How Can LNG Take to the Skies?

Rig Zone ^ | July 18, 2013 | Matthew V. Veazey

[thackney]

Compared to Jet Fuel, LNG requires more volume, but has less mass. Those properties work well with trains and large ships, but I don't know which might be more important for air travel. It may limit or influence design of air frames.

[BitWielder1]

It may be easier and cheaper to deal with liquid fuels than gas fuels that need to be compressed and cooled.
However, as long as gubmint does not get the bright idea to mandate it, if there is an economical solution, someone will come up with it.
Bummer though if you have to land at an airport that does not have LNG refilling.
Of course that is the same for any new fuel tech.

[Jeff Chandler]

If LNG is used for a greater percentage of trains and ships, it will affect the demand for petroleum based fuels which will push prices lower for jet fuel which is more practical for aircraft to use, just as gasoline and diesel are more practical for cars.

[Myrddin]

More volume means more surface area and more drag. The rapid shifting of mass as the fuel is consumed will be a challenging weight and balance issue.

[DBrow]

Jet fuel has a boiling point of 349F and a flash point of 140F. LNG has a boiling point of -256F and a flash point of -306.

I would expect some spectacular fireworks in the event of a crash.

[Erik Latranyi]

LNG must remain cooled to remain liquefied. That is why the article talked about “boil-off”.

LNG is not bad in the air, where temps are lower, but the insulation required on the tarmac.....hours of standing is pretty large and would result in additional weight.

It doesn’t matter if LNG does not work in aircraft. Use it for trains and trucks. That alone would reduce demand for diesel and pressure on refineries, lowering fuel costs for everyone.

CNG is spreading fast, however, so I think LNG may be left in the dust with regard to infrastructure.

[pallis]

I don’t know about airplanes, but if long haul truckers could get set up for it, and an infrastructure could be put in place, it should make things cheaper for them. They might have to stop more often.

[Blood of Tyrants]

Pipe dream. High pressure tanks for LNG means that wings can no longer be used for carrying fuel which means that the fuselage must get much larger to make room for less thermally efficient fuel.

[American in Israel]

Kerosene is jet fuel, LNG is a flying BOMB!

Insane idea.

[mountainlion]

Jet fuel needs a low pressure tank. LNG takes a high pressure tank capable of withstanding 3500 PSI plus a safety margin. This will be much heavier fuel tank. When Jets are charging for extra baggage, overweight flyers and hiring skinny flight attendants I would think it would not go over good.

[katana]

Question, does the lower mass (and weight per cubic liter of fuel, I'd assume) make up for, more than make up for, or fall short of (add weight)? Needing 50% more space for fuel is one thing but anything that adds weight is more worrisome in aircraft safety and economy.

Then you've got the issue with thermal stress and fuel burn off on a fuel tank where the exterior surface temperature on an Arizona runway might be hot enough to fry an egg but the fuel inside is liquefied gas cold.

If they are only considering doing this because of the imbecilic carbon emission issue they can GF themselves.

[thackney]

LNG is not pressurized, only cooled.

[thackney]

Since LNG first has to be vaporized before it will ignite, and if leaking out it hast to dilute with atmosphere down to ~15%, by then it will have lifted far from the crash since it is much lighter than air, the folks on this thread expecting an explosion are going to be disappointed.

[thackney]

The same amount of energy compared to Jet Fuel will have less mass but require more volume.

So to travel the same distance, they would carry(lift) less weight in fuel. But the tanks will take up more space.

The tanks would be insulated. As hot as Arizona might seem, the temperature differential doesn’t make much difference given how cold it is -260°F. So 390° delta isn’t that much more to over come than the typical 365° delta.

The fuel would cost significantly less. That is why it is being used already in trucking, marine and locomotive. Still new and a small market, but it is growing.

[thackney]

LNG takes a high pressure tank capable of withstanding 3500 PSI plus a safety margin.

You are thinking of CNG. LNG is not pressurized, it is super cooled. It will be a heavily insulated tank, but would not have any real pressure. The fuel itself would weigh less than the same energy in Jet Fuel.

[thackney]

The rapid shifting of mass as the fuel is consumed will be a challenging weight and balance issue.

Since it weighs less than the same energy in Jet Fuel, I don't see that as an issue. The extra volume would effect some plane designs.

[Blood of Tyrants]

It is compressed, then cooled to a liquid. Unless you have some serious insulation and/or some serious refrigeration, it will rapidly boil off, which still means that it can’t be stored in the wings.

[bugs_dallas]

Atta would have loved to have an airborne LNG

[kvanbrunt2]

All i know is when an LNG ship comes in to unload in Philly it’s escorted by the coast guard. Not getting near that stuff.

[DBrow]

I expect a huge fire possibly leading to bleve. I, um, no, someone shot an LNG tank with a greentip and there was a prolonged large fire.

When lng is depressurized the temperature drops, which slows the vaporization. But a flare started at the puncture site, which heated up the tank and this made the flare grow to huge proportions. The small tank ran out of gas before the tank wall could overheat and fail. A larger tank, though....

If the flare had been on the tank directly it could have lead to a bleve, boiling liquid vapor explosion, when the burning gas causes the tank wall to fail. This could certainly happen to a wing tank filled with cryo LNG.

http://www.youtube.com/watch?v=GWjxrAhpBQk

http://www.youtube.com/watch?v=1uAPcU2UBIw

http://www.youtube.com/watch?v=Xf3WKTwHpIU

http://www.youtube.com/watch?v=_Tr3iZz_ugA

A bleve is unlikely to occur with Jet A because the boiling point is so high. LNG, though, as you have just seen, is different.