Slate reports that a gallon of Olympic torch fuel, propane, produces 12.669 pounds of CO2. National Geographic News confirms the fuel is propane.
If you are an intelligent and inquisitive reader, you probably realize propane is lighter than water which weighs 8.3 pounds per gallon. How then can a gallon of liquified propane, which weighs 4.2 pounds, produce 12.669 pounds of CO2? You can find the explanation in chemistry term here, but I will explain it in more layman terms.
Look at the two dimensional and three dimensional structure of a propane molecule here. Each molecule of propane (C3H8) has 3 atoms of carbon and 8 atoms of hydrogen. A carbon atom is 12 times heavier than a hydrogen atom, which has a weight of 1. The carbon in a molecule of propane has the weight of 36 units and the hydrogen has the weight of 8 units for a total of 44 units for the entire molecule.
When this molecule of propane is burned, the hydrogen atoms are replaced with oxygen atoms which are 16 times heavier than a hydrogen atom. When the C3H8 propane molecule is burned, it becomes 3 molecules of CO2. The new product weight jumps from 44 units to 132 units, an increase of 3 times because oxygen is 16 times heavier than hydrogen. The extra weight comes from the oxygen. Here is the math:
3x12 + 8x1 = 44 units of weight for C3H8
3x12 + 6x16 = 132 units of weight for CO2
So a 4.2 pound gallon of propane becomes 12.6 pounds of CO2 when it is burned. The 12.669 pounds mentioned above in the article is correct. So yes the reports are accurate. That is how much CO2 is produced when a gallon of propane is burned.
The same thing happens when you burn gasoline on your drive to work. The carbon dioxide produced weighs more than the gasoline. Your jet ride on vacation does the same thing. Heating your home with propane, natural gas, fuel oil, coal, wood, or corn does it. Burning a candle does it. Any hydrocarbon used as a source of heat will produce more weight of carbon dioxide than the weight of the hydrocarbon that is burned. It is a law of the physical world that cannot be changed. Without this production of the heavier amount of CO2, we will not have heat. The global warming nuts might not like it, but it’s a fact of life that cannot be changed.