Ask A Scientist© General Science Archive

>Name: Rafael Leal
>
>Student.
>
>Age: 30's

>>Hello, scientists.
>>
>>The last time I drop by here I received a good answer, thank you. Now I
>got a different question to ask, please:
>>
>>It is about environment and gasoline.
>>(I am sorry if some phrases sound strange but I am still learning english)
>>
>>
>>MTBE IN VENEZUELA, SOUTH AMERICA.
>>
>>I live in Venezuela, South America, this is a petroleum exporter country
>and is still the only nation in the world using leaded gasoline in all its
>motorized vehicles.
>>
>>Dupont, the only manufacturer of the lead (I dont know the name in english
>of the additive made of lead, in spanish is "tetra etilo de plomo") for
>this gasoline in the world got its lead factory open and working just for
>Venezuela to buy this additive.
>>
>>But this will end soon, on October 1st. 1999 a new law will be passed to
>obligate everyone here to convert to unleaded gasoline with MTBE additive
>instead of lead. New automobiles will be available only for unleaded
>gasoline and old cars will be given a lapse of time to change to the new
>gasoline.
>>
>>The newspapers and other media here in Venezuela are making lot of noise
>about the "environment protection" that will bring a gasoline which does
>not pollute the air because it got no lead, and MTBE is the key factor to
>burn clean and pure without harmful gases to human health. That is what
>newspapers and TV says here, they call it the "green gasoline", the new way
>of oil companies to take care for our environment.
>>
>>I know from email messages received that MTBE additive is a very dangerous
>chemical which can pollute waters in a way that makes it really scaring to
>think of it, because is so volatile and water soluble, and very tiny
>amounts of it is enough to mess up water reservoirs.
>>
>>Well, I think the above is true by the things I have read.
>>
>>The question I got is in reallity a question plus an excercise.
>>
>>
>>The question is:
>>What possition does an intelligent person should have on this matter? To
>"hate" the new gasoline and ask for keeping on lead gasoline, or to see
>good the change? also other options that I have not thought are welcome! (I
>mean as a concerned citizen for the environment and general health of other
>citizens in my country)


>>The excercise is:
>>Please, if it possible, I need somebody to analyze the following words.
>This is written by a Venezuelan scientist about "the facts" of lead-unlead
>gasolines. Please check out for the true of these arguments and other
>commentaries you may have:
>>(I am translating from spanish, so please excuse any strange phrase)
>>(The answer will be sent to the person who wrote this and others
>concerned of it, of course stating the source: NEWTON/ANL home page)
>>
>>
>>
>>This are some facts:
>>
>>1. There is no apropriate substitute in the short term for gasoline.
>>
>>2. The biggest consumer of "tetra etilo de plomo (TEL)" (the lead additive
>that I don't know how to translate to english) in the world is Venezuela.
>By fact Dupont factory keeps producing TEL thanks to our consumption.
>>
>>3. Other problems caused by lead, besides the affectation of intelectual
>capabilities and others, are related to the huge volume of polluted muds
>that are produced in gas stations tanks. Any technology to the treatment
>and disposition of these muds must be developed in Venezuela because the
>first world countries no more uses TEL additives.
>>
>>4. results of reasearch in our university and other studies seem to
>indicate that subway tunnels work as lead traps. In the suspended dust on
>these tunnels are found lead values of more than 20,000 ppm (parts per
>million) or 0.2%. This is explained by the location of the subway
>ventilation systems and to the affinity of lead to atmospheric dust. Alike
>situations are found on all tunnels, not just subway ones, in Caracas, the
>capital of Venezuela.
>>
>>5. Is very easy to apply to studies made in other countries after they
>have used gasoline with MTBE for long time and has detected some problem.
>
>
>On the other hand we don't know the hide effects of massive and continued
>use of gasoline with lead additives, the most in cities with huge
>populations because we don't practice epidemiology in Venezuela. This
>science is the one which allows to differentiate between baloney and
>effectively identify cause/effect relations.
>>
>>6.- The investment made by Venezuela to produce MTBE and TAME was gigantic
>and promoted by the requirement of those whom now say that those additives
>don't are the appropriate.
>>
>>7. The MTBE problem is its high volatility and water solubility. It is not
>due to combustion but to what is known as fugitive emissions. As gasoline
>evaporates in gas stations, tanks, etc, carries MTBE to the atmosphere and
>it dissolves in rain water, reaching land waters and polluting them. It
>also occur by leaks to sewer systems when the fuel is used for cleaning.
>Also MTBE is resistent to biodegradation which enlarges the problem. Being
>all this true, the magnitude of the pollution is much lesser that with TEL
>additives and also can be minimized with good operative practices.
>>
>>8. By the last, I would want to see what are going to use for mobilization
>the ones who highly criticize the use of gasoline with or without lead, and
>with or without MTBE. Will it be by horse? or by foot? or by sail?


First of all, the English name for "tetra etilo de plomo" is "tetraethyl
lead."

This compound is used in gasoline to improve the "octane rating" of the
fuel.  Chemically, what this principally means is that it prevents the
gasoline from igniting in the cylinder when the fuel/air mixture is
compressed but before the spark fires.  This early ignition causes the
engine to run roughly, or "knock," and to continue to run a little after
the engine is turned off, or "diesel."  Other alternatives to tetraethyl
lead tend to cost more for the same octane enhancement.

I was not aware that MTBE was used as an anti-knock additive.  The main use
I have heard for it is to suppress carbon monoxide emissions.  Ethanol is
also sometimes used in the U.S. for this purpose.

The main problem with MTBE, as I understand it, is that some people are
sensitive to it, and it makes them sick in very low concentrations.  I
don't like the smell of MTBE myself, but I don't exactly like the smell of
gasoline anyway, with or without MTBE.  It is true, however, that the MTBE
odor is easy to recognize.

One thing for sure is that lead-containing additives pose a more serious
long-term health and environmental threat than MTBE.  The MTBE will
eventually break down, but lead is lead forever.

The "facts" in the piece quoted below appear correct to me.  I would like
to emphasize a point made by your Venezuelan scientist, that the principal
problems with MTBE is "fugitive emissions,"  and that good operating
practices are the best way to minimize environmental releases.  For this,
it is important for people throughout society, from the industry owners who
decide what equipment to install in their plants, to the operators of
machinery, who avoid spills, to the consumers, who should avoid using
gasoline for cleaning.

As for what people who oppose any use of gasoline would prefer to do, well,
right now there aren't any good alternatives.  Perhaps in the future fuel
cell technology or electric cars will work, but they aren't advanced enough
now.  In many ways, horses are more polluting than cars, especially in
urban areas.  One alternative that I like is the bicycle:  I commute to
work by bicycle, and make most of my other trips (to the store, etc.) by
bicycle as well.  But I recognize that this is not possible for everyone.

                Richard Barrans Jr., Ph.D.
                Chemical Separations Group
                Chemistry Division CHM/200
                Argonne National Laboratory
                9700 South Cass Avenue
                Argonne, IL 60439
                richb@anl.gov

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