1 lb fuel has 3 lbs of CO2. Including production most fuels have more CO2 than jet fuel. Liquid Hydrogen from coal 3.3 times CO2 of oil based jet fuel, methane from coal 2.3 x, jet fuel from coal 1.8x, jet fuel from coal catching CO2 is about 1.5x, Bio jet .5x, liquid hydrogen from H2O and nuclear is the cleanest .1 time CO2 of oil. Bio soy jet fuel would require 5.7 sq km (Europe). Hydrogen from H2O would use about 3000 gallons of water per gallon on jet fuel. 1000gal/kelo fuel. I vote for coal. Its the next most clean and available. Coal jet fuel could be about $45 per barrel. Anyone got 10 billion for coal jet fuel plant?