Converting (extracting) fuel from seawater? Really?

[mkjayakumar]

If only the fighter jets are all electric powered.. then we are talking..

 

[Nubo]

You cannot 'reduce storage capacity' and still launch aircraft in a fire fight because when the excrement impacts the rotating air movement device you're burning jet fuel orders of magnitude faster than the synfuel plant can produce it. An F-18 burns around 4000 lbs per hour (about 600 gallons) on average...

But, would it not still be worthwhile to have ability to generate fuel, as a contingency? Sure, other means may be more efficient and cheaper, but if our group/fleet/world is really in a bad situation, isn't some fuel better than no fuel? If the plant could generate enough fuel for a sortie over the course of a day or two, for example? Realistic?

Assuming you could turn ALL power into fuel, which would be the hypothetical , but never achievable upper limit, 200 MW would make 20000 l per hour, which would be enough, based on a burn rate of 2000 l/h, to power 10 planes for one h.In practice that number would be closer to 1.
1 out of 80 seems insignificant. So what is the military application for this?

I'm not sure why the 1-hour output is critical, unless you're talking about keeping aircraft in the sky 7x24. While that may be desirable, I was thinking more in terms of a tough situation where the ability to put a strike force into the air might make a difference even if it took several days to accumulate the necessary fuel. Then again, God save us all if it comes down to that.

 

[LTLFTcomposite]

^ That's a little like saying my Leaf charges at a rate of 12 mile/hour therefore that's its top speed.

Maybe the navy is looking for a carbon-neutral fuel supply for ships and planes.

 

[AndyH]

I'm not sure why the 1-hour output is critical, unless you're talking about keeping aircraft in the sky 7x24. While that may be desirable, I was thinking more in terms of a tough situation where the ability to put a strike force into the air might make a difference even if it took several days to accumulate the necessary fuel. Then again, God save us all if it comes down to that.

Klap likes hypotheticals. The approximately 6000 folks on an aircraft carrier, on the other hand, do not.

So you want to understand an aircraft carrier? Well, just imagine that it's a busy day, and you shrink San Francisco Airport to only one short runway and one ramp and gate. Make planes take off and land at the same time, at half the present time interval, rock the runway from side to side, and require that everyone who leaves in the morning returns that same day. Make sure the equipment is so close to the edge of the envelope that it's fragile. Then turn off the radar to avoid detection, impose strict controls on radios, fuel the aircraft in place with their engines running, put an enemy in the air, and scatter live bombs and rockets around. Now wet the whole thing down with salt water and oil, and man it with 20-year-olds, half of whom have never seen an airplane close-up. Oh, and by the way, try not to kill anyone.

Senior officer, Air Division

http://www.fas.org/man/dod-101/sys/ship/docs/art7su98.htm

This is not the place to make fuel.

Additionally, many of the day's missions that depart the carrier require air to air refueling - and that's most often accomplished by aircraft that cannot fly from a carrier. There's no way any single carrier can provide the fuel for all of their daily mission as even if they could hypothetically produce 100% of the day's supply of fuel, they couldn't deliver it.

 

[donald]

This is not the place to make fuel.

A very colourful description, but you might equally argue that it is not the place to put a nuclear reactor!

I think it would be just fine to generate fuel in an installation buried 20 stories below the runway.

So what if it adds 100 tons of equipment and an extra metre of length to the vessel? If it is designed in from the start, it'll do its stuff and generate a steady supply of fuel that reduces the demands on the supply chain.

Cutting to the chase - if this is a practicable means to generate GTL fuels then, depending on the efficiency, it would mean electric vehicles powered by nuclear power stations are made redundant compared with ICE vehicles powered by nuclear-generated GTL. The energy density of liquid hydrocarbons makes it, in practice, a more practical energy vector than electrons the energy of which you have to bunch up somehow in a battery to make it portable.

 

[Graffi]

Does anyone here read Clive Cussler's books about the ship, Oregon, that has the Hydro.... something or another drive, that is powered by sea water??? In the book (Fiction) he goes into detail about how the drive works. Very interesting books, at least I enjoy reading them.

 

[klapauzius]

^ That's a little like saying my Leaf charges at a rate of 12 mile/hour therefore that's its top speed.

Maybe the navy is looking for a carbon-neutral fuel supply for ships and planes.

If you wanted to e.g. drive across the US, that would be indeed your average speed. Whether that matters more than top speed depends on your goals...

So which does matter more in a modern naval battle, average number of sorties/h or top number of planes in the air at any given time?

Pulling some info from the net, I find that during desert storm, there were between 55 to 96 sorties per day per carrier.
So at 1 sortie/h fuel support, that means with the new technology, about 25% to 50% of sorties could be supported (in a an operation like desert storm).

Maybe more interesting would be to see how many sorties per day were flown during the big naval battles in the pacific during WW2?

