Last month the Navy Research Lab powered a radio-controlled P-51 model using a "gas to liquid" process that takes seawater and turns it into fuel.
According to a jargon-rich NRL press release, the process goes something like this: An innovative and proprietary NRL electrolytic cation exchange module (E-CEM), both dissolved and bound CO2 are removed from seawater at 92 percent efficiency by re-equilibrating carbonate and bicarbonate to CO2 and simultaneously producing H2. The gases are then converted to liquid hydrocarbons by a metal catalyst in a reactor system.
In other words, seawater goes in the tank and the motor cranks up and the airplane flies.
"In close collaboration with the Office of Naval Research P38 Naval Reserve program, NRL has developed a game changing technology for extracting, simultaneously, CO2 and H2 from seawater," said Dr. Heather Willauer, NRL research chemist. "This is the first time technology of this nature has been demonstrated with the potential for transition, from the laboratory, to full-scale commercial implementation."
Equally amazing is how nobody seemed to notice, or if they noticed they didn't seem to care. (This is when conspiracy theorists blame Big Oil.)
Here's a video that shows the R/C P-51 flight: