While oil may be a very potent power source, most of the energy is wasted via heat when put into a traditional internal combustion engine. Hence why engines get so hot. BMW thinks it can use that lost heat energy to improve fuel consumption…and they’re making good progress.
BMW has been approaching this technology from two angles; a turbosteamer, and a thermoelectric generator. Both devices use scavenged heat energy to improve performance in different ways. Green Car Congress has all the technical mumbo jumbo if you want to try to decipher it, but I’ll try to break it down and keep it simple best I can here.
The turbosteamer device was first unveiled in 2005, and uses the same principles that large power plants use to scavenge heat energy. BMW was reportedly was able to improve fuel efficiency by up to 15% on a four-cylinder engine. But the system was large, cumbersome, and impractical for cars at the time.
Six years later though, and BMW has successfully reduced the size of the system, which recovers heat from the car’s exhaust, and uses that to heat up a high-pressure fluid. This fluid turns to steam, powering a turbine that produces electricity. BMW engineers say that when the system is ready for the road (in about ten years) it will be able to supply all of a car’s electrical needs, taking a load off of the engine and improving efficiency by up to 10% over long trips.
The Thermoelectric Generator
The second technology that BMW has been working to improve is a thermoelectric generator. It uses the Seebeck Effect, which states that electricity can be generated between two thermoelectric semiconductors at different temperatures. This system, which recovers heat energy from the exhaust gas re-circulation (EGR) system, can provide up to 600 watts of power. This system can also deliver an immediate blast of hot air during cold starts, should the driver desire. The improvements on emissions and fuel economy is a relatively paltry 2%…but all those little numbers really begin to add up in the long run.
It’s a very neat technology that I’ll be keeping a close eye on. After all, it makes a lot of sense if you ask me.
Source: Green Car Congress
Chris DeMorro is a writer and gearhead who loves all things automotive, from hybrids to HEMIs. You can read about his slow descent into madness at Sublime Burnout or follow his non-nonsensical ramblings on Twitter @harshcougar.