Abstract: An energy source includes an internal combustion engine with a cooling jacket in which a vapor of a working medium (steam in the case of water) is generated; a turbine connected to receive the vapor from the cooling jacket and having a rotating component rotated by the passage of the vapor; a generator rotated in response to rotation of the rotating component to generate electricity; and a heating coil powered by electricity produced by the generator, the heating coil being disposed to heat the medium in the cooling jacket to assist in providing vapor. The energy source may be used in a motor vehicle, and the steam (when water is used as the working medium) and the generated electricity can be used as energy sources for external loads, such as heating and powering a building.