Do Bicycles Actually Have a Lower CO2 ‘Footprint’ Than Cars? (Updated)
UPDATE: As mentioned in the original article, the figures I used and the math may not be correct and I asked commenters to offer “corrections,” as some have. I put corrections in quotation marks because the correctors can’t quite agree how inflated my figures are.
One says — based on Yahoo Answers, no doubt a highly credible scientific source — that my figure was 15 times too high. Another says that I was 27 times too high.
When the “correct” figures have a 200% range, I’m not so sure that the corrections are reliable. In any case, a human on a bicycle puts out a non-trivial amount of CO2 that may in fact be on the same order of magnitude as an internal combustion engine.
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Transportation Secretary Ray LaHood wants us to ride bikes to work instead of our cars.
One of the reasons he gives is environmental — what could be greener than riding a bike? Walking perhaps, and actually LaHood wants us to wear out the shoe leather too, but for most people walking to work isn’t an option. Riding a bicycle, which can easily hit 20 mph or more, is a viable alternative to driving for many folks.
Not to poke fun, just being observant — LaHood’s physique is not that of an endurance enthusiast. I don’t think Ray follows his own advice.
Unlike Secretary LaHood, I know something about bicycles. I’ve been a serious recreational cyclist for about 16 years and typically ride 2,000 to 4,000 miles a year, using my bike for both transportation and pleasure. When I worked for DuPont, I commuted by bicycle seven months out of the year, about 20 miles a day including the training loop I did on the way home. I’ve been a staunch advocate for alternative transportation, and I literally have the scars (and a stainless steel plate) to prove it.
But while I’d love to see more bike lanes (and fewer rotaries) and some serious enforcement to make drivers aware of sharing the road, from an environmental standpoint bikes are no panacea.
This may be a surprise to the folks at the EPA, but people produce carbon dioxide. We breathe in air, make use of the oxygen, and exhale carbon dioxide. Breathe in, breathe out. CO2 output at rest is not significant, but at aerobic distances and heart rates, that CO2 expelled becomes a non-trivial amount when compared to an internal combustion engine.
One of LaHood’s “recommended actions” to encourage the use of bicycles for transportation is to collect data on biking trips — though he does not suggest calculating the carbon emissions of your biking vs. a car trip.
This is all quick and dirty, and if my figures are wrong, please provide me with more accurate data or correct my math.
It appears that an average adult male will exhale 0.00899 kg/min of CO2 at rest. I had trouble finding data on the amount of CO2 exhaled when exercising aerobically, but I think we can use VO2, the volume of oxygen you can get into your blood, as a proxy. For adult men average VO2 at rest is 3 ml/kg/min. VO2 max varies depending on age and fitness, but adult male non-athletes have a VO2 max of between 36 and 52, while runners, cyclists, and other aerobic athletes can get their VO2 max into the 60-80 range. I think it’s safe to say that CO2 is exhaled proportionally to the amount of oxygen processed.
Using an average VO2 max for non-athletes of 44, that’s 14.6 times resting VO2. You’re aerobically exercising at about 2/3 of your maximum heart rate, which would be 9.8 times resting. So if VO2 at aerobic levels is about 10 times greater than VO2 at rest, then the amount of CO2 you expel on a bicycle is also 10 times greater than you exhale at rest.
Driving a car is essentially a rest state. If you put out 0.009 kg/min of CO2 at rest, then on a bicycle working aerobically you are putting out an additional 0.081 kg/min of CO2. At 15 miles per hour, 15,000 miles is 60,000 minutes. At a rate of 0.081kg/min, that works out to 4,860 kg of CO2. That’s 10,692 pounds.
You would exhale 5.34 tons of CO2 on a bike that you wouldn’t generate while driving a car.
Looking at the major manufacturers selling cars in North America, most had a fleet average for 2009 of between 8 and 10 tons of CO2 per year per vehicle based on a 15,000 mile average. So it appears, at least in terms of CO2 emissions, that riding a bike might have less of an environmental impact than driving the average car in America: 5.34 tons vs. 8 to 10 tons.
However, if two people carpool to work, they will emit less CO2 than if they were both riding bicycles.
That was against a fleet average, though. How do bicycles compare to the vehicles that emit the least CO2?
Of the top 10, the best is the Toyota Prius at 3.81 tons of CO2 per 15,000 miles. Number two is the Honda Insight, at 4.5 tons per year. The rest of the top ten put out between 5 and 6 tons/yr CO2.
Riding a bike comes in fifth place.
So there are already four cars on the market that have lower CO2 emissions when carrying a single passenger, the driver, than a man on a bicycle. For the vast majority of new cars sold today, carpooling with as few as two people eliminates any environmental advantage, at least in terms of CO2, that bicycles have.
