An apparatus for generating electrical power from the waste heat generated by an internal combustion engine includes a first pipe wall through which a heated medium flows, a thermoelectric generator disposed exteriorly to the inner pipe wall, and a second pipe wall disposed exteriorly to the thermoelectric generator. The first pipe wall and the second pipe wall form at least a partially double-walled pipe. The first pipe wall saves as a high-temperature source. The second pipe wall serves as a low-temperature source.