More carbon emissions from riding a bicycle than taking the train? Best answer on the web

Posted in: darrelrussell.com edit
07 Jan 2009
  • Hi,

    I was feeling very virtuous that I ride my bicycle to work rather than
    drive or go by train.

    But then I thought that the train is probably more efficient than me
    at converting energy to motion... so this might mean that I produce
    more carbon-dioxide emissions from riding my bike than taking the
    train.

    I don't suppose it will change what I do... but can someone confirm
    which method of transport is more environmentally friendy, with links
    to relevant web-sites?

    thanks,
    Richard


  • Forget about CO2 and consider energy. Energy usage should correlate well with polution. Passenger trains get about 250 passenger miles per gallon (100 to 500 depending on occupancy). This equates to about 126 kilocalories per passenger mile. Riding a bicycle at 15 miles per hour uses about 35 kilocalories per mile of which 27 is due to cycling and 8 are from basal metabolism. This includes lots of assumptions about weight, wind, hills, and other things, but is probably typical. So a bicycle is almost 5 times as efficient as the train.


  • Hi Richard,

    What an interesting question!

    How much energy the train expends converting energy to motion really seems moot in this scenario, as the train is running whether you are on it or not. The extra energy the train might expend if you were on it is beyond the scope of this question! :-) However, the number of people riding the train is surely varied day to day, so we really don?t need to worry about the amount of energy needed if you were on the train. The train is running daily, whether or not you are aboard.
    That said, if you are ON the train, and not putting off additional CO2 from riding in a car, on a motorcycle or bicycle, you ARE ?saving? CO2. Keep in mind you are putting off CO2 while ON the train too, but a bit less and you are burning less energy sitting than pedalling a bike.
    Since this is not a true ?scientific? answer, I?ll go with the figure I found on the link below- Humans exhale about 300 grams CO2 per person per day http://www.mrp3.com/bobf/global_warming.html

    And this site:

    PharmaciaRetirees put it in pounds: ?Humans exhale 2.2 pounds of CO2 per day or 803 pounds per year (over 1000 pounds per year for joggers).? http://www.pharmaciaretirees.com/environment.htm

    For some reason British citizens give off more CO2, according to this site. The site has some nice graphics on energy expended for walking, biking, etc.: http://www.skeltongrange.org.uk/transport.html

    A motorcycle gives off about 0.3 pounds of CO2 per mile, in addition to what you exhale while riding it!
    So, in comparing a bicycle to a motorbike, with normal activities, you?d exhale about 2.2 pounds a day, a bit higher if you go by bicycle. If you rode a motorcycle just 10 miles, you are adding an additional 3 pounds of CO2 to the environment.
    Therefore, far less CO2 is produced if you ride a bike versus a motorcycle. Now, since the average human exhales about 803 pounds of CO2 per year, and a jogger puts off about 1000 pounds a year, let?s put a bicycle rider at about 900 pounds a year. Riding a motorcycle will add 900 pounds of CO2 after riding just 3,000 miles, in addition to the 803 pounds a year you add just by being. Any motorcycle riding will increase CO2 output.
    A train/subway gives off about 0.6 pounds of CO2 per mile, while a bus puts out about 0.7 pounds of CO2 per mile, according to the Delta Land Trust site. http://www.deltalandtrust.org/scorecard.html

    You will add a bit less CO2 to the air by riding the train, since it is running anyway. Riding a bicycle to and from the train station instead of in a car, releases far fewer greenhouse gasses and you get the health benefit of the exercise! A bicycle will add far less than a motorcycle. All of these will add far less than a single passenger in a car!
    I don?t know if you were referring or a motorcycle or a bicycle in the question. There are benefits to your health and wallet if you ride a bicycle, especially if you DON?T ride along a busy highway, where you will breathe in more pollutants like CO (Carbon monoxide).

    Some useful sites:
    ==================

    ?Surprise! The answer to the first question is the bicycle. The bicycle is the most efficient way to get around Walking, skate boarding, roller blading or riding an animal takes more energy, in the form of food, than peddling a bicycle. As noted in the graph below, the next most efficient ways to get around are to share a ride with others in a van, train, bus, or car. The most common way Americans get around, however, is in a car or truck with only one person in it and this is the least efficient and least environmentally sound way of getting around, second only to the airplane.? And
    ?Walking, biking, mass transit, and new car sharing options, NEVs, e-bikes, and motorcycles could improve our quality of life, by slowing down our pace and reducing road congestion and emissions from transportation.? http://www.nesea.org/greencarclub/funways.html

    ?A round trip of 1600 kms, (London to the South of France) by car with the bike on the roof, creates 360 kg of CO2, the main greenhouse gas. If you go by train and hire a bike when you arrive, you'll create 100 kg of CO2. If you go by plane, with your bike in the hold, you'll generate a whopping 850 kg per person, which is more than the amount produced by heating an average size house for a year! Estimates of the contribution airplanes make to global warming are up to 15% and rising. To arrest the acceleration of global warming it is accepted that the West (that's you, my friend) must cut CO2 output by 80%.? http://www.bristolcyclingcampaign.org.uk/grim/reaper31.htm

