Navy plans to make jet fuel from sea water

D Tibbets · Post by **D Tibbets** » Tue Nov 27, 2012 5:46 am

Two questions concerning ammonia. What is the energy density compared to diesel like jet fuel? Not good if the aircraft range is cut in half.
And, how much more frightening is the ammonia from a damage control standpoint, both from the toxicity and the explosion hazard?

Dan Tibbets

Joseph Chikva · Post by **Joseph Chikva** » Tue Nov 27, 2012 9:36 am

D Tibbets wrote:Two questions concerning ammonia. What is the energy density compared to diesel like jet fuel? Not good if the aircraft range is cut in half.
And, how much more frightening is the ammonia from a damage control standpoint, both from the toxicity and the explosion hazard?

Dan Tibbets

From Wiki http://en.wikipedia.org/wiki/Ammonia :
Density 0.86 kg/m3 (1.013 bar at boiling point)
0.73 kg/m3 (1.013 bar at 15 °C)
From Ammonia Combustion with Near-Zero Pollutant Emissions http://www.ucs.iastate.edu/mnet/_reposi ... /Meyer.pdf
NH3 is a source of NOx in flames. So, avoiding CO2 emmisions we will get NOx that is not good too.
There in that presentation is also written that low NOx emission is possible too. But as understand - inspecial conditions. Do turbojet motors provide such conditions? I do not know.

Ok, power density.
Again from wiki http://en.wikipedia.org/wiki/Heat_of_combustion
Heating value
Kerosene - 46.2 MJ/kg
Ammonia - 22.5 MJ/kg

density of kerosene is 0.78– 0.81. So, the same order as ammonia with about two times lower heating value.
So, energy density of ammonia storing will be about two times lower than jet fuel's energy density.

KitemanSA · Post by **KitemanSA** » Tue Nov 27, 2012 3:02 pm

D Tibbets wrote:Two questions concerning ammonia. What is the energy density compared to diesel like jet fuel? Not good if the aircraft range is cut in half.
And, how much more frightening is the ammonia from a damage control standpoint, both from the toxicity and the explosion hazard?

A1: Since the VAST majority of fuel is used by the ships, retaining HCs for flight ops would not be significant.
A2: According to several papers I have read, it is no more dangerous than using gasoline. It is not actually toxic but is what is called an "inhalation hazard". It is lighter than air so will tend to disperse in the open. It is also VERY difficult to get to explode.

A just for interest sake, please be aware that ammonia injection is one way that diesel engine makers now meet the very low NOx requirements, NH3 + NOx > N2 + H2O.

Joseph Chikva · Post by **Joseph Chikva** » Tue Nov 27, 2012 3:12 pm

KitemanSA wrote:NH3 + NOx > N2 + H2O.

How about NH3+O2=>NO+H2O ?
Low NOx emission is possible only for special conditions.
In conventional conditions e.g. in boilers for regulating of NOx there is a special hardware regulating surplus air coefficient.
What can you say about combustion conditions in turbojet motors?
I can to say nothing. And you?

paperburn1 · Post by **paperburn1** » Tue Nov 27, 2012 4:20 pm

Used to work with ammonia in diazo duplication. The smell will drive you out of the room long before toxic levels are reached. . when we fight fires on a ship do they still use OBA that could be an ignition source for it.

hanelyp · Post by **hanelyp** » Tue Nov 27, 2012 7:13 pm

I looked at ammonia as an airship lift gas, considering toxicity and flammability. Sizable margin between odor response and toxicity, as makes sense for a chemical produced naturally by some biological action. Fairly difficult to ignite mixed in air, even deliberately.

ladajo · Post by **ladajo** » Tue Nov 27, 2012 7:37 pm

paperburn1 wrote:Used to work with ammonia in diazo duplication. The smell will drive you out of the room long before toxic levels are reached. . when we fight fires on a ship do they still use OBA that could be an ignition source for it.

Nope, been using "Scott" Airpacs for while. OBAs went the way of the Dodo some time ago.

KitemanSA · Post by **KitemanSA** » Wed Nov 28, 2012 12:20 am

Check it out yourselves.

http://nh3fuelassociation.org/

Joseph Chikva · Post by **Joseph Chikva** » Wed Nov 28, 2012 3:12 am

KitemanSA wrote:Check it out yourselves.

http://nh3fuelassociation.org/

Checked and:
Energy content:
Diesel fuel -- 36.1 MJ/liter
Ammonia --- 11.62 MJ/liter

paperburn1 · Post by **paperburn1** » Wed Nov 28, 2012 2:22 pm

ladajo wrote:
paperburn1 wrote:Used to work with ammonia in diazo duplication. The smell will drive you out of the room long before toxic levels are reached. . when we fight fires on a ship do they still use OBA that could be an ignition source for it.
Nope, been using "Scott" Airpacs for while. OBAs went the way of the Dodo some time ago.

good ridance, darn near choked to death in once one time.(ok maybe a slight exageration as I am still here)

D Tibbets · Post by **D Tibbets** » Wed Nov 28, 2012 4:47 pm

KitemanSA wrote:
D Tibbets wrote:Two questions concerning ammonia. What is the energy density compared to diesel like jet fuel? Not good if the aircraft range is cut in half.
And, how much more frightening is the ammonia from a damage control standpoint, both from the toxicity and the explosion hazard?
A1: Since the VAST majority of fuel is used by the ships, retaining HCs for flight ops would not be significant.
A2: According to several papers I have read, it is no more dangerous than using gasoline. It is not actually toxic but is what is called an "inhalation hazard". It is lighter than air so will tend to disperse in the open. It is also VERY difficult to get to explode.

A just for interest sake, please be aware that ammonia injection is one way that diesel engine makers now meet the very low NOx requirements, NH3 + NOx > N2 + H2O.

Concerning A1, The question was generating fuel for aircraft use on ships. The on board fuel storage and the aircraft fuel storage tankage would both have to be doubled for the same range for the ship or plane. Assuming a nuclear carrier with rapid in situ production of ammonia, the ships tankage could be reduced, but this still leave the range penalty for the planes.

Concerning A2. The question is not the fire hazard between ammonia and gasoline, but between ammonia and diesel. I am reminded of the of the Japanese aircraft carrier that blew up in WWII. Torpedo damaged the ship, but it was survivable, till damage control allowed for venting of gasoline fumes from damaged tanks and the ship blew up.

Admittedly I know little about ammonia handling, but farmers are familiar with liquid ammonia and the care needed. More than a few have been killed. I'm not concerned about normal handling on a ship, but what about a condition such as occurred on the Forrestal where half the flight deck was on fire and aircraft fuel tanks were cooking off.The fuel was essentially Diesel, not gasoline (or volatile ammonia) and still it took heroic efforts and loss of life to save the ship. Sometimes I wonder how any WWII carriers survived with their gasoline powered aircraft. Obviously tremendous effort in design and fire control procedures was key.

As for injecting ammonia to reduce NOx emmisions, does that consume energy, or release more energy?
Dan Tibbets

ladajo · Post by **ladajo** » Wed Nov 28, 2012 9:26 pm

Forrestal fire was exacerbated by Class-D metal fires. Once the high energy metallics of the aircraft caught, it was a done deal.

WWII carriers were tinder boxes, especially the escort carriers. The Japanese lost a number of carriers due to poor practice in combat. They learned eventually to do it better, but it was too late. The US knew early on to do simple things like not leave ordnance out in the hangers, as well as purging of all fuel lines not in use.

KitemanSA · Post by **KitemanSA** » Wed Nov 28, 2012 9:40 pm

D Tibbets wrote:Concerning A1, The question was generating fuel for aircraft use on ships. The on board fuel storage and the aircraft fuel storage tankage would both have to be doubled for the same range for the ship or plane. Assuming a nuclear carrier with rapid in situ production of ammonia, the ships tankage could be reduced, but this still leave the range penalty for the planes.

The title mentions jets, the article opened:

Refueling U.S. Navy vessels, at sea and underway, is a costly endeavor in terms of logistics, time, fiscal constraints and threats to national security and sailors at sea.

In Fiscal Year 2011, the U.S. Navy Military Sea Lift Command, the primary supplier of fuel and oil to the U.S. Navy fleet, delivered nearly 600 million gallons of fuel to Navy vessels underway, operating 15 fleet replenishment oilers around the globe.

My first response allowed as how 90% of the benefit would be obtained by converting the SHIP'S turbines to ammonia. Once again Dan, keep up please.

KitemanSA · Post by **KitemanSA** » Wed Nov 28, 2012 9:43 pm

D Tibbets wrote:As for injecting ammonia to reduce NOx emmisions, does that consume energy, or release more energy?

I believe that the catalyzed reaction is exothermic.

ladajo · Post by **ladajo** » Wed Nov 28, 2012 10:11 pm

The fuel supplied by MSC is for ships and aircraft. I can get some more specific numbers if need be. The other point is that there are more than 15 oilers in service. MSC has over 100 operational units (a soft and ever moving target due to contract vessels). The Ready Reserve Force includes over another 50 or so parked here and there.

Re-fueling assets of the Combat Logistics Force Program (CLF) includes AO (15), AOE(4) and AKE(12) platforms for a total of 31.

The pdf file found here is instructive if you are curious.

http://www.msc.navy.mil/inventory/