A huge factor is air shipping; something I could have told you almost 50 years ago as a sophomore engineering student. (Naval architecture so a lot of wing and foil theory and calcs.) For fun I calculated the fuel required to fly my 155 pound body 800 miles from Boston to Detroit. (School was in Ann Arbor.) All I needed was distance and altitude. I used the flight efficiency of a sailplane and picked a realistic engine efficiency out of a hat. (I was taking thermodynamics and propulsion at the time.)
I wish I had kept the calcs. I'd do them again but after all this time and my head injury, they're no longer easy and my mistakes wouldn't be obvious to me like they were then. The fuel cost for this scrawny body was huge! Extrapolate to a full plane and you know that those jets are essentially tankers (and no wonder those that hit the WTC did what they did).
By contrast, bicycles, trains and merchant ships are some of the most efficient means of transporting goods ever created. (Bicycles, being rather small, have cargos limited to not much more than one live body.) All three can be as high as 1000 miles to the gallon vs a conventional car. Cars are an order of magnitude better than planes. Re: ships - those that carry heavy cargos and are slow are super efficient. High speed ships far less so. They have to battle a resistance curve (wave making) that makes our bicycle aero challenges look like rolling resistance. Very, very crudely, speed to the third power vs air resistance - speed to the second power vs rolling resistance - speed to the first power. |