressure within narrower ranges maintains a differential pressure between the anode and cathode side of the separator, which can increase the lifetime of the separator, decrease or avoid gas crossover issues, or a combination thereof.

BRIEF DESCRIPTION OF THE FIGURES

The drawings illustrate generally, by way of example, but not by way of limitation, various aspects of the present invention.

FIG. 1 illustrates an electrolyzer system, in accordance with various aspects.

FIG. 2 illustrates the current, anode outlet temperature, and cathode outlet temperature data from an electrolyzer as the current density was rapidly driven from 1.5 A/cm² to 100 mA/cm² and back up to 1.5 A/cm², in accordance with various aspects.

FIG. 3 illustrates the current, anode outlet pressure, and cathode outlet pressure data from an electrolyzer as the current density was rapidly driven from 1.5 A/cm² to 100 mA/cm² and back up to 1.5 A/cm², in accordance with various aspects.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to certain aspects of the disclosed subject matter. While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that the exemplified subject matter is not intended to limit the claims to the disclosed subject matter.

Throughout this document, values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of “about 0.1% to about 5%” or “about 0.1% to 5%” should be interpreted to include not just about 0.1% to about 5%, but also the individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. The statement “about X to Y” has the same meaning as “about X to about Y,” unless indicated otherwise. Likewise, the statement “about X, Y, or about Z” has the same meaning as “about X, about Y, or about Z,” unless indicated otherwise.

In this document, the terms “a,” “an,” or “the” are used to include one or more than one unless the context clearly dictates otherwise. The term “or” is used to refer to a nonexclusive “or” unless otherwise indicated. The statement “at least one of A and B” or “at least one of A or B” has the same meaning as “A, B, or A and B.” In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting; information that is relevant to a section heading may occur within or outside of that particular section.

In the methods described herein, the acts can be carried out in a specific order as recited herein. Alternatively, in any aspect(s) disclosed herein, specific acts may be carried out in any order without departing from the principles of the invention, except when a temporal or operational sequence is explicitly recited. Furthermore, specified acts can be carried out concurrently unless explicit claim language recites that they be carried out separately or the plain meaning of the claims would require it. For example, a claimed act of doing X and a claimed act of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process.

The term “about” as used herein can allow for a degree of variability in a value or range, for example, within 10%, within 5%, or within 1% of a stated value or of a stated limit of a range, and includes the exact stated value or range.

The term “substantially” as used herein refers to a majority of, or mostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%. The term “substantially free of” as used herein can mean having none or having a trivial amount of, such that the amount of material present does not affect the material properties of the composition including the material, such that about 0 wt % to about 5 wt % of the composition is the material, or about 0 wt % to about 1 wt %, or about 5 wt % or less, or less than, equal to, or greater than about 4.5 wt %, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.01, or about 0.001 wt % or less, or about 0 wt %.

Method of Operating an Electrolyzer

Various aspects of the present invention provide a method of operating an electrolyzer. The electrolyzer includes an electrochemical cell. The method can include detecting and/or causing a change in an electrical output of an electrolyzer power source electrically connected to an anode and a cathode of the electrochemical cell. The detecting can be performed in any suitable way, such as via an instrument that monitors the electrical output and reports a detected change, based on an electronic setpoint, or a combination thereof. The electrochemical cell can include the anode, the cathode, and a separator between the anode and cathode. The anode and the cathode are electrically connected to the electrolyzer power source. The electrochemical cell can include an anode compartment that encloses the anode. The electrochemical cell can include a cathode compartment that encloses the cathode. The electrochemical cell can include a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment. The electrochemical cell can include an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment. The method can include, responsive to the detected and/or caused change in the electrical output, feedforward controlling the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range.

The predetermined pressure range of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector can be 0 bar gauge (barg) to 40 barg (0 kPa to 4000 kPa), 0 barg to 30 barg, 0 barg to 20 barg, 0 barg to 5 barg, 0 barg to 3 barg, 0 barg to 1 barg, 0 barg to 0.5 barg, or less than or equal to 4000 KPa and greater than or equal to 0 kPa and less than, equal to, or greater than 100 kPa, 250, 500, 1,000, 1,500, 2,000, 2,500, 3,000, or 3,500 kPa.

The feedforward controlling of the electrolyzer can be performed in any suitable way. The feedforward controlling of the electrolyzer can include modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof.

In various aspects, the method further includes, responsive to the detected and/or caused change in the electrical output, feedforward controlling the electrolyzer to maintain a temperature of the separator of the electrochemical cell within a predetermined temperature range.

The predetermined temperature range of the separator of the electrochemical cell can be 10° C. to 140° C., or 40° C. to 100° C., or 50° C. to 95° C., or 85° C. to 95° C., or less than or equal to 140° C. and greater than or equal to 10° C. and less than, equal to, or greater than 15° C., 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 72, 74, 76, 78, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 92, 94, 96, 98, 100, 105, 110, 115, 120, 125, 130, or 135° C.

The method can include detecting a change in a pressure of the cathode electrolyte output stream gas collector, a pressure of the anode electrolyte output stream gas collector, or a combination thereof. The method can include, responsive to the detected change in pressure, feedback controlling the electrolyzer to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range.

In various aspects, the method can further include detecting a change in a temperature of the anode electrolyte output stream, a temperature of the cathode electrolyte output stream, or a combination thereof. The method can include responsive to the detected change in temperature, feedback controlling the electrolyzer to maintain the temperature of the separator of the electrochemical cell within the predetermined temperature range.

In various aspects, the method includes using knowledge of the cell's gas production rates and power dissipation rates as a function of current density to set the inlet stream temperatures such that the outlet stream temperatures from both the anode and cathode remain within an small preselected range and to set the anode-and cathode-side ventilation systems' backpressure controllers to efficiently accommodate rapid changes in produced gas pressure by the electrochemical cell.

In various aspects, pressure of the anode or cathode output stream gas collector can change based on a variable temperature of the anode or cathode electrolyte output stream, such as during startup conditions with the outlet temperature warming up. In various aspects, the anode of cathode electrolyte output stream temperature can be steady.

