Patent Application
20250236971
This application claims priority to IN 202421003721 filed on Jan. 18, 2024, the entirety of which is herein incorporated by reference.
The present invention relates generally to electrolysers and more specifically to a new design for electrolyser cells.
Electrolysis is the process by which an electrolyte, such as water for example, is broken down into its constituent components by an electrochemical reaction. The electrolysis process occurs in an electrochemical cell which is the building block of the electrolyser. It breaks down the electrolyte into their ionic species by application of electricity at the anode and the cathode. Electrolysers include a partition within the cell that enables the appropriate ionic components to diffuse through while preventing the mixing of the byproducts of the ionic reactions from anode to the cathode.
Examples of electrolysers include water electrolysers, ammonia electrolysers, and chlor-alkali electrolysers depending on the byproduct they produce. Further, water electrolysers are classified into different types, based on operating conditions and the type of electrolyte used. The three most common types of water electrolysers are alkaline electrolysis (AEL), proton exchange membrane electrolysis (PEM), and solid oxide electrolysis (SOE).
Among these options, PEM electrolysers have many advantages as they are adapted to operate at a higher current density compared to AEL and SOE. Further during the operation, PEM electrolysers typically have high load flexibility which allows them to be used with renewable energy sources. In addition, specifically in water electrolysers, the cross-permeability of hydrogen and oxygen gases across the membrane in the PEM electrolysis cell is very low, and it produces hydrogen with an improved purity as it uses a solid proton conducting membrane. It may also be noted that the compact module design of PEM also supports high pressure operation and is adapted to operate under differential pressure conditions.
However, the PEM electrolysers also suffer from several disadvantages such as the high cost involved in manufacturing and operation. Operation at high current density, efficiency of conversion and mass transport limitations remain an ongoing challenge in electrolyser technology. One specific challenge is the movement of the oxygen gas bubbles formed at the anode is limited by the inertia of the liquid electrolyte (water, in this example) present in the channel and the volume of the flow field in the channel. Also, the mode of transport of water and gases using the channels engraved in the bipolar plates becomes a limiting factor in terms of efficiency and current density due to mass transport, pressure, flow differentials and bubble formation and removal. As we increase the current density, the generation of gas bubbles increases. Due to their restriction on the movement, they block access to the membrane limiting the active area available for the electrochemical reactions to occur at the electrode and making the whole process mass transport limited. This is known as bubble covering phenomenon and it is dependent on various factors such as current density, temperature, pressure, water inlet velocity among others. This phenomenon leads to higher overpotentials especially at higher current densities increasing the energy required for electrolysis and decreasing the efficiency of the process.
Therefore, there is a need for an electrolyser that is highly efficient, supports higher current densities and also be cost effective while overcoming the flooding and bubbling issues that occur in traditional electrolysers.
The following summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, example embodiments, and features described, further aspects, example embodiments, and features will become apparent by reference to the drawings and the following detailed description. Example embodiments provide system and method for identification of similar images across various domains.
In one embodiment of the present invention, an electrolyser is provided. The electrolyser is configured to split an electrolyte into a first component and a second component using an electric current. The electrolyser comprises an anode and a cathode collectively forming the electrodes. The electrodes are formed using unipolar hollow tubes of a single conductive material and wherein one side of the electrode comprises a plurality of pores. The electrolyser also includes a first gas diffusion layer disposed adjacent to the anode and a second gas diffusion layer disposed adjacent to the cathode. The first and second gas diffusion layer (GDL) is configured to facilitate the flow of the gases. The electrolyser further comprises a membrane electrode assembly (MEA) disposed within a hollow space formed between the anode and the cathode and configured to facilitate a formation of the first component and the second component during the electrolysis. The MEA includes a membrane, an anode catalyst layer disposed adjacent to the first GDL and the cathode catalyst layer disposed adjacent to the second GDL. The anode catalyst layer and the cathode catalyst layer are configured to speed up the formation of the first component and the second component which are then collected outside the electrolyser via outlet pipes.
