TEL: Is there a Plan B ?

A couple of years ago I created a website to sell aviation-related items that publicize flying on unleaded auto fuel, or mogas as we call it. One bumper sticker that I created has proven to be prescient, “What You Going To Do When the TEL Runs Out?” That date may be rapidly approaching.

While I was doing some research on how much TEL — tetraethyl lead — is needed to produce avgas, I found some interesting information about the future of TEL. If my calculations are correct, the U.S. uses maybe 106,000 gallons of TEL each yr. That was computed by taking the number of gallons in 2 grams of TEL, because the maximum amount of TEL in 100LL is 2 grams/gallon, although we know now that some refineries are using maybe 19% less TEL by making 100 VLL, and multiplying that by a maximum of 200 million gallons/yr. of avgas production, which is probably generous, but surely declining.  2 grams = 0.0005283441025 gal, so multiply that by 200,000,000 gallons of gasoline = 105669 gallons of TEL. I invite readers to check my math or tell me where I am wrong about the amount of TEL needed for annual avgas production.

Then I went looking on the Internet for the annual production of TEL by Innospec, the only company in the world that produces it. Haven’t found the number yet and I doubt that it is published anywhere, but I found something much more interesting in this report. Down near the bottom of the page it says: “Innospec stated in its 10-K Securities and Exchange Commission report of 2010 that the company expected all sales of TEL for automobile gasoline use to cease in 2012, thus suggesting that its stated plans and the objectives of The LEAD Group were not far apart. The NCP has learned that Innospec now believes sales may continue into 2013.”

According to Innospec, TEL is only made for auto fuel production in a few third world countries and for avgas production. When Innospec stops making TEL for auto fuel sometime in 2013 that means that the only user of TEL will be the minuscule amount of avgas production left in the world, a steadily declining market, which Innospec publicly admits … great business model.

Of course as the demand declines, they can charge any amount they want because they already are a monopoly. Thank goodness TEL makes up such a tiny amount of the recipe for avgas, and as the refiners have already proven, they can make 100 octane avgas with even less TEL than the maximum 2 grams/gallon allowed by the ASTM D910 spec for 100LL, thus resulting in 100VLL.

What is interesting about this whole matter concerns The LEAD Group. It turns out The Lead Education and Abatement Design (LEAD) Group Incorporated has been trying to get Innospec to stop making TEL for auto fuel for the last couple of years. You can learn about their activity here, a report that includes a historic timeline about the use of TEL in aviation fuel at the very end of the report. So, it turns out that it is not just the Friends of the Earth (FOE) that is trying to get the lead out, there are other organizations that are leaning on government agencies around the world to curtail the production of TEL.

When TEL production for autos cease this year or in 2013, what do you believe the real prospects are for continued production of TEL for more than a couple of more years? What will happen if some unforeseen disaster befalls the only plant in the world that makes TEL in the mean time? This leads to some interesting questions that I have not heard the aviation alphabets, the ARC, the FAA nor the EPA address:

  1. What will really happen to 100LL avgas worldwide when Innospec stops making TEL? It is not if they stop making it, it really is when they stop making it, even though Innospec claims they will make TEL for aviation for as long as we need it.
  2. How much TEL is stored at refineries? Do they keep a six-month supply, a one-year supply, which is only 106,000 gallons in the U.S., or a longer supply?
  3. Does TEL have a specific shelf life?

I invite our readers to answer these questions if they really know. If we knew the answers to these questions we would have a reasonable handle on the real event horizon for the end of 100LL and have a better understanding on how much time is really left to find the magic unleaded 100 octane replacement.

If the event horizon is short it would be obvious to everyone in GA that we need a Plan B, which is something I have never heard discussed openly. Why not? It is obvious that the future of 100LL avgas is probably not going to be determined by the FOE/EPA litigation, but by the economics of producing TEL or some other successful legal challenge to Innospec.

Contributed by Dean Billing

The GAfuels Blog is written by two private pilots concerned about the future availability of fuels for piston-engine aircraft: Dean Billing, Sisters, Ore., a pilot, homebuilder and expert on autogas and ethanol, and Kent Misegades, Cary, N.C., an aerospace engineer, aviation sales rep for U-Fuel, and president of EAA1114.



