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Hydrogen production by water electrolysis – operating expenses. Recent patent review

Aenert news. Invention analysis
Previously, in our article dated 21.03.2024 we have revised recent patents aimed at improving the efficiency of hydrogen production by water electrolysis. Another important problem in this technology is high operating costs of water electrolysis facilities, such as power consumption, regular maintenance, replacement of degraded or corroded elements, etc. Today we will have a look a recent patents related to this subject. For this purpose, we collected over 400 patents published in the past 5 years. These patents can pertain to any of the existing electrolysis technologies and solve other problems in addition to high operating costs.
First, let us examine a list of the top applicants by their patenting share in the pool of recent patents on electrolysis and aimed at solving the problems high operating costs:

Applicants’ share in the intellectual property market, %. Patents, 2019-2023

Value: Market involvement ratio*; Y axis: Ownership ratio;Bubble size: Volume ratio.
*(Market involvement ratio = volume ratio multiplied by ownership ratio, where Volume ratio - share of applicant documents in total number of documents, Ownership ratio - applicant's participation share in total number of documents)

In a chart below we provide information on the types of electrolysis the authors use in their inventions. The leading group of documents belongs to alkaline water electrolysis, followed by polymer electrolyte membrane electrolysis and solid oxide electrolysis:

As of special aspects of electrolysis covered in the collection of recent patents on electrolysis aimed at solving the problem of high operating costs, electrolyser is the most widely encountered technological element. It is followed by inventions disclosing system as a whole and high-temperature steam electrolysis:

Below are top IPC indices that were assigned to these inventions:

IPCShareIPCs assigned

According to the International Patent Classification, the IPC indices above have the following definitions: C25B1/04 - by electrolysis of water; C25B11/091 - consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds; C25B11/06 - by the catalytic materials used; B82Y40/00 - Manufacture or treatment of nanostructures; C25B15/08 - Supplying or removing reactants or electrolytes; Regeneration of electrolytes; C25B9/19 - with diaphragms; B82Y30/00 - Nanotechnology for materials or surface science, e.g. nanocomposites; C25B9/23 - comprising ion-exchange membranes in or on which electrode material is embedded; C25B11/031 - Porous electrodes; C25B11/075 - consisting of a single catalytic element or catalytic compound.
In terms of rating points, following are the most prominent documents in the collection of recent patents on water electrolysis solving the problem high operating costs:

Rating: 21
CN114196966B / CAS DICP Dalian Institute of Chemical Physics (CN) / Proton membrane and CCM (continuous current module) integrated preparation method and device for PEM (proton exchange membrane) water electrolysis;
KR101991730B1 / De Nora Permelec Ltd (JP); Kawasaki Heavy Industries, Ltd. (JP) / Anode for alkaline water electrolysis and method for producing anode for alkaline water electrolysis;
JP6615682B2 / De Nora Permelec Ltd (JP); Kawasaki Heavy Industries, Ltd. (JP) / Anode for alkaline water electrolysis and method for producing anode for alkaline water electrolysis;
Rating: 20
CN112126946B / CAS DICP Dalian Institute of Chemical Physics (CN) / Composite membrane for acid-base water electrolysis and preparation method and application thereof;
US11118274B2 / 3M Innovative Properties Company (US) / Ionic polymer membrane for a carbon dioxide electrolyzer;
US10619255B2 / De Nora Permelec Ltd (JP); Kawasaki Heavy Industries, Ltd. (JP) / Anode for alkaline water electrolysis and method for producing anode for alkaline water electrolysis;
CA3018074C / De Nora Permelec Ltd (JP); Kawasaki Heavy Industries, Ltd. (JP) / Anode for alkaline water electrolysis and method for producing anode for alkaline water electrolysis;
CN108779563B / De Nora Permelec Ltd (JP); Kawasaki Heavy Industries, Ltd. (JP) / Anode for alkaline water electrolysis and method for producing anode for alkaline water electrolysis;
FR3045215B1 / Commissariat à l'énergie atomique et aux énergies alternatives (FR) / Stand-alone system for clamping a high-temperature SOEC/SOFC stack;
US10263264B2 / Commissariat à l'énergie atomique et aux énergies alternatives (FR) / Method for high-temperature electrolysis or co-electrolysis, method for producing electricity by means of an SOFC fuel cell, and associated interconnectors, reactors and operating methods.

