So all this research that is going into hydrogen fuel cells, hybrid technology, and other alternate energy sources for automobiles, is there any corresponding research for airplanes or trucks, or other such things that require huge amounts of fuel, whether it is jet fuel or diesel fuel?
For trucks, they can use biodiesel.
For planes, I doubt it. You need a very special cross between energy density (so you don't carry extra weight) and flammability. For planes, I believe they are working on things that will reduce pollutants, and flammability