Only those who will risk going too far can possibly find out how far one can go.

- T.S. Eliot -

Have I emitted less carbon dioxide by riding my bike?

Recently American politician Ed Orcutt suggested (and late apologised) that cyclists contribute to atmospheric pollution by breathing more than other people, here’s the contents of an email he sent to a bike shop owner;

You claim that it is environmentally friendly to ride a bike. But if I am not mistaken, a cyclist has an increased heart rate and respiration…Since CO2 is deemed to be a greenhouse gas and a pollutant, bicyclists are actually polluting when they ride

This got me thinking about my ‘carbon footprint’ and if commuting by bike had actually reduced the amount of carbon I have produced (methane is another matter) in the past 12 months.  I’ve taken some of these figures from a book by Mike Berners-Lee called How Bad Are Bananas? The Carbon Footprint of Everything so don’t blame me if they look a bit dodgy – read the book and make your our decision on how accurate they are.  I have tried to be honest and the figures are based on the emissions of the food needed to power my legs.

Here are the numbers and assumptions;

  • From March 2012 to today (8 March 2013) I have bike commuted just over 2600 miles;
  • Consequently, I have avoided driving 2600 miles;
  • For a cyclist, 100g per mile of CO2 is an average emission based on eating cereal and bananas (source);
  • My car emits approximately 154g of CO2 per km (source)
  • If I drive the car, I still need to eat.

Here are the sums;

  • 154g per km is 247g per mile
  • 2600 miles in the car would generate 642200g of CO2, which is 0.64 tonnes
  • 2600 miles on the bike would generate 260000g of CO2, which is 0.26 tonnes

Based on this rather crude calculation if looks initially like I saved 0.38 tonnes of CO2 emissions, BUT the bicycle emissions are based on the carbon footprint of the food I consume to power said bicycle. Therefore, when you consider that I still eat when I drive a car, the saving is actually 0.64 tonnes.  Before you ask, this does exclude the CO2 produced during the manufacture / transportation of both vehicles, which I guess would be more for the car.

Finally, and stolen from the Guardian.  One other thing: by taking my car off the road in rush hour, I cut everyone else’s queuing time as well, and reduce the emissions they belch out while they wait. It’s a little-known fact that a car on a congested road can produce as much as three times the amount of CO2 as the same car travelling at a steady speed.

I’m not sure if this proof is conclusive but I would suggest that if we all ride our bikes more, we would be healthier and the planet might be saved!