Having already reached my goal of 4500 miles of commuter cycling for the year, I raised the bar to 5500 miles (6000 miles if you listen to the goading of my friend Todd). Looking back, I began to wonder about the differences in CO2e (CO2 emissions) for the 4500 miles of cycling versus 4500 miles of driving. A little web research uncovered this study from the European Cycling Federation (ECF) - Cycle more Often 2 cool down the planet: Quantifying CO2 savings of Cycling. Released in November of 2011, this guide attempts account for all the CO2e involved in transportation by bicycle and by car. This includes not just the emissions involved daily use, but also those that result from producing and maintaining automobiles and bikes. The study also attempts to account for CO2e related to the production of food that cyclists must consume to fuel their cycling. Though this study focuses on the EU (European Union), it is nevertheless an interesting read and can be used to make broad assumptions about CO2e in the US. And it helped to estimate just how much CO2e I had contributed by cycling 4500 miles (7200 km).
When considering GHG (greenhouse gas) emissions, the study estimates the amount of raw materials in the average bike, assumes a lifetime of 8 years, and a distance traveled of about 2400 km per year to arrive at 5 grams CO2e/km. The authors assume the average cyclist weighs 70 kg (155 lbs), travels at 16 kph (10 mph), and burns about 4 kilocalories per kilogram per hour. There are various ways to try to determine the GHG emissions related to a cyclist's diet, but that depends on the cyclist's diet because some foods (like meat) require more energy to produce. In the end, the study concludes that cycling contributes 21grams CO2e/km. The average car contributes 271 grams CO2e/km. If you're not particularly fit physically, consider that electric-powered/assisted bicycles have an estimated CO2e of just 22 grams/km.
I weigh 78 kg (about 172 pounds) and average about 26 kph (16 MPH) on my bike commute, so I probably generate slightly more than 21grams CO2e/km. With all my gear, my bike is close to the 19.9 kg (44 pounds) assumed in the study, but I cycle considerably more per year. So I assumed 22 grams CO2e/km and given that 4500 miles is 7242 kilometers, I generated about 329 kilograms CO2E (or 725 pounds). Driving that same distance would have generated about 1962 kilograms of CO2e (or 4326 pounds - just over 2 tons US). That's 6 times more CO2e for driving versus cycling. If you're thinking the discussion of CO2e and cycling falls into the category of "who cares?" consider that in the European Union (EU), about a quarter of all GHG are produced by transportation.
While there are similar statistics for the US, I've focused on the ECF's study for two reasons: One is that they have nicer, simpler graphics and two, the study shows how various strategies for increasing bicycling as transportation could help EU countries meet the stated CO2e goals for the year 2050. By contrast, the EPA's CO2e reduction strategies look decidedly disorganized and ineffectual. Just sayin' ...
The ECF study suggests three strategies that could be used independently or in combination to meet goals to reduce CO2e - Avoid travel, shift travel to public transportation and non-motorized transportation and improve the CO2e footprint for motorized transport, If you've been thinking there's nothing you can do to significantly reduce CO2e by cycling more and driving less, consider these graphics from the study.
