Navy plans to make jet fuel from sea water

[Joseph Chikva]

FYI

The question boils down to the volume/ weight of a hydrocarbon or ammonia production facility and and it.s output rate. I have the impression that these limiting factors are far from being met, irregardless of the type of ship bearing the plant.

Not sure why you say this. Assume ~10 escort ships per CSG at ~75MW per ship, the two AONs would need to produce ~1500MW power each, given efficiencies. We put that kind of power into carriers now, shock / battle hardened, instant restartable, i.e. EXPENSIVE power now.

Only "expensive"?
How about to see how comparable size "Fukishima 1" 1827 MW looks like?

http://en.wikipedia.org/wiki/List_of_nu ... r_stations

Also roomy elecrolizers, roomy ammonia synthesis loop, etc.
I understand that carriers are really big ships, but not so big to allow such installations.
And phrase "EXPENSIVE power" gives me idea that since 1 December you do not like your "smart" idea yourself.
Good luck.

[KitemanSA]

Anyone have any RATIONAL comments about the size of nuclear power plants the navy can fit into ships? Anyone?

[Joseph Chikva]

Anyone have any RATIONAL comments about the size of nuclear power plants the navy can fit into ships? Anyone?

You are forgetting that not only nuclear power plants but electrolyze section, air separation section and ammonia synthesis section as well.
More about water electrolyze you can read here: http://www.cres.gr/kape/publications/pa ... OLYSIS.pdf
As namely electrolyze section would be the roomiest from entire hardware.

[D Tibbets]

Nothing except... The actual nuclear fission reactor is fairly compact and energy dense, Bussard estimated that a working Polywell (vacuum vessel and associated support equipment would be similar in size. The containment building in a fission plant is so big because it contains the reactor and steam plant, maintenance structures, fuel rod storage pools, etc. A D-D Polywell would need a similar steam plant (thus Bussard's proposal to tie a Polywell reactor into a existing coal fired plant). The reactor replaces the coal incinerator, but most of the rest of the equipment is similar. This could change significantly with a P-B11 direct conversion reactor. The direct conversion equipment is mostly within the vacuum vessel, while transformer yards, etc would be different in order to handle the high voltage output. There would be a cooling system, but no high pressure steam handling and turbine building.

An important point on the size of the Polywell P-B11 reactor is that with direct conversion the efficiency of output energy converted to useful electrical power would be ~ 2 to 2.5 times as great as that obtainable with a steam cycle.. This translates into possibly smaller reactors, less cooling requirements, along with elimination of the steam plant. The technology may be challenging, but I speculate that a fusion power system that fits inside a submarine might be capable of 2-3times as much useful power, compared to existing fission plants.

If a current nuclear carrier gets around on it's reactor(s), then the above advantage would result in that much more power, and this could drive fuel production facilities to produce a similar amount of stored energy to drive a second carrier or escort ships. Of course this assumes that space concerns, and conversion efficiencies of the fuel production plant can be be met.

Again, I think CO2 capture and conversion to hydrocarbon fuel is the first choice because of safety concerns, and the ~2:1 miles per gallon advantage over ammonia. If only the ammonia system can be made to work, then it could be useful as a second choice.


PS: In his GOOGLE talk, Bussard mentioned setting up a Poloywell and ethanol production plant on a large barge, then taking sugar cane or other feedstock to produce the ethanol. Admittedly starting from CO2 would require more effort, but this may give an indication of size that Bussard envisioned. He was initially trained as a nuclear engineer, so he is not ignorant of the various engineering issues involved.


Dan Tibbets

[GIThruster]

The direct conversion equipment is mostly within the vacuum vessel, while transformer yards, etc would be different in order to handle the high voltage output. There would be a cooling system, but no high pressure steam handling and turbine building.

The problem is we still have no idea how efficient direct conversion would be. I recall BLP's claims a decade ago about wanting to use direct conversion, or what they called "plasmadynamic conversion" but they did a study and found it is so inefficient that it is not useful except in very rare situations where mass and volume are critical, such as in spacecraft or in the operation here under consideration. Just because direct conversion is plausible with no new physics doesn't mean it's a solid engineering choice.

OTOH, the new supercritical CO2 turbine from Sandia just a few months ago is way passed the guesswork stage. It is more efficient than standard steam turbines and much smaller and energy dense. I'd expect it will eventually replace boilers in all future ships and other applications where volume and mass of the conversion cycle are at a premium. Given this, it's pretty pointless to argue over this jet fuel application in the absence of facts. If US Navy decides they can build something that supplies fleets with jet fuel in situ, they'll likely chase it down.

[Joseph Chikva]

Nothing except... The actual nuclear fission reactor is fairly compact and energy dense, Bussard estimated that a working Polywell (vacuum vessel and associated support equipment would be similar in size.

