If you have not read my previous article on global warming, little of the following will make sense. Please read it if you have not done so already.
The more I think about my original essay on global warming, the more I realize that I have a problem with my essay. No, not the problem that I disagree with a lot of people on the causes, results and cures for global warming; I still consider the louder factions of environmental activism to be a great global warming threat due to all the hot air that they are expelling.
The problem, rather, is my explanation of the stabilization of the atmosphere through the effects of burning fossil fuels. In my example, carbon dioxide helps prevent global warming because its specific heat is higher than the oxygen it replaces, requiring more heat to increase in temperature than oxygen. No, the problem is not incorrect calculation on my part (at least not as far as I can tell). No, the problem is that my explanation is really only valid for coal.
Because coal is, technically, nothing but carbon, it makes an even exchange of oxygen moles for carbon dioxide moles. Because one O2 is converted to one CO2 for each carbon atom in coal, the exchange is even during coal combustion. Everything works perfectly in my example if I were talking only about coal. However, we weren’t.
The problem I mention should have been obvious to me before. But it was only during reflection that I figured out why I couldn’t stop thinking about this global warming thing. The problem is exactly in my chosen example: methane.
When one methane molecule burns, it creates one molecule of carbon dioxide and two molecules of water while removing two diatomic molecules of oxygen from the atmospheric system. I attempted to explain it away by showing the specific heat of water vapor. However, I should have thought about the fact that the vapor pressure (in simpler English, the tendency to evaporate) of water isn’t all that high at average earth temperature and, because of that, the water vapor created by combustion of methane is entering the ocean rather than the atmosphere.
This is true of all the hydrocarbon and petroleum fuels – particularly the alkanes, which include such famous names as methane, ethane, butane, and octane. This is a problem because water vapor is not helping the overall atmospheric system because, of course, it tends to condense into liquid water and leave the system.
Yes, the water vapor does evaporate into the atmosphere and stabilize the temperature, but there is already so much water on the earth that, even if we put more water vapor into the air, it would not have much effect. If water vapor was going to get into the atmosphere from evaporation, it has already had plenty of opportunity to get there, thanks to the abundance of liquid water that is available to evaporate.
This makes things even more interesting when you consider the legendary ideal gas equation:
pV=nRT
p = pressure
V = volume
n = number of moles
R = Gas Constant
T = temperature
Because pV/nT = R in all cases,
(p1V1)/(n1T1) = (p2V2)/(n2T2)
This is very similar to the old (p1V1)/T1 = (p2V2)/T2 that most high school students are familiar with. However, because we are changing the number of moles in the mixture, (which does not happen in most high school laboratory experiments), we will need to account for this change in the number of moles in the atmosphere.
We’ll assume pressure and volume to remain constant. This means that we can divide them out on each side, giving:
1/(n1T1) = 1/(n2T2)
Resulting in:
n2T2 = n1T1
Which means that when we start with methane (which I shall assume to have been pulled out of the ground rather than from the atmosphere, thus making it a non-entity in the atmospheric system I used in my prior essay), the atmospheric system change from oxygen to carbon dioxide and water vapor will tend to increase the temperature of the overall system when the water vapor condenses and leaves the atmosphere.
This means that, for methane, the initial atmospheric specific heat capacity is 58.76 kJ/K for the two moles of oxygen we’re starting with and the specific heat capacity is 37.232 kJ/K for the mole of carbon dioxide that stays in the atmosphere.
The numbers get better for the larger alkanes, such as octane (C8H18), which trades 12 1/2 moles of oxygen for 8 moles of carbon dioxide. But that is still far from an even heat tradeoff, with 367.25 kJ/K for the 12 1/2 moles of oxygen being traded for 297.856 kJ/K for the 8 moles of carbon dioxide.
All this makes for some interesting conclusions.
These conclusions are the idea that “cleaner” fossil fuels such as methane -- the principal ingredient in natural gas -- allow the atmosphere to warm up faster than if we were relying on octane -- a major ingredient in gasoline -- or coal, which is considered the dirtiest of all. Not to mention the fact that coal provides the most carbon dioxide fuel for photosynthesis, a process that tends to cool the earth. Which I believe I mentioned before.
