200-Year-Old NASA-Tested Engine May Be the Key to 100 MPG SUVs

In his attempt to develop the next generation of experimental powertrains, Texas inventor Josh MacDowell has gone way back in time. By pairing modern hybrid batteries and electric motors with a 200-year-old design called a Stirling engine, MacDowell claims to have created a a range-extended electric vehicle powertrain he says gets 100 miles per gallon in a small SUV. And he's already nabbed a patent for it.

Created by Scottish minister Robert Stirling in 1816, the Stirling engine is a closed-system engine that uses internal differences in air temperature to move two pistons, which can then perform mechanical work.According to Houston’s KHOU 11 News, instead of using the Stirling to perform work, MacDowell attached a thermopile—a linked series of conductors that can generate voltage from differences in temperature—to the business end of the engine. So the Stirling powers the thermopile, the thermopile creates voltage to charge the batteries, and the batteries power the electric motors that turn the wheels.

One of the biggest benefits to MacDowell’s Stirling is its thermal efficiency, which reaches about 50 percent thanks to an internal regenerative heat exchanger. Even the most finely tuned gasoline engine, like that in a Toyota Prius, can only reach 40 percent thermal efficiency.

Link to article: http://www.thedrive.com/news/4017/200-year-old-nasa-tested-engine-may-be-the-key-to-100-mpg-suvs