Thursday, November 01, 2012

Co2 emissions human vs car

I have been wondering if it actually is better for the environment to ride a bike than drive.  What I question is how much CO2 am I putting out breathing hard while riding the bike as compared to a car.   The TLDR version of this is yes your bike is way better.  

Here is why.
Figuring out the numbers below is very complicated and you can complicate it very quickly by adding anything from a riders fitness, the course and factors like the CO2 involved in heating the water for a post ride shower or growing the food for the post ride meal.
Take the numbers as the best estimates I could find and should not be quoted as fact.
My 2009 Honda fit puts out about 287grams of CO2 per mile
Running a 10 minute mile is about 126 grams of CO2 per mile
Cycling at about 12 miles/hour is about 60 grams of CO2 per mile

The bike wins the low score but as the smart person I quote below points out it doesn't really matter how much I CO2 I produce while on my bike.  

"It doesn't matter how much carbon dioxide you exhale when you ride
your bike, because none of it contributes to the buildup of carbondioxide in the atmosphere.  This buildup is caused by burning fossilfuels, which releases carbon that has been bound up in the slow carboncycle for millions of years.  All the carbon you exhale came fromplants that you ate.  Or from animals or fungi you ate, but theanimals and fungi got it from plants.  The plants got it from theatmosphere.  So the carbon you exhale was in the atmosphere no morethan a year or two previously, and even if you hadn't eaten it andexhaled it, it would soon end up back in the atmosphere.  Bacteriawill eat it if nothing else (it will 'rot'). The movement of carbonthrough the fast carbon cycle does not change the composition of theatmosphere. So by riding your bike you are not contributing to thegreenhouse effect at all."

 I think it is great that I am not part of the slow carbon cycle.  I didn't think I rode fast enough.


queasyfish said...

I'm picturing you and your fellow suburban-sprawlers standing around the cul-de-sac like: "ya, I'd ride my bike (45 miles) to work, but I read it's almost as bad for the environment as driving my Escalade"...

queasyfish said...

Thanks for posting something, I like reading it.

Jared said...

That's funny Q. It actually is more from me questioning my own trust of all things green. I like to know why I believe what I believe.