In various aspects, the method includes performing the method using not more than one of the electrochemical cell. In other aspects, the method includes performing the method using a multiplicity of the electrochemical cells in the electrolyzer. The multiplicity of electrochemical cells can be arranged in the form of a stack of the electrochemical cells. With a multiplicity of cells, the inputs and outputs of the cathode compartments can be combined, such that the cathode electrolyte input stream can flow to the cathode compartment of each of the electrochemical cells, and the cathode electrolyte output stream can flow from the cathode compartment of each of the electrochemical cells. The cathode electrolyte output stream gas collector can collect gas formed by the cathode of each of the electrochemical cells. The inputs and outputs of the anode compartments can be combined, such that the anode electrolyte input stream can flow to the anode compartment of each of the electrochemical cells, and the anode electrolyte output stream can flow from the anode compartment of each of the electrochemical cells. The anode electrolyte output stream gas collector can collect gas formed by the anode of each electrochemical cells. In various aspects, the anode and cathode can be fed from the same stream, such as in a filter-press style electrolyzer. The electrolyte stream can be divided into anode and cathode electrolyte streams internally to the cell stack (e.g., filter-press) or externally to a cell stack. The electrolyte stream is maintained as two separate streams after contacting with the anode/cathode to prevent mixing of produced hydrogen and oxygen from the electrolysis.

The feedforward controlling the electrolyzer and/or the feedback controlling (in aspects including feedback controlling) the electrolyzer can independently include modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof. In various aspects, by referring to a lookup table, an operator can set the inlet stream temperature and/or outlet pressure control parameters contained in their respective control elements as a function of current density such that the outlet stream temperatures, the cathode pressures, the anode pressures, or a combination thereof, do not fluctuate significantly. Alternatively or additionally, inlet stream temperature and/or outlet pressure control parameters can be set automatically as a function of current density, such that the outlet stream temperatures, the cathode pressures, the anode pressures, or a combination thereof, do not fluctuate significantly.

The feedforward controlling can be performed by a feedforward control system. The feedforward controlling can be performed by a programmable logic controller (PLC), by a distributed control system (DCS), or a combination thereof. The feedforward controlling can include determining the current density of the electrochemical cell from the determined and/or caused electrical output, and using a relationship between current density and a temperature of the separator and/or a relationship between current density and produced gas pressure of the electrochemical cell to determine to what extent to perform modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof, in order to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range and/or to maintain the temperature of the separator within the predetermined temperature range. In various aspects, the method can further include determining the relationship between current density and a temperature of the separator, the relationship between current density and produced gas pressure of the electrochemical cell, the relationship between current density and produced gas pressure of the electrochemical cell and temperature of the separator, or a combination thereof.

In various aspects, the feedforward controlling can be performed at the same rate as a rate at which the feedback controlling is performed. As used herein, the rate at which the controlling is performed refers to the delay between the time a condition is inputted to the control system and the time the control system takes to complete a respective adjustment to the electrolyzer system. In various aspects, the feedforward controlling can be performed at a rate that is greater than a rate at which the feedback controlling is performed. For example, the feedforward controlling can be performed at a rate that is at least 1.1 times a rate at which the feedback controlling is performed, or a rate that is 2 to 1,000 times a rate at which the feedback controlling is performed, or less than or equal to 1,000 times and greater than or equal to 2 times and less than, equal to, or greater than 3 times, 4, 5, 10, 15, 20, 50, 100, or 500 times.

The feedback controlling can be performed by a feedback control system. The feedback controlling can be performed by a proportional-integral-derivative (PID) controller. The feedback controlling can includes modifying a pressure valve configuration on the cathode electrolyte output stream gas collector and/or modifying a pressure valve configuration on the anode electrolyte output stream gas collector opening valves to change the pressure of the cathode electrolyte output stream gas collector and/or anode electrolyte output stream gas collector, and/or modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, or a combination thereof, to change the temperature of the separator. The feedback controlling can be performed at the same rate at which the feedforward controlling is performed. The feedback controlling can be performed at a lower rate than a rate at which the feedforward controlling is performed. The feedback controlling can be performed at a rate that is less than 0.9 times a rate at which the feedforward controlling is performed, or at a rate that is 0.001 to 0.9 times a rate at which the feedforward controlling is performed, or less than or equal to 0.9 and greater than or equal to 0.001 and less than, equal to, or greater than 0.005, 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, or 0.8 times. The feedback controlling and the feedforward controlling can be performed sequentially. The feedback controlling and the feedforward controlling can be performed in parallel or at least partially in parallel.

In various aspects, an inlet temperature loop controlling temperature of the anode and/or cathode electrolyte input stream would incorporate a reference from a feedforward controller based on current density setpoint and observed voltage. The feedforward control can account for varying operating conditions (e.g., flow rate, outlet temperature setpoint, or ambient temperature). In various aspects, in addition to the feedforward control by current density, a cascaded outlet temperature controller can also manipulate the inlet temperature via a PID controller tuned for slow response. This scheme can allow the outlet temperature to fine tune the inlet temperature and reject disturbances after the quick response from the feedforward controller. An alternative outlet temperature control scheme can regulate only one of the two stream temperatures (anode or cathode) and allow the other stream temperature to follow. In various aspects, the cooling duty of an electrolyzer feed heat exchanger can be adjusted as a function of electrolyzer load to control temperature of the anode and/or cathode electrolyte input stream. The heat exchanger can include a cooling water flow loop that can incorporate a reference from a feedforward controller based on current density. This scheme can allow the electrolyzer temperature control to operate in a smaller region allowing for more linear, predictable control.

In various aspects, the ventilation (e.g., outlet pressure) control element (e.g., a back-pressure control valve) can be automated using a feedback PID controller and/or feedforward controller scheme. For example, the outlet pressure control can be manipulated via a feedforward controller based on operating current density. In addition to the feedforward control based on current density, the outlet pressure can be controlled via a PID controller tuned for slow response, allowing the outlet pressures to be fine-tuned after the fast response from the feed forward controller. In various aspects, multiple back-pressure control valves in parallel can be controlled with the same or varying settings, allowing for a wider range of operation while preserving highly granular and linear control.

