In accordance with one embodiment, a system includes a posimetric pump configured to increase pressure of a feedstock to provide a pressurized feedstock. The system also includes a fixed bed gasifier configured to gasify the pressurized feedstock, wherein the fixed bed gasifier comprises an enclosure, a feedstock inlet configured to receive the pressurized feedstock, at least one agent inlet configured to receive at least one gasification agent, a syngas outlet configured to output a syngas, an ash outlet configured to output ash, and a fixed bed configured to support the pressurized feedstock while allowing flow of the at least one gasification agent through the pressurized feedstock.