Notices
Results 1 to 14 of 14

Thread: ethanol is toxic

  1. #1 ethanol is toxic 
    Forum Ph.D.
    Join Date
    Dec 2006
    Location
    Norway
    Posts
    927
    was reading a website called the car-bible, and this came up, while reading on fuels:


    Clean exhaust - it depends on your definition of the word "clean".
    ch3cho

    Something that isn't widely publicised is the difference in emissions between corn-based ethanol, as used in America, and sugar-based ethanol, as used in Brazil. We're all told that ethanol blend fuels produce cleaner exhaust and with sugar-based ethanol, that's absolutely true. Even with corn-based ethanol, the gasses measured at an emissions check are lower (about 25% less CO2), which still looks good. But there is something an ethanol E85 vehicle will produce through the exhaust that might surprise you. The exhaust gas contains acetaldehyde (CH3CHO) and lots of it, especially if the fuel source or combustion process is contaminated with water (like cold-start condensation). Acetaldehyde is a known carcinogen (source, source) and suspected neurotoxin (source), and when exposed to its vapors, you or I would likely develop irritation of the eyes, skin and the respiratory tract. In fact, Acetaldehyde is ranked as one of the most hazardous compounds (worst 10%) to ecosystems and human health. It's obvious why this isn't widely publicised, but then you might ask the question "why don't we see this in the emissions test?". Simple. The emissions test doesn't look for it. You can't detect and measure something you're not looking for.
    But wait - it gets better. The corn-based ethanol production process consumes more fossil fuel energy than ethanol's actual calorific value. In other words, to produce a gallon of ethanol to be used in E85, it takes more fossil fuel energy than you could simply get by putting a gallon of refined non-blend petrol in your car. And as you know, regular petrol also gives better economy.

    website link: http://www.carbibles.com/fuel_engine_bible_pg2.html


    when you have eliminated the impossible, whatever remains, however improbable, must be the truth
    A.C Doyle
    Reply With Quote  
     

  2.  
     

  3. #2  
    Moderator Moderator AlexP's Avatar
    Join Date
    Jul 2006
    Location
    NY
    Posts
    1,838
    Interesting... We probably do tend to overlook things (may even be willing to overlook them) such as, in this case, acetaldehyde when we really want a particular outcome, in this case, a cleaner fuel source. We're willing to conveniently overlook bad outcomes if they would hinder our progress in getting what we want.


    "There is a kind of lazy pleasure in useless and out-of-the-way erudition." -Jorge Luis Borges
    Reply With Quote  
     

  4. #3  
    Forum Professor
    Join Date
    Sep 2007
    Posts
    1,079
    What is the reaction that leads to acetaldehyde in the case of corn (sugar), but no acetaldehyde in the case of glucose?
    Reply With Quote  
     

  5. #4  
    Forum Isotope Bunbury's Avatar
    Join Date
    Sep 2007
    Location
    Colorado
    Posts
    2,590
    The corn-based ethanol production process consumes more fossil fuel energy than ethanol's actual calorific value.
    This is wrong. Please read the Argonne National Laboratory report summary. I'm not an advocate of ethanol. I just prefer facts to opinions on something as important as this.

    http://www.ncga.com/ethanol/pdfs/Wang2005.pdf

    Regarding cane sugar ethanol, there is a project underway to produce this in the western US using Brazilian technology, but not using the Brazilian method of harvesting. In Brazil the leaves, which are useless to the producer, are burned off in the fields, leaving the canes standing. The canes don't burn due to their high water content. In the US the leaves and other waste will be burned in clean-burning furnaces to produce steam and electricity for the processing plant.

    I'd like to know the answer to freeradical's question too.
    Reply With Quote  
     

  6. #5  
    Forum Freshman rjc34's Avatar
    Join Date
    Oct 2007
    Posts
    42
    that report you show shows not one thing about the other gasses formed when burning an ethanol blend. It only points out less CO2 is formed...
    Reply With Quote  
     

  7. #6  
    Forum Isotope Bunbury's Avatar
    Join Date
    Sep 2007
    Location
    Colorado
    Posts
    2,590
    that report you show shows not one thing about the other gasses formed when burning an ethanol blend. It only points out less CO2 is formed...
    If you are referring to the Argonne report, I posted it in response to an inaccurate statement made in the last paragraph of dejawolf's post about fossil fuel burning, which the Argonne report directly addresses. Perhaps you didn't read all of dejawolf's post.
    Reply With Quote  
     

  8. #7  
    Forum Sophomore Matt Lacey's Avatar
    Join Date
    Sep 2006
    Location
    Southampton, England
    Posts
    119
    Acetaldehyde is formed as a result of partial oxidation of ethanol. It's actually the chemical that causes hangovers as a result of overindulgence...