The predetermined pressure range of the cathode electrolyte output stream gas collector can have a difference between a maximum and a minimum pressure of 0.001 psi to 1 psi, 0.01 psi to 0.5 psi, or 0.1 psi to 0.3 psi, or less than or equal to 1 psi and greater than or equal to 0.001 psi and less than, equal to, or greater than 0.005 psi, 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, or 0.95 psi. The predetermined pressure range of the anode electrolyte output stream gas collector can have a difference between a maximum and a minimum pressure of 0.001 psi to 1 psi, 0.01 psi to 0.5 psi, or 0.1 psi to 0.3 psi, or less than or equal to 1 psi and greater than or equal to 0.001 psi and less than, equal to, or greater than 0.005 psi, 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, or 0.95 psi. The predetermined pressure range of the cathode or anode electrolyte output stream gas collector can have a maximum and minimum that deviate from a desired operating pressure by 0.01% to 10%, or 1% to 10%, or less than or equal to 10% and greater than or equal to 0.01% and less than, equal to, or greater than 0.05%, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, or 9%. The predetermined pressure range of the cathode and/or anode electrolyte output stream gas collectors can be substantially maintained while the current density in the electrochemical cell is changing. For example, after a change in current density in the electrochemical cell, the predetermined pressure range of the cathode and/or anode electrolyte output stream gas collectors can be achieved within 1 minute to 30 minutes, 1 minute to 15 minutes, 1 minute to 5 minutes, or in less than or equal to 30 minutes and greater than or equal to 1 second and less than, equal to, or greater than 10 seconds, 20, 30, 40, 50 seconds, 1 minute, 2 minutes, 3, 4, 5, 10, 15, 20, or 25 minutes. The change in current density in the electrochemical cell can be 1 kA/min to 100 kA/min, 50 kA/min to 100 kA/min, or less than or equal to 200 kA/min and greater than or equal to 1 kA/min and less than, equal to, or greater than 2 kA/min, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 150, 170, or 190 kA/min. The predetermined pressure range of the cathode and/or anode electrolyte output stream gas collectors can be maintained over a change in load or current from the electrical output of the electrolyzer power source or a change in the current density in the electrochemical cell of 0.001% to 10000%, or 1% to 100%, or less than or equal to 10,000% and greater than or equal to 0.001% and less than, equal to, or greater than 0.005%, 0.01, 0.05, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 120, 150, 200, 250, 300, 400, 500, 700, 1,000, 2,000, 5,000, 7,000, or 9,000%.

The predetermined temperature range of the separator can have a difference between a maximum and a minimum temperature of 0.01° C. to 10° C., or 0.1 to 5° C., or 0.5 to 4° C., or less than or equal to 10° C. and greater than or equal to 0.01° C. and less than, equal to, or greater than 0.05° C., 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, or 9.5° C. The predetermined temperature range of the separator can have a maximum and minimum that deviate from a desired operating temperature by 0.01% to 10%, or 1% to 10%, or less than or equal to 10% and greater than or equal to 0.01% and less than, equal to, or greater than 0.05%, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, or 9%. The predetermined temperature range of the separator can be maintained for any suitable amount of time, such as 1 minutes to 7 days, or 1 minutes to 10 minutes, or less than or equal to 7 days and greater than or equal to 1 minute and less than, equal to, or greater than 2 minutes, 3, 4, 5, 6, 8, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60 minutes, 1.5 h, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20 h, 1 days, 2, 3, 4, 5, or 6 days. The predetermined pressure range of the separator can be maintained over a change in load or current from the electrical output of the electrolyzer power source or a change in the current density in the electrochemical cell or of 0.001% to 10000%, or 1% to 100%, or less than or equal to 10,000% and greater than or equal to 0.001% and less than, equal to, or greater than 0.005%, 0.01, 0.05, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 120, 150, 200, 250, 300, 400, 500, 700, 1,000, 2,000, 5,000, 7,000, or 9,000%.

The separator of the electrochemical cell can include a porous membrane (e.g., a microporous membrane or a nanoporous membrane), an ion-exchange membrane, an ion-solvating membrane, or a diaphragm. The separator can include an anion exchange membrane (AEM), a cation exchange membrane (CEM), a proton exchange membrane (PEM), or a bipolar ion exchange membrane (BEM). The anode of the electrochemical cell can include nickel, stainless steel, an alloy of nickel, Raney nickel, sandblasted nickel, or a combination thereof. The form of the anode can include a woven mesh, foam, felt, a plate, a sheet, expanded metal, or a combination thereof. The anode can include a catalyst coating, such as one or more d-group transition metals (e.g., manganese, iron, cobalt, nickel, copper), a metal or alloy of a platinum group metal (e.g., platinum, palladium, ruthenium, rhodium, iridium, platinum-rhodium, platinum-ruthenium), or a combination thereof. The cathode of the electrochemical cell can include nickel, stainless steel, an alloy of nickel, Raney nickel, sandblasted nickel, or a combination thereof. The form of the cathode can include a woven mesh, foam, felt, a plate, a sheet, expanded metal, or a combination thereof. The cathode can include a catalyst coating, such as a coating containing one or more d-group transition metals (e.g., manganese, iron, cobalt, nickel, copper), a metal or alloy of a platinum group metal (e.g., platinum, palladium, ruthenium, rhodium, iridium, platinum-rhodium, platinum-ruthenium), or a combination thereof. The catalyst coating of the anode and/or cathode can include any suitable pnictogen or chalcogen counterions. Examples of the catalyst coating can include oxide or nitride compounds.

The feedforward controlling the electrolyzer and/or the feedback controlling the electrolyzer (in aspects that include feedback control) can include modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, or a combination thereof, and modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof. The feedforward controlling the electrolyzer and/or the feedback controlling the electrolyzer can include modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, or a combination thereof. The feedforward controlling the electrolyzer and/or the feedback controlling the electrolyzer can include modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof. The feedforward controlling the electrolyzer and/or the feedback controlling the electrolyzer can include modifying a flow rate of the cathode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, or a combination thereof.

The feedforward controlling the electrolyzer and/or the feedback controlling the electrolyzer (in aspects that include feedback control) can include modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode input stream, modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, or a combination thereof. The modifying of the temperature of the cathode electrolyte input stream and the modifying of the temperature of the anode electrolyte input stream can include modifying operating parameters of an electrolyte input stream heat exchanger. The modifying of the temperature of the cathode electrolyte input stream can include modifying operating parameters of a cathode electrolyte input stream heat exchanger. The modifying of the temperature of the anode electrolyte input stream can include modifying operating parameters of an anode electrolyte input stream heat exchanger.

The feedforward controlling the electrolyzer and/or the feedback controlling the electrolyzer (in aspects that include feedback control) can include modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof. The modifying of the pressure valve configuration on the cathode electrolyte output stream gas collector can include opening, closing, or setting a new pressure valve value (e.g., percentage open) of one or more valves that are fluidly connected to the cathode electrolyte output stream gas collector. The modifying of the pressure valve configuration on the anode electrolyte output stream gas collector can include opening, closing or setting a new pressure valve value (e.g., percentage open) of one or more valves that are fluidly connected to the cathode electrolyte output stream gas collector.

The pressure valves can be on the gas vent streams after the gas and liquid are separated after coming out of the electrolyzer. The separation can occur in a specific gas-liquid separation vessel, a holding tank, or similar apparatus. There can be one or more gas valves on each stream and there can be one or more gas streams from the electrolyzer, e.g., one being hydrogen and one being oxygen. The pressure setpoints for each stream can be different from each other, e.g., one can be higher than the other, for process optimization such as affecting fluid dynamics and mass transfer.