The only cars that, fully loaded with passengers, have bigger carbon footprints than a bicycle are exotic supercars like Lamborghinis — and then only because they are two-seaters. A four seat Lambo might very well be greener than a bicycle built for two.
The EPA wants to regulate carbon dioxide as a pollutant. Every government agency with more than 3,000 employees exceeds the de minimus triggering limit of the EPA’s proposed regulations for CO2 simply with the amount of air they breathe in and out while at work.
Maybe the first place to start is with all the hot air spewing out of Washington.
Brilliant article. However Mr. Schreiber missed one other factor for a human-cycle C02 factory: passing gas, about 1/3 of the people pass gas with methane in it, methane is known to be 21 times more heat trapping than C02, whereas automobiles exhaust no methane.
You are right about methane (CH4) being a major contributor as a green house gas. Because of its molecular weight and orientation, methane holds heat much more efficiently than carbon dioxide (CO2). However a much more realistic number is that methane in 4x more capable of trapping heat.
The pajamatarians’ spoof detector must be on the fritz today, Dr. Bones.
LaHood obviously doesn’t come from Ohio, either. Riding a bicycle anywhere, around here, simply isn’t a realistic option from October to March, or sometimes April.
Also, LaHood seems to be determined to ignore the fact that goods must be moved. And short of putting rail lines down every street in America or going to horsedrawn wagons, they have to move by truck. Anyone want to calculate the CO2 output of a Peterbilt with a loaded 40-foot box behind it?
Also, he needs to explain how elderly or semi-invalid citizens are supposed to move by foot or bicycle.
Lahood is a perfect example of this administration. He is a radical ideologue with almost zero real-world experience, an overweening arrogance about his own self-perceived brilliance, a need for adulation from the cloistered academic “enlightened elite’”- and a boundless contempt, bordering on actual hatred, for the American people, or even the human race generally.
He’s just one more who needs to be fired- now.
clear ether
eon
You’re overlooking something, Ronnie. We could save all that CO2 you’re talking about cyclists expending if everybody was just inflating their tires.
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Clever. However, the global warming argument is not about carbon dioxide currently cycled between plant and animal life, but about the burning of fossil fuels which adds carbon dioxide from millions of years ago into the atmosphere.
We don’t eat oil, coal or natural gas, our CO2 came from the atmosphere. It is only when we burn these buried petroleum products that we raise CO2 levels. So go ahead and ride your bicycle without guilt.
As we are forced back to a carbohydrate society from a carbon society. We will then need approx. 40 acres and a mule to survive for a family of four. Up at the crack of dawn and toil in the fields till dark. Working the fields, feeding the livestock, our bodies wearing out by age 50. Sign me up lol.
Oho, now it’s “…about the burning of fossil fuels which adds carbon dioxide from millions of years ago into the atmosphere.” I’ve never heard that one before, but it seems that those who warn of us “ecocide,” and all its trappings, will dig for any argument that advances their cause.
It’s estimated that 97-98.5% of all air pollutants emitted annually are from volcanoes. (Help me. Are those current or paleolithic pollutants? If paleolithic, the EPA had better start regulating the volcanoes.)
Then there are termites, who emit more CO2 than all autos on the planet. Global warming, caused by mankind, whether it be from “…carbon dioxide currently cycled between plant and animal life…” or from the teensy little additions from Al Gore’s mouth – or his private plane, for that matter – is, at best, unprovable.
We all know that Gorbachev joined the green movement many years ago, and what the implications of that are. So, JonB, I have to ask you. Are you simply a useful idiot? Or are you an apparatchik?
I did a similar calculation a few years ago and came to the same conclusion. Riding a bicycle put more CO2 into the air then if I drove to work. By the way, the new VW diesels put out CO2 on the order of a Prius. Diesels engines put out on average 25% less CO2 then an equivalent gasoline engine so you are in 6th place.
JonB:
The source of CO2 is irrelevant. There is no special effect from CO2 produced by combustion instead of respiration. Respiration is combustion by a biological process. Mr. Schrieber’s calculation are correct.
I wonder what the results would be if we added the co2 emissions from the production of all the extra food we consumed to pedal everywhere.
Ron,66% of MHR?meh.
Here’s another indirect cost of biking to work –
If its any decent distance and/or somewhat hilly, there are going to be a lot of extra showers (presumably with some hot water) people are taking as a result. Even if you aren’t too sweaty overall (which would be rare here on the Gulf Coast), you’re head under the helmet will sweat if you have any non-trivial amount of hair.
Just shifting your shower time from morning-at-home to morning-at-work (presuming you’re lucky enough to have access to one there) doesn’t solve the problem, either: When you ride home in the evening you’re sweaty again — do you stink up your own house and bed (and wife) by limiting yourself to what used to get away with, usually only one daily shower?
Who showers twice? I take s shorter shower at work after riding than I would at home so the next guy can take over…
It would be interesting to see what everyone biking to get to work would do for a company employing about 500 or so people in a building. They would need to build a separate building for showers, pick up the water heating costs (which would eat into their profit margin), provide electricity for the lights, hair dryers, air-conditioning/heating of the premises.
All jokes aside, biking regularly gives an advantage on the other side, that the medical bills from obesity etc. would be cut to size… cheers
How about the manufacturing of bikes, hybrid cars and windmills solar panels, etc. Do enviros think these products magically appear? It takes mining of ore for the metals, oil exploration and refining and processing for tires and plastics and fuel, transportation of these products to plants to produce the parts that go into the “green” machines.
I’d like to know what the “carbon footprint” is for all of the processes to take place for a bike – from the workers driving to work to design, mine, process, produce and deliver the final product.
You have to calculate the life cycle cost output of C02. That is all the C02 produced while designing, manufacturing, selling, using, and disposing of the car and human.
Correction re 8. reformed socialist: “Then there are termites, who emit more CO2 than all autos on the planet.” I should have said all the autos in the U.S., not on the planet.
All the Carbon or Carbon Dioxide in the atmosphere is natural. It all came from the earth. It does not matter if it came from coal, oil, tree, etc. We can tell where the carbon comes from by measuring the isotopes but it really does not matter. Yes the atmospheric concentrations have been increasing but we have already passed years ago the ability of carbon dioxide to effectivly block Infared Radiation from returning to space. This is because like most things in nature the effect is not linear but follows a logrithmic curve. That means in order to see the same effect or change in output the input must be doubled.
What the AGW crowd really want is the reduction of humans on the planet. They want this reduction by any means. Global Warming is just the latest cause they have adopted to accomplish this. I have seen the same people since the first Earth Day sputing the same old dire predictions that have always been dead wrong on everything.
If we want a cleaner planet the best way to accomplish this is by spurring the economic developement of third world countries. It is the poor countries that have the biggest families. It is the poor countries that still burn wood, charcoal, and even scat for fuel in order to cook and heat. People from developed nations pollute less, have smaller families etc. I have worked all over the world and have seen this first hand.
Poor people worry about where the next meal is coming from and not if hey are polluting while doing it. Wealthy countries can afford to worry about pollution. I have seen in my lifetime vvast improvements in air quality, water ways, lakes etc. in the United States and most of the developed nations. Countries like Brazil are where we were in the mid 60′s on the road to economic developement but have already made huge gains but more is needed to be done as a too large a percentage of their population is still too poor.
The real enemy is anything that prevents economic developement. The total hypocrisy of the AGW crowd and from the left as a whole is mind blowing. They claim to be for all the good things but if we followed their advice things would get worse not better.
So, JonB, I have to ask you. Are you simply a useful idiot? Or are you an apparatchik?
reformed socialist: Actually I’m a global warming skeptic who reads both sides of the issue — unlike yourself.
I’m just giving the argument for why ethanol, derived from yearly crops, is considered neutral in the carbon budget (aside from the fossil fuels used for cultivation and transportation). When ethanol is burned, the carbon released is absorbed by next-year’s crop.
You’ll note that all carbon footprint calculations are based on fossil fuels used by an individual or group, but not the CO2 they respire — not even when bicycling.
And no, volcanoes do not emit 97-98.5% of all atmospheric pollutants, at least not when it comes to CO2. See http://blogs.edf.org/climate411/2007/05/21/volcanoes/. Their output in that respect is miniscule compared to modern civilization.
Unfortunately global warming advocates can use articles like this one by Ronnie Schreiber to make global warming skeptics look foolish.
You don’t know what you are talking about. Bike riding only produces about 12 grams of co2 per mile where as driving a Prius produces 242 grams co2 per mile. Even if you put 4 people in the Prius, giving 60.5 grams per person mile, the bike still wins out favorably. Do the math: Bike CO2 per mile = 11.4 grams co2 per mile based on a molar weight of glucose of 180.6, a molar weigh of co2 of 44.1, calories per gram of glucose of 4.5 and calories per mile of bike riding of 35. (6*44.1/180.6)*(35/4.5) = 11.4. The Prius gets 242 grams per mile CO2 from the figures he lists, which appears to be correct.
I will buy the same make and model bicycle that Ray LaHood uses to go to work.
with those people it seems to be “do as I say” not ” do as I do”…
The Left is truly delusional…….
Unfortunately global warming advocates can use articles like this one by Ronnie Schreiber to make global warming skeptics look foolish.
Doing a side-by-side analysis of two alternative methods of transportation in order to determine which is quantitatively better is “foolish”?
How else are people supposed to make comparisons? Throw darts at dartboards?
JonB, you certainly don’t sound like a skeptic, so maybe you’re just an astute propagandist.
