
Making Jet Fuel From Seawater While at Sea - joe24pack
http://www.nrl.navy.mil/media/news-releases/2012/fueling-the-fleet-navy-looks-to-the-seas
======
jws
Extract CO2 and H2 from seawater, react to form hydrocarbons of varying
lengths, then refine. Presumably all powered by the nuclear reactors.

 _initial studies predict that jet fuel from seawater would cost in the range
of $3 to $6 per gallon to produce_

~~~
ChuckMcM
That is exactly why its such a big deal. Current jet fuel costs over $8/gal
delivered. It costs so much because even if it comes out of the refinery at
San Diego at $2/gal it has to be loaded into an oiler [1] and then driven out
to sea where the carrier task group is.

If you're on a nuclear powered aircraft carrier you have plenty of electricity
so this is a pretty huge win.

Of course an alternative way to make this feasible for the fleet would be to
build a nuclear powered oiler. It could process seawater into jet fuel as it
cruised along with the fleet and transfer fuel as needed, but to this day fuel
transfer at sea is one of the more dangerous things they do.

[1] <http://en.wikipedia.org/wiki/Replenishment_oiler>

~~~
jnw2
<http://en.wikipedia.org/wiki/USS_Gerald_R._Ford_(CVN-78)> notes that
``Unfortunately the power limitations for the Nimitz class make the
installation of the recently developed [Electromagnetic Aircraft Launch
System] impossible.'', which seems to indicate that existing nuclear powered
aircraft carriers don't always have large amounts of electricity to spare.
However, more electricity will be available on future aircraft carriers.

~~~
ChuckMcM
If you look at the power requirements for the EMALs system you will see why a
Nimitz class carrier can't power it. Not only is it a crapload of power, its
needed all at once. The JP4 from Seawater project can run at much lower powers
and for long periods of time.

~~~
jrabone
And in fact, here is another illustration of just how hard it is to replace
conventional energy storage systems with electricity. High pressure steam
stores an enormous amount of energy. EMALs effectively uses 4 flywheels as
rotational energy stores, suggesting battery / supercap technology just isn't
viable. It does have an efficiency advantage over steam though.

~~~
jnw2
I bet batteries don't tend to like going from full to empty in the time it
takes to launch a plane.

I wouldn't be surprised if later in the Ford class's life, we do see
supercapacitors taking over.

~~~
ChuckMcM
Batteries operate by the principle of ion formation. The chemical process is
exothermic with respect to the transfer of electrons from the cathode to the
anode. So the more charge that is moved the hotter the batteries get. This is
often the limiting factor for charge conversion.

Capacitors on the other hand simply store charge using electrostatic field
attraction, the only barrier to their current flow are the i2r heat generated
in the conductive paths (a superconducting supercapacitor for example could
dump all of its charge instantly without any problems, if such a thing
existed, its manufacturer would be worth more than Apple :-)

Flywheels store energy mechanically as angular momentum, they have good energy
density, and can return it quickly by being attached to a generator, but are
generally hard to deal with in systems with an external acceleration because
their tendency to precess if that acceleration results in a rotation that is
perpendicular to the flywheel. The proposed carrier ones I've seen are shown
as being on gimbals for that reason.

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sien
This is a good reason why Tesla cars are folly.

This is why electric vehicles won't work. I'll copy in most of a comment I
made a few days back.

Let's say tomorrow some grad student gets fusion going at a very low price.
The best way to use this to power cars would be to use it to create a fuel
with a high energy density. If you had 'free energy' you'd extract C02 from
the atmosphere and turn it into a hydrocarbon.

For more info look at:

<http://en.wikipedia.org/wiki/Energy_density>

and this interview with Nobel Prize winning Physicist Robert Laughlin

[http://www.econtalk.org/archives/2010/08/laughlin_on_the.htm...](http://www.econtalk.org/archives/2010/08/laughlin_on_the.htm..).

the key quote is: "The ones that are technically trained get it right away:
hydrocarbons, which we burned today have the greatest energy density possible
of all fuels. Things that have carbon in them. Will people fly airplanes?
Usually people say yes for the same reasons. Well, how are you going to make
the airplanes fly? Battery. Batteries are pretty heavy. Oh--you can't have
airplanes unless you have hydrocarbon fuels. You could in theory do it with
hydrogen, but it's highly dangerous, noxious fuel. Quantum-mechanically, we
know the energy content of those fuels is optimal. There will never be
anything that beats them." A massive breakthrough in energy density for
batteries might be possible but it's unlikely. Huge resources have been put
into improving batteries and while they have improved it's not been enough to
get near the energy density of hydrocarbons.

~~~
ta12121
No.

Electrolysing water to make H2 and extracting CO2 from the environment, and
then synthesizing hydrocarbons from them, is _extremely_ energy inefficient.

Sure, theoretically, it can be done, and maybe one day it could even be done
efficiently. But Tesla is making battery-electric cars that work _today_.

The military does not care about efficiency because they have nuclear reactors
on their ships and their goal is to not to have to transport liquid fuel.

