US Navy Tries To Turn Seawater Into Jet Fuel

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.'"

Comments

But the beauty is

[Brett Buck]

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. '

        But it's easy to put a nuclear reactor in a ship, and not so easy to put one in a fighter jet.

        Brett

Re:But the beauty is

[Thanshin]

Just imagine what would've happened if a nuclear reactor crashed into WTC. The bottom of the sea doesn't have this problem.

You clearly haven't seen many disaster movies.

There are many ways a nuclear ship and a NY sky scraper can crash against each other, including:

- Giant wave.
- Godzilla.
- Earthquake
- Giant Octopus.

Re:But the beauty is

[Jurily]

I never really considered Godzilla as an argument for nuclear reactors in airplanes.

Re:But the beauty is

[lgw]

The obvious application here is for a (nuclear-powered) aircraft carrier to make fuel for the aircraft that it carries. So wave power and the like might be interesting in a civilian offshoot of this tech, but the Navy has nuclear power to start with.

In civilian use, many of the most efficient engines in commercial use are diesel-electric. Gas-electric hybrids aren't quite as efficient yet, but probably will be soon. Turning non-fossil-fuel-based electric power (whether nuclear, wave power, unicorn giggles, or whatever the hippies will finally accept) plus CO2 into gas or diesel fuel, then burning that fuel in a car in a normal way to drive around is carbon neutral, and works with existing cars and existing refueling stations.

This would seriously kick ass as a way to break dependency on non-renewable fossil fuels but still use the same cars we drive today. 100% win IMO. Of course, there are people whe really just hate gas engines, and only pretend to care about CO2 and renewable resources and so on, but you can never make everyone happy.

Re:But the beauty is

[Anonymous Coward]

Yeah, but I've come up with this brilliant idea for that. See, up until now, gasoline powered devices come with all their gasoline installed at the factory, like you said, and once the gasoline is gone, you have to throw out your car/lawnmower/Molotov cocktail and get a new one. But, my brilliant idea involves a hole in the gas tank through which you can pour more gasoline. I know, I know, it sounds crazy. Who would want a hole in the side of their car? Plus, all your gas would evaporate, it would be dangerous, etc. But the hole is only part of my ingenious plan. I've come up with a threaded stopper for the hole that you can screw into it to seal it. Plus, a little door to go on the side of the car with the gas-hole behind it, to make it unobtrusive. There are some big obstacles to my plan though. This revolutionary idea is going to require a huge investment. We're going to need to put gasoline pumps everywhere, at what I call a "filling station". It's going to take some time to get everything set. Still, I think it will be worth it.
On a side note, the obvious advantage that volatiles like gasoline have over batteries in terms of energy density is free oxygen. The energy density of gasoline isn't worth squat in space, for example. It needs plenty of oxygen to work, but you don't have to carry the oxygen with you. If you had to lug around an oxygen canister with the gasoline to make it work, batteries might become much more attractive. This is why fuel air explosives give so much bang for the buck. It's harder to make the process work than conventional explosives, but you don't have to pack the fuel air bomb with its own oxidant.

Re:But the beauty is

[Rogerborg]

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 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:But the beauty is

[Rogerborg]

fighter jets don't have easy access to seawater anyway..

Carrier based jets have very easy access to seawater. Once.

Re:But the beauty is

[jamesh]

I never really considered Godzilla as an argument for nuclear reactors in airplanes.

And this lack of foresight is why you have no place in todays military.

Re:But the beauty is

[mpe]

But it's easy to put a nuclear reactor in a ship, and not so easy to put one in a fighter jet.

A nuclear powered aircraft carrier needs regular supplies of jet fuel, via ships which are easier to sink than a warship.
Having a carrier able to produce fuel for its aircraft solves a major logistics issue as well as potentially freeing ships from escort/guard duty.

Makes sense

[seifried]

Nuclear powered aircraft carrier, so you've got a pretty good supply of energy there, being able to convert electricity into jet fuel would save them money and reduce the amount of fuel they have to carry (reducing the amount of flammable liquids held in a ship that might get hit by a missile), and could end the need to resupply fuel, all in all very sexy if you're going in to combat.

Re:Makes sense

[NewbieProgrammerMan]

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:Cost effective?

[Dunbal]

oceans absorb CO2

CO2 + H20 H2CO3

H2CO3 ==> HC03- + H+ with a pKa of 3.6

This means that we will eventually turn the oceans into Coca Cola. Not too good for the flora and fauna, I can imagine. There's a practical limit to the CO2 that the oceans can absorb.

Of course if we could create some sort of genetically engineered algae that happened to produce carbonic anhydrase, you'd be able to degas huge amounts of ocean water just by pouring it into your algae tank...

Re:Trying to avoid Methane?

[afidel]

Exactly, it removes one of the biggest and most vulnerable pieces of the supply chain to a carrier group, fuelers for the aircraft. If this becomes a reality soon I think good old CVN-65 (Enterprise) may get a reprieve from retirement. There's nothing quite like the spare capacity in those 8 reactors to power something like this =)

You're missing the point.

[Anonymous Coward]

This has got nothing to do with creating free energy, and it's got nothing to do with environmentalism. It's all about military strategy.

Your nuclear-powered carrier fleet is on patrol in a war zone. Resupply convoys are a risky business. How do you keep your planes in the air without a constant supply of jet fuel?

You make your own on board. Who cares if it's "thermodynamically a huge waste"? You've got a freaking NUCLEAR REACTOR. It's got plenty of energy to spare, all you gotta do is repackage that energy into a form that can be poured into an aircraft fuel tank.

Re:You're missing the point.

[im_thatoneguy]

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:Cost effective?

[serviscope_minor]

I mean, forget about all the CO2 produced when vast amounts of energy are expended to obtain, store, ship, and heat all that non-naturally occurring hydrogen - you don't need to know about THAT CO2

Indeed. You don't need to know about it because it doesn't exist. The energy source is nuclear, not carbon based. If you didn't know that the US has nuclear powered ships, then you are clearly not a geek. Please hand in you card on the way out.

60% of a nuclear reactor is "waste" heat

[Colin Smith]

So it may actually be more efficient thermodynamically.

Re:Cost effective?

[pluther]

By the time there is no oil left for navy ships, I am betting another fuel source will have come along

You mean, like maybe the Navy might find a way of turning seawater into jet fuel?

Re:Or...

[WED Fan]

Nuclear planes? This was tried way back when. They never really got to a full test but their biggest problem was once you actually got a working reactor on an aircraft, what did you do when they crashed? Not a good idea. The few bombs we've lost over the years, most no in populated areas, have been enough of a public relations disaster.