Speaking of LaHood, he says, ““This is the end of favoring motorized transportation at the expense of nonmotorized.” What in the heck does that mean? Is this kind of like the deal where schools can’t spend any more on boy’s sports than they do on the girl’s teams? Is this a wise thing for an administration that just took over a car company to say?
Also, JonB, what about all the evidence pointing to water being the #1 greenhouse contributor, and not CO2? Of course, you’re going to say that’s bad science, aren’t you?
One more thing…I love bike riding and prefer it where possible but let’s get practical. My driving commute is 20 minutes in the morning and 40 minutes going home. My biking commute is 2.5 hours going to and a little over 3 hours coming back (uphill home). The route by bike is 1.3 times as long as by car since I can’t use the highway. Add the hassle of showering and changing clothes and my work day in hours is 10 +2.5 +3 + .7 or 16.2 hours by bike vs roughly 11 hours by car. The car gives me 5.2 hours per day of family time. By bike, family time comes out of sleep time and dinner is at 8pm if we want to sit down together. Hassles, time, and moving children are the problems bikers have to deal with and compared to those CO2 doesn’t even rank. If biking to works for you, I envy that but don’t think bike paths are going to pay off for most of us. Unless you also tax gas and cars into oblivion but that strays into my previous comment.
How else are people supposed to make comparisons? Throw darts at dartboards?
venividivici: I prefer addressing the actual arguments made by global warming advocates, as opposed to ridiculing arguments that they aren’t making. The latter approach is called attacking a straw man and it is a fallacy.
Furthermore, even if one accepts Schreiber’s flawed approach, I’m sure his calculations are wrong as Bob @ 8:43 demonstrates.
Intuitively it makes no sense to me that transporting ~200 lbs (bicycle + rider) by burning carbohydrates would produce C02 anywhere near that produced by transporting ~3000 lbs (car + driver) by burning hydrocarbons.
JonB, you certainly don’t sound like a skeptic, so maybe you’re just an astute propagandist.
reformed socialist: That’s called an ad hominem, which is another fallacy.
Bob sez:
>Bike riding only produces about 12 grams of co2 per mile where as driving a >Prius produces 242 grams co2 per mile.
Agreed. But the overall picture is much more complex. It takes fossil energy to grow, harvest, and process food — far more then is needed to extract and process petroleum for a given amount of end-use energy. Corn alcohol fuel is a bad idea for similar reasons.
Nevertheless, I’d bet that the cyclist puts out considerably less _net_ CO2 than the Prius. The 20x lower power requirement of the bike overcomes a lot of overhead. Still, I don’t see any of this as compelling to anyone, either way. Like the author of the article I also bike a lot, but it’s certainly not to lower my CO2 footprint.
I agree with the other folks here that using oversimplified arguments like in the article to argue against GW alarmism is not a good strategy. It just creates easy targets for the GW crowd.
Also, JonB, what about all the evidence pointing to water being the #1 greenhouse contributor, and not CO2? Of course, you’re going to say that’s bad science, aren’t you?
reformed socialist: You argue like a leftist. First you insult me then when you lose one point, you switch to another. Meanwhile because I’m not adhering to your talking points, you suspect me of being an agent for the other side.
The proportion of water vapor to CO2 is a different and far better argument against global warming than Schreiber presents.
The counter-argument from global warming advocates is that in addition to the specific greenhouse effect of CO2, increasing CO2 precipitates positive feedback cycles that make CO2 a key driver of global temperature. Given the tiny proportion of CO2 in the atmosphere, that’s a tough argument to make.
From what I read, global warming scientists haven’t nailed that mechanism down and mainly they rely on correlations between CO2 and temperature to make their case.
However, as skeptics and Climategate have shown, the underlying temperature data needs to be redone from the ground up in a public, transparent manner. Likewise the rest of the AGW calculations and models.
This is beyond idiotic. Firstly, bicycles can be used as either tools for transportation or for exercise. Commuting by bicycle is not performed anywhere near VO2 max. That would be akin to putting out as much effort on the bicycle as during a steady jog. Yeah, not so much.
Commuters do not ride at averages of 15mph either, as they have to stop frequently for red lights, traffic, etc. A lot of bicycling for transportation involves stopping, waiting, and coasting. Not exactly aerobically challenging stuff.
Finally, most idiotic is that the writer neglects to account for the aerobic benefit of light exercise. An aerobically fit person has a lower respiratory rate and heart rate than an unfit person. Therefore at a resting state, they take in less O2 and put out less CO2. This compensation obviously not happen to automobiles.
I should be surprised that Secretary of Transportation LaHood is so ignorant of science but since he is an Obama appointee, I am not. Has Mr. Lahood heard of the climategate scandal, that there is no global warming, that human activities are not causing this non-existent state? that carbon dioxide is necessary for plant life and thus for the lives of all animals? The only air pollution that can have a dire effect on us all is the hot air emitted by the scientific ignoramuses.