In various aspects, the control scheme can be the same or different for each gas stream or for each valve in the system. For example, it can be applied to one valve on one gas stream, but it could also be applied to one valve on each gas stream, or there may be configurations where multiple valves on multiple gas streams are controlled. The control parameters can be different for each gas stream because different volumes of gases are produced on each side on an electrolyzer, e.g., twice the amount of hydrogen as oxygen.

The electrical output of the electrolyzer power source can be an uncontrolled variable that is not controlled by or dependent on input power from a power provider to a facility that includes the electrolyzer, and that is not controlled by an operator of the electrolyzer. In other aspects, the electrical output of the electrolyzer power source can be controlled. For example, the electrical output of the electrolyzer power source can be controlled by or dependent on the input power from a power provider to a facility that includes the electrolyzer, and/or can be controlled by an operator of the electrolyzer. In various aspects, an operator of the electrolyzer may manually control the amount of current received by the electrolyzer.

The detecting the change in the electrical output of the electrolyzer power source can include measuring a voltage and/or current of the electrolyzer power source, determining a current density of the electrochemical cell, or a combination thereof. In various aspects, the causing a change in the electrical output of the electrolyzer power source can include setting or controlling a voltage and/or current of the electrolyzer power source to be different than a previous voltage and/or current. The current density of the electrochemical cell can be 10 mA/cm² to 10 A/cm², 100 mA/cm² to 2 A/cm², or less than or equal to 10 A/cm² and greater than or equal to 10 mA/cm² and less than, equal to, or greater than 20 mA/cm², 40, 60, 80, 100, 150, 200, 250, 500, 750 mA/cm², 1 A/cm², 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, or 9 A/cm². The electrolyzer power source can include solar power, wind power, a battery (e.g., lithium-ion, sodium-ion, flow battery, and the like), geothermal power, hydroelectric power, tidal power, public utility grid power, or a combination thereof. The electrolyzer power source can change at least twice a day, or can change at least once or twice in a span of 10 minutes, or 5 minutes, or 2 minutes, or 1 minute. The method can include operating the electrolyzer in a dynamic way, e.g., using the amount of electricity generated from a wind or solar generation facility, where the number of times the outlet pressure is controlled based on increasing and decreasing current happens many times per day. This is different than some electrolyzers that might operate at a constant current except for startups and shutdowns, where controlling the current and/or pressure slowly would be acceptable. In various aspects, the method can include achieving steady-state operation within 15 minutes, within 10 minutes, within 5 minutes, or within 1 minute or less of the detected change in the electrical output of the electrolyzer power source, and/or within 15 minutes, 10 minutes, 5 minutes, or within 1 minute or less of the onset of electrical output from the electrolyzer power source.

The detecting the change in temperature of the anode electrolyte output stream can include measuring the temperature of the anode electrolyte output stream. The detecting the change in temperature of the cathode electrolyte output stream can include measuring the temperature of the cathode electrolyte output stream. The detecting the change in pressure of the cathode electrolyte output stream gas collector can include measuring the pressure of the cathode electrolyte output stream gas collector with a pressure sensor that is in a space fluidly connected to the cathode electrolyte output stream gas collector. The detecting the change in pressure of the anode electrolyte output stream gas collector can include measuring the pressure of the anode electrolyzer output stream gas collector with a pressure sensor that is in a space fluidly connected to the anode electrolyte output stream gas collector.

In various aspects, the electrochemical cell can operate at low pressure (e.g., less than 5 bar gauge) and at current densities of as low as 100 mA/cm² and up to 2 A/cm²; e.g., a 20:1 wide production range with high current densities. The electrochemical cell can be operated dynamically, e.g., to adjust the current density to any desired value within the wide production range on demand. Rapid adjustment of the production rate can enable optimization depending on demand and availability or energy pricing. The low-pressure operating conditions can help to enable operation at low current densities (e.g., 100 mA/cm2) while maintaining low gas crossover across the separator, and can also facilitate rapid changes in current density. Feedback algorithms can allow rapid changes in current density while minimizing impact on fluid temperature within the cells (e.g., +/−5° C.) and minimizing impact on cell pressure (e.g., +/−0.5 psi). The rapid changes can occur in about 1 minute or less than 1 minute, less than 5 minutes, less than 10 minutes, or less than 15 minutes, such as when spanning the full 20:1 current density range. U.S. patent application Ser. No. 17/938,319, published as US 2023/0107017, is hereby incorporated by reference in its entirety.

Electrolyzer System

Various aspects of the present invention provide an electrolyzer system. The electrolyzer system can be any suitable system that can carry out an aspect of the method of operating an electrolyzer described herein. The electrolyzer system includes an electrochemical cell in an electrolyzer. The electrochemical cell can include an anode, a cathode, and a separator between the anode and cathode. The electrochemical cell can include an anode compartment that encloses the anode and a cathode compartment that encloses the cathode. The electrochemical cell can include a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment. The electrochemical cell can also include an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment. The electrolyzer system can optionally include a detector that is configured to detect a change in an electrical output of an electrolyzer power source that is electrically connected to the anode and the cathode of the electrochemical cell. The electrolyzer system can also include a feedforward control system that, responsive to the detected change in output and/or a caused change in output, is configured to feedforward control the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range.

Various aspects of the present invention provide an electrolyzer system. The electrolyzer system can be any suitable system that can carry out an aspect of the method of operating an electrolyzer described herein. The electrolyzer system includes an electrochemical cell in an electrolyzer. The electrochemical cell can include an anode, a cathode, and a separator between the anode and cathode. The electrochemical cell can include an anode compartment that encloses the anode and a cathode compartment that encloses the cathode. The electrochemical cell can include a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment. The electrochemical cell can also include an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment. The electrolyzer system can optionally include a detector that is configured to detect a change in an electrical output of an electrolyzer power source that is electrically connected to the anode and the cathode of the electrochemical cell. The electrolyzer system can include a feedforward control system that, responsive to the detected change in output and/or a caused change in output, is configured to feedforward control the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range. The electrolyzer system can include a detector that is configured to detect a change in a pressure of the cathode electrolyte output stream gas collector, a pressure of the anode electrolyte output stream gas collector, or a combination thereof. The electrolyzer system can also include a feedback control system that, responsive to the detected change in pressure, is configured to feedback control the electrolyzer to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range.