    Anyway, it's still present in some concentrations in normal exhaust gases and also from things like tobacco smoke, so it's not exclusive to ethanol burning - I haven't read anything on this as I write this, so I don't know how much the difference in acetaldehyde emissions are between petrol and ethanol based cars.

    I'm not particularly an advocate of ethanol fuels either but it strikes me that there may be some exaggerations here.
    Reply With Quote  
     

  9. #8  
    Forum Professor
    Join Date
    May 2005
    Posts
    1,893
    This is all pointless without numbers. How much acetaldehyde is produced? How much would the average person be exposed to if everyone used these fuels? How much is safe?
    Reply With Quote  
     

  10. #9  
    Forum Isotope Bunbury's Avatar
    Join Date
    Sep 2007
    Location
    Colorado
    Posts
    2,590
    The numbers are here - and graphs and maps and more numbers. I don't think it differentiates among sources of ethanol (corn vs. cane or other), at least I didn't see that in a somewhat cursory look.

    http://pubs.acs.org/cgi-bin/sample.c.../es062085v.pdf

    In sum, due to its similar cancer risk but enhanced ozone
    health risk in the base emission case, a future fleet of E85
    may cause a greater health risk than gasoline. However, because
    of the uncertainty in future emission regulations, E85
    can only be concluded with confidence to cause at least as
    much damage as future gasoline vehicles. Because both gasoline
    and E85 emission controls are likely to improve, it is
    unclear whether one could provide significantly more emission
    reduction than the other. In the case of E85, unburned
    ethanol emissions may provide a regional and global source
    of acetaldehyde larger than that of direct emissions.
    Reply With Quote  
     

  11. #10  
    Forum Freshman rjc34's Avatar
    Join Date
    Oct 2007
    Posts
    42
    you know what, screw this. I'm getting a windmill and some solar panels and driving an ELECTRIC car.

    Problem Solved.
    Reply With Quote  
     

  12. #11  
    Forum Ph.D.
    Join Date
    Feb 2005
    Location
    Dublin, Ireland
    Posts
    945
    ethanol is toxic
    we have known that a long time.

    The emission figures could be reduced perhaps not easily but potentially using a catalytic converter.

    today all cars have one, and they are designed to work with today's fuels. if ethanol is used as a fuel in the future, and cars are designed for that purpose then given the stance on health and climate they will more or less be obliged to try to design one to suit ethanol run cars.
    Stumble on through life.
    Feel free to correct any false information, which unknown to me, may be included in my posts. (also - let this be a disclaimer)
    Reply With Quote  
     

  13. #12  
    Forum Professor sunshinewarrior's Avatar
    Join Date
    Sep 2007
    Location
    London
    Posts
    1,525
    Quote Originally Posted by goodgod3rd
    ethanol is toxic
    we have known that a long time.

    The emission figures could be reduced perhaps not easily but potentially using a catalytic converter.

    today all cars have one, and they are designed to work with today's fuels. if ethanol is used as a fuel in the future, and cars are designed for that purpose then given the stance on health and climate they will more or less be obliged to try to design one to suit ethanol run cars.
    'Sides, couldn't you just have a tank for the unburnt residue that you could drink afterwards? :wink:
    Reply With Quote  
     

  14. #13  
    Forum Ph.D.
    Join Date
    Feb 2005
    Location
    Dublin, Ireland
    Posts
    945
    :0 that thought also crossed my mind too but then i remembered i dont drink pure ethanol. i prefer mine with a hint of Guinness or whiskey and white.
    Stumble on through life.
    Feel free to correct any false information, which unknown to me, may be included in my posts. (also - let this be a disclaimer)
    Reply With Quote  
     

  15. #14  
    Forum Ph.D. Wolf's Avatar
    Join Date
    May 2007
    Location
    Here
    Posts
    969
    Guess we'll just have to get all our ethanol from beer brewing instead.
    Wolf
    ---------------------------------------------------------
    "Be fair with others, but then keep after them until they're fair with you." Alan Alda
    Reply With Quote  
     

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •