Ethanol and Carbon Dioxide
From a letter in the Wall Street Journal:
The only correct way of comparing the relative amounts of carbon dioxide produced by combustion of ethanol against gasoline as the automotive fuel is the one based on the relative calorific values of the two fuels and also after taking into account the amount of carbon dioxide emitted when ethanol is produced by the fermentation process from sugar can or corn.
Ethanol’s calorific value is only 0.6 times that of gasoline on per unit weight basis. A careful study of the chemistry involved in fermentation and combustion processes and a simple calculation will show that, to generate the same amount of energy, the quantity of carbon dioxide emitted when ethanol is used as fuel will be 1.56 times the quantity of carbon dioxide emitted when gasoline is used as fuel.
Interesting point, but I wonder if the calculation includes the carbon dioxide taken up by the corn or sugar cane plant during its growth. The carbon released during fermentation and combustion has to come from somewhere, and the prime candidate is the atmosphere. To me, this would imply that no net carbon dioxide enters the atmosphere as a result of producing and burning ethanol. Unless, of course, gasoline or diesel engines are used during the growing, tilling, harvesting, transport, and other processes between seed and gas tank.
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Stumble It!
December 4th, 2006 at 3:59 pm
Interesting … So, your theory is that the amount of carbon dioxide that a plant releases when “consumed” is equal to tha amount of carbon dioxide gathered during its life cycle.
By extrapolation, would this also indicate that the amount of oxygen that a human consumes during his life cycle wil also equal the amount of oxygen released at death and during decomposition?
December 4th, 2006 at 7:13 pm
My theory is that *no net* carbon dioxide enters the atmosphere from this process. I’m allowing for the notion that some carbon taken in by plants doesn’t make it into the atmosphere by any pathway. Of course, since a lot of crop waste gets plowed under where it decomposes and enriches the soil, that carbon is still available to be broken by soil bacteria.
But all this carbon comes from somewhere, and based on the chemistry of photosynthesis, the atmosphere is the prime choice. (That’s why carbon dating of plant material works as well as it does. The carbon incorporated into plant tissue is all “fresh” carbon from the air.)
Incidentally, your extrapolation into oxygen balances is deeply flawed. Plants store carbon from carbon dioxide in tissues, or use it to make sugars and starches. Animals use oxygen to break down sugars and starches to recover energy. If anything, all the oxygen a human consumes during his life will equal the amount of carbon dioxide used to make the sugars and starches he has consumed.
December 4th, 2006 at 10:13 pm
Zero sum game still applies. All elements are basically unchanged, merely recombined or broekn apart. Matter becomes energy and energy becomes matter. Thus, if no additional carbon is created from plant consumption of carbon dioxide, no addtional pollution in the atmosphere, right? Thus, we have no polution problem at all. All remains as it was in a zero sum game.
December 5th, 2006 at 1:27 am
In the long run, it’s a zero sum game.
Part of the problem we’re running into with fossil fuels is that we’re releasing carbon that’s been locked away from the environment for tens of millions of years.
Depending on how corn or sugar cane are processed, the carbon is all “fresh”, and only a small fraction winds up being taken out of the atmosphere.
One of the arguments over the impact the USA has on global warming centers on whether our forests make us a net carbon dioxide source, or a net carbon dioxide sink. If trees incorporate more carbon into their structure than we release by burning fuel, we’re a net carbon sink, and the global warming ninnies owe us an apology.
December 5th, 2006 at 1:56 am
Interesting treatise. However, the carbon dioxide that is created by such natural processes as human and animal metabolism, decay of dead material, volcanic eruptions, forest and brush fires, etc. is estimated to be about 440 trillion pounds per year.
Carbon dioxide released from burning fossil fuels is about 15 trillion pounds per year.
Variation in the natural production of carbon dioxide might well exceed the 15 trillion pounds produced by fossil fuel combustion.
An interesting statistic is that the increase in the amount of carbon dioxide in the atmosphere since 1850 is equal to about 1/5 of the amount of carbon dioxide generated by burning fossil fuels.
Where did this “missing” carbon dioxide go?
When a plant incorporates carbon dioxide into its substance through the magic of photosynthesis, it cares not where the carbon dioxide came from. Farmers know that when there is a higher concentration of carbon dioxide because they are downwind of a coal burninng power plant or a large city with its suburbs and automobile commuters, they can produce more food and fiber crop per acre. Simply put the more carbon dioxide we put into the air the more plants grow.
Chemical weathering is also nature’s way of clearing the air of carbon dioxide. Some scientists theorize that the rise of the Himilayas, Andes, Alps, Rockies, and other mountain regions, led to the cycle of ice ages in the last 2 million years. These mountain ranges interfere with cloud movement and the pile up of clouds result in heavy rains. Rainwater contains carbon dioxide absorbed from the atmosphere and is thus an acid that wears away the exposed rock.
