This work comprises the study of several mixtures of air with O-2, CO2 and steam in a pilot scale gasification plant. Out of eight substrates characteristic of south-central and southern Portugal, Miscanthus was chosen for revealing the highest potential for energy generation and for its friendliness from an ecological standpoint. Experiments with Miscanthus were performed in a pilot scale reactor and generated results were compared with ones from a numerical model, which consists of a EulerianEulerian approach within the Fluent framework that is able to describe the transport of mass, momentum and energy for both solid and gas phases. The numerical model was used to compare several gasifying agent mixtures and their impact on syngas composition and respective quality indices under similar operating conditions. The influence of equivalent, steam/biomass and CO2/biomass ratios on syngas produced as well as temperature and cold gas efficiency were studied, and the most suitable application for each mixture was appraised based on the results. (C) 2017 Elsevier Ltd. All rights, reserved.