Various aspects of the present invention provide an electrolyzer system. The electrolyzer system can be any suitable system that can carry out an aspect of the method of operating an electrolyzer described herein. In various aspects, the electrolyzer system includes an electrochemical cell in an electrolyzer. The electrochemical cell includes an anode, a cathode, and a separator between the anode and cathode, wherein the anode and the cathode are electrically connected to an electrolyzer power source. The electrochemical cell can include an anode compartment that encloses the anode. The electrochemical cell can include a cathode compartment that encloses the cathode. The electrochemical cell can include a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment. The electrochemical cell can also include an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment. The electrolyzer system can optionally include a detector that is configured to detect a change in an electrical output of an electrolyzer power source that is electrically connected to the anode and the cathode of the electrochemical cell. The electrolyzer system can include a feedforward control system that, responsive to the detected change in output and/or a caused change in output, is configured to feedforward control the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range and/or to maintain a temperature of the separator of the electrochemical cell within a predetermined temperature range. The electrolyzer system can include a detector that is configured to detect a change in a temperature of the anode electrolyte output stream, a temperature of the cathode electrolyte output stream, a pressure of the cathode electrolyte output stream gas collector, a pressure of the anode electrolyte output stream gas collector, or a combination thereof. The electrolyzer system can also include a feedback control system that, responsive to the detected change in temperature and/or pressure, is configured to feedback control the electrolyzer to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range and/or to maintain the temperature of the separator within the predetermined temperature range. In various aspects, the feedforward controlling the electrolyzer and the feedback controlling the electrolyzer include modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof.

Tangible Non-Transitory Computer Readable Medium

In various aspects, the present invention provides a tangible non-transitory computer readable medium, the computer readable medium storing one or more computer applications that, when executed by one or more processors, causes the one or more processors to perform a method that can include determining whether a change is detected and/or caused in an electrical output of an electrolyzer power source electrically connected to an anode and a cathode of an electrochemical cell. The electrochemical cell can include the anode, the cathode, and a separator between the anode and cathode. The electrochemical cell can include an anode compartment that encloses the anode and a cathode compartment that encloses the cathode. The electrochemical cell can include a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment. The electrochemical cell can also include an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment. The method can also include, responsive to determining that a change is detected and/or caused in the electrical output of the electrolyzer power source, feedforward controlling the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range.

In various aspects, the present invention provides a tangible non-transitory computer readable medium, the computer readable medium storing one or more computer applications that, when executed by one or more processors, causes the one or more processors to perform a method that can include determining whether a change is detected and/or caused in an electrical output of an electrolyzer power source electrically connected to an anode and a cathode of an electrochemical cell. The electrochemical cell can include the anode, the cathode, and a separator between the anode and cathode. The electrochemical cell can include an anode compartment that encloses the anode and a cathode compartment that encloses the cathode. The electrochemical cell can include a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment. The electrochemical cell can also include an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment. The method can include, responsive to determining that a change is detected and/or caused in the electrical output of the electrolyzer power source, feedforward controlling the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range. The method can include determining whether a change in a pressure of the cathode electrolyte output stream gas collector, a pressure of the anode electrolyte output stream gas collector, or a combination thereof, is detected. The method can also include, responsive to determining that a change is detected in the pressure, feedback controlling the electrolyzer to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range.

Various aspects of the present invention provide a tangible non-transitory computer readable medium, the computer readable medium storing a computer application that, when executed by a processor, causes the processor to perform a method that can include determining whether a change is detected and/or caused in an electrical output of an electrolyzer power source electrically connected to an anode and a cathode of an electrochemical cell. The electrochemical cell includes an anode, a cathode, and a separator between the anode and cathode, wherein the anode and the cathode are electrically connected to the electrolyzer power source. The electrochemical cell can include an anode compartment that encloses the anode. The electrochemical cell can include a cathode compartment that encloses the cathode. The electrochemical cell can include a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment. The electrochemical cell can also include an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment. The method can include, responsive to determining that a change is detected and/or caused in the electrical output of the electrolyzer power source, feedforward controlling the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range and/or to maintain a temperature of the separator of the electrochemical cell within a predetermined temperature range. The method can include determining whether a change in a temperature of the anode electrolyte output stream, a temperature of the cathode electrolyte output stream, a pressure of the cathode electrolyte output stream gas collector, a pressure of the anode electrolyte output stream gas collector, or a combination thereof, is detected. The method can include, responsive to determining that a change is detected in the temperature and/or pressure, feedback controlling the electrolyzer to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range and/or to maintain the temperature of the separator within the predetermined temperature range.

In various aspects, the present invention provides a tangible non-transitory computer readable medium, the computer readable medium storing one or more computer applications that, when executed by one or more processors, causes the one or more processors to perform the method.

EXAMPLES

Various aspects of the present invention can be better understood by reference to the following Examples which are offered by way of illustration. The present invention is not limited to the Examples given herein.

An electrolyzer with three electrochemical cells, with active areas greater than 27000 cm², compressed in a stack, was operated between 1.5 A/cm² and 100 mA/cm². The electrolyzer system had controls to measure and adjust the temperature and pressure within the cells. The system also included electrolyte holdup tanks, pumps, heat exchangers, flow distributors, gas-liquid separators, piping, instrumentation, safety systems, PLC, power supplies, and a power source. During operation, the system was ramped down from 1.5 A/cm² to 100 mA/cm² over a period of 1-5 minutes, held for a period of between 1-5 minutes, and ramped up from 100 mA/cm² to 1.5 A/cm² at the same rate as the downward ramp.

FIG. 1 illustrates the electrolyzer system 100. Table 1 lists the names of the components in the electrolyzer system.

TABLE 1
Components in electrolyzer system 100 shown in FIG. 1.

Feature	Item Description

101	PLC
102	KOH Holding Tank
103	KOH Feed Pump
104	KOH Feed Cooler
105	KOH Feed Heater
106	Anode Feed Temperature Control Valve
107	Cathode Feed Temperature Control Valve
108	Anode Feed Flow Control Valve
109	Cathode Feed Flow Control Valve
110	Cooling Water Flow Control Valve
111	Anode Pressure Control Valve
112	Cathode Pressure Control Valve
113	DC Power Source
114	Cell Anode Compartment
115	Cell Cathode Compartment
116	Cell Membrane Separator
117	Anode Outlet Vapor-Liquid Separator
118	Cathode Outlet Vapor-Liquid Separator
119	Cooling Water Outlet Temperature Sensor
120	Cooling Water Flow Sensor
121	Anode Feed Flow Sensor
122	Cathode Feed Flow Sensor
123	Anode Feed Temperature Sensor
124	Cathode Feed Temperature Sensor
125	Anode Outlet Pressure Sensor
126	Cathode Outlet Pressure Sensor
127	Anode Outlet Temperature Sensor
128	Cathode Outlet Temperature Sensor
129	Cell Stack Current Sensor
130	Cell Stack Voltage Sensor
131	KOH Feed Stream
132	Cooling Water Feed Stream
133	Cooling Water Return Stream
134	Anode KOH Inlet Stream
135	Cathode KOH Inlet Stream
136	Anode Combined Gas-Liquid Outlet Stream
137	Cathode Combined Gas-Liquid Outlet Stream
138	O2 Gas Vent Stream
139	H2 Gas Vent Stream
140	Anode KOH Outlet Stream
141	Cathode KOH Outlet Stream

FIG. 2 illustrates the current, anode outlet temperature, and cathode outlet temperature data from the electrolyzer as the current density was rapidly driven from 1.5 A/cm² to 100 mA/cm² and back up to 1.5 A/cm². The temperatures varied only about 2° C. throughout the whole experiment.

