The Barbecue and CO2

In the last post, we talked about respiratory production of carbon dioxide, an environmentally innocuous process. We hear about the contribution of industry to carbon dioxide production, but I want to focus on something we can all relate to: the backyard barbecue grill.

The ubiquity of propane cannot be overstated. The stuff is all over the place and it isn’t limited to the twenty pound tank that fits beneath the barbecue grill. In my part of the world, New England, it’s used for standby electric generators, heating pools, hot water, fireplaces, etc. The use of it creates CO₂ and I want to bring that down to practical focus for the average person.

The combustion of propane (C₃H₈) follows the following chemical equation for complete combustion:

C₃H₈  +   5O₂  →  3CO₂  +  4H₂O

This chemical equation tells us that for every molecule of propane burned, it needs five molecules of oxygen. The gas that combustion produces contains three molecules of carbon dioxide and four molecules of water. Without going through the “chemical math,” what this is telling us is that for every pound of propane combusted, three (3) pounds of carbon dioxide is produced. It also tells us that for that one pound of propane about 3-2/3 pounds of oxygen is required and it yields about 1-2/3 pounds of water vapor in the process. Oh . . . and it produces heat too. All approximate, of course.

The 20 pound propane tank one purchases at the hardware store or supermarket, will put 60 pounds of CO₂ into the atmosphere when combusted. Think about it.

Carbon Dioxide - An Original Source

We hear about carbon dioxide (CO2) as one of a number of atmospheric gases that are responsible for anthropogenic global warming. This is primarily due to the burning of fossil fuels. As a percentage of the atmosphere, CO2 is minuscule, less than four one hundredths of a percent (actually 0.38% or 380 parts per million (ppm)). 

One source of carbon dioxide is, well, us. Every time we exhale, we create CO2. As a matter of fact, every time every living, breathing thing exhales, it produces carbon dioxide. So how much do we produce? On average, a human produces about 2.3 pounds of it per day (based on various web sources). It adds up. Take a look at this table I constructed. 

CO2 per person each day: 2.3 pounds

2008 Earth Population: 6,694,254,040 (World Bank)

Human CO2 Production each day: 15,396,784,292 (Billion) lbs.

Human CO2 Production each year: 5,619,826,266,580 (Trillion) lbs.

Human CO2 Production each year: 2,809,913,133 (Billion) tons

About three billion tons per year. Sounds like a lot. Should we be worried that  human beings, by their mere breaths, are contributing to global warming? Not  really. We humans among all of the animals, plants, oceans, etc. are part of the natural carbon dioxide cycle of the earth. The real issue is the long run and the debate about global warming. But we can  avoid that debate by burning much less fossil fuels and being much more  efficient in our use of major sources of energy---What I call in my book, "Conservation Without Deprivation."