[This post originally appeared on the Our Streets Minneapolis blog.]
Many bike commuters cite reducing carbon emissions as their reason for biking. Does switching from a car or bus to a bike reduce one’s carbon footprint and by how much?
Photo by Ajith George
Japan, China, the Netherlands, and Denmark collect the most data on carbon emissions and bikeable cities. These countries have large cities with bike infrastructure utilized by a good portion of their populations.
The Institute for Transportation and Development Policy (ITDP), cited by Streets blog, studied how biking could reduce carbon emissions by a substantial amount.
Currently bikes and e-bikes make up 6% of miles traveled in world cities. If by 2050, bikes and e-bikes make up 14% of travel in world cities, there would be an overall 11% reduction in carbon emissions.
The statistics above focus on the world community and carbon emissions. How does daily commuting by bike, bus, or car affect one’s individual carbon footprint? The European Cyclists Federation has person to person statistics.
If you take a bus or car out of the equation the carbon emissions drop dramatically. To produce a bike produces, on average, 5 g of CO2 per km ridden. Bikes do not require fuel in the same sense of cars and buses, so the ride does not release any more carbon emissions. Food intake, and the energy which it produces to help a cyclist propel their bike, is the final piece of a bike commute carbon footprint. Cyclists on the average European diet will add 16 g of CO2 per km ridden. The amount of CO2 released changes based on the cyclists’ diet. In particular meat has a very high carbon footprint.
The comparison of CO2 released during production and per km is 313 g of CO2 for a car and 16 g of CO2 for a bike. This presents a clear picture: commuting with a bike reduces an individual’s carbon footprint significantly.
If we are to reach the goals expressed above, and reduce our global carbon emissions via increased bike usage, the ITDP suggests making several global changes including:
-Developing large-scale networks of bike infrastructure
-Implementing bike-share, with an emphasis on connections to transit
-Revising laws to protect cyclists and pedestrians
-Investing in walking and transit
-Coordinating regional land use planning with transportation investments
Investing in alternative transportation, particularly transportation that yields significantly less CO2 than the standard transportation (personal vehicle) is important work for cities when it comes to achieving our climate change goals.
If you are looking to reduce your carbon footprint, reducing or eliminating your automobile travel is a great way to do it and research shows that it does have an effect.
When looking at large-scale change, cities and nations need to start implementing infrastructure that supports behavior change to reach our climate change goals. If we are not doing this, folks are less likely to ride their bikes or walk rather than use a personal automobile because they feel unsafe doing so.
At Our Streets Minneapolis, we believe that all streets should be safe for all people, particularly those using the most vulnerable modes of transit: biking, walking, and rolling. If you’d like to work towards a Minneapolis that has more of the infrastructure listed above consider joining one of our work groups which meet once a month to discuss advocacy and volunteer opportunities around important bikeways and pedestrian work.
Can you clarify: is the 16g of fuel for the bike rider solely the energy needed to propel the bike, not fuel their bodies generally? (In other words, all the people riding in cars and buses also need food to fuel their bodies.)
Right. There should not really be a meaningful difference in food-related carbon emissions between modes.
There absolutely should be a difference. Your body on a bike is equivalent to a very inefficient 1/4 horsepower engine. If you are going to travel a certain distance, it takes a certain amount of power, and you get that power by converting chemical energy, the same way an internal combustion engine does.
You convert food, not gasoline, into energy. That is theoretically carbon neutral; the growing of your food took a certain amount of carbon out of the atmosphere. But once you start adding up the carbon costs of food production, transportation, storage (especially refrigeration), it is a lot less clear that the food you eat is less carbon intensive on a per Watt basis than gasoline.
An internal combustion engine is also about two times as thermodynamically efficient than a human body. Thus, the work that takes an engine 1 MJ joules of gasoline (21 grams of gas) will take 2 MJ of rice (368 grams of cooked rice, almost 2.5 cups).
Which brings us to the next point; gasoline is much more carbon efficient than any sort of food. I calculate that 1 MJ of gasoline has 18g of carbon, while 1 MJ of cooked rice has 55g of carbon. Eventually, through decomposition, most of that carbon will end up back in the atmosphere, either burned as energy and respired by your body, or passed and decomposed.
So all in all, the human body is a very poor engine. But it is also a painful engine to operate at full speed all the time, unlike your car, so it naturally regulates itself to use the least energy possible.
TLDR: The CO2 bike savings is not due to the human body eating farmed food being more efficient than a gas engine: the opposite is probably true. The CO2 savings is due to the ‘engine’ being 1/4 horsepower instead of 150 hp like your car.
The point is that a person sitting in a car is using very nearly the same amount of food/fuel to run their body as the person on the bike.
Yeah, maybe there’s an extra 15 calories per kilometer or so, but it’s not very much.
I believe the concept is, when you bicycle for transportation, you have to consume more food to power your body to get from point A to point B rather than the energy it takes to sit in a car. That is the 16 g so it varies from the carbon footprint of the average diet of the person overall. Obviously it is a much different type of fuel and not equivalent to the fuel going into the engine of a car or bus. This is based on the articles linked in my piece.
I do have to question the “CO2 produced during production” numbers. A car weighs more than 100x what a bike does, so why is the production CO2 only 20x of what a bike is? That and it is difficult to believe that the CO2 produced during production is only equal to the amount produced in riding one km. Just the raw material production alone has to be orders of magnitude above that. Is this just based on final assembly? Were the wrong units used?
There is no question that bikes are more environmentally friendly. It is sad that there is not more incentive to tap into this resource in the US. Cars are driven 100,000+ miles while I would guess that most bikes never get to 1000 before being abandoned. In terms of cost per mile, bike have to be the least expensive mode of transportation there is.