A turbosteamer is a term used by BMW to describe a combined cycle engine. Waste heat energy from the internal combustion engine would be used to generate steam (see Waste Heat Recovery Unit) for a steam engine which would create supplemental power for the vehicle. The turbosteamer device is affixed to the exhaust and cooling system. It salvages the heat wasted in the exhaust and radiator (as much as 80% of heat energy) and uses a steam piston or turbine to relay that power to the crankshaft. The steam circuit produces 14 hp (10 kW) and 15 ft⋅lbf (20 N⋅m) of torque at peak (for a 1.8 Straight-4 engine), yielding an estimated 15% gain in fuel efficiency. Unlike gasoline-electric hybrids, these gains increase at higher, steadier speeds.
BMW has been the pioneer of this concept as early as 2000 under the direction of Dr. Raymond Freymann, and while they were designing this system to fit to most current BMW models, the technology didn't reach production.
- R. Freymann, W. Strobl, A. Obieglo: The Turbosteamer: A System Introducing the Principle of Cogeneration in Automotive Applications. Motortechnische Zeitschrift, MTZ 05/2008 Jahrgang 69, pp.404-412.
- Gizmag article discussing BMW's turbosteamer
- Article on BMW's alternative Combined Cycle Hybrid technology
- Looking for the next gram. BMW Group. Retrieved 5 December 2011.