Difference between 100LL and Jet-A
- Thread starter mandm
- Start date
- Joined
- Mar 10, 2013
- Messages
- 19,562
- Location
- Oakland, CA
- Display Name
Display name:
Bro do you even lift
- Joined
- May 11, 2010
- Messages
- 20,703
- Location
- Charlotte, NC
- Display Name
Display name:
Snorting his way across the USA
I'm going to guess stockpiling of Jet A would level out the price. I would -think- gasoline would be more expensive to make than diesel or jet fuel since less processing (cracking anyway) would be required. But right now diesel is more expensive than gasoline. Dunno.
RussR
En-Route
The demand level isn't even close. The 172 in your avatar holds what, 50 gallons? Even the smallest jets hold 300 gallons. The Cessna Citation series of jets hold between 700 and 2000+ gallons. And then there's the thousands of airlines flying every day. A 737 can hold up to almost 7000 gallons.
So yeah, economies of scale. 100LL is such a small drop in the bucket compared to Jet fuel. It's literally a boutique fuel.
Yes.
Jet fuel is easier and cheaper to produce than AVGAS plus jet fuel is refined at much greater quantities than AVGAS.
ateamer
Pattern Altitude
Just on a quick glance at numbers from six years ago, 24 billion gallons of Jet A, vs 168 million of 100LL. 142 times as much Jet A is being sold.
Then there’s the military
FormerHangie
En-Route
Last month, according to the USEIA, 330,000 barrel (42 gallons) of avgas was consumed. The figure for Jet fuel was 47,265,000, and for mogas it was 277,432,000.
So, yes, lack of volume is part of the issue. Another problem is that avgas has lead in it and requires special handling, adding to the transportation cost, and only a few refineries make avgas.
So, yes, lack of volume is part of the issue. Another problem is that avgas has lead in it and requires special handling, adding to the transportation cost, and only a few refineries make avgas.
Rgbeard
En-Route
- Joined
- Aug 26, 2017
- Messages
- 4,343
- Location
- Phoenix, AZ and Ensenada, Mexico
- Display Name
Display name:
rgbeard
Do you know the difference between gasoline and diesel fuel?
Essentially, this is the same question.
Essentially, this is the same question.
This. It can't be pipelined in its finished form and only certain refineries produce it. It then has to be tankered (usually train) to a terminal that can off load it into trucks for delivery. Back when you could still get Grade 80 our airport found that the terminals stopped handling it and it had to be trucked from further and further away (more $$).
JET A is pipelined, sometimes directly to the airport (I remember a few years back when Dulles switched to this, they were about five miles from the Colonial Petroleum pipeline and they finally got a drop from there). Prior to that there was a never ending stream of tanker trucks that would make the deliveries to the fuel farm off Route 28. They finally closed that hole in the wall down (I always comment about the noise wall between the airport and Route 28... I guess the airport was unhappy with the traffic noise).
hindsight2020
Final Approach
- Joined
- Apr 3, 2010
- Messages
- 6,998
- Display Name
Display name:
hindsight2020
even if it was unleaded, the economies of scale would make it a boutique consumption. Recreational aviation will never avail itself to automotive economies of scale. That said, Jet A is more expensive than 100LL (self-serve) in my area currently; so much for economies of scale. *shrugs*
Mxfarm
Line Up and Wait
100LL has no speculator involvement influencing the price
Back when mo-gas STCs a friend that ran a refinery ( Crude Dude) commented that you could get 100LL for about 2 cent per gallon more than mo-gas.
This was at the refinery and your had to take the entire batch. Transporting /storage is $$$.
This was at the refinery and your had to take the entire batch. Transporting /storage is $$$.
Mikey B
Pre-takeoff checklist
Jet A (which is basically kerosene) is part of the "middle distillates" segment of the refinery product slate, where avgas is in the lighter "naphtha" segment. As such, Jet A is closely related to heating fuels, which tend to be seasonally more pricey in the winter. So in theory, jet would tend to be higher relative to avgas in the winter, and the opposite in the summer. (Note that I'm not saying necessarily higher than avgas.) But throw in the current Ukraine mess, post-Covid demand recovery, and the boutique status of avgas ... who knows.
