There were two points of research in this graduation work. The first was IFBB technology (Integrated generation of Solid Fuel and Biogas from Biomass) used for preparation of the substrate for fermentation. The second point was to test reactor with sludge cloud (completed with external biomass separator). This reactor was filled by substrate (prepared by IFBB technology) from agricultural biogas energy plant located in Chotýčany. After IFBB preparation substrate was filled in laboratory reactor´s group. Then it was inoculated by digestate. Digestate is a substance, which is in the end of fermentation process. That substance was first taken in biogas station Chotýčany, then, for comparsion, from station Věžovatá Pláně. Results are that IFBB technology is good for substrate preparation and folowing fermentation is better. Reactor with sludge cloud is good for intensive fermentation. Efficiency of the reactor was measured by CHSKCr. The best fermentation was found after using inoculum from Věžovatá Pláně. The best temperature for fermentation was 50 degree Celsius for both inoculums.