In another embodiment, an electrolyser module is provided. The electrolyser module comprises a plurality of electrolysers electrically coupled together and configured to perform electrolysis of water in response to the application of an electric current. Each electrolyser comprises an anode and a cathode collectively forming the electrodes, the electrodes in turn are formed using unipolar hollow tubes formed using a single conductive material and one side of the electrode comprises a plurality of pores. The electrolyser also includes a first gas diffusion layer is disposed adjacent to the anode and a second gas diffusion layer disposed adjacent to the cathode. The first and second gas diffusion layer (GDL) is configured to facilitate the flow of the gases. The electrolyser further comprises a membrane electrode assembly (MEA) disposed within a hollow space formed between the anode and the cathode and configured to facilitate a formation of the first component and the second component during the electrolysis. The MEA includes a membrane, an anode catalyst layer disposed adjacent to the first GDL and the cathode catalyst layer disposed adjacent to the second GDL. The anode catalyst layer and the cathode catalyst layer are configured to speed up the formation of the first component and the second component which are then collected outside the electrolyser via outlet pipes.
These and other features, aspects, and advantages of the example embodiments will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Various example embodiments will now be described more fully with reference to the accompanying drawings in which only some example embodiments are shown. Specific structural and functional details disclosed herein are merely representative for purposes of describing example embodiments. Example embodiments, however, may be embodied in many alternate forms and should not be construed as limited to only the example embodiments set forth herein.
Before discussing example embodiments in more detail, it is noted that some example embodiments are described as processes or methods depicted as flowcharts. Although the flowcharts describe the operations as sequential processes, many of the operations may be performed in parallel, concurrently or simultaneously. In addition, the order of operations may be re-arranged. The processes may be terminated when their operations are completed, but may also have additional steps not included in the figures. It should also be noted that in some alternative implementations, the functions/acts/steps noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed substantially concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. As used herein, the singular forms “a,” “an,” and “the,” are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the terms “and/or” and “at least one of” include all combinations of one or more of the associated listed items. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
The present invention relates to a new electrolyser that provides improved efficiency with better operating conditions.
Gas diffusion layers (GDL) 34-A and 34-B are configured to facilitate the flow of the gases to the membrane electrode assembly (MEA). GDL 34-A is disposed adjacent to the anode 12 and and GDL 34-B is disposed adjacent to the cathode 14.
Membrane electrode assembly (MEA) is configured to facilitate the formation of anions and cations during the electrolysis process. In one embodiment, the membrane is formed using materials that enable only the transport of H+ ions while blocking the permeability of gases and the electrolyte. The MEA comprises of three components namely membrane 32, anode catalyst layer 40-A and cathode catalyst layer 40-B.
Membrane 32 is a semipermeable barrier that is configured to conduct a specific type of ions while blocking another set of ions. In one embodiment, the membrane is formed using perflourosulfonic acid polymer, like Nafion®. Anode catalyst layer 40-A is disposed adjacent to the anode 12 and GDL 34-A. Similarly, cathode catalyst layer 40-B is disposed adjacent to the cathode 14 and GDL 34-B. The anode catalyst layer and the cathode catalyst layers are configured to allow the ionic reactions to be catalyzed at the surfaces and the formation of specific components such as hydrogen, oxygen, etc. In one embodiment, the anode catalyst layer and cathode catalyst layer are coated on the respective sides of membrane 32. In another embodiment, the anode catalyst layer and cathode catalyst layer are coated on GDL 34-A and GDL 34-B respectively. In one embodiment, the anode catalyst layer is formed using a platinum or iridium alloy and the cathode catalyst layer used is formed using platinum.
Electrolyte transport layer 36 is disposed in between GDL 34-A and anode 12. This layer is configured to facilitate the transport of electrolytes to the anode. Further the electrolyte transport layer also enables the electrolyte to be evenly distributed over the anode. The electrolyte transport layer further enables the absorption, retention, and controlled release of electrolyte as needed for optimal system performance without obstructing the components, such as oxygen pathway.
Gasket 38 is configured to mechanically seal the membrane electrode assembly (MEA) to the gas diffusion layer (GDL) and the electrodes. In one embodiment, gasket 38 is formed using silicone.
