It may seem fanciful but the US Naval Research Laboratory is working on the development of a process that would take seawater and, a few steps down the line, produce jet fuel from it, via a gas-to-liquids process.
NRL has successfully developed and demonstrated technologies for the recovery of CO2 and the production of H2 from seawater using an electrochemical acidification cell, and the conversion of CO2 and H2 to hydrocarbons (organic compounds consisting of hydrogen and carbon) that can be used to produce jet fuel."The reduction and hydrogenation of CO2 to form hydrocarbons is accomplished using a catalyst that is similar to those used for Fischer-Tropsch reduction and hydrogenation of carbon monoxide," adds Willauer. "By modifying the surface composition of iron catalysts in fixed-bed reactors, NRL has successfully improved CO2 conversion efficiencies up to 60 percent."
Why is the Navy investigating a procedure that frankly seems a long way off from implementation? The same reason they are testing converting some ships and planes to use algae-based biofuels: Fuel supply.
If seawater could be used to produce jet fuel, either on land-based plants or at sea, a nearly unlimited supply of fuel could be sourced close to where it had to be used. To give a sense of scale, last year the Navy operated 15 refueling ships around the world, delivering almost 600 million gallons of fuel.
The Navy anticipates being able to eventually bring the cost of producing jet fuel from seawater down into the $3-6 per gallon range.
As for the green credentials, well, it would reduce energy usage in transporting fuel, presuming this fuel would be made close to the point of use, but otherwise it's just jet fuel, not any greener at all in terms of emissions.