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Power The Military Science

US Navy Tries To Turn Seawater Into Jet Fuel 402

Posted by samzenpus
from the ocean-in-the-tank dept.
Hugh Pickens writes "New Scientist reports that, faced with global warming and potential oil shortages, the US Navy is experimenting with making jet fuel from seawater by processing seawater into unsaturated short-chain hydrocarbons that with further refining could be made into kerosene-based jet fuel. The process involves extracting carbon dioxide dissolved in the water and combining it with hydrogen — obtained by splitting water molecules using electricity — to make a hydrocarbon fuel, a variant of a chemical reaction called the Fischer-Tropsch process, which is used commercially to produce a gasoline-like hydrocarbon fuel from syngas, a mixture of carbon monoxide and hydrogen often derived from coal. The Navy team have been experimenting to find out how to steer the CO2-producing process away from producing unwanted methane by finding a different catalyst than the usual one based on cobalt. 'The idea of using CO2 as a carbon source is appealing,' says Philip Jessop, a chemist at Queen's University adding that to make a jet fuel that is properly 'green,' the energy-intensive electrolysis that produces the hydrogen will need to use a carbon-neutral energy source; and the complex multi-step process will always consume significantly more energy than the fuel it produces could yield. 'It's a lot more complicated than it at first looks.'"
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US Navy Tries To Turn Seawater Into Jet Fuel

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  • Closed Loop (Score:3, Informative)

    by maz2331 (1104901) on Thursday August 20, 2009 @02:11AM (#29129705)

    It removes CO2 from the water, where it will eventually return through the same process that put it there in the first place.

  • by Tmack (593755) on Thursday August 20, 2009 @02:28AM (#29129787) Homepage Journal

    jet aircraft (each costing millions), runs on jet fuel, not methane

    But rockets (and rocket planes) do Carmack and Armadillo Aerospace [armadilloaerospace.com] have been doing just that for NASA.

    Tm

  • Re:Cost effective? (Score:4, Informative)

    by dakameleon (1126377) on Thursday August 20, 2009 @02:44AM (#29129875)

    There's a practical limit to the CO2 that the oceans can absorb.

    I think the point being made above is that if we're sucking the CO2 out of the ocean in the first place, it'll make a buffer to absorb what we've extracted. Or to use an analogy, we're emptying the carbon sink on the one hand and topping it up with the other, hopefully leaving things even.

  • by im_thatoneguy (819432) on Thursday August 20, 2009 @03:26AM (#29130069)

    And by my Google search estimates a carrier only has enough fuel for about 1,000 flights before exhausting its supply and needing a tanker.

    I imagine during combat operations that doesn't last terribly long. And having to pull along side another vessel and safely pumping that fuel has got to provide some pretty serious tactical limitations.

  • Re:Makes sense (Score:3, Informative)

    by goodmanj (234846) on Thursday August 20, 2009 @03:55AM (#29130189)

    I believe step 3 in your plan is

    3) Large amounts of radioactive material fly out the back of the jet, contaminating everything in sight.

    Nuclear aircraft [wikipedia.org] are quite feasible, provided you really, really don't care about flyover country.

    (Oh, by the way: you can skip the steam in step 1, and just heat the air directly.)

  • Re:But the beauty is (Score:5, Informative)

    by Rogerborg (306625) on Thursday August 20, 2009 @04:40AM (#29130407) Homepage

    Can't that "non-fossil-fuel-based electric power" alone propel the car? Why do we need to make more fuel, resulting in more emissions, and poor energy conversion efficiency?

    What part of "works with existing cars and existing refueling stations" is confusing you hippes?

    There's only recently been an announcement [gas2.org] of a standard plug for electric cars. Note that an "announcement" is not manufacturing, or even a commitment to manufacturing. We've still got the inevitable patent wrangles, the embrace-extend debacles, breakaway standards, and the litigation and class action suits to go before we'll have a standard plug, and then we have to build the charging infrastructure, on top of a creaking already over-strained electrical grid.

    Sorry, I put far too much thought into that. Try to read it really slowly.

  • Re:Makes sense (Score:5, Informative)

    by NewbieProgrammerMan (558327) on Thursday August 20, 2009 @05:11AM (#29130575)

    Plenty of energy - not so much to spare once you account for propulsion, hotel loads, steam for the catapults, etc...