FIG. 3 illustrates the current, anode outlet pressure, and cathode outlet pressure data from the electrolyzer as the current density was rapidly driven from 1.5 A/cm² to 100 mA/cm² and back up to 1.5 A/cm². The two outlet pressures fluctuated by a maximum of less than 0.4 psi and then settled rapidly during the rapid changes in current density.

The terms and expressions that have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the aspects of the present invention. Thus, it should be understood that although the present invention has been specifically disclosed by specific aspects and optional features, modification and variation of the concepts herein disclosed may be resorted to by those of ordinary skill in the art, and that such modifications and variations are considered to be within the scope of aspects of the present invention.

EXEMPLARY ASPECTS

The following exemplary aspects are provided, the numbering of which is not to be construed as designating levels of importance:

Aspect 1 provides a method of operating an electrolyzer comprising an electrochemical cell, the method comprising:

• • detecting and/or causing a change in an electrical output of an electrolyzer power source electrically connected to an anode and a cathode of the electrochemical cell, the electrochemical cell comprising
    • the anode, the cathode, and a separator between the anode and cathode,
    • an anode compartment that encloses the anode,
    • a cathode compartment that encloses the cathode,
    • a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment, and
    • an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment; and
  • responsive to the detected and/or caused change in the electrical output, feedforward controlling the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range.

Aspect 2 provides the method of Aspect 1, wherein the feedforward controlling the electrolyzer comprises modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof.

Aspect 3 provides the method of any one of Aspects 1-2, further comprising, responsive to the detected and/or caused change in the electrical output, feedforward controlling the electrolyzer to maintain a temperature of the separator of the electrochemical cell within a predetermined temperature range.

Aspect 4 provides the method of any one of Aspects 1-3, further comprising:

• • detecting a change in a pressure of the cathode electrolyte output stream gas collector, a pressure of the anode electrolyte output stream gas collector, or a combination thereof; and
  • responsive to the detected change in pressure, feedback controlling the electrolyzer to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range.

Aspect 5 provides the method of any one of Aspects 1-4, further comprising:

• • detecting a change in a temperature of the anode electrolyte output stream, a temperature of the cathode electrolyte output stream, or a combination thereof; and
  • responsive to the detected change in temperature, feedback controlling the electrolyzer to maintain the temperature of the separator of the electrochemical cell within the predetermined temperature range.

Aspect 6 provides the method of any one of Aspects 1-5, wherein the feedforward controlling the electrolyzer and/or the feedback controlling the electrolyzer comprise modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof.

Aspect 7 provides the method of any one of Aspects 1-6, comprising performing the method using not more than one of the electrochemical cell.

Aspect 8 provides the method of any one of Aspects 1-7, further comprising performing a method using a multiplicity of the electrochemical cells in the electrolyzer.

Aspect 9 provides the method of Aspect 8, wherein

• • the cathode electrolyte input stream flows to the cathode compartment of each of the electrochemical cells;
  • the cathode electrolyte output stream flows from the cathode compartment of each of the electrochemical cells;
  • the anode electrolyte input stream flows to the anode compartment of each of the electrochemical cells; and
  • the anode electrolyte output stream flows from the anode compartment of each of the electrochemical cells.

Aspect 10 provides the method of any one of Aspects 8-9, wherein

• • the anode electrolyte output stream gas collector collects gas formed by the anode of each electrochemical cells; and
  • the cathode electrolyte output stream gas collector collects gas formed by the cathode of each of the electrochemical cells.

Aspect 11 provides the method of any one of Aspects 1-10, wherein the feedforward controlling is performed by a feedforward control system.

Aspect 12 provides the method of any one of Aspects 1-11, wherein the feedforward controlling is performed by a programmable logic controller (PLC), by a distributed control system (DCS), or a combination thereof.

Aspect 13 provides the method of any one of Aspects 1-12, wherein the feedforward controlling comprises determining the current density of the electrochemical cell from the determined and/or caused electrical output, and using a relationship between current density and a temperature of the separator and/or a relationship between current density and produced gas pressure of the electrochemical cell to determine to what extent to perform modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof, in order to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range and/or to maintain the temperature of the separator within the predetermined temperature range.

Aspect 14 provides the method of Aspect 13, further comprising determining the relationship between current density and a temperature of the separator and/or the relationship between current density and produced gas pressure of the electrochemical cell.

Aspect 15 provides the method of any one of Aspects 4-14, wherein the feedforward controlling is performed at a rate that is greater than a rate at which the feedback controlling is performed.

Aspect 16 provides the method of any one of Aspects 4-15, wherein the feedforward controlling is performed at a rate that is at least 1.1 times a rate at which the feedback controlling is performed.

Aspect 17 provides the method of any one of Aspects 4-16, wherein the feedforward controlling is performed at a rate that is 2 to 1,000 times a rate at which the feedback controlling is performed.

Aspect 18 provides the method of any one of Aspects 4-17, wherein the feedback controlling is performed by a feedback control system.

Aspect 19 provides the method of any one of Aspects 4-18, wherein the feedback controlling is performed by a proportional-integral-derivative (PID) controller.

Aspect 20 provides the method of any one of Aspects 4-19, wherein the feedback controlling comprises

• • modifying a pressure valve configuration on the cathode electrolyte output stream gas collector and/or modifying a pressure valve configuration on the anode electrolyte output stream gas collector opening valves to change the pressure of the cathode electrolyte output stream gas collector and/or anode electrolyte output stream gas collector, and/or
  • modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, or a combination thereof, to change the temperature of the separator.

Aspect 21 provides the method of any one of Aspects 4-20, wherein the feedback controlling is performed at a lower rate than a rate at which the feedforward controlling is performed.

