Monday, June 1, 2009

Interesting Conversations

Happen on Facebook!

A colleague of mine, Don Duggan-Haas, forwarded me this exchange he had on Facebook. It's really interesting, and I thought I would share it with you:

Don was asked this question:

How many planted trees would offset my Honda Civic's yearly use? Yeah, yeah, I know. Not that simple. Humor me.

Here's his answer:
Lots and lots. And it depends on the type of tree. But seriously, let's step through at least some of what goes into the calculation.

Gasoline has a density of about .7 g/cc. That means a gallon of gas has 70% of the weight of a gallon of water. So, you can imagine that. Do imagine that. Imagine yourself holding a gallon jug that's 70% full. It would weigh about six pounds. Pause and think about that -- every gallon of gas you put in your car weighs about six pounds and after you drive for a while, that stuff is gone from your tank? Where did it go?

To answer that question, you need to think about what gasoline is. Most of the weight of that gasoline comes from the carbon within it. There's some hydrogen and a bit of other stuff too.

When you burn the gasoline, the carbon combines with oxygen, O2, from the air to make carbon dioxide, CO2. That means that the CO2 from your tailpipe weighs in at about three times the weight of the gasoline you started with.

Photosynthesis reverses that -- takes the carbon from the air and combines it with hydrogen and oxygen to make the cellulose (and some of the oxygen goes back into the atmosphere).

So, using VERY rough estimates, you should plant roughly enough trees to equal the weight of the gasoline you burned. Each gallon is about six pounds. Do you burn 10 gallons a week?

That's 60 pounds a week, or about 3000 pounds a year. You need to plant enough trees that they grow about 3000 pounds in a year.

I can easily lift a 12 year old scotch pine tree over my head (our five or six foot Christmas trees). So, a young pine is putting on maybe a few pounds a year.

Let's be generous and say five pounds a year. So, that'd be about 600 trees. Happy planting!

And don't even think about flying.
Thanks for sharing Don!


Dina said...

Heyyyy....that was *my* question!

Dugganhaas said...

Yep. It was a good one.