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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.'"
...they could just hire Jesus.
But it's easy to put a nuclear reactor in a ship, and not so easy to put one in a fighter jet.
Brett
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.
Methane is a good fuel in its own right. Using solar power this could be a good general source of transportable energy.
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It removes CO2 from the water, where it will eventually return through the same process that put it there in the first place.
For the life of me I can't see how this will be cost effective or environmentally friendly.
Oh it's carbon neutral, didn't you read? 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 (kinda like the extra $14 trillion dollars the US government is currently printing/spending - what you thought the "bailouts" totaled 2 trillion?). But the carbon monoxide goes in, and comes out, in a 1:1 environmentally friendly ratio.
This is after all a US government program. You can TRUST the US government!
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jet aircraft (each costing millions), runs on jet fuel, not methane
But rockets (and rocket planes) do Carmack and Armadillo Aerospace have been doing just that for NASA.
Tm
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Thermodynamically a huge waste.
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...
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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.
Man who leaps off cliff jumps to conclusion.
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.
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.
SJW n. One who posts facts.
So it may actually be more efficient thermodynamically.
Deleted
You mean, like maybe the Navy might find a way of turning seawater into jet fuel?
If the masses can keep you down, you're not the Ubermensch.
Wind power has lots of advantages, but one major drawback - it is intermittent. If you have an industry which is very energy intensive but has low capital cost, this presents an opportunity: build your plant, and run it only when the wind is blowing and power is very cheap. This works especially well if your product is easily storable.
This process is clearly energy intensive and produces an easily storable product - whether it has the required low capital cost is much less clear. (Although the interest of the navy suggests they're wanting to use aircraft carrier nuclear power, but once developed it could find wind-powered civilian use.)
Water desalination and aluminium smelting might also qualify (I don't know the capital costs of these). Recharging electric cars certainly does (given that you're buying the car anyhow), except that you have a very limited storage capacity.
Despite not being low capital, data centres are even starting to go this way, being built with the intention of only running them when electricity is cheap (or less is required for air conditioning.) In this case the product is extremely transportable rather than easily storable.
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Perhaps they plan to build carriers with larger reactors that have greater output than the needs of the ship itself, so that the excess output can be used to power a small on-board jet fuel production plant? In that scenario, who cares if the energy required outweighs the work done by the resulting fuel?
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.
Hydrogen is a stupid fuel, except for fusion (and, maybe fuel cells).
Storage is a royal pain, since hydrogen molecules are very small and simply wander off from containers, surrounding them with a highly flammable gas. If pressurized and cooled to liquid, they wander off less, but you have added costs of weight to the vehicle and compression/cooling to the production side.
Per weight/volume, hydrogen generates relatively little power compared with hydrocarbon fuels . In general, the more carbon in the fuel molecules, the more energy available in combustion (you're not going to run high-performance aircraft on fuel cells). The C-C bonds are cheap to break compared to H-H bonds and C-O bonds provide decent return, so the net output is more. Diesel cars/trucks generate more useful power and better fuel efficiency than gasoline cars or hybrids. Similarly, there's a lot of energy in the long-chain molecules of kerosene/paraffin used as jet fuels.
Really? Turning sea water into jet fuel is more complicated than it looks? Cause from here it looks pretty freaking complicated.
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