~~~
sien
If they can hit $3 / gallon why does it matter?

Tesla's cars are wildly price inefficient because they cost $100K. For 10K you
can get a decent car that has 4 times the range.
<http://en.wikipedia.org/wiki/Tesla_Roadster>

How many gallons of fuel can you get for 90K?

They are nice toys for rich people. Perhaps there is a market for that. Good
luck to them.

But for mass transit unless you can get the price of the batteries to plummet
it just does not work.

~~~
ta12121
$3 a gallon is what the fuel costs today when it comes straight out of the
ground. Claiming to be able to build and run a nuclear reactor and then
synthesize the fuel through multiple energy inefficient steps all for the same
price is a pipe dream.

~~~
danielharan
It's not competing against the price straight out of the ground; it's
competing against fuel that's been refined and delivered to a moving ship
somewhere potentially very far away. Instead of $3 a gallon, it could be up to
10X more.

~~~
antidoh
And, dollar cost of the fuel is not the only cost of maintaining a "long
supply tail." There's also the dollar cost of all the ships and sailors on
that tail, and there's the logistical opportunity costs: we have to protect
that tail with military resources that might otherwise have gone to more
directly military purposes, and the head of the tail (the military activity at
the front) is held back and slowed down by a "heavier" supply tail.

This doesn't eliminate the tail (we still have to deliver ammunition,
lubricating oil, food etc. to the fleet) and it doesn't eliminate
replenishment at sea (we still have to get that stuff from supply vehicles to
ships), but it does lighten the supply load and create more military options.

~~~
danielharan
Exactly. Less replenishment means more flexibility.

Lots of people killed by IEDs on long supply lines in Afghanistan is an
extreme example of the human and military costs. Some of those died to fuel
A/C for uninsulated tents... madness.

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spullara
When energy is cheap, plentiful and clean things like this are possible. If
only we built more nuclear power plants and solar power farms. Turning coal
into jet fuel isn't a great idea :)

~~~
ryanwaggoner
Rejoice then, because this will almost certainly be done on carriers powered
by nuclear power plants.

~~~
spullara
But of course! That was sort of my point...

~~~
ryanwaggoner
Duh...my bad. It's late :)

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rdl
One of the main endurance (and damage control) problems for a nuclear carrier
is the huge amount of jet fuel used by the air wing, so this would be a huge
deal. After jet fuel, they just need to underway replenish armaments and food,
both of which are easier than fuel (food isn't dangerous, and most missions
don't expend weapons now, so the total volume is lower than for fuel).

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FrojoS
Once again, military research might lead the way. Note, if they invest into
this, it's _not_ because of reduced price, increased efficiency or reduced
greenhouse effects, but because of an _strategic_ advantage against "the
enemy".

Personally, I read about similar methods, for synthesizing carbon based fuels,
many times before. Most of them were private founded but rather small scale. I
can't judge if there was a significant science or engineering breakthrough.
So, I suspect the only thing that might have changed, is that a clever guy
convinced the military this would be a huge strategic advantage.

The ironic thing is, the US could instead focus on producing all their fuel at
home to end the dependency on oil from the middle east. Then, they would have
an even bigger strategic advantage and wouldn't need as much military
investment. Anyway, we might end up with synthetic carbon based fuel with all
its advantages - and probably the military can keep their carriers.

~~~
1rae
I think Sasol (SA) has this Gas-To-Liquid fuel system working, and on a larger
commercial scale
[http://www.sasol.com/sasol_internet/frontend/navigation.jsp?...](http://www.sasol.com/sasol_internet/frontend/navigation.jsp?navid=21300010&rootid=2)

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wamatt
Very interesting.

