The impact of biomass feedstock composition and pre-treatments on tar formation during biomass gasification

Gasification is a favourable technology for distributed power generation. However, commercialisation and scale up have been hampered by problems associated with tar formation. Tars are detrimental to operational efficiency as they can condense downstream initiating corrosion and blockages, thus resulting in a reduction in an overall yield during the gasification process. So far there are two main routes to reduce tar formation, namely thermal tar cracking at higher gasification temperatures, or catalytic tar cracking by using different types of heterogeneous catalysts, depending on the reaction system’s configuration. Nevertheless tar still represents a potential issue during gasification, therefore further studies have been focused on trying to find a relationship between biomass composition and tar formation and composition. In this chapter we discuss various alternatives for biomass pre-treatment as a way to reduce tar formation during gasification through compositional manipulation. Engineering solutions provide a primary route to reduce tar formation, but further integrated processing offers increased system efficiently generated using tailored feedstocks. This may be achieved by harvesting energy or products from pre-treatment stages aimed at reducing tar formation and ash composition.