Ok, and may be I do not understand many things.
But let's talk about technical issues.
As I understand Direct Energy Converter's working principle, that should separate positively charge particles from negativelly charged with the help of electric/electromagnetic field.
That is possible only when debye length exceeds geometrical dimenssions of device: http://en.wikipedia.org/wiki/Debye_length

the Debye length is the distance over which significant charge separation can occur

And that is possible only after very significant expansion of plasma, as result of which debye length increases too.
For example, you can not separate plasma in TOKAMAK having typical value of debye length 0.1 mm amd geometric dimensions of meters order.

Regardless to what Dr. Bussard has estimated.

[KitemanSA]

Anyone have any RATIONAL comments about the size of nuclear power plants the navy can fit into ships? Anyone?

You are forgetting that not only nuclear power plants but electrolyze section, air separation section and ammonia synthesis section as well.
More about water electrolyze you can read here: http://www.cres.gr/kape/publications/pa ... OLYSIS.pdf
As namely electrolyze section would be the roomiest from entire hardware.

Actually, I am envisioning a LFTR plant with the sulphur iodine chemohydrolysis system, but who is counting!
Thanks for the paper, I may read it if I find time.

[KitemanSA]

Scanned it. Didn't see anything much about volume of the electrolyzer section. Lots of storage volumes and one section the briefly mentioned amps per tenths of a cubic cm. but nothing system. Did I miss it or did you send me on yet another of your worthless sidetracks?

[Joseph Chikva]

And ok, for providing you idea I've recalled who in Russia produces water electrolezers.
http://ekb.ru/products/119?action=small
Electrolizer producing 2.5 nm3/h of hydrogen without auxiliary hardware has dimensions 1.5 x 1.065 x 2.145 m
Total system volume 9.22 m3
Like numbers?

[KitemanSA]

I obviously won't call on your Russian friend.

[Joseph Chikva]

I obviously won't call on your Russian friend.

Which Russian friend? For what?

If you can not estimate yourself here is estimation of volume occupied by elecrolize section:

Power 1500 MW = 1500000 kW
can produce 1500000/4.3 kW*h/m3 = 348837 m3/h of hydrogen

From another side the volume 1.5 x 1.065 x 2.145 m = 3.4266375 m3 produces 2.5 m3/h and so 1 m3 working volume produces 1.370655 m3/h of hydrogen.

So, you need only for elecrilize section not less than 348837 * 1.370655 = 478'135 m3 electrolizer.
Be noted that this is only electrolizer's volume without any needed auxiliary equipment that is not small too.
Recall that for 3.4266375 m3 elecrolizer, entire system occupies 9.22 m3.
My estimation is that you need not less than 1'000'000 m3

Can you provide such a volume only for electrolizer section even in carrier size ships?
Add there also volume needed for power plant, ammonia making section, storage, etc.

Good luck.

[Joseph Chikva]

Ok, I see you can not answer

Nimitz-class carriers

Length:
Overall: 1,092 feet (332.8 m)
Waterline: 1,040 feet (317.0 m)

Beam:
Overall: 252 ft (76.8 m)
Waterline: 134 ft (40.8 m)

Draft:
Maximum navigational: 37 ft (11.3 m)
Limit: 41 ft (12.5 m)

So, even considering rectangular hull and doubling draft (as we are not limited in height), available space is only:
317 x 40.8 x 25 = 323'340 m3 vs. 1'000'000 m3 needed only for electrolyze section.

[Nydoc]

1500MW power each, given efficiencies. We put that kind of power into carriers now, shock / battle hardened, instant restartable, i.e. EXPENSIVE power now.

Are you sure this is the case?

Nuclear power plants are simpler and smaller, with reduced maintenance and personnel requirements. ... The nuclear power plant on CVN-21 -- the next-generation carrier now undergoing detailed design in Newport News -- is expected to require only half the manpower than power plants on Nimitz-class ships, the GAO letter to Bartlett said. The yard has also said the electricity that the new power plant creates -- more than 2.5 times the juice of a Nimitz ship -- will translate into many additional manpower reductions throughout the ship.

http://articles.dailypress.com/2006-07- ... t-carriers

A Nimitz class carrier has a maximum propulsion of 260000 bhp. This is about 194 MW, so I would have thought that a Gerald R. Ford class carrier could produce about 485 MW.

[paperburn1]

Its like the TARDUS bigger on the inside than the outside

[Joseph Chikva]

A Nimitz class carrier has a maximum propulsion of 260000 bhp. This is about 194 MW, so I would have thought that a Gerald R. Ford class carrier could produce about 485 MW.

As I understand, Mr. Kiteman proposes to use aircraft carrier's size ship but not to use that as carrier but to use that as "oiler" (the ship is intended to produce fuel using nuclear energy for escort ships that are not nuclear powered).
485 MW of nuclear power is not enough for this purpose.

Kiteman's idea is an evolution of another idea to produce only jet fuel onboard.
Then idea to use ammonia instead hydrocarbons came, then this worthless idea.