I don’t really see the point in attacking cycling as a way of transporting people. Obviously it won’t work for some and it will for others. It’s more pleasant (and possible) in certain seasons than others. More people cycling takes a little traffic off the roads for those who are driving. No, it’s not practical for shipping steel or computers, but I think that’s irrelevant to this article.
For the reasons bob and aerox state, it’s better environmentally-exactly how much is probably not worth arguing over, but certainly moving 200 pounds by the most efficient means ever discovered against moving 2800 pounds with an internal combustion engine must–just by common sense–be environmentally preferable. Bikes and cars are made out of similar stuff, so the manufacturing footprint of a 30-pound bike is certainly a small fraction of the footprint of manufacturing a car.
However, among all the bike commuters I know (a few dozen), not one cites our environment as the main reason they do. They do it because it’s faster or cheaper or healthier or funner or mentally cleansing or some combination of these. Studies have shown that bike commuters are the happiest commuters. My personal conversations jives with this finding. Bike commuters often talk about their commutes with excitement and pleasure; other commuters often talk about theirs with loathing. Are there counterexamples? Of course, but on average this is what I’ve found.
So I think it makes good sense to make it easier for more people to bike. Not everyone, of course. But if another million or two people start to use a bike as transportation now and again, what’s not to like about that?
Wow. I was trying to be polite, but the whole premise of this article is preposterous. I am skeptical of alarmist warming but making this argument about bicycling is embarrassing. The plants we eat, or the plants that animals we eat have eaten, takes CO2 out of the atmosphere to grow. We exhale it back out. No change in atmospheric CO2 levels as a result. Get it? What is a problem is burning fossil fuels because that CO2 was being stored below ground until it was burned. Why is this hard to understand?
Intuitively it makes no sense to me that transporting ~200 lbs (bicycle + rider) by burning carbohydrates would produce C02 anywhere near that produced by transporting ~3000 lbs (car + driver) by burning hydrocarbons.
Sorry, the scientific method doesn’t care about your intuition.
@5 jonb. “the global warming argument is not about carbon dioxide currently cycled between plant and animal life, but about the burning of fossil fuels which adds carbon dioxide from millions of years ago into the atmosphere”
Huh? How can you say with a straight face – and then defend it over and over again in this thread. AGW activists want us to do “A” instead of “B” because “A” supposedly results in less CO2 emissions. But if it turns out that “B” actually results in lower emissions that “A”, you still have to do “A” because “A” uses fossilized plant fuels and they are bad. So why are they bad again … because they create more CO2? No, that can’t be it because in this case they don’t. So is Cap and Trade about global warming or isn’t it? Other aspects of fossil fuels that enviros don’t like are already well addressed politically and they are selling cap and trade based on CO2. But when the argument doesn’t work out – well it doesn’t matter because fossil fuels are “bad”.
Discovery of fossil fuels and the development of technology to process them into useful life-enhancing products has been the most significant driver of our ever improving standard of living. And environmental problems are ultimately solved by wealth creation within societies. Government edicts and regulations can do nothing by themselves. Go ahead and plot environmental health versus standard of living for all countries in the world. See a trend there?
Pro AGW arguments don’t do well unless addressed to people who do not care to examine them critically. Stop trying to sell your biases and delusions and stop trying to enlist the coercive power of government in your fight to control the rest of us. Go ride your bike.
Did it occur to anyone here that the article just takes the usual “CO2 bilancing” business to its logical extreme? And should thus not be taken as a serious argument against biking?
Really, i’d love to see a follow-up, including the warming effects of the water vapour emitted by the cyclist! Cyclists constantly drink and sweat out water, this not only exacerbates water scarcity but promotes water vapour feedback!
I wouldn’t be surprised to see some serious dersertification along cycling lanes real soon now (before 2100!).
Commenter Bob’s numbers seem more realistic (Bike riding only produces about 12 grams of co2 per mile where as driving a Prius produces 242 grams co2 per mile.) On my daily 4 mile commute I don’t even come close to my max heart rate.
What are the carbon emissions of pulling the fuel out of the ground, transporting it thousands of miles, refining it, and then transporting it again to the gas station? Additionally some trips involve special trips to buy gas (2.5% of all trips according to the 2001 national household travel survey) I don’t know the answer to those questions but it needs to be factored.
What Secretary LaHood was saying is that the needs of bicyclists must be considered in all transportation plans, the concept is called Complete Streets (Google it). Ride your bike for a while on our road system and you begin to lose count of the close calls you have with sometimes irate motorists. We can do better than 800 bicyclist fatalities and 500,000 hospital visits every year with good road design and an education program that teaches all of us to co-exist.
