TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: The method for producing a synthesis gas further comprises introducing one or more material comprising a metal and an electrolyte into the solid acid mixture of (a) or the water mixture of (e). A compressed gas is injected into the reactor in step (b) or (c) and the produced synthesis gas is discharged out of the reactor in step (d) as mixed with the compressed gas. The reactor or the underground bedrock reactor in step (b), (c), (f) or (g) is maintained at a temperature of 310-1400 K and at a pressure of 1 atm or higher. The steps (a)-(d) or (e)-(h) are repeated sequentially. Preferred Components: The compressed gas comprises hydrogen, nitrogen, argon, carbon monoxide, carbon dioxide, methane and steam. The carbon compound is of formula (C( alpha )H( beta )O( gamma )N( delta )S( epsilon )P( eta )). The solid acid comprises igneous rock such as basalt and granite, sedimentary rock such as limestone and sandstone, metamorphic rock such as shale and marble, zeolite, bentonite, kaolinite, attapulgite, montmorillonite, zinc oxide, aluminum oxide, titanium oxide, cerium oxide, vanadium oxide, silicon oxide, chromium oxide, calcium sulfate, manganese sulfate, nickel sulfate, copper sulfate, cobalt sulfate, cadmium sulfate, magnesium sulfate, iron sulfate, aluminum sulfate, calcium nitrate, zinc nitrate, iron nitrate, aluminum phosphate, iron phosphate, chromium phosphate, copper phosphate, zinc phosphate, magnesium phosphate, aluminum chloride, titanium chloride, calcium chloride, calcium fluoride, barium fluoride, calcium carbonate, magnesium carbonate, coal, activated carbon, graphite and charcoal. The metal comprises aluminum, zinc, iron, cobalt, manganese, chromium, nickel and titanium or an alloy. The electrolyte comprises sodium chloride, potassium chloride, sodium nitrate, potassium nitrate, sodium sulfate, potassium sulfate, lithium carbonate, sodium carbonate, potassium carbonate, sodium dihydrogen phosphate, sodium hydrogen phosphate, sodium hydroxide, potassium hydroxide, calcium chloride, magnesium chloride, calcium nitrate, magnesium nitrate, calcium sulfate, magnesium sulfate, calcium hydroxide, magnesium hydroxide, sulfuric acid, phosphoric acid, nitric acid and hydrochloric acid. The solid acid, the metal and the electrolyte are in powder form and the powder has a particle size of 500 mesh or greater. The solid acid mixture or the water mixture in which the metal is further included has a structure in which a metal particle is deposited in a pore of the solid acid powder and the deposited metal particle has a diameter not greater than 10 mu m. The solid acid mixture or the water mixture in which the metal is further included has a structure in which a metal particle is coated on the surface of the solid acid powder or the solid acid powder is coated on the surface of the metal powder and the coated metal film or solid acid film has a thickness greater than 10 nm and not greater than 10 mu m. The solid acid mixture or the water mixture in which the electrolyte is further included has a structure in which an electrolyte particle is deposited in a pore of the solid acid powder or the metal powder and the deposited electrolyte particle has a diameter not greater than 10 mu m. The solid acid mixture or the water mixture in which the electrolyte is further included has a structure in which an electrolyte particle is coated on the surface of the solid acid powder and the metal powder or the solid acid powder is coated on the surface of the metal powder and the electrolyte powder and the coated electrolyte film or solid acid film has a thickness greater than 10 nm and not greater than 10 mu m. The solid acid mixture comprising the carbon compound and the solid acid comprises the carbon compound in an amount 0.1-50 wt.% and comprises the solid acid in an amount 50-99.9 wt.%. The solid acid mixture comprising the carbon compound and the solid acid and further comprising the metal comprises the solid acid mixture of the carbon compound and the solid acid in an amount not smaller than 70 wt.% and comprises the metal in an amount smaller than 30 wt.%. The solid acid mixture comprising the carbon compound and the solid acid and further comprising the metal and the electrolyte comprises a mixture of the carbon compound, where the amount of solid acid and the metal is not smaller than 80 wt.% and the amount of electrolyte is smaller than 20 wt.%. The water mixture comprising the water and the carbon compound comprises the water in an amount 70-99.9 wt.% and comprises the carbon compound in an amount 0.1-30 wt.%. The water mixture comprising the water, the carbon compound and the solid acid comprises a mixture of the water and the carbon compound in an amount not smaller than 85 wt.% and comprises the solid acid in an amount smaller than 15 wt.%. The water mixture comprising the water, the carbon compound and the solid acid and further comprising the metal comprises a mixture of the solid acid and the metal in an amount not greater than 15 wt.% and comprises the metal in an amount not greater than 5 wt.%. The water mixture comprising the water, the carbon compound and the solid acid and further comprising the metal and the electrolyte comprises a mixture of the solid acid, the metal and the electrolyte in an amount not greater than 15 wt.%, where the metal is in an amount of not greater than 5 wt.% and the electrolyte is in an amount not greater than 3 wt.%.alpha = 1-100;beta = 0-200;gamma = 0-100; anddelta , epsilon , eta = 0-10.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The reactor is a multi-walled reactor comprising 70% or more of iron and comprises one or more material comprising SUS steel, carbon steel, a mixture of SUS steel and carbon steel, concrete, iron-reinforced concrete and a steel. The underground bedrock reactor comprises a dense natural bedrock layer through which methane cannot pass and the rock formation at the bottom of the underground bedrock reactor comprises porous rock having a porosity of 0.01 vol.% or greater. EXAMPLE - Solid acids (comprising bentonite, alumina, silica, zinc oxide, titanium oxide, shale, limestone, granite, and basalt) were pulverized to an average size of 0.2 mm. 97 wt.% of the resulting solid acid powder was mixed with 3 wt.% of graphite powder having an average size of 0.1 mm and 10 wt.% of water was adsorbed on 90 wt.% of the mixture. The water-adsorbed mixture was introduced into the reactor up to 98 vol.% of the internal volume of the reactor through a solid acid inlet and the solid acid inlet was closed. While injecting argon gas through a compressed gas inlet at a rate of 100 ml/minute, air inside the reactor was expelled by flowing argon gas into the reactor for 20 hours with a synthesis gas outlet open. Then, after closing the outlet, the compressed gas inlet was closed when the pressure inside the reactor reached 100 atmosphere. The reactor was heated by a heater equipped outside. With the temperature at a lower portion inside, the reactor maintained at 423 K, a cooling water inlet and a cooling water outlet provided at the top of the reactor were opened and the temperature at an upper portion inside the reactor was maintained at 323 K by supplying an adequate amount of cooling water to a cooler equipped at the top upper portion inside the reactor. The reactor was maintained at a pressure of around 150 atmosphere. Inside the reactor, hydrogen produced from water splitting by the solid acid reacts with graphite to produce a synthesis gas. With 10-day intervals, 10 ml of the gas inside the reactor was discharged through the synthesis gas outlet and the volume percentages of hydrogen, methane gas and total organic compounds in the gas were measured by gas chromatography.