Because of the scarcity of nonrenewable natural resources, such as petroleum and natural gas, the use of biofuel is needed. Gasification is a major process used to obtain renewable fuels from biomass; however, the gas cleaning system is a constraint for its broad utilization. During the pyrolysis process, a mixture of organic compounds in the gas phase is produced and must be removed from the gases before it is used in the most practical applications. In order to remove such organic compounds, which are known as tar, large, sophisticated, problematic, and expensive gas cleaning systems are added to the gasifier gas exit. Previous papers have shown that the plasma torch has the potential to destroy produced tar, being a simpler and less-expensive system than traditional gas cleaners. This work presents a qualitative and quantitative evaluation of a microwave plasma system running on tar destruction and its reforming. In order to evaluate a 1 kW microwave plasma system performance, an apparatus was developed and installed at ITA Laboratory of Plasmas and Processes (LPP-ITA). The system runs at atmospheric pressure with nitrogen and argon as carrier gas under a large range of flow rates. Experiments were performed using a gas mixture of N 2 , H 2 O, ethanol, and tar at controlled concentration in order to simulate the gases produced by a gasifier. The injected tar was obtained from pine pyrolysis and characterized for energy purposes. In order to reduce tar viscosity, it was diluted in commercial ethanol (92.5% ethanol and 7.5% water) and its concentration varied from 0.8 g tar /Nm gas 3 to 4.2 g tar / Nm gas 3 . Species formed in the microwave plasma torch were identified using an optical spectrometer. The reactor exit gases had their composition evaluated on tar content as well as for noncondensable gases. As a result, this paper shows that no tar content was detected at the reactor outlet, indicating that all supplied tar was destroyed in the plasma reactor. The main detected products were CO and solid carbon (C (s) ). Furthermore, neither NO nor CO 2 were detected, and an indication of H 2 formation was obtained. This paper concludes that the microwave plasma system is capable of destroying and reforming tar efficiently and produces mainly H 2 , CO, O 2 , and C (s) as byproducts.

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New experimental techniques, as well as modern variants on known methods, have recently been employed to investigate the fundamental reactions underlying the oxidation of biochar. The purpose of this paper was to experimentally and statistically study how the relative humidity of air, mass, and particle size of four biochars influenced the adsorption of water and the increase in temperature. A random factorial design was employed using the intuitive statistical software Xlstat. A simple linear regression model and an analysis of variance with a pairwise comparison were performed. The experimental study was carried out on the wood of Quercus pubescens, Cyclobalanopsis glauca, Trigonostemon huangmosun, and Bambusa vulgaris, and involved five relative humidity conditions (22, 43, 75, 84, and 90%), two mass samples (0.1 and 1 g), and two particle sizes (powder and piece). Two response variables including water adsorption and temperature increase were analyzed and discussed. The temperature did not increase linearly with the adsorption of water. Temperature was modeled by nine explanatory variables, while water adsorption was modeled by eight. Five variables, including factors and their interactions, were found to be common to the two models. Sample mass and relative humidity influenced the two qualitative variables, while particle size and biochar type only influenced the temperature.

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