Aspect 22 provides the method of any one of Aspects 4-21, wherein the feedback controlling is performed at a rate that is less than 0.9 times a rate at which the feedforward controlling is performed.

Aspect 23 provides the method of any one of Aspects 4-22, wherein the feedback controlling is performed at a rate that is 0.001 to 0.9 times a rate at which the feedforward controlling is performed.

Aspect 24 provides the method of any one of Aspects 4-23, wherein the feedback controlling and the feedforward controlling are performed sequentially.

Aspect 25 provides the method of any one of Aspects 4-24, wherein the feedback controlling and the feedforward controlling at performed in parallel.

Aspect 26 provides the method of any one of Aspects 1-25, wherein the predetermined pressure range of the cathode electrolyte output stream gas collector has a difference between a maximum and minimum pressure of 0.001 psi to 1 psi.

Aspect 27 provides the method of any one of Aspects 1-26, wherein the predetermined pressure range of the cathode electrolyte output stream gas collector has a difference between a maximum and minimum pressure of 0.001 psi to 0.3 psi.

Aspect 28 provides the method of any one of Aspects 1-27, wherein the predetermined pressure range of the anode electrolyte output stream gas collector has a difference between a maximum and minimum pressure of 0.001 psi to 1 psi.

Aspect 29 provides the method of any one of Aspects 1-28, wherein the predetermined pressure range of the anode electrolyte output stream gas collector has a difference between a maximum and minimum pressure of 0.001 psi to 0.3 psi.

Aspect 30 provides the method of any one of Aspects 1-29, wherein the predetermined temperature range of the separator has a difference between a maximum and minimum temperature of 0.01° C. to 10° C.

Aspect 31 provides the method of any one of Aspects 1-30, wherein the predetermined temperature range of the separator has a difference between a maximum and minimum temperature of 0.01° C. to 4° C.

Aspect 32 provides the method of any one of Aspects 1-31, wherein the separator comprises a porous membrane (e.g., a microporous membrane or a nanoporous membrane), an ion-exchange membrane, an ion-solvating membrane, or a diaphragm.

Aspect 33 provides the method of any one of Aspects 1-32, wherein the separator comprises an anion exchange membrane (AEM), a cation exchange membrane (CEM), a proton exchange membrane (PEM), or a bipolar ion exchange membrane (BEM).

Aspect 34 provides the method of any one of Aspects 1-33, wherein the anode comprises a woven mesh, foam, felt, a plate, a sheet, expanded metal, or a combination thereof, that comprises nickel, stainless steel, an alloy of nickel, Raney nickel, sandblasted nickel, or a combination thereof.

Aspect 35 provides the method of any one of Aspects 1-34, wherein the anode comprises a catalyst coating, such as one or more d-group transition metals (e.g., manganese, iron, cobalt, nickel, copper), a metal or alloy of a platinum group metal (e.g., platinum, palladium, ruthenium, rhodium, iridium, platinum-rhodium, platinum-ruthenium), or a combination thereof.

Aspect 36 provides the method of any one of Aspects 1-35, wherein the cathode comprises a woven mesh, foam, felt, a plate, a sheet, expanded metal, or a combination thereof, that comprises nickel, stainless steel, an alloy of nickel, Raney nickel, sandblasted nickel, or a combination thereof.

Aspect 37 provides the method of any one of Aspects 1-36, wherein the cathode comprises a catalyst coating, such as one or more d-group transition metals (e.g., manganese, iron, cobalt, nickel, copper), a metal or alloy of a platinum group metal (e.g., platinum, palladium, ruthenium, rhodium, iridium, platinum-rhodium, platinum-ruthenium), or a combination thereof.

Aspect 38 provides the method of any one of Aspects 4-37, wherein the feedforward controlling the electrolyzer and the feedback controlling the electrolyzer comprises

• • modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, or a combination thereof, and
  • modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof.

Aspect 39 provides the method of any one of Aspects 4-38, wherein the feedforward controlling the electrolyzer and the feedback controlling the electrolyzer comprises modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, or a combination thereof.

Aspect 40 provides the method of any one of Aspects 4-39, wherein the feedforward controlling the electrolyzer and the feedback controlling the electrolyzer comprises modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof.

Aspect 41 provides the method of any one of Aspects 4-40, wherein the feedforward controlling the electrolyzer and the feedback controlling the electrolyzer comprises modifying a flow rate of the cathode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, or a combination thereof.

Aspect 42 provides the method of any one of Aspects 4-41, wherein the feedforward controlling the electrolyzer and the feedback controlling the electrolyzer comprises modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, or a combination thereof.

Aspect 43 provides the method of Aspect 42, wherein the modifying of the temperature of the cathode electrolyte input stream and the modifying of the temperature of the anode electrolyte input stream comprises modifying operating parameters of an electrolyte input stream heat exchanger.

Aspect 44 provides the method of any one of Aspects 42-43, wherein the modifying of the temperature of the cathode electrolyte input stream comprises modifying operating parameters of a cathode electrolyte input stream heat exchanger.

Aspect 45 provides the method of any one of Aspects 42-44, wherein the modifying of the temperature of the anode electrolyte input stream comprises modifying operating parameters of an anode electrolyte input stream heat exchanger.

Aspect 46 provides the method of any one of Aspects 4-45, wherein the feedforward controlling the electrolyzer and the feedback controlling the electrolyzer comprise modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof.

Aspect 47 provides the method of Aspect 46, wherein the modifying of the pressure valve configuration on the cathode electrolyte output stream gas collector comprises opening, closing, or setting a new pressure valve value (e.g., percentage open) of one or more valves that are fluidly connected to the cathode electrolyte output stream gas collector.

Aspect 48 provides the method of any one of Aspects 46-47, wherein the modifying of the pressure valve configuration on the anode electrolyte output stream gas collector comprises opening, closing or setting a new pressure valve value (e.g., percentage open) of one or more valves that are fluidly connected to the cathode electrolyte output stream gas collector.

Aspect 49 provides the method of any one of Aspects 1-48, wherein the detecting the change in the electrical output of the electrolyzer power source comprises measuring a voltage and/or current of the electrolyzer power source, determining a current density of the electrochemical cell, or a combination thereof.

Aspect 50 provides the method of any one of Aspects 1-49, wherein the electrolyzer power source comprises solar power, wind power, a battery, geothermal power, hydroelectric power, tidal power, public utility grid power, or a combination thereof.

Aspect 51 provides the method of any one of Aspects 1-50, wherein the detecting the change in temperature of the anode electrolyte output stream comprises measuring the temperature of the anode electrolyte output stream.