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  1. flyunleaded says

    Update 5/29/2010, about Innospec and TEL.  While researching info for forum at Martin Field, WA (S95) that I am presenting this Saturday, I found this:

    “In the last paragraph, Innospec speaks of the continuing strong demand for TEL. Others, however, have reported that as of 2011 the only volume user of the additive will be general aviation. And, where Innospec was operating on a 24/7 basis this time in 2009, they are currently on a single shift five days per week.
    On a positive note:
    • There is 2 years’ TEL inventory in the system
    • Innovec (sic) ships using containerized methods which assures multiple shipping
    • The current plant has considerable idled production, and is physically very large.
    If some event happens to destroy the current production line {e.g., fire}, the idled
    plant could be quickly brought on line.”  from 

    So, it appears TEL has a long shelf life and there is a bunch of it around, at least as of 2010.  Interestingly enough, auto use of TEL was not phased out in 2011, nor probably this year either … maybe 2013.

    Now that ARC has tipped its hand that we may need TEL for another 11 years, or so, Innospec knows their event horizon.  But we don’t know theirs.  Would you want to keep an aging plant running another 11 years for a constantly dwindling market?  Of course if there is an infinite shelf life for TEL, they could just produce about a million gallons of it, if my computation above was correct, and shut down the plant tomorrow. Then we would all know exactly what the future of 100LL really is.

  2. Kent Misegades says

    Autogas has been an FAA-approved aviation fuel since 1982 and can power 70%-80% of all piston engined airplanes.   Nearly all LSAs, E-ABs and many warbirds can burn autogas legally and safely.   Nearly all of the latest aircraft engines are designed to operate on autogas.  We’re talking here about ethanol-free autogas obtained from a terminal, not an ethanol-blend at the local gas station.  Before any new boutique fuel is considered, autogas needs to be available as it greatly lowers the cost of flying and will always be produced in vastly greater volumes than aviation-specific fuel.  It is not for every airplane, although the ADI water-injection system from Petersen and AirPlains would make this possible.

  3. flyunleaded says

    The point of my post is that we need a REAL plan B.  Hjelmco AVGAS 91/96 UL is not a plan B.  It is ASTM D910 compliant which means it has TEL in it.  When TEL goes away, D910 becomes obsolete and Lars will not have an approved product, in fact the only approved aviation fuel at that point is ethanol free auto fuel or jet fuel.  Nobody will be able to continue to market a product under ASTM D910.  The DOD asked ASTM to tweak the D910 spec to provide for a non TEL D910 fuel with an octane of at least 91.  ASTM told them they couldn’t do that, and that DOD would have to get a new spec which they did, it is ASTM D7547, 91UL avgas which is getting approval in Europe, but not in the U.S.  I hope you will ask Lars what he will do when TEL disappears.

    Of course the perfect storm is brewing because we will probably not have any ethanol free auto fuel in the U.S. either as the unintended consequences of the federal RFS mandate in EISA 2007 swamps the gasoline pool by the end of this year.

  4. says

    For anyone living in the Southern California area, there is a town hall seminar and discussion on June 30th at 9:00 AM at the Museum of Flying in Santa Monica about the Future of AVGAS. More information is available here:

    I believe that there is a suitable and proven alternative fuel that will work in most general aviation piston engines. The fuel is called AVGAS 91/96 UL. It has been distributed in Sweden for more than 20 years and millions of flight hours have been flown with it. There are ways to make the other engines work on this fuel, too. In the interim, two types of fuel could be offered at airports – 91/96 UL and 100LL. When you go to the gas station for your car, you can choose between three of four types of fuel – why can’t we have that kind of choice for our airplanes?

    • flyunleaded says

      Ben – be advised that Hjelmco AVGAS 91/96UL is ASTM D910 compliant, which means it has TEL in it, albeit in a very small amount.  We would be much better off it the aviation alphabets, engine and airframe manufacturers and the FAA would get the new 94UL avgas spec, ASTM D7592, approved for all engines and airframes that were certified for the old 80/87 and 91/96 D910 fuel specs so anyone could order it.

      • says

        Agreed. An ASTM spec without a requirement for TEL would be optimal. My understanding is that Hjelmco AVGAS 91/96UL has TEL only to comply with D910 and that it can meet all other requirements of D910 without lead.

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