    ?Carbon monoxide (CO) -- A colorless, odorless, poisonous gas, produced by incomplete burning of carbon-based fuels. including gasoline, oil, and wood. Carbon monoxide is also produced from incomplete combustion of many natural and synthetic products. For instance, cigarette smoke contains carbon monoxide. When carbon monoxide gets into the body, the carbon monoxide combines with chemicals in the blood and prevents the blood from bringing oxygen to cells, tissues, and organs. The body's parts need oxygen for energy, so high-level exposures to carbon monoxide can cause serious health effects. Massive exposures to CO can cause death. Symptoms of exposure to carbon monoxide can include vision problems, reduced alertness, and general reduction in mental and physical functions. Carbon monoxide exposures are especially harmful to people with heart, lung, and circulatory system diseases.? http://www.smallbiz-enviroweb.org/compliance/glossary.html

    http://www.liftshare.org/download/car-passengers-analysis.pdf


    ?Carbon Dioxide (CO2) -- A colorless, odorless, gas that occurs naturally in the earth's atmosphere. Significant quantities are also emitted into the air by fossil fuel combustion. Emissions of CO2 have been implicated with increasing the greenhouse effect.? http://www.triangleair.org/glossary.htm

    ?Looking ahead, carbon dioxide emissions from transportation sources in the United States are projected to grow at an average annual rate of 1.8 percent between now and 2020. This compares to an overall increase in CO2 emissions in the U.S. of 1.4 percent per year, meaning emissions from transportation will become an even larger part of the problem in the years ahead. This continuing growth will result from projected increases in vehicle-miles traveled-translated, this means more cars driving greater distances-as well as growth in freight shipments and air travel.? http://www.pewclimate.org/press_room/speech_transcripts/transcript_transport335.cfm

    ?Carbon dioxide (CO2) emissions from the consumption of gasoline, diesel, and other fossil fuels are the principal cause of global warming, which brings health and economic risks from climate change.? http://www.greenercars.com/whybuy.html

    http://wwwistp.murdoch.edu.au/teaching/N212/n212content/topics/topic4/papers/sustranspt/sustranspt.html
    Auto vs. Bike
    http://www.kenkifer.com/bikepages/advocacy/autocost.htm



    About the CO2 we exhale:
    http://www.conspairacy.com/calculations/perperson.html

    I hope this has answered your question. If not, or if any part of my answer is unclear, please request an Answer Clarification, before rating.
    Regards, Crabcakes


    Search Terms
    ============
    Greenhouse gasses + train + bike + motocycle
    CO2 exhaled
    Carbon dioxide output vehicles


  • Hi racecar,
    You said "Crabcakes says that you are contributing zero CO2 to the
    atmosphere by riding the train, since the train would run anyway, but
    I disagree. "
    I never said that. What I said was "Keep in mind you are putting off CO2 while ON the train too, but a bit less and you are burning less energy sitting than pedalling a bike." What I said was this "How much energy the train expends converting energy to motion really seems moot in this scenario, as the train is running whether you are on it or not. The extra energy the train might expend if you
    were on it is beyond the scope of this question! :-) However, the
    number of people riding the train is surely varied day to day, so we
    really don?t need to worry about the amount of energy needed if you
    were on the train. The train is running daily, whether or not you are
    aboard."

    The paragraph comments on the amount of energy needed to move the train.


  • Hi Puma,

    I just came across this site, and thought you might be interested in seeing it:

    http://www.earthday.net/footprint/info.asp

    Regards, Crabcakes


  • Thanks, crabcakes, the links you provide answered my question. Also, racecar's comment about the slow and fast carbon cycle was really interesting, and answered the question that I should have asked!


  • It doesn't matter how much carbon dioxide you exhale when you ride your bike, because none of it contributes to the buildup of carbon dioxide in the atmosphere. This buildup is caused by burning fossil fuels, which releases carbon that has been bound up in the slow carbon cycle for millions of years. All the carbon you exhale came from plants that you ate. Or from animals or fungi you ate, but the animals and fungi got it from plants. The plants got it from the atmosphere. So the carbon you exhale was in the atmosphere no more than a year or two previously, and even if you hadn't eaten it and exhaled it, it would soon end up back in the atmosphere. Bacteria will eat it if nothing else (it will 'rot'). The movement of carbon through the fast carbon cycle does not change the composition of the atmosphere. So by riding your bike you are not contributing to the greenhouse effect at all. However, the train is also an environmentally friendly way to get to work. Still not as good as the bike though: Crabcakes says that you are contributing zero CO2 to the atmosphere by riding the train, since the train would run anyway, but I disagree. That is like saying there is no reason to vote, because your vote won't change the outcome of the election. If more people rode bikes, the trains could be smaller and maybe run less often, so producing less CO2.