You are close. Gasoline (100 LL and auto gas) contains unsaturated compounds (toluenes, xylenes, unsaturated hydrocarbons and related compounds) to reduce knocking. These are present up to ~30 percent or so. These compounds are blended into gasoline:
https://www.valero.com/sites/defaul...s_-_002-ghs_unleaded_gasoline_rev1_5-14_0.pdf
https://www.aviation-fuel.com/pdfs/MSDS_for_AvGas_100LL_from_P66_dated_3-04-13.pdf
Gasoline, jet fuel, and other products are made from "cracking" larger molecules in petroleum we don't use as much. Here's a simplified flow diagram:
https://www.cer-rec.gc.ca/en/data-a...e-oil-into-products-like-gasoline-diesel.html
The process to make gasoline from heavier petroleum compounds started just before WW2:
https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/houdry.html
Mikey B
Pre-takeoff checklist
Gosh, thanks -- I hope my 30+ years in the industry would get me "close"!
I was trying to simplify for the non-refiners, but yes, there are many processes beyond atmospheric distillation that go into production of finished petroleum products, including avgas and Jet A.
My apologies! That diagram is nicely detailed.Gosh, thanks -- I hope my 30+ years in the industry would get me "close"!
I was trying to simplify for the non-refiners, but yes, there are many processes beyond atmospheric distillation that go into production of finished petroleum products, including avgas and Jet A.
Dad, is that you?Gosh, thanks -- I hope my 30+ years in the industry would get me "close"!
I was trying to simplify for the non-refiners, but yes, there are many processes beyond atmospheric distillation that go into production of finished petroleum products, including avgas and Jet A.
<------- son of a retired chemical engineer that designed refineries for 35 years.
texasclouds
En-Route
Jet fuel goes in jets, and 100LL goes in bug smashers.
Mikey B
Pre-takeoff checklist
Nope lol! Not an engineer -- early on, a petroleum marketer (sold jet fuel to the airlines long ago), later an energy economist.
I would always ask my dad if he had designed any distillation towers that day. That or heat exchangers
Can you just put auto gas in a single piston that uses 100LL? I’ve seen some companies selling STCs but it seems like a certificate only, does anything need to be done to the engine?
Depends very much on the engine. Most of the planes using autogas now were designed to run the old 80 grade aviation fuel. These can run non-ethanol auto fuels at various octanes with an STC. There are only a few planes which require any mod to the plane to do so, the STC just proves that the fuel system/engine combo was tested and that things like vapor lock were not considered any more of a problem.
However, something like 80-90% of the 100LL consumed is used by higher compression engines that can not run on autogas. There are a handful of alternative fuels out there. Continental says they're pretty hopeful that they can get rated power with most of the ones proposed.
Per the STCs it needs to be non-ethanol mogas. Each STC provides the process for this.
The STC provides the necessary FAA approval to use mogas as the engine/aircraft was not certified to use it originally. In most cases, the STC only requires the installation of some placards and a logbook/337 entry. Some other aircraft require modification to the fuel system in order to use the STC. All of which can be determined prior to purchasing the STC.
PaulMillner
Line Up and Wait
There are typically at least four process plants (steps) involved in making mogas or avgas components. Jet usually only requires two processing plants, so less energy and overhead in manufacturing. Almost a majority of jet is the result of hydrocracking, a form of cracking in the presence of a CoMo catalyst at 800F in the presence of high-pressure hydrogen, say 3,000 psig.
Diesel specifications changed in recent years, requiring rather severe hydroprocessing to reduce sulfur content and aromaticity. Diesel actually has less sulfur in it now than jet. Twenty year ago, diesel had 10 to 100 times more sulfur than jet fuel. The diesel hydroprocessing is relatively scarce, and supply/demand raises diesel prices.
Actually, avgas isn’t pipelined in any form, other than as crude oil. The light ends (say isopentane), aviation alkylate, aromatics (say toluene) and lead are combined at the refinery, where all but the lead are manufactured.
The industry term for moving by train is rail... but most avgas moves from the refinery by barge to water-proximate terminals, and then is trucked from there. There is some rail transport of finished avgas (notably Phillips 66 in Borger Texas is not on any useful waterway, nor is Exxon Imperial Oil in Alberta). But barging is MUCH cheaper than rail, and rail cars are in short supply due to crude oil transport demand.
