The CO2 proportionality paradox
 

Paradox to me, anyway :-)

Would someone *please* correct the mistake in my reasoning below, since it is quite obviously wrong, but I do not know why:

Gas combustion is hydrocarbon oxidation. Using O2 as the oxidizer, the end products are H2O and C02. This suggests that as oxidation increases in efficiency in end-product produced, so does the C02. Yet we *know* that the Prius produces less C02, not more.

Said another way: if it isn't C02 coming out of the Prius tailpipe, what from is the oxidized carbon in ??

I will take kudos up front for posting what may turn out to be the dumbest question ever, but it is annoying me ...
------------
oh, I got it :-)
No matter, I'll leave the question for others that enjoy headaches (CO free, naturally).

Hi EricGo:

___I am not sure what you are asking but CO2 figures are based on Fuel consumed no matter if it’s an H2 or an Insight. ~ 19.6 pounds of CO2 are produced per gallon of fuel consumed no matter the SI-ICE vehicle. This does not include the refinement and transportation of said gallon of fuel to your local station which totals out to ~ 28 pounds.

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net

Hi Wayne.

You are right, of course. I for a moment thought that the engine's efficiency was due to more complete combustion. What is actually happpening is increased conversion of heat to mechanical movement.

I'm afraid I epitomize the danger of knowing a bit of biochemistry, while being an engineering idiot. Hopefully I'll improve along with my MPG.

In the meantime, I have a couple more *really* stupid questions..

Pounds vs. Gallons
 

I am confused. Gasoline weighs 5.85 pounds per gallon, so how does one get 19.6 pounds of CO2 after combustion? Or is there an order of magnitude mistake somewhere?

Cheers, Doug

Gas is mostly (CH)x. So in combustion you make H20 and C02. The numbers differ because you are discounting the hydrogen, but including oxygen taken from air.

Hi Doug:

___EricGo hit it on the head. Remember the SI-ICE’s stoichiometric fuel-air ratio? 14.7 times the amount of air as fuel through the combustion process is where the 19.6 #’s comes from.

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net

Re: The CO2 proportionality paradox
 

We know no such thing. The Prius produces the same amount of CO2 as any other ~50mpg car.

What varies is the amount of CO, NOx, NMOGs, PMs.

troy

Re: The CO2 proportionality paradox
 

The context was: less CO2 produced than cars with lesser mpg.

As for CO, Nox, NMOG, and PM -- none are directly related to mpg, but are post-combustion processes. The 25 mpg SULEV Ford Focus is an obvious example that this is so.