# How to Make Hydrogen Gas Using Sulfur Dioxide and Electricity > This patent describes a special kind of electrolysis cell that uses sulfur dioxide gas at one electrode to help produce hydrogen gas more efficiently. - **Patent:** US 20090045073 - **Original title:** Electrolysis cell comprising sulfur dioxide-depolarized anode and method of using the same in hydrogen generation - **Owner:** Giner Electrochemical Systems - **Status:** Active - **Times cited:** 9 - **Field:** chemical_manufacturing, energy, telecommunications, materials ## What it does The patent describes an electrolysis cell designed to generate molecular hydrogen (H2) by oxidizing sulfur dioxide (SO2). The cell includes a frame (claim 1a) and a separator, such as a proton exchange membrane (PEM) (claim 3), which divides the cell into chambers. An anode, which is a fluid diffusion electrode (claim 1c, claim 4), is placed away from the separator's anodic side, creating a first chamber filled with an electrolytic solution, such as aqueous sulfuric acid (claim 6). A cathode is connected to the separator's cathodic side (claim 1e). In operation, gaseous sulfur dioxide is fed to the anode, where it reacts, while hydrogen gas is produced at the cathode. This process uses sulfur dioxide to reduce the overall energy required for hydrogen production compared to just splitting water. ## What it does NOT cover - Electrolysis cells that generate hydrogen without oxidizing sulfur dioxide at the anode. - Systems where the anode is not a fluid diffusion electrode (e.g., a solid metal plate electrode not designed for gas or liquid reactants). - Hydrogen generation methods that do not use an ionically-conductive separator, such as a proton exchange membrane. - Electrolysis cells where the anode and cathode do not define specific chambers for sulfur dioxide, electrolyte, and hydrogen. - Methods of hydrogen production that rely solely on water splitting without a depolarizing agent. ## The clever bit The clever part is using sulfur dioxide as a reactant at the anode to "depolarize" the cell. Instead of needing a high voltage to split water at both electrodes, the sulfur dioxide reacts more easily, reducing the total energy input required to generate hydrogen. This makes the overall process more energy-efficient. ## Real-world examples 1. Industrial hydrogen production facilities 2. Chemical plants using sulfur dioxide byproducts 3. Advanced electrolysis systems for energy storage ## Why it matters Generating hydrogen efficiently is important because hydrogen is a clean fuel and a key industrial chemical. Traditional water electrolysis uses a lot of electricity. This patent describes a method that uses sulfur dioxide as a "depolarizer" at the anode, meaning it reacts instead of water, potentially lowering the electrical energy needed to produce hydrogen. This approach could make hydrogen production more economical, especially if sulfur dioxide is available as a byproduct from other industrial processes. ## Frequently asked questions ### What does How to Make Hydrogen Gas Using Sulfur Dioxide and Electricity cover? This patent describes a special kind of electrolysis cell that uses sulfur dioxide gas at one electrode to help produce hydrogen gas more efficiently. ### Who owns patent US 20090045073? This patent is owned by Giner Electrochemical Systems. ### When does this patent expire? This patent is expected to expire on August 1, 2028, when the invention enters the public domain. ### What is patent US 20090045073 cited by? This patent has been cited by 9 later patents that build on its ideas. ### What problem does this patent solve? Generating hydrogen efficiently is important because hydrogen is a clean fuel and a key industrial chemical. Traditional water electrolysis uses a lot of electricity. This patent describes a method that uses sulfur dioxide as a "depolarizer" at the anode, meaning it reacts instead of water, potentially lowering the electrical energy needed to produce hydrogen. This approach could make hydrogen production more economical, especially if sulfur dioxide is available as a byproduct from other industrial processes. ### What does this patent NOT cover? Electrolysis cells that generate hydrogen without oxidizing sulfur dioxide at the anode. **Full plain-English explainer:** https://patentbrief.org/patent/us/20090045073/electrolysis-cell-comprising-sulfur-dioxide-depolarized-anode-and-method-of-usin **Original patent:** https://patents.google.com/patent/US20090045073 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [Making Hydrogen Gas from Sulfur Dioxide and Water at Low Temperatures](https://patentbrief.org/patent/us/9574276/production-of-low-temperature-electrolytic-hydrogen) — This patent describes a method for producing hydrogen gas using an electrochemical cell that reacts gaseous sulfur dioxide and water at a relatively low temperature, generating protons that become hydrogen. - [How to Make Hydrogen Gas and Cupric Chloride Using an Electrolysis Cell](https://patentbrief.org/patent/us/8636880/electrolysis-cell-for-the-conversion-of-cuprous-chloride-in-hydrochloric-acid-to) — This patent describes an electrochemical cell that uses cuprous chloride in hydrochloric acid to produce hydrogen gas and cupric chloride, separated by a special membrane. - [Dome-Shaped Plates for Efficient Hydrogen Production in Electrolyzers](https://patentbrief.org/patent/us/20250027216/electrolyzer) — This patent describes an electrolyzer that uses uniquely dome-shaped plates to improve how water is split into hydrogen and oxygen, enhancing efficiency and product separation. - [Making Chemicals from Carbon Dioxide and Steam Using Electricity](https://patentbrief.org/patent/us/20110132770/process-for-producing-compounds-of-the-cxhyoz-type-by-reduction-of-carbon-dioxid) — This patent describes a process that uses electricity to split steam and then reacts the resulting hydrogen with carbon dioxide or carbon monoxide to create various carbon-based compounds, like fuels or plastics. - [How to Make Big Electrodes for Splitting Water](https://patentbrief.org/patent/us/20210123152/method-for-preparing-large-area-catalyst-electrode) — This patent describes a simple, energy-saving way to create large, efficient catalyst electrodes using a mix of iron, cobalt, and nickel compounds through an electrical plating process.