Making Jet Fuel From Seawater While at Sea

http://www.nrl.navy.mil/media/news-releases/2012/fueling-the-fleet-navy-looks-to-the-seas

by joe24pack • 14 years ago

72 80 14 years ago

nrl.navy.mil

gunn• 14 years ago

Okay great. Where does the energy come from?

landryraccoon• 14 years ago

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

pixie_• 14 years ago

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

jws• 14 years ago

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

ChuckMcM4• 14 years ago

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

jnw27• 14 years ago

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.

Mvandenbergh2• 14 years ago

Given the refining steps you'd need after making the hydrocarbon feedstock and the dangers inherent in that process, I'm sure that they'd do this on a separate ship.

001sky• 14 years ago

An alternative way to make this feasible for the fleet would be to build a nuclear powered oiler

--Interesting Idea, depending on the incremental weight, complexity and volatility of the Carrier system.

Gravityloss• 14 years ago

We can look at it this way too: assume an oiler has maybe 10,000 t of oil and takes ten days to travel: 1E7 kg with energy density of 1E7 J/kg, in 1E6 seconds means an average power supplied by one oiler to be in the order of 100 megawatts. Or 10 kg/second. If that synfuel generation rate can be sustained, then the oiler is not needed.

The Nimitz class carriers have two 100 MW reactors: http://en.wikipedia.org/wiki/A4W_reactor

Of course, there's efficiencies, probably the oilers don't always go full speed, there's different distances etc etc...

If we assume 1% efficiency and one dedicated reactor, then we get 0.1 kg/second, 8 tons per day. You could load about two Hornets' internal fuel tanks with that.

In the sea you could probably also try other things than nuclear reactors, like farm algae and harvest it to produce biofuels (biofuel has already been tested in a B-52), or put solar or wind plants out in the ocean where there's space. No energy storage problems if the fuel is generated in situ.

Sukotto• 14 years ago

That's a great deal.

Jet Fuel (Kerosene) closed at $3.135/gallon today[1]. And that doesn't include the cost of transporting it from the Gulf Coast to where your Navy needs it.

[1] Sep 28, 2012: http://www.eia.gov/dnav/pet/pet_pri_spt_s1_d.htm

ChuckMcM4• 14 years ago

To be fair you have to subtract off Federal taxes which the government doesn't pay for the fuel it buys which brings it down closer to $2/gal.

fpp• 14 years ago

A bit of history on the work of the NRL on modified Fischer-Tropsch processes / Hydrogenation:

From Wikipedia on Fischer-Tropsch: ( http://en.wikipedia.org/wiki/Fischer–Tropsch_process )

Carbon dioxide reuse

In 2009, chemists working for the U.S. Navy investigated a modified Fischer–Tropsch process for generating fuels. When hydrogen was combined with the carbon dioxide over a cobalt-based catalyst, the reaction produced mostly methane gas. However, the use of an iron-based catalyst reduced methane production to 30 per cent with the rest being predominantly short-chain, unsaturated hydrocarbons [27] The introduction of ceria to the catalyst's support, functioning as a reverse water gas shift catalyst, furthermore increased the yield of the reaction. [28]. The short chain hydrocarbons were successfully upgraded to liquid fuels over solid acid catalysts, such as zeolites.

[A patent application and a more in-detail research paper describing the process(es) is referenced there.]

Overall this looks very interesting as a military application (independence from other sources, logistics).

You will find more articles from 2009+ on this topic by searching for "Fischer-Tropsch seawater".

spullara2• 14 years ago

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 :)

ryanwaggoner2• 14 years ago

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

spullara2• 14 years ago

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

rdl• 14 years ago

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).

wamatt• 14 years ago

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• 14 years ago

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.

sien2• 14 years ago

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....

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.

Mvandenbergh2• 14 years ago

Most people miss the difference between hydrocarbon fuels as energy source* and as energy carrier. If you make HC fuels from atmospheric or oceanic carbon, you have a nice closed cycle.

(*) Technically fossilised solar energy of course.

ta121215• 14 years ago

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.

sien2• 14 years ago

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.

ommunist• 14 years ago

I think you are right. Also that last mile Boosted Desk surfing transport is quite a thing. Batteries are forever.

iwwr• 14 years ago

It's energy inefficient, but you're thinking in terms of energy scarcity we have today. What if we had 10x more electric energy capacity (most likely due to nuclear resurgence)?

comicjk• 14 years ago

Lithium-air batteries (an immature technology, certainly) have an energy per gram 3.5 times less than gasoline's. But electric motors are about 3.5 times more efficient than internal combustion engines. And the technology to produce synthetic fuels from CO2 is pretty much as far from mass scale as lithium-air batteries.

