Mon Apr 07, 2014 at 05:00 PM PDT
Navy lab makes gasoline from seawater, as low as $3 per gallon
The U.S. Naval Research Laboratory (NRL) announced today
that they have manufactured long-chain hydrocarbons -- that is
essentially gasoline -- entirely from seawater, and used the fuel to
power a flying model aircraft.
Using a patented electrochemical process, they have simultaneously extracted dissolved CO2 ions and created hydrogen gas from seawater. The resulting mixture of gases is then reformed into long-chain hydrocarbons in a chemical reaction.
Using a patented electrochemical process, they have simultaneously extracted dissolved CO2 ions and created hydrogen gas from seawater. The resulting mixture of gases is then reformed into long-chain hydrocarbons in a chemical reaction.
attribution: US Naval Research Laboratory
Last year I diaried about a 2010 study done by the NRL
that suggested a very similar process was feasible for manufacturing
jet fuel at sea, using excess electricity from a dedicated
nuclear-powered factory ship. The key to the process is the realization
that a liter of seawater contains 140 times as much CO2 as a liter of air. In seawater, nearly all of the CO2
is actually in the form of bicarbonate ions, which should make
extraction from water fairly straightforward because of the electrical
charge they carry.
So it's a pleasant surprise to see that the Navy not only was paying attention to their own research, but they have also moved from theory to practice and have actually manufactured real fuel using a similar process.
One big caveat: obviously, there is no free lunch, and this process requires energy as input. But since it is entirely feasible to use non-fossil energy sources to power the process, the fuel created could be essentially fossil-free (carbon neutral) gasoline. The oceans and atmosphere exchange CO2 readily in massive quantities, so taking it from one place is functionally the same as taking it from the other.
The NRL press release contains this interesting quote:
I'm not enough of a chemist to know whether there is an energy advantage in creating the hydrogen this way rather than by electrolysis of water -- but I'm betting some Kossack out there can figure it out and post in the comments. If there is, that would be huge.
The NRL press release seems to buy into that estimate, putting the cost of their new process at between $3 and $6 per gallon. (The implication is that the total energy inputs are comparable to those in the 2010 study, which assumed that all the required H2 would be made from electrolysis.)
So it's a pleasant surprise to see that the Navy not only was paying attention to their own research, but they have also moved from theory to practice and have actually manufactured real fuel using a similar process.
One big caveat: obviously, there is no free lunch, and this process requires energy as input. But since it is entirely feasible to use non-fossil energy sources to power the process, the fuel created could be essentially fossil-free (carbon neutral) gasoline. The oceans and atmosphere exchange CO2 readily in massive quantities, so taking it from one place is functionally the same as taking it from the other.
The NRL press release contains this interesting quote:
Using 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.Note that they're not specifically claiming the H2 was electrolyzed by splitting water. That's because the bicarbonate ion is formed when a CO2 molecule combines with a OH- (hydroxyl) ion, forming the bicarbonate ion HCO3-. So there is at least the theoretical possibility that the NRL process might run something like this: 2(HCO3-) --> 2(CO2) + H2 + O2 + 2(e-)
I'm not enough of a chemist to know whether there is an energy advantage in creating the hydrogen this way rather than by electrolysis of water -- but I'm betting some Kossack out there can figure it out and post in the comments. If there is, that would be huge.
Cost
In the 2010 study, a cost analysis of a jet fuel-from-seawater factory ship came in at about $6 per gallon. But about half the capital cost was for the ship. so presumably a beached reactor would have been able to manufacture fossil-free jet fuel for roughly half that.The NRL press release seems to buy into that estimate, putting the cost of their new process at between $3 and $6 per gallon. (The implication is that the total energy inputs are comparable to those in the 2010 study, which assumed that all the required H2 would be made from electrolysis.)
No comments:
Post a Comment
Please leave a comment-- or suggestions, particularly of topics and places you'd like to see covered