One embodiment includes an on-board thermoelectric vehicle system for generating electrical energy using a heated fluid stream, including at least one thermoelectric device having a high temperature junction and a low temperature junction, and a body of high conductivity foam shaped and located to increase heat transfer from the heated fluid stream to the high temperature junction or to increase heat transfer from the low temperature junction of the thermoelectric device.
 The United States Government has rights in this invention pursuant to Cooperative Agreement No. DE-FC26-04NT42278 awarded by the United States Department of Energy. The United States Government has rights in this invention pursuant to contract no. DE-AC05-00OR22725 between the United States Department of Energy and UT-Battelle, LLC.