As I type this I'm listening to my colleague Ilan Kroo, professor in Aerodynamics at Stanford University and a world renowned airplane designer. The topic of his lecture is Sustainable Aviation: Future Air Transportation and the Environment.
A few blogs ago I gave some current numbers on the efficiency of air travel vs car travel. A Boeing 737 with 75% occupancy gives about 80 miles/gallon for each passenger. This compares favorably to a car, but then, we would not drive across the Atlantic.

Forget alternative energies: in the short term the only feasible solution to reducing greenhouse gas emissions and petroleum dependencies is energy efficiency. There is much to be gained, especially in the U.S., where energy consumption per person has risen above that of any other country in the world. Professor Jim Sweeney directs the new Precourt Institute for Energy Efficiency on the Stanford University campus. Energy efficiency measures can reduce our consumption significantly whilst not hurting our economy nor lifestyle: there is no excuse not to go this way.