Now, now, children, he does say “this is quick and dirty”. Can someone source that 242 g/mi figure for a Prius?
Hopefully all the people driving to work in this scenario also don’t end up driving to the gym and use the stair machines to get their exercise. Or really do anything that raises their heart rate in any way ever in their lives.
Huh? How can you say with a straight face…
Mike G.: Easily enough, and I meant what I said.
However, I can’t even tell what your point is beyond some unhappiness with what I have said, which others here have said as well.
Yeah, we can have a lot of fun with this, and yes, it all depends on how you crunch the numbers. If you accept the fact that CO2 in the atmosphere doesn’t really care where it came from (plants will grow on the CO2 from fossil fuels just as well as on that from our breath), the bicycle isn’t quite as green as many would have us believe.
For that matter, it isn’t as economical as you’d think, either, especially if you ride a higher-end machine. Consider the purchase cost, maintenance (tires, tubes, lube, tune-ups at the shop, chains, brake-pads, specialized riding gear) and so on… then divide that cost by the number of miles you ride. It’s been many years since I last did the calculation, but it was actually a little higher than what it cost me to drive to work in a small car. I decided the “intangible” benefits outweighed the cost and continued the bicycle commute, but I didn’t brag anymore about how much money I was saving.
Bottom line… there just aren’t any magic solutions that will get rid of your carbon footprint (suicide is NOT an option)!
Personally, I am proud of my large and vigorous carbon footprint. More carbon = more life. Even if anthropogenic CO2 levels could significantly impact world temperatures, so what? Global warming is a non-danger. It’s impossible for it to be a danger.
Assuming Lahood & co. truly believe carbon is evil, proving that bikes are no solution will not sway them for a second from their desire to force us out of our cars. They went into politics because they like pushing people around. They’re all like an 8-year-old boy with a magnifying glass and an anthill.
Bravo! I did a similar analysis when the folks at a local TV station set up several stationary bikes at the Minnesota State Fair and had volunteer fair goers pedal them, storing the electricity in batteries to power their evening newscast. I did a few basic biochemical calculations and determined that not only was the cost of the electricity produced about ten times what it cost off the grid, but the cyclists produced more CO2 than a diesel engine running a generator. I sent the results to the producer, who responded that she would “pass it along.” Yeah, right to the shredder. Greenies don’t like seeing their fantasies exploded by facts.
Cycling nearly 3 h everyday continuously for a year puts you outside the realm of an average commuter and into the realm of serious rider. Even if the numbers are correct this assumption can’t be.
Petroleum is actually ancient, oxygen generating algae … the original “green” fuel. This fact is going to be extremely traumatic for the global warming/carbon footprint hysterical bed wetters.
Even worse … all living things are carbon … and have footprints. Horrors !!!!!
Greenies should do their part to lessen CO2 emissions: return themselves, the CO2-methane emitters, to mother Gaia to feed the CO2-eliminating greeneries.
Less greenies, more greeneries; less BS, less CO2, cleaner air.
Check your math.
0.00899 kg CO2/min at rest + 0.081 kg/min additionally when performing equals 130kg CO2/day, for a person doing a 24 hour marathon.
In order to emit that much CO2, 190kg pure sugar must be eaten.
This is obviously so impossible as to invalidate everything you say.
I know you’re joking, but that’s no excuse for bad math
I believe the link between blood VO2 and oxygen processed isn’t as direct as one might believe. If you calculate from food intake, starchy, sugary foods are approximately 2/3 carbon.
TdF-riders intake up to 7000 calories pr day, (not all from starch, but what the hell). There’s 4 calories/gram starch, equals 1,7kg starch (whoa! that includes gatorade, though.)
That would mean that Lance Armstrong outputs 1,13 kg Carbon pr. day. You and me? A little less.
P.S. You doublecheck my math too, allright? Fair’s fair.
Ronnie,
5 tonnes of CO2 for bicycling?? I believe your numbers are way off the charts here, and don’t agree with the theory of respiration. Come have a look at my analysis. http://cozybeehive.blogspot.com/2010/03/how-much-co2-do-you-exhale-while.html
A car with a capacity of 13 gallons and 20 mpg average gives you 260 miles of travel burning some 117 kg of CO2. If you drive 30,000 miles a year like most of the people I know do, you would have to fill your tank 115 times. At the end of the year, you have put almost 13 tonnes of CO2 into the atmosphere. People who ride bikes for transportation should not even produce 5% of that, leave alone riding that much distance. Besides all that, the CO2 impact from expiration should be very little. Whats the solution for this? To stop breathing I suppose.
