To lower the price of fuel. Even if you saved all that fuel with power plants it still wouldn't put much of a dent in. I am not worried about cleaner better fuel effeciant cars. Here is why. If you have ever seen how many lbs of fuel an airliner takes to travel a great distance it is a bit crazy. Especailly on flights that are not full.
I would love to see a wind powered airplane or a solar powered plane lol. If that was to happen, well people would be getting a ride for their money thats for sure.
But everyone is sooooo worried about what the car does and not the airplane. There are still airplanes today being built on 1930s technology and can not be upgraded due to FAA.
Now you could argue and say planes take Jet A and not Gas, but then you have to take a look at trucks and their diesel prices. There is not much difference between Jet A and diesel.