Heat Recovery to Improve Highway Mileage
Hybrid vehicles make great use of regenerative braking and the efficiencies of electric motors for lower speeds and stop-and-go driving. Some hybrids are so good that they have better MPG ratings in the city than they do on the highway. But out on the highway, a hybrid doesn’t fare any better than a vehicle with standard gas engine. Regenerative braking is the way hybrids recover energy during stop-and-go driving, but at highway speeds, there is nothing helping feed back energy into the system, and hybrids are at par with non-hybrids.
Honda has now come out with a demonstration vehicle (using a Japan-only Honda Stream hybrid) that recaptures waste heat from the gasoline engine and runs a small Rankine cycle generator from that to recharge the battery pack.