As a matter of fact, no, I am not being paid by the coal companies. Not that I’ll mind if they make me an offer.
Now then, what does this mean? I’m not sure myself. It seems to me that it means water vapor resulting from combustion is problematic in its own way. However, I’m not entirely sure about that either. Because the water is in vapor form when it enters the atmosphere, it is initially a stabilizing agent. However, when it cools off, it not only releases its heat into the atmosphere, it also exits the atmosphere, providing no assistance to the system.
But then again, I’m not sure how water works into the heat transfer system. After all, water absorbs a great deal of heat when it evaporates, then carries the heat away into the atmosphere. (This is why you sweat when you’re hot: the water absorbs heat to evaporate and, by evaporating, it carries the heat away.)
When the water rises up toward the top of the troposphere, it condenses and forms clouds. And in order to condense, it needs to drop off a great deal of heat. And by doing this in the upper reaches of the troposphere, the heat is delivered closer to the area where heat can be radiated out to space, which is a key portion of keeping the earth at the right temperature. So it seems that water vapor has its purposes too.
Unfortunately, I’m not sure how the water vapor produced by burning some fuels affects the temperature of the system. My guess is that the answer is, "Depends on who you ask." And the correct answer, from what I can tell, is rather more complex than I can adequately account for.
What I can account for is the fact that oxygen molecules in the atmosphere are being converted, eventually, to liquid water, which takes them out of the system. Thus, as the atmosphere loses molecules and, therefore, moles of gas are being lost, the system (atmosphere) will tend to warm up. And, because there are fewer moles of gas to warm up, the system will also tend to warm up more quickly when heat is added to it. And, because I am saying that global warming is being caused by heat created by burning fuels, this works just fine with my previous explanation.
My current conclusion is that water vapor created in combustion initially helps prevent global warming, then becomes a cause. My opinion on this may change, however.
My opinion change may come about because the additional water vapor is added to the oceans, lakes, what have you, and the water is also storing some heat energy. Any water above the thermocline tends to react to the temperature of the air above it and it acts as a large, layered heat storage unit. Contrast this with dry land, which does not change temperature at any sort of significant depth beneath the surface, and you see that water also has its part to play in the system.
Additionally, any rise in the sea level increases the surface area of the oceans, which also increases the volume of the water above the thermocline.
This may very well be a push on water vapor. The idea of oceans as environmental heat storage devices of varying size only just occurred to me. This will take a great deal of thought on my part and probably more than a few equations.
So, in this model that I have created, coal is the ideal fuel for keeping carbon dioxide under control. And the more we rely on hydrocarbons for our power needs, the more global warming we will experience. And, in particular, the more natural gas we rely on, the more global warming we will experience. Which, if we are to agree that global warming is starting to get out of control, we may say that the more we try to fix it through the current anti-carbon dioxide model, the worse it will get.
Now then, if my opinions are correct -- which they probably aren't -- we can make the following conclusions about the model of global warming that I am proposing:
Interestingly, this seems to be the case, since we are continually told that the last winter was the warmest on record while the summers have not reached the record summer warmths of the Dust Bowl years. So it seems that I might not be as insane as we all might hope.
Me neither. Me neither.
I was going to end there, but then I realized that I have more to say:
If I am right in the idea that the water vapor created in hydrocarbon combustion is eventually a problem, we can conclude the following:
As we tend away from high carbon dioxide output energy production, the system will become more unstable and temperatures will rise faster. This is because less heat will be required to increase the temperature of the atmospheric system and there will not be as much carbon dioxide fuel for the photosynthesis that cools the planet.
Note that I am not saying that solar, wind, tidal, etc. forms of energy are also contributing to global warming. The energy that they are creating was already in the system and the radiation and friction warming one might expect from them was already available to the system. Its conversion from one form to another, more than likely, will have no effect on the warmth of the globe. But, then again, I could be wrong on that too.
I, personally, am not saying that "renewable" energy is contributing to global warming. But someone will. Mark my words and remember you heard it here first, someone will.