Jet Fuel From Seawater Is Possible, Still Impractical
Air contains about .04 percent carbon dioxide, but ocean water holds about 140 times that much -- and using electricity to split the water molecules and then combining them with hydrogen creates a hydrocarbon fuel ... and it works. For now, the problem is that it doesn't work especially well. Navy chemists have gone so far as to process seawater into "unsaturated short-chain hydrocarbons," according to NewScientist, "that with further refining could be made into a kerosene-based jet fuel." If they power the reaction with a clean energy source the military could correctly claim to be flying mostly "carbon neutral." At this stage, the process is still producing an undesired byproduct -- 30 percent methane. It also takes substantially more energy to create the fuel than the fuel itself can yield. Navy chemist Heather Willauer is leading the project and believes the efficiency of the process needs to be significantly improved, which may be achieved by applying a new catalyst to the process.
Early attempts using a cobalt-based catalyst yielded methane, almost exclusively, along with some liquid fuel compounds and waxes. Switching to an iron catalyst shifted the balance to 30/70. But, again, the complex chain of reactions requires a significant amount of energy and every step added to the process is likely to add complications and cost.