This paper examines the Fischer-Tropsch technology for the biomass-to-clean fuels scenario.A comparison of the activities,selectivities and lifetimes of iron and cobalt catalysts for Fischer-Tropsch synthesis is made.For the more severe conditions,iron is the more active catalyst,whereas a cobalt catalyst may be more active at low severity conditions.In spite of many reports,there are still considerable differences in defining catalyst activity.The selectivity for methane likewise shows a wide range of reported results.Under the proper conditions,both catalysts are capable of operating for 6 months or more.