Environmental control system for aircraft utilizing turbo-compressor

An environmental control system (30) includes a higher pressure tap (134) to be associated with a higher compression location (134) in a main compressor section (254) associated with a gas turbine engine (210). A lower pressure tap (32) is associated with a lower pressure location (132), which is at a lower pressure than the higher pressure location. The lower pressure tap (32) communicates to a first passage (36) leading to a downstream outlet and a second passage leading into a compressor section (54) of a turbocompressor (42). The higher pressure tap (34) leads into the turbine section (52) of the turbocompressor (42) such that air in the higher pressure tap (34) drives the turbine section (52) to in turn drive the compressor section (54) of the turbocompressor (42). A combined outlet (44) of the compressor section (54) of the turbocompressor (42) and the turbine section (52) intermix and pass downstream to be delivered to an aircraft use.