70-80% of the chemical energy going into a gasoline engine ends up being lost via heat, and a lot of this is lost via the hot exhaust gases. So there's a fair amount of scope to recover some of this lost heat and turn it into useful energy.
But to be honest, given the relatively low delta-T's involved, I really didn't think anyone would be able to crack this problem soon with any kind of practical setup.
Which is why I'm so surprised that BMW appear to have achieved exactly that!
http://www.greencarcongress.com/2005...ing_.html#more
Incredible!