The largest patent family of those included in this collection and having at least one patent published in the past five years comprises 38 patent documents and is represented by core document US11371153B2 (Core document is a base document for which a complete description of the invention is available in generally-accessible patent databases). It is followed by two patent families comprising 36 and 35 patent documents (US11566541B2 and US20180245224A1, respectively):

Method for operating a water electrolysis device / P: US11371153B2 / IPC: C25B15/02, C02F1/42, C25B15/08, C25B13/08, C25B1/04, C25B9/19, C25B9/23, C25B9/73 / Höller Stefan / Hoeller Electrolyzer Gmbh (DE) / Appl. date: 23.04.2018; Publ. date: 28.06.2022 / United States Patent and Trademark Office / Core document: US11371153B2 / Technology categories: PEME / Technology elements: SAW / Problems: LEMP, HORR / Technical solution types: D, M / Claims: 17 / Rating: 16;
Solid oxide electrolysis system with thermal energy storage system / P: US11566541B2 / IPC: F01K3/02, B63H11/00, B63H11/12, B63H11/14, B63H11/16, F01K3/08, F01K3/18, F01K11/02, F01K13/02, F01K15/00, F01K19/04, F03D9/18, F03G6/00, F22B29/06, F22B35/10, F28D20/00, H01M8/04007, H01M8/04014, H01M8/04029, H02J1/10, H02J3/00, H02J3/04, H02M1/00 / O'Donnell John Setel; Von Behrens Peter Emery; et al. / Rondo Energy Inc. (US) / Appl. date: 09.02.2022; Publ. date: 31.01.2023 / United States Patent and Trademark Office / Core document: US11566541B2 / Technology categories: SOEL / Technology elements: HTSE, SAW / Problems: LESP, HORR, HOOC / Technical solution types: D, M / Claims: 30 / Rating: 17;
Electrolyzer / A: US20180245224A1 / IPC: C25B1/46, C25B11/03, C25B15/00, C25B11/04, C25B11/051, C25B1/04, C25B9/19, C25B9/73 / Takahashi Suguru; Madono Akihiro; et al. / De Nora Permelec Ltd (JP) / Appl. date: 27.04.2017; Publ. date: 30.08.2018 / United States Patent and Trademark Office / Core document: US20180245224A1 / Technology categories: AEL / Technology elements: Els / Problems: HORR, HOOC, HCM, ESI / Technical solution types: D / Claims: 7 / Rating: 12.

The following abbreviations are used in the documents above: D - Device; M - Method; AEL - Alkaline water electrolysis; PEME - Polymer electrolyte membrane electrolysis; SOEL - Solid oxide electrolysis; ESI - Environmental and Safety issues; HCM - High cost of materials; HOOC - High OPEX / Operation & consumables; HORR - High OPEX / Repair & replacement; LEMP - Low efficiency / Main process; LESP - Low efficiency / Secondary process; HTSE - High-Temperature Steam Electrolysis; Els - Electrolyser; SAW - System as a whole.

Following are short summaries of documents from some of the largest patent families in the collection:

Patent US11566541B2 published by Rondo Energy Inc. (US) in 31.01.2023 discloses a thermal energy storage (TES) system that can be used in solid-oxide water electrolysis systems to decrease the power needed for the electrolysis process. In the TES, a fluid (such as water or CO2) is passed via a fluid movement system through a storage medium heated by a renewable energy-powered heating element. The fluid is heated and then directed for heating to a solid oxide electrolysis cell with an operating temperature range of 700°C - 900°C. Then the fluid is recirculated to the TES to extract remaining heat. In the electrolysis cell, the fluid is split into an anode-side flow where oxygen is swept from the anode, and a cathode-side flow that exits the cell together with hydrogen, the products are then directed to a secondary or tertiary processes (e.g. a thermal cycle power generation, a refinery process, preheating for further recycling). Two fluids can be used in the circuit, for the cathode and the anode, respectively. The system can also be adapted for synthesis gas production or for operation in a fuel cell mode. Claims of the invention further provide a method of operating the system.
According to the authors, besides improving the efficiency of the electrolysis devices, the system is designed to prevent thermal runaway that reduces the lifetime of a heater in prior-art solutions.
The invention belongs to a family comprising 36 patent documents published in 2022-2023 in the US, AU, CA, WO, and EP patent offices.

