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The advanced dual fluidized bed steam gasification technology allows the generation of a medium-calorific product gas from various feedstocks. Thereby, biogenic residues, municipal and industrial wastes e.g., sewage sludge or rejects from pulp and paper industry can be utilised. This paper presents the development step of this technology from pilot to demonstration plant scale i.e. the step from technology readiness level 4 to 6. The newly erected demonstration plant at the Syngas Platform Vienna is designed for 1 MW_th fuel input power and incorporates a counter current column as the upper part of the gasification. This design choice already resulted in an improvement of product gas quality in pilot scale. By comparing the data gathered from multiple years of 100 kW_th pilot scale testing at TU Wien with first results from the new demonstration plant via mass and energy balance simulation, fluidisation regimes and temperature and pressure profiles, the success of the scale-up of the reactor design is proven. The first full load operation achieved a conversion of 1 MW fuel input power into 769 kW product gas power. This translates to 256 kg/h dry biomass being converted into 245 Nm³/h of dry product gas. Although first experiments with the reference feedstock high-grade wood chips showed good reproducibility of the results achieved in pilot scale, challenges still remain. The expected product gas composition was different compared to pilot scale results, as the volume share of hydrogen was lower and the relative content of carbon monoxide and carbon dioxide inverted. While the results show an important intermediate step in the process development, the challenges of improving product gas quality and increasing overall conversion efficiency remain to be tackled.