NOVELTY - Method for producing hydrogen and capturing carbon dioxide, involves: (A) mixing magnesium bearing minerals with at least one of at least one acid and chelating agent to form a magnesium-rich solvent including magnesium hydroxide; (B) mixing a gas including carbon dioxide with the magnesium-rich solvent in a reactor; and (C) increasing a temperature and a steam pressure inside the reactor until a portion of the magnesium hydroxide in the solvent and the carbon dioxide in the gas react to form magnesium carbonate and hydrogen.    USE - For producing hydrogen, capturing carbon dioxide(claimed) and forming calcium carbonate. The calcium carbonate is used as fire retardant, toothpaste, or cosmetics. The carbon dioxide is useful for e.g. food, beverage, and chemical industries. The hydrogen is useful as fuel source such as in fuel cells or internal combustion engines.    ADVANTAGE - The method provides improved method for capturing carbon dioxide and forming hydrogen where such prior art methods suffer form slow dissolution kinetics of minerals. Most of prior studies on carbon mineral sequestration were focused on pretreatment of minerals, including heat treatment of serpentine and wet-attrition grinding of Mg-bearing minerals. These methods are highly energy intensive and since current energy sources are fossil-based, net amounts of carbon contained by those pretreatment schemes have been found to be significantly less than amount of carbon dioxide reacted. The improved method is carbon capture, utilization and storage (CCUS) scheme that combines carbon dioxide capture and storage technologies. It is shown that abundance of minerals, particularly those containing high magnesium fractions e.g. olivine and serpentine, far exceeds total carbon dioxide that could be produced from fossil fuel reserves. Mineralized carbon is significantly more thermodynamically stable than gaseous carbon, and carbonation reactions are exothermic. Thus, carbon mineralization is most secure and permanent solution for carbon storage that does not require long-term monitoring. The method involves water-gas shift reaction that provides in situ carbon capture. The method produces mineralized carbon capture product with minimal energy demands with no sorbent/solvent regeneration required and reduced or no need for expensive typical water-gas-shift catalysts, by utilizing in-situ carbonation process. Use of carbon dioxide reduction technology with such high efficiency instead of current extreme temperature and pressure reactions reduces industrial carbon footprints. Thus, method offers alternative to expensive carbon capture units and water-gas-shift reactors. The method improves efficiency of carbon capture and hydrogen production from refining of hydrocarbon fuels. The method utilizes Mg(OH)2 as sorbent, forming carbon-magnesium mineral. The Mg(OH)2 is easily obtained in non-carbonate mineral form, such as olivine and serpentine. This is great improvement over calcium-based sorbents such as Ca(OH)2, which are found carbonated and require extensive energy resources to produce and replenish sorbent. The Mg(OH)2 is introduced in solution and provides method for capturing carbon dioxide produced by water-gas-shift reaction, thus driving reaction to produce more hydrogen via Le Chatelier's Principle. The resulting carbon-magnesium minerals are thermodynamically stable and can be used further. A single reactor is used to enhance hydrogen production and capture carbon dioxide. The method offers high efficiency carbon capture without relying extensive or expensive solvent/sorbent regeneration. The method offers benefits to point source emitters e.g. power plants, cement manufacturers, and refineries, operating in regions and countries utilizing carbon cap-and-trade or carbon tax. The method provides stable captured form of carbon dioxide for industries that purchase carbon dioxide, and produces hydrogen as alternative fuel source. The method also forms stable by-products such as hydromagnesite and nesquehonite.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a system for producing hydrogen and capturing carbon dioxide, comprising: a dissolution reactor for mixing magnesium bearing minerals with at least one of at least one acid and chelating agent to form a magnesium-rich solvent including magnesium hydroxide; a carbonation reactor in fluid communication with the dissolution reactor, where the carbonation reactor is configured for reacting a gas including carbon dioxide with the magnesium-rich solvent to form magnesium carbonate and hydrogen in the presence of at least one catalyst; a heat source in fluid communication with the dissolution reactor and the carbonation reactor, where the heat source is configured to heat the carbonation reactor to increase a temperature inside the reactor; a steam source in fluid communication with the carbonation reactor, where the steam source is configured to inject a steam into the carbonation reactor to increase a steam pressure inside the carbonation reactor; and a control module for controlling the heat source and the steam source; where the carbonation reactor is configured to withstand an increase in the temperature and the steam pressure inside the reactor until a portion of the magnesium hydroxide in the solvent and the carbon dioxide in the gas react to form magnesium carbonate and hydrogen.    DESCRIPTION OF DRAWING(S) - The figure shows chart for the method for producing hydrogen and capturing carbon dioxide.