The result is less carbon dioxide in the air and more calcium carbonate in the water. This is why we have a Musselshell County in Montana.
Simply put, plant photosynthesis and chemical weathering are two mechanisms that can compensate for carbon dioxide generated by fossil fuel use.
It is also one reason why I believe that neither global warming nor a new ice age is anything we can either cause or prevent. There are too many other factors, all natural, going on that can cause climate change.
You don’t seriously believe that the last Ice Age was caused by Neanderthals burning too much firewood? Me neither.
December 5th, 2006 at 3:35 am
You’re correct that there isn’t a net increase in carbon dioxide in the atmosphere from fermenting and burning ethanol. However, if you DIDN’T ferment the sugar cane or corn and then burn it, there would be a net DECREASE in carbon dioxide in the atmosphere, because the plants would absorb carbon dioxide, but not release it back into the atmosphere. So the overall effect of fermenting and burning ethanol is an increase in carbon dioxide.
December 5th, 2006 at 8:02 am
Actually, no part is isolated. Note the part about increased carbon dioxide causing an increase in plant life as a balance. Thus, a decrease in the amount of carbon dioxide should cause a matching decrease in plant life lowering the consumption and effectively balancing the amount of carbon dioxide within a certain range.
If you want, imagine removing all carbon dioxide from the air and you would in effect suffocate all plant life. So, somewhere around the middle a balance is achieved.
It’s still a zero sum game. Changing the levels of carbon dioxide will cause a reaction that attempts to rebalance the equation.
December 5th, 2006 at 10:51 am
Let’s not wander too far off the topic. The point of the letter to the editor of the Journal was not an in-depth exploration of the carbon cycle and long-term global climate change. It dealt only with the impact of running cars on ethanol vs. gasoline.
If someone at a party asks, “Ginger, or Mary Ann”, you’re not expected to start rhapsodizing over the virtues of Mrs. Howell, never mind Morticia Addams.
The engineer who wrote the letter stated that, when you add in the amount of carbon dioxide released by the process of fermenting, each mile of driving using ethanol puts 50% more carbon dioxide into the air than driving the same mile fueled by gasoline.
I’m simply pointing out that when you look at the source of the carbon in each case, ethanol is more environmentally friendly.
Ethanol comes from plants, which pulled the carbon dioxide that’s generated out of the air very recently, so the carbon dioxide generated by processing them can be no more than what was pulled out in the first place.
Gasoline comes from petroleum, which represents carbon that had been sequestered for millions of years. It has to be counted as an addition to the carbon load in the atmosphere.
That’s all I wanted to address when I cited that letter. Delving into volcanic action and weathering and million-year carbon cycles is like responding to “Ginger, or Mary Ann” by pointing out how unlikely it is for seven castaways to go undetected in one of the most highly travelled areas of the globe for more than a week. It’s factually true, and probably relevant, but it’s way off topic.
December 5th, 2006 at 10:53 am
(Once again, you can never tell what topic will catch fire.)
December 5th, 2006 at 12:55 pm
On topic, ethanol is less environmentally friendly. Assuming that the numbers are correct that 50% more carbon is put into the atmosphere when only 15% of the fuel is from ethanol and the remaining 85% (E85 … remember) is the original fossil fuel carbon dioxide.
Since it is already defined on a per mile basis, there is no need to point out that the few test results that you can find indicate an almost 1/3rd reduction in mileage. This could account for the added carbon dioxide release rate.
Back to the topic: At a laymen’s level of math, 50% increase on carbon dioxide for a 15% reduction on new carbon is not a good payback. That’s a net increase of 35% of new carbon from fossil fuel. This too, ignores the added 35% increase in carbon dioxide from planting through havesting. The net yield only gets worse.
December 5th, 2006 at 3:05 pm
Off topic – How about nuclear power and electric vehicles? For the long term it seams like a better bet.
December 5th, 2006 at 3:25 pm
I’ve read and heard that when ethanol is added to gasoline, an additive that will increase MPG on any auto by about 100%, will not work.
The additive is A C E T O N E.
Look it up on the net and see for yourself.
NoHate-NoFear-NoGuilt-JustLove
December 5th, 2006 at 3:50 pm
try the nuclear option and you’ll get an increase in carbon dioxide due to all the greenies hyperventilating at once. It’s therefore environmentally unfriendly.
December 5th, 2006 at 5:31 pm
increase in carbon dioxide due to all the greenies hyperventilating
WOW! Just think of all that plant growth!