Nozzle assembly 48 is coupled to anode 12 and is configured to transport an electrolyte to the electrolyser. For the purpose of this description, the electrolyte used is water. However, it may be noted that other electrolytes may also be used. Upon application of a current, water is split into its constituent components hydrogen and oxygen at the cathode and the anode surface. The hydrogen and the oxygen are transported outside of the electrolyser using outlet pipe 24 and 26 respectively. Valve 42, inlet 44 are coupled to the cathode whereas inlet 46 is coupled to the anode and are collectively used to control the pressure inside the electrolyser cell. Excess water is drained out via water outlet 26.
It may be noted that the electrolyser described herein addresses the mass transport limitations, prevents bubble formation, and improves the flow and pressure distributions. As the electrolyser uses unipolar plates, the cost of the electrolyser is substantially reduced. Also, the unipolar plates reduce the formation of bubbles thereby increasing the performance of the electrolyser. The electrode plate is described in further detail below.
Anode 50 is formed by a hollow rectangular tube 52. The rectangular plate further comprises a plurality of pores 56. In one embodiment, the ratio of the pores to the total area of the anode is maximized while maintaining the mechanical integrity of the anode. In one embodiment, the pores are oval shaped. However, the pores can be if any shape/size and typically depends on the surface area of the anode. This is done to enable the electrolyte to access the catalytic surfaces on the MEA and for the resultant gases to be transported into the hollow electrodes.
Nozzle assembly 54 is configured to spray the electrolyte on the anode during the electrolysis process to prevent bubbling at the anode and restricting the gas flow. The electrolyte is transported to the anode via inlet 58. The above description of
Control system 76 is coupled to electrolysers and is configured to continuously monitor a plurality of parameters while the electrolyser is in operation. Specifically, the control system is configured to supply water to the electrolysers in a controlled manner of atomizing or pulsing the water into the electrode cavity at regular intervals. Instead of running the electrolyser in a flooded state, water is supplied through a pulsing mechanism triggered by the sensor in response to feedback of either hydrogen production or voltage variations. In one embodiment, the water is introduced into the electrode cavity at regular intervals in a pulsed manner, adhering to a duty cycle ranging from 15% to 20%. The operation of the electrolyser is described in further detail below.
The signal from the pressure sensor is fed back into the water recirculation system. When the pressure reduces below a certain threshold value, the water is introduced into the anode for the hydrogen production to ramp up again. This feedback is continuous process, and this enables the supplying of water in pulsed manner. The water supply is controlled at the anode end using a valve 90. The flow of the gases is monitored and controlled by mass flow meters 88. The moisture content after passing the gases through dehumidifier 92 is measured using moisture sensor. As the process is exothermic, the constant monitoring of temperature is also done. The temperature is monitored in the stack using a temperature sensor 86. All the sensors and the valve are controlled by electrolyser control system 76. Additional heat exchangers can be added to the system to control the temperatures within certain acceptable ranges.
It may be noted that the polarization curve for the electrolyser has a lower overpotential which corresponds to lower electrical energy requirement and higher operational efficiency as compared to traditional state of the art PEM electrolysers. This benefit become even more evident at higher current densities as we reach the mass transfer limitations of the current designs (greater than 2 A/cm2). As the electrolyser is not mass transfer limited, the current density can be increased, and higher quantity of electrolyte can be transported to the anode surface without any significant increase in overpotential. This allows the optimization of the efficiency and reaction rate independently which has never been demonstrated in other designs. In one embodiment, operational efficiencies are between 90 and 95%.
The present invention allows for balanced pressure operation on the cathode and the anode which improves the reliability and lifetime of the electrolysers and allow for operations at higher pressures. Also, the flexibility of operational current densities allows this electrolyser to operate at higher power in transient conditions as compared to the rated capacity which will make the integration of this design with infirm renewable power sources like solar and wind much more feasible.
In the illustrated embodiment of the design the hollow tube is stainless steel (SS) material. It may be noted that additional coatings can be added to the surfaces to reduce the corrosion and/or change the properties of the surface to enable the movement of electrolyte and escape of gases. The use of hollow rectangular tube as electrodes results in huge increase in the volume and cross sectional area for the electrolyte and gas transport.
While only certain features of several embodiments have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the scope of the invention and the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202421003721 | Jan 2024 | IN | national |
