TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The supply is arranged in the bottom region of the tank and the discharge in the tank lid region (18). The tank exhibits a grate (13) for housing a porous material at its lower one-third portion. The tank exhibits an inner-lying heating coil (15). The tank possesses a chamber (19) for collecting the produced methane gas at its upper end below the discharge. A measuring device for measuring the methane content, pH values and the temperatures are present in the tank lid region. A connecting pipeline (22) is present at the tank between the supply and the discharge. A recirculation pump is present in the connecting pipeline.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The exhaust/effluent gas from a variety of sources such as combustion engines, sewage treatment plants and conventional biogas plants are used as feedstock for passage through the reactor. A flue gas (11) is produced from suitable biomass in at least a wood combustion device. Different types of biomass are filled into six wood combustion devices that are connected in a modular group and are then carbonized in an oxygen-deficient atmosphere. A problematical biomass such as mature wood, railroad ties and old tires are employed for the filling up of the wood combustion devices. The optimization of the mass flux of the biomass to be disposed is disintegrated into relatively small material sizes (finger nail size). In the process, preferably three groups of the wood combustion devices are employed. In the process, a group of preferably two wood combustion devices is formed. In the first group of the wood combustion devices, preferably lignin-containing biomasses are carbonized until active charcoal is obtained. The activated charcoal produced in the first group of the first and second wood combustion device is discharged from the same and led as activated charcoal filter into the second group of the third and fourth wood combustion devices. In the second group of the third and the fourth wood combustion devices, preferably old tires that are cut into pieces are additionally carbonized. In the third group of the fifth and sixth wood combustion devices, activated charcoal as filter and carbon dust and old tires as additional biomass are carbonized up to their mineral components (ash). The flue gases of the three groups of wood combustion devices are led individually or as a whole through a reactor for the production of methane gas. The increased carbon dioxide content of the exhaust gas is cyclically led through the reactor until a desired methane yield (e.g. above 90%) is achieved. As microbes for the liquid nutrient medium in the reactor(s), a methanosarcina strain and/or a thermoautortrophic bacterium is used. As porous material in the reactor, coke, preferably industrial lignite coke (14) is used. As liquid nutrient medium, besides microbes, distilled water and a medium made of different minerals, vitamins, buffer systems and suitable chemicals are fed into the reactor. After the filling up of the liquid nutrient medium into the reactor, a circulation takes place for the purpose of mixing the contents. The liquid nutrient medium is heated at 50-60degrees C, preferably 50degrees C. During the supply of the exhaust/effluent gas containing carbon dioxide into the reactor(s), the temperature of the liquid nutrient medium is increased to 68-80degrees C, preferably 70degrees C. The setting of the optimal ambient conditions for the microbes takes place through a suitable adjustment of the pH value. The preferred pH value is about 6.5. EXAMPLE - No suitable example given.