 

[klapauzius]

Klap likes hypotheticals. The approximately 6000 folks on an aircraft carrier, on the other hand, do not.

Hey, this whole thread is about hypotheticals..
I think the military, including the crew of carriers, does play war games all the time (which are all based on hypotheticals).
This might be due to the scarcity of large naval battles these days...

 

[klapauzius]

Cutting to the chase - if this is a practicable means to generate GTL fuels then, depending on the efficiency, it would mean electric vehicles powered by nuclear power stations are made redundant compared with ICE vehicles powered by nuclear-generated GTL. The energy density of liquid hydrocarbons makes it, in practice, a more practical energy vector than electrons the energy of which you have to bunch up somehow in a battery to make it portable.

I am not so sure about that..there will be losses in the conversion from electric power to fuel, which is then burned in vastly inefficient vehicles (as compared to electric vehicles).

Just a toy calculation:

Yes, the energy density is hard to beat, but the overall efficiency will be terrible...this might work for the military, but for civilian applications? Anyway, average daily consumption in the US was 366 million gallons a day, or the energy equivalent of ~ 1.4 * 10^13 watt hours. A 1 GW nuclear power plant can output 24 * 10 ^9 watt hours per day or (at 100% conversion efficiency) ~ 0.17 % of US daily consumption.....

So, to reach autonomy, we need 577 new nukes. Since 100% efficiency is not real, probable more.

 

[AndyH]

Klap likes hypotheticals. The approximately 6000 folks on an aircraft carrier, on the other hand, do not.

Hey, this whole thread is about hypotheticals..
I think the military, including the crew of carriers, does play war games all the time (which are all based on hypotheticals).
This might be due to the scarcity of large naval battles these days...

Klap - I've been involved in 'war games' and in reviewing/updating operations plans. They are concrete! Has anyone seen a pilot's checklist? Or the volumes of checklists used in the cockpit? "If this happens, do this first, this second, this third, while also continuing to fly the airplane and while continuing to not hit anything with said airplane." The checklists are there and the lines on the checklists are there because we've been flying for a long time - and every single one of the lines in the checklists was paid for by the life of the first guy or gal that discovered that not doing that thing was hazardous to one's health.

Extend the checklists and procedures to encompass a flight of 10 aircraft. Then add two refueling tankers - one inbound, one outbound. Then add more airplanes to fly above the strike package to protect them. Then add at least one airborne warning and control (AWACS) aircraft (E2C or E3A). Then add ships - hopefully one being an aircraft carrier. And if the AWACS is from the USAF, you'll need to add a land base and their weather folks, radar folks, ground support equipment and refueling folks. Then there are folks that work interoperability between USAF and USN assets. Wait - is the land base in a foreign country or the carrier group in foreign waters? Now we have folks from the host nation involved as well. What? The airplanes are on ground attack or troop support missions? Crap - now we've go to add forward area controllers, ground units, info on where the 'friendlies' are operating so we don't hurt them, etc.

Hypotheticals aren't part of the mix.

 

[AndyH]

This is not the place to make fuel.

A very colourful description, but you might equally argue that it is not the place to put a nuclear reactor!

I think it would be just fine to generate fuel in an installation buried 20 stories below the runway.

Colorful yet dramatically accurate.

One might also 'argue' that no self respecting pilot should be forced to operate from a bobbing postage stamp in the middle of an ocean. But the aircraft, the systems, and the postage stamp are designed to perform the needed function. Same for the nuclear reactors - these aren't the same as the units formerly in service at Fukushima - they too are designed for the environment in which they serve.

The problem with fuel generation on a carrier is NOT about "what's an extra metre among friends?" it's about the number of other vessels in a carrier group that use JP8. It's about flexibility, cost effectiveness, mission readiness, contingency planning.

Some things to think about:
1. Which is a better target: A single aircraft carrier, or an aircraft carrier and two other ships tied together transferring fuel?
2. How do the other aircraft in the carrier group continue to operate when the carrier is sunk and the GTL plant and storage tanks go to the bottom with it? Come on - the helicopters need fuel - we've got downed pilots to rescue - who's got the fuel?

Generating jet fuel from sea water and/or atmospheric CO2? Hell yes! Disabling an entire carrier battle group because the single point of failure took a missile? What are you smoking, son?

 

[klapauzius]

Klap - I've been involved in 'war games' and in reviewing/updating operations plans. They are concrete!

So, I am curious, what is the mode of operation for a carrier in a major naval engagement:

a) As many sorties as possible, i.e. continuous operations round the clock

or

b) Brief intense activity, followed e.g. by days of inactivity (during which i.e. the carrier, or whatever seaborne fuel generator the navy has in mind, could make enough fuel to power the next missions for its planes).

If b) was the typical scenario, at-sea fuel generation might work...

