Non-isothermal pyrolysis of torreﬁed stump – A comparative kinetic evaluation Khanh-Quang Tran a,⇑ , Quang-Vu Bach a , Thuat T. Trinh b , Gulaim Seisenbaeva c a Department of Energy and Process Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway b Department of Chemistry, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway c Department of Chemistry, Swedish University of Agricultural Sciences, Box 7015, SE-75007 Uppsala, Sweden highlights  The ﬁrst pyrolysis kinetic study of torreﬁed stump.  Three pseudo-components model with n – 1 is the most suitable for the kinetics.  The torreﬁed stump has higher activation energy than the untreated stump. article info Article history: Received 31 October 2013 Received in revised form 25 June 2014 Accepted 6 August 2014 Available online 28 August 2014 Keywords: Non-isothermal kinetics Kinetic modelling Slow pyrolysis Torreﬁed biomass Norway spruce stump abstract The pyrolysis of native and torreﬁed stump materials was studied in the kinetic regime by means of a thermogravimetric analyzer operated in the non-isothermal fashion. Three different kinetic models appli- cable to biomass pyrolysis were evaluated for the collected data, which include a single-reaction model, two three pseudo-components models, and a distributed activation energy model (DAEM). It was shown that the single-reaction model was not suitable to simulating stump biomass pyrolysis. The other models including the three pseudo-components model with n = 1 and n – 1, and the DAEM demonstrated very good ﬁts between simulated and experimental curves. However, the three pseudo-components model with n – 1 is recommended as the most suitable for simulation and prediction of kinetic behaviour of slow pyrolysis for both untreated and torreﬁed stump, considering that it offers the best ﬁts to the exper- imental data and that the generated reaction orders are realistic, being slightly higher than unity. It appears that the torreﬁed stump has higher activation energy than its native material. The activation energy predicted for the native stump pyrolysis is in the range of 105.2–108.9 kJ/mol, 183.5–183.6 kJ/ mol, and 40.3–48.01 kJ/mol for hemicelluloses, celluloses, and lignin, respectively. That for pyrolysis of the stump torreﬁed at 200 °C is 105.13–111.19 kJ/mol, 183.68–185.79 kJ/mol, and 40.49–50.70 kJ/mol, respectively. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Biomass resources have been used by mankind for a very long time in order to meet its primary energy needs and to power human development. With increasing concerns of human impacts on the environment and climate, biomass is once again considered as an important energy source to meet a signiﬁcant portion of the increasing energy demand in the modern world. The challenges today in using biomass as fuel are various, but can be best related to scale and density, among which the scale of energy demand by far exceeds all the needs in past [1]. Both the increasing world pop- ulation and the energy intensity of modern life compound the high demand for energy as never before. Consequently, the extraction of biomass from forest and agriculture for use as fuel has become a common practice in various countries and increased the burden on the soil. In addition to the problems of land-use conﬂict and increased food price, today people even fear the problem of com- peting for wood between the paper and energy industries [2]. One way to meet the growing demand of forest biomass for energy application, without increasing the annual harvesting vol- ume of stem wood, is to utilize tree stump, which may be deﬁned as all belowground and aboveground wood and bark mass of a tree beneath the merchantable timber cross-section. It is reported that when tree stumps and small round-wood from thinning are used to replace fossil fuels, the potential CO 2 reduction will be about http://dx.doi.org/10.1016/j.apenergy.2014.08.026 0306-2619/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +47 73 59 36 25; fax: +47 73 59 35 80. E-mail address: khanh-quang.tran@ntnu.no (K.-Q. Tran). Applied Energy 136 (2014) 759–766 Contents lists available at ScienceDirect Applied Energy journal homepage: www.elsevier.com/locate/apenergy