with increased concerns over greenhouse gas emission and decreasing fossil fuel supplies, biomass is increasingly seen as an alternative option for energy and chemical production. there are several technologies available to upgrade biomass to useful energy and fuel products, and one of the most promising is gasification. tar formation is the major challenge for biomass gasification. formation of tars represents not only a decrease in gasification efficiency, but would cause some operation issues such as fouling and potential clogging due to the condensation of tars as they cool downstream.