Since there have been no battles involving carriers, since WW2, I have no idea what people think is the best strategy to win battles these days...

 

[klapauzius]

2. How do the other aircraft in the carrier group continue to operate when the carrier is sunk and the GTL plant and storage tanks go to the bottom with it? Come on - the helicopters need fuel - we've got downed pilots to rescue - who's got the fuel?

Generating jet fuel from sea water and/or atmospheric CO2? Hell yes! Disabling an entire carrier battle group because the single point of failure took a missile? What are you smoking, son?

How do aircraft continue to operate, when the carrier is sunk? Is that practical question?
Naively I would say they cease to operate, unless they happen to be in the air and can reach land? Or another carrier?
In any case, you could refuel the rest of the fleet with the traditional means, i.e. tankers?

Keep in mind: This whole fuel generation scheme can only work with nuclear power, so whatever people have in mind with this, they have to put a nuclear reactor on a ship in order to make it work.

I would think you pick a ship for it which is really big, hard to sink and well protected....

 

[AndyH]

The problem with fuel generation on a carrier is NOT about "what's an extra metre among friends?" it's about the number of other vessels in a carrier group that use JP8. It's about flexibility, cost effectiveness, mission readiness, contingency planning.

Some things to think about:
1. Which is a better target: A single aircraft carrier, or an aircraft carrier and two other ships tied together transferring fuel?
2. How do the other aircraft in the carrier group continue to operate when the carrier is sunk and the GTL plant and storage tanks go to the bottom with it? Come on - the helicopters need fuel - we've got downed pilots to rescue - who's got the fuel?

3. How does the rest of the battle group operate when the GTL plant is dead because the highest priority target in the group is out of service? (The carrier and likely the submarine(s) ha(ve/s) a pair of nukes below decks - the rest of the ships burn diesel/bunker fuel/JP8/other viscous dino-sludge...)

Klap - homework for you. Google carrier battle group. Look up the other ships assigned to the group and check the aircraft inventory on those ships. Hint - helicopters are aircraft. The Navy site makes it easy - just click a ship.

http://www.navy.mil/navydata/ships/carriers/powerhouse/cvbg.asp
http://en.wikipedia.org/wiki/Carrier_battle_group
http://science.howstuffworks.com/carrier-group.htm

edit... This is an excellent view of modern multi-role air combat. Note the number of aircraft in a sortie over the Nellis range - then recall that a single carrier can launch 80 F-18s.

[youtube]http://www.youtube.com/watch?v=rt_zoWSlwQQ[/youtube]

 

[smkettner]

In any case, you could refuel the rest of the fleet with the traditional means, i.e. tankers?

My perspective is the supply tankers are sitting ducks crossing the ocean. However an additional support ship with a nuke producing fuel with the proximity of the protective fleet could prove valuable. AFAIK cutting the supply lines is one of the oldest military strategies.

 

[donald]

There is no reason to presume it is 'EITHER' nuclear generated GTL, 'OR' victualling tankers coming alongside.

One way or the other, generating 'some' GTL will reduce the burden on refuelling and might make the difference between launching enough aircraft to defend the fleet whilst steaming into wind, and having to haul to for a half hour and do-like-a-sitting-duck to take on some extra fuel, by when it might all be over.

A GTL from seawater device should add to the capability, and as experience is gained with the technology it may take on a greater role, or be retired as an unsuccessful initiative.

On the subject of EVs (!?) yes, I agree that there would generally be more losses generating nuclear GTL and using that in ICE, but not exclusively. The generation of heat as a byproduct for ICEs make liquid fuel very attractive for colder climates. Maybe the focus on EVs in the mild climates of California has distorted that discussion point. To generate the amounts of heating folks tend to expect from cars in sub-zero, I think you will find ICEs actually work out pretty efficient at converting fuel into 'used' calorific value.

 

[klapauzius]

On the subject of EVs (!?) yes, I agree that there would generally be more losses generating nuclear GTL and using that in ICE, but not exclusively. The generation of heat as a byproduct for ICEs make liquid fuel very attractive for colder climates. Maybe the focus on EVs in the mild climates of California has distorted that discussion point. To generate the amounts of heating folks tend to expect from cars in sub-zero, I think you will find ICEs actually work out pretty efficient at converting fuel into 'used' calorific value.

I seriously doubt that...The leaf is at least 2-3 times more efficient than any current ICE car. If all that heat, even in sub zero temps ( I suppose Fahrenheit, which means really cold) would go to heat the cabin, it would feel like a sauna...

Imagine taking the average driving power of the Leaf, double it, and then imagine what the heater output at that power level would be (from the 11' resistive heater).

And unless you live at the south pole, there will come spring/summer, so what to do with all the extra heat then?


Most of the time, most the heat from ICEs is just wasted, so as soon as the range problem has been solved, there is no reason to burn fuel in civilian applications...