I Want You To Check My Calculations
A few weeks ago a gentleman wrote in to put down the idea that our paltry human presence could have any effect on the environment. I had wondered the same thing so eventually I had a few hours available so I pulled up my keyboard and calculator and did a bit of research.
According to the USGS, " Human activities release more than 130 times the amount of CO2 emitted by volcanoes--the equivalent of more than 8000 additional volcanoes like Kilauea (assuming it is active). [Gerlach et.al, 2002]
Hmmm. Could that be correct? I did a bit more looking.
CO2 is the second most plentiful gas released by volcanoes after water and it is estimated that that value is 145 to 255 million tons per year [Gerlach, 1999, 1991] OK so how much is just from the oil we use?
The big question I found was "what is a barrel of oil?"
Some sites say its 31.5 gallons some say its 42 gallons. Another said its 52.8 gallons. Another site said to use 159 liters per barrel which was the 42 gallon value. So using a Handbook of Industrial Chemistry I used the average barrel as 42 gallons. It's in the middle so should be close enough for highway work.
Per http://www.eia.doe.gov/basics/quickoil.html and a conversion from metric tons to US short tones there are 8.08 barrels per ton of oil or 247 lbs per barrel.
Or converting that to density would make it 247/42 = 5.889 lbs per gallon... Better double check that. Per the physics fact book the average density of petroleum is approximately 800 kg/m3 or 6.676 lbs per gallon. And per another site it was 8.76 lb per gallon. 6.676 lbs per gallon * 42 gallons per barrel is 280 lbs per barrel. So were in the ballpark. Again I decided to use the value more in the middle.
42 gallons per barrel*6.676lbs per gallon *2.205 kg/lb=618.3 kg per barrel. Gotta love the metric system. Can we please settle on one or the other!
Now, how much CO2 is in a gallon of fuel, some sites say its 14.3 kgs per gallon which would equate to 600 kg per 42 gallon barrel. The site "Quiet Road" http://numero57.net/?p=255 uses 3.15 kg per kg of oil and 317 kg per barrel. Where he calculates that, “when fuel oil is burned, it is converted to carbon dioxide and water vapor. Combustion of one kilogram of fuel oil yields 3.15 kilograms of carbon dioxide gas. Carbon dioxide emissions are therefore 3.15 times the mass of fuel burned. Using this multiplier a barrel of oil assuming it is will produce a minimum of 317 kg of CO2 when consumed." I'm assuming that he is taking out the oil used for other purposes otherwise the number is a bit on the low side as using the EPA estimated 20 lbs per gallon * 42 gallons per barrel would be closer to 840 lbs or 840lbs CO2 /2.205 lbs/kg = 381 kg CO2 per barrel. http://www.epa.gov/oms/climate/420f05001.htm I wanted to double check those figures with my notes from small engine repair but that was back in 1978 so I must have misplaced them somewhere.
Where did the 20 lbs per gallon come from:
The Intergovernmental Panel on Climate Change (IPCC) guidelines for calculating emissions inventories require that an oxidation factor be applied
to the carbon content to account for a small portion of the fuel that is not oxidized into CO2. For all oil and oil products, the oxidation factor used is
0.99(99 percent of the carbon in the fuel is eventually oxidized, while 1 percent remains un-oxidized.)
Finally, to calculate the CO2 emissions from a gallon of fuel, the carbon emissions are multiplied by the ratio of the molecular weight of CO2 (m.w. 44) to the molecular weight of carbon (m.w.12): 44/12.
CO2 emissions from a gallon of gasoline = 2,421 grams x 0.99 x (44/12) = 8,788 grams = 8.8 kg/gallon = 19.4 pounds/gallon
CO2 emissions from a gallon of diesel = 2,778 grams x 0.99 x (44/12) = 10,084 grams = 10.1 kg/gallon = 22.2 pounds/gallon
Getting to the end now:
317/42=7.5 kg carbon dioxide per gallon of crude oil
=16.64 lbs of carbon dioxide per gallon of crude oil (Again, that's on the low side compared to the government figures but we'll let it slide).
16.64*42*83,600,000 barrels of oil per day per http://www.eia.doe.gov/basics/quickoil.html (2006 data) =5.8E10 lbs per day
=29,217,573 tons per day.
That's 10.7 trillion tons of CO2 per year!
Now what were we doing? Oh yeah, comparing oil emissions of CO2 to volcanoes:
Taking the 10.7E9 tons of CO2 from oil (only) / 255E6 tons of CO2 from volcanoes
= 42 X as much carbon was being emitted from oil as from volcanoes.
Now let's start figuring out the CO2 from all of the coal and natural gas and cows and decaying peat fields and people and........
In conclusion, we make the volcanoes look like ... you pick the euphemism.
Tastyfrzz