I am a cyclist, and this calculation intrigued me. The results didn’t feel right, as it doesn’t make sense that it would take a similar amount of energy to move a person + cycle (100kg say) to a fuel efficient vehicle (1000kg). Of course not all the energy is used for movement, some is wasted in both cases. But as the wasted energy appears as heat/sound etc, we can be sure that as there isn’t a huge amount of wasted energy as I don’t feel that hot after a bike ride!
So I looked at the C02 that you think a person could exhale. “0.081 kg/min of CO2″. The density of C02 is 1.98kg/m3, so that is 0.0409m3/min = 40900 litre/min = 681 litre/s. Not only is this a huge volume (I don’t think I can exhale nearly ten times my volume in 1s), the air exhaled is not 100% C02, it’s about 4%. So to get your figures, I would have to exhale 25×681 litre of air per second!
Does this sound right? Do you need to issue a retraction? Or do I?
6. You say “We don’t eat oil, coal or natural gas” We effectively do. Our food is grown with fertilizer (made from fossil fuels, see also the Haber process), then there are the sprays, transportation, etc. In fact the main argument against the so called eco fuels made from corn or palm oil is that it takes more fuel to make them than is produced!
I think this is the figure that needs to be checked:
“It appears that an average adult male will exhale 0.00899 kg/min of CO2 at rest.”
This reference (http://answers.google.com/answers/threadview?id=86080) says approx 432L of CO2 per day is expired at rest =
0.3L per minute =
0.0000003m3 per minute =
0.000000594kg per minute (1.98kg per m3)
Oops – there are 1000 litre in 1m3, not 1 million. But still, this leaves
432L of CO2 per day is expired at rest =
0.3L per minute =
0.0003m3 per minute =
0.000594kg per minute (1.98kg per m3)
This is still 15 times your figure.
Do you seriously ride “2000-4000″ miles a year ? I wonder if you’re propelled by all that mega tonnage of CO2 you’re expelling.
However, there is a difference in Co2 from fossil fuels and CO2 from exhalation.
The first is dug, or pumped, out of the ground where it has been stored for yonks, so adding to available CO2; whereas the expelled CO2 is part of the (existing) carbon dioxide cycle.
Your very rough estimate of how much CO2 a bicycle rider exhales seems awfully fast and loose if you’re going to use it to support such a bold claim. If I just think of the exhaust stream blowing from the tailpipe of my F-250 pickup even at idle, I simply can’t imagine even Al Gore exhaling that much wind at any kind of sustained pace, even under exertion. Think of the size of an auto tailpipe with a V8 pumping it, and now think of the size of your own windpipe and how hard your lungs are capable of pumping. This claim simply doesn’t make any sense, and the math supporting it seems awfully sketchy.
Even if we take it as a given that an exercising person exhales more CO2 than a cruising car, there’s the fundamental difference between circulating carbon already in the system versus adding new carbon into it. Think of the difference between an aquarium pump driving a water fountain versus a hose pouring into a washtub. The latter overflows, while the former remains in a steady state (even if it pumps more volume.) Pulling carbon out of rock layers in the ground and gassifying it into the atmosphere is the hose in the washtub, while eating plants or plant-eating animals and exhaling carbon from the broken-down sugars is the aquarium pump.
Even if we accept that a bicyclist can exhale more CO2 than comes out of a car exhaust, there’s the fundamental difference between circulating carbon already in the system versus introducing new carbon into it. Think of the difference between an aquarium pump running in a fish tank versus a hose pouring into a washtub. The latter overflows, while the former maintains a steady state. Eating plants or plant-eating animals and then exhaling carbon from the broken-down sugars is like the aquarium pump. Pulling carbon out of underground rock layers and releasing it as gas into the atmosphere is like the hose in the washtub.
There is a lot of misunderstanding of the cause of climate change here. The important difference between burning fossil fuels and respiration (breathing out CO2) is the timescale at which you are reintroducing carbon into the atmosphere vs what would have happened “naturally”:
The carbon in oil was laid down millions of years ago when algae/plants/dinosaurs died and were buried. Without humans drilling for oil and burning it in cars, that carbon may or may not eventually return to the atmosphere, but if it did it would do so via the million-year-timescale weathering of rocks and exposure of oil/natural gas back to the atmosphere. A very slow process. Burning fossil fuels takes carbon that was trapped in the ground and deposited over a timescale of millions of years and pumps it into the atmosphere in a matter of days/hours/minutes. IE: driving a car effectively adds carbon to the atmosphere at a much higher rate than it is removed from the atmosphere.
Respiration (like when you are riding a bike), takes the carbon that you ingested from your breakfast and expels it into the atmosphere. But previously (within the past few weeks or so) that carbon was removed from the atmosphere by the plants that originally took it in via photosynthesis. Either you ate the plants or you ate the animals that ate the plants. Either way you are participating in the natural day/week timescale cycling of carbon between atmosphere and organic material.
so the main difference is timescales: Fossil fuel reintroduces the carbon into the atmosphere much faster than would occur naturally (from weathering of rocks occuring on million-year timescales). Respiration reintroduces the carbon into the atmosphere at the same rate as would happen naturally. Anthropogenic climate change is a result of the former, not the latter.
