A waste heat exchanger may include an inner tube, an outer tube, a fin assembly and a plurality of heat electric modules The inner tube has a plurality of holes. Disposed inside the inner tube is a plurality of inlet channels and a plurality of outlet channels. The plurality of inlet channels and the plurality of outlet channels are disposed to correspond to each other. The plurality of inlet channels and the plurality of outlet channels are connected to the plurality of holes. A fluid flows through the plurality of inlets and the plurality of holes to get into the outlet channels. The outer tube is disposed outside the inner tube. The conductive assembly is positioned between the inner tube and the outer tube. The conductive assembly is disposed on an outside surface of the inner tube and an inside surface of the outer tube.