Abstract: The invention is concerned with a modular gas turbine engine assembly. The assembly includes a tubular case to which are assembled a gasifier module and a power output module. The gasifier module and the power output module are each slidably sealed to respective inwardly extending, generally removable flanges within the case. The gasifier module has a first tubular housing fixedly detachably attachable with a first end thereof adjacent a first end of the case with the axis of the first housing aligned generally with the axis of the case, a compressor generally within a second end of said first housing, a combustor generally extending outwardly from said first end of said first housing and a first integral shaft extending from the compressor to adjacent the combustor. A gasifier turbine extends generally outwardly radially from the shaft and has first blades positioned to be in the path of the exhaust gases exiting the combustor to drive the first shaft and thereby drive the compressor.