Aspect 52 provides the method of any one of Aspects 1-51, wherein the detecting the change in temperature of the cathode electrolyte output stream comprises measuring the temperature of the cathode electrolyte output stream.

Aspect 53 provides the method of any one of Aspects 1-52, wherein the detecting the change in pressure of the cathode electrolyte output stream gas collector comprises measuring the pressure of the cathode electrolyte output stream gas collector with a pressure sensor that is in a space fluidly connected to the cathode electrolyte output stream gas collector.

Aspect 54 provides the method of any one of Aspects 1-53, wherein the detecting the change in pressure of the anode electrolyte output stream gas collector comprises measuring the pressure of the anode electrolyzer output stream gas collector with a pressure sensor that is in a space fluidly connected to the anode electrolyte output stream gas collector.

Aspect 55 provides an electrolyzer system comprising:

• • an electrochemical cell in an electrolyzer, the electrochemical cell comprising
    • an anode, a cathode, and a separator between the anode and cathode,
    • an anode compartment that encloses the anode,
    • a cathode compartment that encloses the cathode,
    • a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment, and
    • an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment;
  • an optional detector that is configured to detect a change in an electrical output of an electrolyzer power source that is electrically connected to the anode and the cathode of the electrochemical cell; and
  • a feedforward control system that, responsive to the detected change in output and/or a caused change in output, is configured to feedforward control the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range.

Aspect 56 provides an electrolyzer system comprising:

• • an electrochemical cell in an electrolyzer, the electrochemical cell comprising
    • an anode, a cathode, and a separator between the anode and cathode,
    • an anode compartment that encloses the anode,
    • a cathode compartment that encloses the cathode,
    • a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment, and
    • an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment;
  • an optional detector that is configured to detect a change in an electrical output of an electrolyzer power source that is electrically connected to the anode and the cathode of the electrochemical cell;
  • a feedforward control system that, responsive to the detected change in output and/or a caused change in output, is configured to feedforward control the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range;
  • a detector that is configured to detect a change in a pressure of the cathode electrolyte output stream gas collector, a pressure of the anode electrolyte output stream gas collector, or a combination thereof; and
  • a feedback control system that, responsive to the detected change in pressure, is configured to feedback control the electrolyzer to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range.

Aspect 57 provides an electrolyzer system comprising:

• • an electrochemical cell in an electrolyzer, the electrochemical cell comprising
    • an anode, a cathode, and a separator between the anode and cathode, wherein the anode and the cathode are electrically connected to an electrolyzer power source,
    • an anode compartment that encloses the anode,
    • a cathode compartment that encloses the cathode,
    • a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment, and
    • an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment;
  • an optional detector that is configured to detect a change in an electrical output of an electrolyzer power source that is electrically connected to the anode and the cathode of the electrochemical cell;
  • a feedforward control system that, responsive to the detected change in output and/or a caused change in output, is configured to feedforward control the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range and/or to maintain a temperature of the separator of the electrochemical cell within a predetermined temperature range;
  • a detector that is configured to detect a change in a temperature of the anode electrolyte output stream, a temperature of the cathode electrolyte output stream, a pressure of the cathode electrolyte output stream gas collector, a pressure of the anode electrolyte output stream gas collector, or a combination thereof; and
  • a feedback control system that, responsive to the detected change in temperature and/or pressure, is configured to feedback control the electrolyzer to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range and/or to maintain the temperature of the separator within the predetermined temperature range.

Aspect 58 provides the system of Aspect 57, wherein the feedforward controlling the electrolyzer and the feedback controlling the electrolyzer comprise modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof.

Aspect 59 provides a tangible non-transitory computer readable medium, the computer readable medium storing one or more computer applications that, when executed by one or more processors, causes the one or more processors to perform a method comprising:

• • determining whether a change is detected and/or caused in an electrical output of an electrolyzer power source electrically connected to an anode and a cathode of an electrochemical cell, the electrochemical cell comprising
    • the anode, the cathode, and a separator between the anode and cathode,
    • an anode compartment that encloses the anode,
    • a cathode compartment that encloses the cathode,
    • a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment, and
    • an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment;
  • responsive to determining that a change is detected and/or caused in the electrical output of the electrolyzer power source, feedforward controlling the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range.

Aspect 60 provides a tangible non-transitory computer readable medium, the computer readable medium storing one or more computer applications that, when executed by one or more processors, causes the one or more processors to perform a method comprising:

• • determining whether a change is detected and/or caused in an electrical output of an electrolyzer power source electrically connected to an anode and a cathode of an electrochemical cell, the electrochemical cell comprising
    • the anode, the cathode, and a separator between the anode and cathode,
    • an anode compartment that encloses the anode,
    • a cathode compartment that encloses the cathode,
    • a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment, and
    • an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment;
  • responsive to determining that a change is detected and/or caused in the electrical output of the electrolyzer power source, feedforward controlling the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range;
  • determining whether a change in a pressure of the cathode electrolyte output stream gas collector, a pressure of the anode electrolyte output stream gas collector, or a combination thereof, is detected; and
  • responsive to determining that a change is detected in the pressure, feedback controlling the electrolyzer to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range.

Aspect 61 provides a tangible non-transitory computer readable medium, the computer readable medium storing one or more computer applications that, when executed by one or more processors, causes the one or more processors to perform a method comprising:

• • determining whether a change is detected and/or caused in an electrical output of an electrolyzer power source electrically connected to an anode and a cathode of an electrochemical cell, the electrochemical cell comprising
    • the anode, the cathode, and a separator between the anode and cathode, wherein the anode and the cathode are electrically connected to the electrolyzer power source,
    • an anode compartment that encloses the anode,
    • a cathode compartment that encloses the cathode,
    • a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment, and
    • an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment;
  • responsive to determining that a change is detected and/or caused in the electrical output of the electrolyzer power source, feedforward controlling the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range and/or to maintain a temperature of the separator of the electrochemical cell within a predetermined temperature range;
  • determining whether a change in a temperature of the anode electrolyte output stream, a temperature of the cathode electrolyte output stream, a pressure of the cathode electrolyte output stream gas collector, a pressure of the anode electrolyte output stream gas collector, or a combination thereof, is detected; and
  • responsive to determining that a change is detected in the temperature and/or pressure, feedback controlling the electrolyzer to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range and/or to maintain the temperature of the separator within the predetermined temperature range.

Aspect 62 provides the method, system, or tangible non-transitory computer readable medium of any one or any combination of Aspects 1-61 optionally configured such that all elements or options recited are available to use or select from.