Surface Navies maybe skimming fuel

[Gray Pennell]

This article is about an idea to get jet and other fuels from sea water.


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

 

[Timerover51]

This article is about an idea to get jet and other fuels from sea water.


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

Unless you are using a nuclear-powered refueling ship, you are using more fuel to electrolyze the hydrogen than you are going to get in product. You are also going to have to have a refinery on-board the ship to process the crude output of the hydrogen-carbon dioxide reaction into JP-5, and some means of storing the unused residue, unless you add that to the process stream, which costs you more energy. You are also going to have to pump an awful lot of seawater through your CO2 extraction system if the concentration is only 2 to 3%. A carrier's air group can go through 4,000 or so tons of JP-5 in a week of operations, so your ship has to go through a couple of hundred thousands tons of sea water for its extraction, and that is just the start of the process.

I think that my tax dollars could be better used.

 

[Gray Pennell]

Here is the military's answer to your points.

http://www.dtic.mil/dtic/tr/fulltext/u2/a533382.pdf

 

[Timerover51]

Here is the military's answer to your points.

http://www.dtic.mil/dtic/tr/fulltext/u2/a533382.pdf

He is talking either OTEC or nuclear. Now take all of his figures and then double the costs, which is about standard cost inflation for a military project.

Have you ever looked at what an Ocean Thermal Energy Conversion plant looks like? I would suggest that you do. One of those is not going to be mobile. It does require pumping large amounts of water from depths of at least 2,000 feet to get a sufficient temperature differential, and you need surface water with a temperature like you would find off of Hawaii. There was a test system operating off of there for a while. That does sort of limit where you are going to operate one of these. The paper mentions Diego Garcia, Guam, and Hawaii. If you produce the fuel there, you still have to get it to where it is wanted, i.e. the aircraft carrier, so you still have the at-sea refueling.

He is also not counting the energy required to produce the nuclear fuel for the reactor, which will be ship-based, and therefore utilize highly-enriched U-235. You are not going to put a natural uranium or a low-enriched uranium reactor at sea. There are quite a few countries which will not allow a nuclear-powered ship in their territorial waters. Given this thing would be carrying a lot of weapon-grade U-235, you are going to need a small naval task force to protect it. If I were a nasty-minded individual with the US as an enemy, I would target this thing with everything that I have. Take it out and the aircraft carrier goes away.

If the navy wants to do this from a shore-plant here, I can sort of see it, although making the jet fuel from coal using the mentioned coal to liquid conversion processes makes a lot more sense. Sasol in South Africa is already producing liquid fuels on that scale. It is heavily subsided. The current price of jet fuel is $3.135 per gallon. That is considerably lower than his cost, without assuming any cost inflation, which as I said, is likely to be about 100% based on standard military cost inflation estimates. Given that you would be trying to put a land refinery at sea, I would suspect that the cost inflation might be a lot higher. Also, refinery explosions are not that unusual, except in this case, a refinery explosion would also involve a functioning nuclear plant.

As I said, I would prefer my tax dollars be used more wisely. Build the synthetic fuel plant in the US, and make if a lot larger than 100,000 gallons a day, which is 2380 barrels of fuel a day.

 

[aramis]

Guys - discuss the tech, fine.
Discuss the use of US tax dollars, and I close the thread as political.

 

[Timerover51]

Guys - discuss the tech, fine.
Discuss the use of US tax dollars, and I close the thread as political.

Fine, I will quit discussing tax dollars. The proposal does not make a whole lot of sense. Before you can build a ship to carry this thing, you need a working prototype so a naval architect can have some idea as to what he is supposed to carry. Given the power requirement, which is close to two carrier reactors, that is going to be a big ship regardless. Carriers have an enormous amount of shielding built into them, along with the heat exchange system, and the steam turbines. The turbines are going to be turning electrical generators, and presumably, maybe some power units to move the ship. All of that costs hull volume. Then add all of the refinery equipment, and the men to operate it, along with ships crew. Unless you are planning to have the carrier permanently alongside, you are going to need storage tanks for the produced fuel. If you are loading a carrier with jet fuel, you need to have enough on board to fully fill the carriers tanks, which means you need to have at least the same size, preferably larger size, than the carrier.

Put it ashore, and you avoid the cost of the ship, and the headaches with trying to do this onboard a ship. Plus, you can use the savings from not building the ship to build a larger unit. The Navy is not the only service to use jet fuel. The Army and the Air Force use some occasionally as well. The Marines have to get their fuel from the Navy.

 

[samuelvss]

The idea is, for use IMTU, taken. When fusion is cheap, hydrocarbons can be made at sea.

As to here and now, the technical challenges are daunting. Moving hydrocarbons from a non-renwable resource to a renewable resource, this makes huge look microscopic. Essentially, this is making nuclear powered jets. It can be on land (DG) and still be a game changer. Reduce your haul time by 80%, then reduce your haul assets needed by something like 50-60%, depending on how much of your turnaround is in transfer.

Ready for prime time? Hardly. The Wright Flyer was profoundly impractical, though.

 

[PFVA63]

Hi

Although I tend to be a bit of a technology skeptic, and OTEC does seem to have a fair amount of hurdles to clear, to me the potential for an OTEC type system in the Earth's near future seems to me to be potentially a fair bit more practical than say something like a Space Elevator or other such familiar sci-fi concepts.

In addition to this, the potential use of an OTEC like system to make artificial hydrocarbons seems lie it may be a practical intermediary step in dealing with diminishing natural hydrocarbons. Because alot of infrastructure appears to be already sunk into burning hydrocarbons in cars, aircraft, and ships etc, the potential for a system where energy in one form (in this case the delta between the solar radiation at sea level and the cooler water at the oceans depths) can be converted into something that may be usable by existing (or hopefully not too heavily modified) craft by means of using an OTEC plant would seem to have some great potential benefits.

As such, for real world applications on Earth I'm willing to keep an open mind about its possibilities.

Of course though I'd suppose that in a Traveller setting where it appears that cheap dependable fusion plants are available, such a system might be a bit out of place, but maybe for certain pre-space flight worlds, or maybe in a 2300AD type setting it might be an interesting concept.

 

[aramis]

Of course though I'd suppose that in a Traveller setting where it appears that cheap dependable fusion plants are available, such a system might be a bit out of place, but maybe for certain pre-space flight worlds, or maybe in a 2300AD type setting it might be an interesting concept.

Actually, think about it for synthesis of lubricants... the most frequently used of which are hydrocarbons. Which is something the fusion plant doesn't replace.

 

[PFVA63]

Hi

That makes a lot of sense. I guess that there are alot of potential possibilities. Thanks for the info.

Regards

PF

 

[Darkwing]

Saw that in the Navy Times. Waste of time. Too much effort. Makes bureaucrats look like they're trying to help the environment. but the cost is excessive. Simply switching to hydrogen for jet fuel and marine fuel would be cheaper and easier, and could be economically created with a fission reactor, not needing the fusion reactor we haven't got yet. It's also a tech that will still be viable once we do have that fusion plant.