Image from: US11566541B2
1 - system; 2 - input energy source; 4 - infrastructure; 5 - input; 10 - thermal energy storage system; 12 - thermal storage structure; 15 - control system; 16 - interface; 19 - additional communication interface; 20 - output; 21 - relevant data sources; 22 - downstream process; 13A - first thermal storage blocks; 13B - second thermal storage blocks; 14A - first assemblage; 14B - second assemblage; 17A,17B,18A,18B - interfaces.

Several patents were granted for an invention disclosed in a family with core patent application US20180245224A1 published in 30.08.2018. Documents of the family were published by De Nora Permelec Ltd (JP). The document discloses an electrolyser comprising an anode in an anode chamber, a cathode in a cathode chamber, a diaphragm between the chambers, a “…reverse current absorption body formed of a sintered compact containing nickel” disposed (not coupled but electrically connected) on an inside of either of the chambers. The electrolyser further comprises a cathode current collector opposed to the cathode and coupled to a reverse current absorption body, and a respective anode current collector. The reverse current absorption bodies are attached to a frame body defining an electrode chamber and an electrode support member. Nickel content in the sintered compact is 45-90 mass %, while the density of the reverse current absorption body is 2.00-6.51 g/cm3.
With reference to prior art solutions, the authors point out that to prevent cathode degradation by reverse current, a weak current is used during shutdowns, which makes a possibility of hydrogen leaking and mixing with oxygen, thus forming an explosive gas mix. Avoidance of the explosion risk leads to additional capital and operating costs. The authors mention durability against reverse current as the object of the invention.

The patent family was published in 2017-2021 in US, AU, CA, WO, KR, CL, EP, HK, JP, ZA, and CN.

Image from: US20180245224A1
100 - electrolytic cell; 102 - frame-like frame; 102A - gasket-bearing surfaces; 104 - partition wall; 106 - gasket; 108 - support member; 110 - anode chamber; 114 - anode; 116 - buffer plate; 120 - cathode chamber; 122 - cathode structure; 126 - elastic body; 128 - cathode current collector; 130 - cathode; 132 - conductive substrate; 134 - reverse current absorption body.

Patent US10619255B2 granted to De Nora Permelec Ltd (JP) and Kawasaki Heavy Industries, Ltd. (JP) on 14.04.2020 discloses an anode for alkaline water electrolysis with a conductive substrate having a surface comprising Ni or Ni-based alloy and a two-layered catalyst on the substrate. The first layer (formed on the conductive substrate) comprises a lanthanide-nickel-cobalt perovskite oxide, while the second layer (formed on the first layer) comprises iridium oxide or ruthenium oxide. According to the claims of the invention, formula for the composition in the first layer is XNiaCo1-aO3, where 0<a<1 and X is lanthanum, cerium, or praseodymium. Further the authors propose that the formula for the composition in the first layer is XNi0.2Co0.8O3 with lanthanum as the lanthanide, and where the amount of the second catalyst is at least 0.2 g/m2.
The inventors aim at producing an alkaline water electrolysis anode exhibiting a good corrosion resistance and reduced overpotential.
The patent belongs to a family comprising 20 patent documents published between 2017 and 2021 in RU, US, AU, CA, WO, KR, TW, CL, EP, JP, ZA, and CN.

Image from: US10619255B2
1 - conductive substrate; 2 - first catalyst layer; 3 - second catalyst layer.

By the Editorial Board