    Actually, most of the time the plant isn't loaded heavily at all--most of its capacity is there solely for moving at high speed. Since you don't do that very often (you get to wherever you're going and then putt around in little rectangles), there's plenty of power available for doing something like this.

    Carriers are big, but they are stuffed full of what they need to fight - and fuel tanks are tucked into odd corners well below the water line. Not much spare room for the major industrial plant required to produce sufficient fuel in a reasonable amount of time.

    For what it's worth, the one I was on had several not-too-small empty spaces, certainly enough to install small test plants. I'm sure if this turns out to be viable, newer ships could be designed with plenty of room for fuel generators.

  • Re:Makes sense (Score:3, Informative)

    by NewbieProgrammerMan (558327) on Thursday August 20, 2009 @05:28AM (#29130663)

    Actually, most surface vessels are not (in the US Navy, anyway), and I don't know of any submersible ships that carry jets. They phased out all of the nuclear powered cruisers and destroyers in the late 90's, leaving the aircraft carriers as the only nuclear powered surface ships. Here's a list [wikipedia.org].

  • Re:Hydrogen (Score:3, Informative)

    by tsotha (720379) on Thursday August 20, 2009 @05:30AM (#29130671)

    Hydrogen is problematic as a fuel. For one thing, it has a terribly low density, which is why the space shuttle has that enormous external fuel tank. For another, H2 is a really, really tiny molecule that will go through just about anything over time. That makes it a lot more dangerous and expensive to deal with.

    It's just not practical for combat aircraft.

  • Re:But the beauty is (Score:3, Informative)

    by budgenator (254554) on Thursday August 20, 2009 @08:33AM (#29131527) Journal

    Back in the Viet Nam era, the army 2 1/2 ton 6X6 truck [wikipedia.org] had a multi-fuel engine that would run on anything from No. 4 bunker fuel [wikipedia.org] to 104 AV gas. Running on gasoline was really hard on the fuel pumps and injectors but was useful in emergencies; the Army is all Diesel or JP8 [wikipedia.org] now so this capability is unnecessary.

  • Re:But the beauty is (Score:3, Informative)

    by init100 (915886) on Thursday August 20, 2009 @09:20AM (#29131931)

    This is what I don't understand - they're taking sequestered carbon out of seawater and burning it back into the atmosphere as jet fuel, at a huge additional energy cost during the conversion. This is 'green'?

    Since the CO2 in seawater comes from the atmosphere, this carbon takes part in a cycle, and thus does not constitute a net increase in atmospheric carbon. On the other hand, taking carbon buried in the ground (coal/petroleum) and putting it in the atmosphere is not a cycle (except possibly on geological timescales).

  • Re:Makes sense (Score:1, Informative)

    by Anonymous Coward on Thursday August 20, 2009 @10:43AM (#29132887)

    Then again, I still don't fully understand what Obama's got planned...

    What do polls of only ultra liberals say today? That is what Obama has planned.

  • Re:Or... (Score:1, Informative)

    by Anonymous Coward on Thursday August 20, 2009 @01:21PM (#29135283)

    Actually, at the time the tornado hit, the Evangelical Lutheran Church in America's nationwide assembly was meeting just across the street from the church, having a debate on a social statement on human sexuality, a precursor to today's debate on whether to allow gay clergy.

  • Re:Or... (Score:3, Informative)

    by StikyPad (445176) on Thursday August 20, 2009 @03:18PM (#29137153) Homepage

    You know, I thought you might have been mistaken regarding the loss of nuclear weapons, but a little searching turned up several documented cases. I certainly never knew that there lies an unexploded nuclear bomb somewhere off the coast of Savannah.

    http://en.wikipedia.org/wiki/1958_Tybee_Island_B-47_crash [wikipedia.org]
    http://news.bbc.co.uk/2/hi/europe/7720049.stm [bbc.co.uk]

    Also, the List of military nuclear accidents [wikipedia.org] is much longer than I expected.

Computers are unreliable, but humans are even more unreliable. Any system which depends on human reliability is unreliable. -- Gilb

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