Auto sales in China are soaring, but there are some dark clouds gathering as pollution concerns...


Auto sales in China are soaring, but there are some dark clouds gathering as pollution concerns cause more major cities to implement sales limits which could slow growth in the industry. The buzz: A new report out of China dramatically links pollution to reduced life expectancy. Even though burning coal is the major culprit of the dire pollution situation in China - auto emissions are also a factor.

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Comments (7)
  • Tdot
    , contributor
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    The Chinese are the sort who will place strong sales and production quotas on "alternatives", like electric vehicles and plug-in hybrids, to try to reduce the gasoline and diesel burning. They may lead the world in less expensive, economical electric vehicles, motors, and batteries in the not too distant future. They may even develop electric highways, where vehicles charge inductively en-route from electrical coils or magnets imbedded in the roads.

     

    Of course, that just shifts the energy source from oil to coal burning power plants (etc.)...
    10 Jul 2013, 11:46 AM Reply Like
  • Engineer&Far
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    Pushing your power source to the large power plant is just what you want to do. A coal fired plant can have scrubbers and 'bags' added to control its pollutants - economically.
    10 Jul 2013, 02:52 PM Reply Like
  • Tdot
    , contributor
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    Interestingly, in the end, given the respective efficiencies, a pound of gasoline burned in an engine moves a car about the same distance as a pound of coal burned in the power plant. And the CO2 emissions are about the same as well.
    10 Jul 2013, 04:17 PM Reply Like
  • Engineer&Far
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    Powerplant steam turbines operate at around 40% efficiency, vs a typical car's 20%. But, perhaps half of the power is lost in electrical transmission to the car's charger. Relative to emmissions, the hotter you burn hydrocarbons, the lower the emissions. That's why modern gas turbine engines on planes are 99% efficient with almost no emmissions except water vapor. They run at over 2000 deg F, which requires nickel and cobalt alloys - and car engines can't afford these. If the power plant turbines run anywhere near the 2000 deg F, they do not produce the same CO2 as a car.
    14 Jul 2013, 02:32 PM Reply Like
  • Tdot
    , contributor
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    There is no way for modern gas turbine engines to be 99% efficient. Doing so would require extracting essentially 100% of the exhaust heat from burning the jet fuel, which is utterly impossible, and it would require zero drag on the air as it passes through the engine and around the nacelle. Not to mention perfect compression efficiency and combustion efficiency.

     

    An industrial gas turbine sitting on the ground, with massive multi-staged turbines for maximum exhaust heat extraction, are about 60% thermally efficient.

     

    An airborne jet engine is substantially less efficient, due to much smaller turbines (they are just "big" enough to drive the main fan and compressors) to capture some of the exhaust heat, still leaving a very hot jet exhausts, and from all the losses in compression and the air drag.
    14 Jul 2013, 03:05 PM Reply Like
  • Tdot
    , contributor
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    Also, as an "Engineer", you seem strangely unfamiliar with the unwanted NOx emissions, which increase with combustion temperature.

     

    When you burn a hydrocarbon fuel in pure oxygen, you indeed get mostly carbon dioxide and water, but with some traces of ozone, carbon monoxide, and some other molecular combinations of carbon, oxygen, and hydrogen, depending on temperature and how close you are to stoichiometric air-fuel ratio (burning rich, lean, etc.), keeping in mind that the combustion oxidation process is never completely uniform. There is also the matter of additives in the fuel, like detergents to help keep injectors clean and such.

     

    Burning it in air though, you have all that nitrogen (78.1%) to contend with, not to mention the other trace elements.

     

    Your statement that "Relative to emmissions, the hotter you burn hydrocarbons, the lower the emissions..." is directly contradicted by NASA:

     

    "Oxides of nitrogen (chemically abbreviated as NOx and pronounced "nocks") increase the production of ozone at typical cruise altitudes of subsonic air travel. These emissions are formed as a result of burning fossil fuels at very high temperatures. Therefore, aircraft emissions containing NOx increase the production of ozone. Aircraft emit significant amounts of NOx when their engines are at their hottest during takeoff and slightly smaller amounts while cruising."

     

    - http://1.usa.gov/12BsldX
    14 Jul 2013, 03:48 PM Reply Like
  • Engineer&Far
    , contributor
    Comments (168) | Send Message
     
    Focus, TDOT...."And the CO2 emissions are about the same as well". You're wrong - and nit-picky, irrelevant screeds won't fix that.
    15 Jul 2013, 11:33 AM Reply Like
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