Posted on 07/18/2013 2:06:47 PM PDT by thackney
Liquefied natural gas (LNG) is finding a home in an increasing number of transportation applications. On land, the fuel is gaining acceptance as a cleaner-burning and cheaper alternative to diesel in truck fleets and rail locomotives. The waterborne transport community is also turning to LNG to power ferries, tankers and other marine vessels.
It will only be a matter of time until the aviation sector begins adopting LNG as a transport fuel as well, according to Graham Dorrington. The senior lecturer in aeronautical engineering at RMIT University in Melbourne, Australia contends that commercial airlines will find the environmental and economic benefits of powering their fleets with LNG too compelling to resist. Burning LNG rather than jet fuel in aircraft engines would help carriers to comply with stricter curbs on carbon emissions, explained Dorrington. In addition, using LNG could help airlines become more competitive because their fuel costs would likely decrease over time, he said.
Dorrington has embarked on a crusade of sorts to promote the use of LNG in air transport, and his aim is to spur a dialogue on the matter between the aviation and LNG communities. Rigzone recently caught up with Dorrington to discuss his views on what needs to happen for LNG-fueled airliners to become commonplace. Dorrington's insights appear in the exchange below.
Rigzone: Do you see the use of LNG in aviation as a global or regional solution? In other words, would it only be economic for routes in countries where LNG is relatively cheap and abundant such as Australia and the United States rather than regions dependent on LNG imports such as the Far East and Europe?
Dorrington: Both. Australian LNG is currently exported at about $15 per Gigajoule (GJ) to Japan, and the at-the-airport price could still be priced at 70 percent of that of diesel or aviation (Jet A/A1) fuel. In other locations it could be priced even lower, so there may be advantages to some countries. In any event, I foresee mixed fleets (Jet A and LNG aircraft) operating globally within the next 20 years.
Rigzone: Is LNG practical for both turbine and piston engines?
Dorrington: Yes. It has been demonstrated in both (by the Russian and American aerospace companies Tupolev and Beech Aircraft, respectively) in the 1980s.
Rigzone: From a technological standpoint, what changes would the commercial aviation sector need to make to fuel airplanes with LNG rather than conventional fuels? Would this apply only to new planes or could existing aircraft be retrofitted cost-effectively?
Dorrington: The retrofit options need to be considered on a case-by-case basis. One problem is that the required fuel tank volume increases by roughly 50 percent for the same range. That's sometimes problematic, but if we consider, say, the Airbus A380, it has a huge internal wing tank volume [and unused center wing box], so there is no volume constraint there. The main design issues are concerned with promoting and inhibiting boil-off. Most engineers think the insulation requirement would be prohibitive, but our studies show this is not actually a major problem. Managing cryogenic fluids isn't easy, but it's become much more routine over the past 20 years.
Rigzone: In terms of infrastructure, what changes would need to be made along the LNG value chain en route to airports and at the facilities themselves?
Dorrington: We are currently in discussions with experts on this topic. They talk about putting in "mini-plants" at airports and some have told me this is no problem whatsoever, but it will be a significant capital cost. You need storage tanks and cryo-cooling facilities, new safety systems, etc.
Rigzone: Airlines have tested drop-in biofuels in an attempt to reduce carbon emissions and stabilize fuel costs. In addition, synthetic jet fuels using the Fischer-Tropsch process have been developed. How would using LNG be more advantageous than and/or complementary to these alternative fuels?
Dorrington: As far as I know, all tested biofuels [to date] are still far more expensive than petroleum derived Jet A fuel – three-plus times the price. Synthetic kerosene might be produced cost effectively, but the overall carbon emissions are significantly greater – nearly double – than using Jet A. Direct use of LNG results in a 20-percent carbon emission reduction, and it's also significantly cheaper. The only other realistic alternative is using carbon offset measures.
Rigzone: I understand that Beech Aircraft and Tupolev experimented with LNG as an aviation fuel three decades ago. What was the impetus for their research, and what did their tests reveal? Also, why has research and development in this area apparently languished?
Dorrington: All the tests done by Beech and Tupolev were positive. I'm not sure exactly why Beech initiated their work. Information on the Tupolev work is still on their website. I think you will find that both these companies had financial difficulties in the 1990s onward, unrelated to the LNG issue, so that may partly explain why the idea did not grow. But the big reason that it is re-growing now is that the LNG price has fallen well below the Jet A price in the past 5 years and is predicted to remain so. Annual-global Jet A sales are about $200 billion and constitute about 35 to 40 percent of airline direct operating costs. That's pinching the airlines badly.
Rigzone: As you know, there have been developments in recent years to carve a niche for LNG in land and marine transportation. What are the key lessons the LNG sector is learning through these experiences, and how can they apply these discoveries to building a market for LNG in air transport?
Dorrington: Regulation and certification requirements. There are real regulatory measures in place now to reduce maritime environmental impacts. Currently the International Air Transport Association is just setting ideal carbon reduction targets. The aircraft industry has to meet imposing technical requirements and exacting certification requirements, so it will be slow in responding to necessary changes. There is currently a strong belief within the aviation sector that only "drop-in" solutions are viable because of the exacting requirements that have evolved over time. Switching to LNG will require new thinking and new certification requirements.
Rigzone: Are any significant initiatives underway with the goal of making LNG a viable option in commercial aviation? If not, what do you think will be necessary to make that a reality?
Dorrington: Basically, experts from the big aircraft manufacturers need to get together with the engine producers, airport operators, airlines and LNG supply companies and engage in a comprehensive-integrated study to determine if this really is a win-win scenario for all. Then business leaders among these stakeholders need to find ways to finance the transition. After that, the regulators need to advise and arrive at new rules, and then governments should get together and set legal operating requirements that limit global emissions through IATA. In short, a load of work has to be done, but this is now necessary in my opinion. We can't keep waiting and hoping the aviation fuel dilemma will simply go away. It needs to be solved. The direct use LNG – possibly blended with liquid biomethane, derived from biogas – is one possible solution that deserves attention now.
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.
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.
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.
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.
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.
Kerosene is jet fuel, LNG is a flying BOMB!
Insane idea.
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.
LNG is not pressurized, only cooled.
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.
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.
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.
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.
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.
Atta would have loved to have an airborne LNG
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.
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.
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