Can someone who knows about this stuff comment on whether the energy required
to _extract_ the H2 from the water, is more than the energy contained in the
_chemical bonds_ of the H2 itself? (assume both sides of the comparison
contain equal number of molecules)

I suspect it is.. otherwise they are potentially sitting on a much more
important innovation, than mere jet fuel.

~~~
jordanb
Consider it from the perspective of the conservation of energy:

2H2 + O2 = 2H2O + energy

The energy is on the right because the reaction is exothermic.

The opposite reaction _must_ be endothermic and must have the _same amount_ of
energy on the left:

2H2O + energy = 2H2 + O2

Otherwise, energy isn't conserved.

Because nothing is 100% efficient, there's also energy lost to inefficiencies.
So the answer to your question is that yes, you need more energy to make the
second reaction happen than is stored in the chemical bond.

------
Roritharr
Isn't this also heavily destructive to our ecosystem because they use the
carbon trapped in the water and release it into our atmosphere? Didn't we want
more trapped carbon than less?

I don't get why everyone finds this great since it takes a very long time for
carbon in the atmosphere to get trapped in seawater.

~~~
zmmz
It's not that simple:

CO2 in atmosphere -> CO2 in water -> Ocean acidification[1] -> Change in ocean
ecosystem

The oceans absorb OC2 from the atmosphere, which you could argue is good, but
it is not without consequences. Putting CO2 in the water moves the problem
from having it in the atmosphere elsewhere, but it's still a problem. In some
ways then, this can be seen as a good thing, because it is undoing the effects
that increased CO2 in the atmosphere has on the oceans. Obviously though, I
doubt that its effects would be at all noticeable.

The wiki article already linked has a chapter called 'Possible Impact'.

1: <http://en.wikipedia.org/wiki/Ocean_acidification>

~~~
Roritharr
I'm not for putting more carbon into the oceans... just against taking the
currently stored carbon out.

~~~
regularfry
There is already too much. Any we can take out is a good thing.

~~~
xefer
But it's taking carbon out of the ocean and releasing it into the atmosphere.
The issue becomes, how long does it take for the released atmospheric CO2 to
be reabeorbed back into he ocean? Does it do more harm in the atmosphere or in
the ocean?

~~~
DennisP
Right now we're taking carbon out of the ground and putting it in the
atmosphere.

The ocean presently has a lot of extra carbon, which it absorbed from the
atmosphere. So this is an indirect way of taking carbon out of the atmosphere
and then putting it back...a closed loop. If we did this for all our
hydrocarbon fuel we'd be carbon-neutral.

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jimworm
France could certainly use this technology. With their abundance of unused
nuclear power and access to the sea, this could bridge the gap between
hydrocarbon powered and electric vehicles.

------
gunn
Okay great. Where does the energy come from?

~~~
landryraccoon
If it's an aircraft carrier, probably the nuclear power plant on board.

~~~
pixie_
Yep, it's a pretty good use of 200MW of power when you're just sitting around
in the ocean.

~~~
dctoedt
> _when you're just sitting around in the ocean_

Watch any of the documentary series about life aboard an aircraft carrier [1]
and you'll see that there's essentially no "just sitting around in the ocean."
But your main point is still accurate: If there's power available, putting it
to work making jet fuel might be a good trade-off for the additional drain on
the nuclear fuel.

[1] E.g., <http://www.pbs.org/weta/carrier/>

~~~
sophacles
From friends and family in the navy: whenever you see a fleet or battle group
"stationed" somewhere, it means they are basically doing right turns in the
middle of the ocean (a joke being that someone has to balance the effect of
all those left turning NASCAR races). While they are doing operations etc, a
lot of this time is considered extremely boring, more so than even long
voyages going somewhere. Further, they usually aren't going full speed, so to
some extent they are "just sitting there", particularly in the effect that
they aren't using the full output of their power systems - leaving lots of
power and (if needed people time) available for fuel "creation".

~~~
dctoedt
Former Navy aircraft-carrier nuclear engineering officer here. The basic point
--- that a carrier might be able to refine its own jet fuel --- is certainly
valid. But so that future readers don't get the wrong idea: _Any_ time a
carrier is at sea, it does a lot of flight ops just about every day, whether
for actual missions, for war games, or just refresher training. That in turn
means most of the crew is hustling, usually 12 to 14 hours a day minimum, and
sometimes 'round the clock. Maintenance has to be done in the gaps. When we
were at sea, it was rare to get six hours of uninterrupted sleep in a night.
Somehow I doubt that has changed.

