A thermal energy harvester and power conversion system employs a bleed air duct containing the flow of high temperature air from an engine. A lower temperature air source is included with an energy conversion device having a hot interface operably engaged to the bleed air duct and a cold interface operably engaged to the lower temperature air source. The energy conversion device generates electrical power from a thermal gradient between the bleed air duct and the lower temperature air source and the electrical power is routed to a power feeder.