Thermochemical assessment of Nicotiana glauca, Panicum virgatum and Elytrigia elongata as fuels for energy recovery through gasification

Abstract

Production of energy from renewable biomass resources would reduce atmospheric CO2 increase associated with fossil fuels use. In this context, the objective of this study is to evaluate the energy potential of three herbaceous biomass crops (Nicotiana glauca, Panicum virgatum and Elytrigia elongata) grown on marginal lands. In order to do so, physicochemical and thermogravimetric characterization and gasification tests of each crop were performed. From the thermogravimetric analysis, it was estimated the activation energies of each energy crop using the Friedman method, obtaining values of 194.3, 224.9 and 220.6 kJ/mol for Nicotiana glauca, Elytrigia elongata and Panicum virgatum respectively. Then, in order to assess their potential as fuels for energy recovery, gasification tests were performed in a fluidized bed gasifier, using air and enriched air as gasifying agents. The ranges of experimental conditions used were the following: gasification temperature: 770-820ºC; ER: 0.15-0.20; oxygen content: 21 and 27% respectively. The gasification gas obtained from these experiments had a calorific value between 3.5-5.0 MJ/Nm3, being always slightly higher for enriched air gasification. Besides, particle and tar contents were in the range of 4-17 g/Nm3 and 4-12 g/Nm3 respectively using air and 4-27 g/Nm3 and 4-18 g/Nm3 using enriched air. The results obtained showed that it is feasible to gasify the three selected crops grown on marginal lands with little differences in the gas produced offering an alternative to obtain a clean energy.