The present invention generally relates to a system that enables one to address various thermal management issues in advanced gas turbine engines. In one embodiment, the present invention relates to a method to extract heat from an air stream, utilize a significant fraction for on-board power generation, and reject a small quantity of heat to the fuel stream safely at, for example, a lower temperature. In another embodiment, the present invention relates to a method to extract heat from an air stream, utilize a significant fraction for on-board power generation, and reject a small quantity of heat to the fuel stream safely at, for example, a lower temperature with no potential air / fuel contact is disclosed.