I agree that we will need carbon-based fuels for jet engines, but as for cars, the physics and economics are by no means as favorable as you represent.

lumberjack• 14 years ago

Your argument is only balanced on that one premise of Fusion or free energy, both of which are still vaporware and will be for decades if not centuries to come. Have you considered that maybe electric cars will fill the gap between now and then if ever? And you consider free energy a possibility but advancement in battery technology too far fetched. I don't agree at all.

dalke5• 14 years ago

"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."

That is incorrect. If the fusion source is compact, and can produce a lot of instantaneous electrical power, and is quick to throttle up and down, then a "Back to the Future"-style Mr. Fusion would be the best way to power cars.

Energy density isn't the only factor. There's also a question of infrastructure. Electrical distribution has few moving parts, while extracting C02 from the atmosphere to make fuel and distributing the fuel has many more mechanical parts. A fusion plant which could produce 50 kW, weighed 2 tons, and could be installed in the back yard of a home would mean that a house could be off the grid and still have power left over to charge the car, while using intermediate hydrocarbon storage would mean trips to fill the car, or heating oil, or cooking gas.

So while I completely agree that airplanes will not be powered by batteries, I don't think that energy density is the only factor to consider in the economics equation.

stcredzero2• 14 years ago

> That is incorrect. If the fusion source is compact, and can produce a lot of instantaneous electrical power, and is quick to throttle up and down, then a "Back to the Future"-style Mr. Fusion would be the best way to power cars.

There's also safety to consider.

Dn_Ab• 14 years ago

Very good point. But it doesn't make Tesla cars a folly so much as put a strong constraint on their long term economic viability: the invention of fusion power or some other method of making energy abundant turned to making hydrocarbons effectively renewable. But that could be decades away, timeline of practical viability is effectively unknown. Considering how speculative this notion of really cheap energy is (for now), I still think Tesla is a good bet. On the event of the floor dropping off the prices in energy markets, there will be few that are dependent on large energy barriers to entry that will emerge unscathed.

It is also effectively win-win. If such a thing becomes possible the costs in much of production will cut very drastically and the potential of things now open would be just incredible. So much of expense is due to energy constraints.

confluence2• 14 years ago

You are wrong.

Electric engines run at 92% efficiency. Car engines run at ~15%. So energy density need not reach equivalence.

That physicist is wrong too (Nobel prizes don't mean you aren't wrong - it just means people listen to you more) - jet engines on planes require oxygen to work - hence capped at ~10 km altitude with massive drag causing ineffecient travel.

10 years till battery tech reaches complete parity for lowest denominator cars, and 7 years before we start to see hyper sonic electric passenger jets being tested way up in the upper atmosphere (no oxygen needed, go as high and fast as you want - London - LA in a few hours - space views - cheap power).

jrabone4• 14 years ago

What? 10 years until battery technology has advanced to the point of parity?

Gasoline has an energy density of 132 MJ/US gal, or say 1500 MJ on a full small tank. Modern engines hit 30% thermal efficiency, but then there are drive train losses etc, so I'll give you the 15% as an absolute worst case, AND give you a 100% efficient electric motor / drive train. Therefore your car needs to provide 225 MJ of stored energy for parity.

The best commercially-available Li-ion battery has an energy density of around 245 Wh/kg, or ~ 880 kJ/kg. Therefore you need at least 255kg of conventional batteries for motive energy parity (ie. not counting heat/AC/light etc.). The equivalent in gasoline (0.77 kg/l), weighs 35 kg.

You are asking for nearly a ten-fold increase in usable energy density in battery technology in ten years, at price-parity with gasoline, and with the charging infrastructure to support it. I don't think it's going to happen - assuming lithium-air batteries ARE commercialised on that time scale, the cost of charging that kind of energy in reasonable time, safely, is going to be the real problem here. Every gas station is going to need its own nuclear power plant!

pigboy• 14 years ago

Energy density is a critical issue for aircraft because lift/drag ratios are capped at around 15 to 30. For every 15-30 N of fuel weight, you must supply at least 1 N of additional thrust (which translates to power, once you multiply by speed).

Cars, on the other hand, experience a combination of aerodynamic and powertrain drag and rolling resistance, of which only (mostly?) the rolling resistance depends on mass. The typical coefficient of rolling resistance is about 10x better than the typical L/D ratio for aircraft (if I believe Wikipedia). Hence, road vehicles are 10x less sensitive to energy density than aircraft.

So a statement that electric vehicles won't work is nonsense, without considering how sensitive the different vehicles are to fuel mass.

FrojoS• 14 years ago

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• 14 years ago

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?...

Roritharr2• 14 years ago

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• 14 years ago

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

Roritharr2• 14 years ago

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

jimworm• 14 years ago

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.

Making Jet Fuel From Seawater While at Sea

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