That’s not accurate, exactly. Typically, avgas is priced at the refinery gate according to a formula that looks at west coast and gulf coast mogas prices, the difference between premium & regular price, and the difference between conventional and reformulated mogas price. Since *all* of those commodities are traded on markets, those prices are definitely market-influenced. If there’s speculation impact on mogas price, it immediately shows up in avgas wholesale price as well.
That was certainly true when mogas was 25 cents wholesale. But that’s been a long while, now… 40+ years? Today, Avgas sells at the refinery gate at 80 cents to $1/gallon more than mogas. But then, there are many other costs/taxes/fees involved between the refinery and the the wingtip.
There’s certainly seasonality in distillate pricing. But, there’s seasonality in gasoline pricing, too! Gasoline demand is much higher in the summer, and avgas is typically priced off mogas posted prices, and so… TWO reasons for distillates and gasoline to swing against each other, winter versus summer. (High distillate demand in winter, high gasoline demand in summer.)
The article you quote disagrees with your simplification! Houdry cracking was a breakthrough, as it was catalytic cracking that improved efficiency (I don’t think there’s any Houdry crackers still operating). But thermal cracking was around since the 1890s, and is mentioned in your referenced article… The refinery I last worked in began construction in 1899, and was considered a marvel… 14,400 barrels per day (over 600,000 gallons per day) of thermal cracking capacity… the largest in the world at the turn of the century. I got to watch the last of those being torn down early in my career…
Only lower compression engines, typically *less* than 1/2 horsepower per cubic inch of displacement, are approved for mogas. Typically, there are no engine modifications. Low wing aircraft sometimes require fuel boost pumps to avoid vapor locking.
Paul
Thermal cracking didn't have the efficiency to make the volumes of gasoline needed for cars or for aircraft.
The article lists 1913 is the introduction of thermal cracking:
You are correct in that the Houdry process has been superseded by more efficient fluidized bed processes and better catalysts.
Aviatorbrew
Pre-takeoff checklist
Very good explanation.Gosh, thanks -- I hope my 30+ years in the industry would get me "close"!
I was trying to simplify for the non-refiners, but yes, there are many processes beyond atmospheric distillation that go into production of finished petroleum products, including avgas and Jet A.
is it also true that you can only get a certain amount of product from each barrel?
Mikey B
Pre-takeoff checklist
As a practical matter, yes, but it can be slightly more than the crude oil input. Some sophisticated refineries routinely get product yields slightly over 100%, as "cracking" heavy fractions into lighter products results in volume gain.
PaulMillner
Line Up and Wait
I acknowledged the increase in efficiency… however, if thermal cracking were the only tool we had, we would have made it meet the need. But gasoline would have been more expensive.
The article is very Amoco-centric, Standard of Indiana. There is a larger world:
“Among several variants of thermal cracking methods (variously known as the "Shukhov cracking process", "Burton cracking process", "Burton-Humphreys cracking process", and "Dubbs cracking process") Vladimir Shukhov, a Russian engineer, invented and patented, the first in 1891 (Russian Empire, patent no. 12926, November 7, 1891).”
By 1899, we’d figured that out in California. Apparently, news traveled to Indiana more slowly back then.
Paul
But Amoco was/is the best, so there's that.I acknowledged the increase in efficiency… however, if thermal cracking were the only tool we had, we would have made it meet the need. But gasoline would have been more expensive.
The article is very Amoco-centric, Standard of Indiana. There is a larger world:
“Among several variants of thermal cracking methods (variously known as the "Shukhov cracking process", "Burton cracking process", "Burton-Humphreys cracking process", and "Dubbs cracking process") Vladimir Shukhov, a Russian engineer, invented and patented, the first in 1891 (Russian Empire, patent no. 12926, November 7, 1891).”
By 1899, we’d figured that out in California. Apparently, news traveled to Indiana more slowly back then.
Paul
PaulMillner
Line Up and Wait
Not so much *is* anymore, they're beyond petroleum now... (wistfully looking into the distance...)But Amoco was/is the best, so there's that.
Paul
Had to say it since my Dad was Amoco.
SkyDog58
Ejection Handle Pulled
- Joined
- Jun 11, 2015
- Messages
- 14,600
- Location
- My own special place.
- Display Name
Display name:
Canis Non Grata
Other than that of crude oil.