December 14, 2005 A large percentage of the energy released when petroleum is burned disappears out the exhaust system as heat. This has always been the case but the amount of energy released looks set to be cut by more than 80% thanks to a new system devised by BMW. BMW’s announcement of the new technology is somewhat of a technological bombshell as it adds yet another form of hybrid automobile – a turbosteamer. The concept uses energy from the exhaust gasses of the traditional Internal Combustion Engine (ICE) to power a steam engine which also contributes power to the automobile – an overall 15 per cent improvement for the combined drive system. Even bigger news is that the drive has been designed so that it can be installed in existing model series – meaning that every model in the BMW range could become 15% more efficient overnight if the company chose to make the reduced consumption accessible to as many people as possible.

Combining the innovative assistance drive with a 1.8 litre BMW four-cylinder engine on the test rig reduced consumption by up to 15 percent and generated 10 kilowatts more power and 20 Nm more torque. This increased power and efficiency comes for, well, … nothing. The energy is extracted exclusively from the heat in the exhaust gases and cooling water so it is essentially a quantum leap in efficiency.

The Turbosteamer is based on the same principle of the steam engine: liquid is heated to form steam in two circuits and this is used to power the engine. The primary energy supplier is the high-temperature circuit which uses exhaust heat from the internal combustion engine as an energy source via heat exchangers. More than 80 percent of the heat energy contained in the exhaust gases is recycled using this technology. The steam is then conducted directly into an expansion unit linked to the crankshaft of the internal combustion engine. Most of the remaining residual heat is absorbed by the cooling circuit of the engine, which acts as the second energy supply for the Turbosteamer.

The development of the assistance drive has reached the phase involving comprehensive tests on the test rig. The components for this drive have been designed so that they are capable of being installed in existing model series. Tests have been carried out on a number of sample packages to ensure that the BMW 3 Series provides adequate space. The engine compartment of a four-cylinder model offers enough space to allow the expansion units to be accommodated.

Ongoing development of the concept is focusing initially on making the components simpler and smaller. The long-term development goal is to have a system capable of volume production within ten years.

“This project resolves the apparent contradiction between consumption and emission reductions on one hand, and performance and agility on the other,” commented Professor Burkhard Göschel.