Microwave and slow pyrolysis biochar-Comparison of physical and functional properties

This article reports work that compares slow pyrolysis and MW pyrolysis of two different feedstock (willow chips and straw), with particular focus on physical properties of resulting chars and their relation to biochar soil function. In these experiments, slow pyrolysis laboratory units at the University of Edinburgh and the MW pyrolysis units at the University of York were used to produce biochar from identical feedstock under a range of temperatures. Physical properties and stability of thus produced biochar from both systems were then analysed and compared. The results showed that using MW, pyrolysis can occur even at temperatures of around 200 degrees C, while in case of conventional heating a higher temperature and residence time was required to obtain similar results. This article presents new data not only on the comparison of biochar from microwave and slow pyrolysis in terms of physical properties, but also in respect to their carbon sequestration potential, i.e. stability. (C) 2012 Elsevier B.V. All rights reserved.