Ray Lahood is right: More bikes is better for the environment. The source of the carbon does matter.
Many many factors in this. Does a fat person breath the same as a healthy person? Does the fat person produce more medical waste?
Not to mention the 2.9 million injured in the collisions with motors.
I love how the “sky is falling ” people always point to hauling goods as though it the same as the wasteful motoring around people do.
Alice, 1 m^3=1000 L, so that means .0003 m^3/min are exhaled at rest. This equals .0006 kg.
I am stunned by the idiocracy you are spewing into the world. I have no arguments, because ANYONE who believes this is SO FAR GONE it would be a waste of time. Please, please, please for the love of everything holy, STOP these ridiculous lies…and, go ride a bike.
Ummm… I haven’t read all 60 posts but I’m hoping some one else came up with this thought along with me. But if you haven’t, has anyone realized that the driver driving the CO2 emitting car is ALSO EMITTING CARBON DIOXIDE? Therefore you have one car and one person emitting CO2 vs. one guy on a bike emitting CO2. Please Please Please Please all of you global warming hoaxers: Stop before you hurt yourself.
I think there are some problems in the calculations because you have overestimated how much CO2 a person breathes out. According the EPA, the average person produces 1 kg of CO2/day. http://www.epa.gov/climatechange/fq/emissions.html#q7
Assume that is the “rest state,” and assume for the sake of argument that exercising increases the rate by 10X. That works out to 0.000694 kg/min at rest and 0.00694 kg/min at aerobic exercise. Over 60,000 minutes, that works out 416 kg in the aerobic state vs. 41 kg at rest. So the bike rider creates only 375 kg (0.4 tons)of additional CO2 over 15K miles — not 4860 kg (5.34 tons).
Dear Libtard trolls: saying “It’s the OLD CO2 thats the problem” over and over again doesn’t mean anything. There’s no proof anywhere that any CO2 is the problem. Which is the entire point of opposing the scam called AGW.
Maybe you would like to address some other myths as well./ Like how much CO2 do windmills emit … I would they are built by hand with no machinery involved. And who about how much does the electricity costs from them.
And then of course there are the huge multitude of Ethanol myths, even the CARB said it costs twice or more the CO2 to use methane as gasoline. Of course that was before Schwarzenegger forced it to be taken down, now they say ‘just more CO2′ than gasoline. And what does it cost per mile driven …
Sometimes I wish the warmists would just stop with the lies and rejoin the real world.
To readers and author Ronnie Schreiber:
The author refers to “when [he] worked for DuPont.” One is left to ask what he did for them by way of calculation or chemical analysis?
The author observes: “This is all quick and dirty, and if my figures are wrong, please provide me with more accurate data or correct my math.”
The author also makes reference to his basic assumptions, and for this readers can be grateful, because it discloses some basic problems with the analysis.
In response to his request for correction, consider the following as but one example of many which are warranted and necessary.
First, reference is made to CO2 emissions from an adult male at rest. The author says: “it appears that an average adult male will exhale 0.00899 kg/min of CO2 at rest.” Practically speaking, this number seems to be wrong, as is demonstrated below.
A quick back calculation based on the Ideal Gas equation (PV=nRT), using the assumed 0.00899 kg/min of CO2 gives rise to 8.99 grams of CO2 per minute. That mass of CO2 would occupy 4.58 liters per minute.
Note: a volume of 22,400 milliliters of CO2 weighs 44 grams at standard temperature and pressure. Thus the author’s 8.99 grams of CO2 would occupy (22,400 *(8.99/44)) = a volume of 4.58 liters.
However, human exhaled breath is only 4.5% CO2 and therefore one must multiply by 22.2 (100/4.5 = 22.2) times to calculate the total volume of breath exhaled in one minute to achieve 8.99 grams of CO2. The result is 101.2 liters of breathe each minute.
Since there are only 60 seconds in a minute, this means that one must breath heavily more than once per second – while at rest! This seems very unlikely.
Moreover, the same calculation applied to the 10 times factor used by the author gives rise to over 1000 liters of breathe per minute. Now that is some heavy breathing!
It seems that this basic assumption by the author is incorrect and what follows is therefore also far afield. It’s origin is not referenced, and so there is no checking which might otherwise be useful.
Here’s my idea: stop busing kids to school, and make them ride their bikes to school by making it easier, by providing (on current streets, not by building new ones) bike lanes and making it socially acceptable again. When I was a kid, a bike was my transportation – my friends and I rode them to school and back, and everywhere around town. Before I reached DL age, if I wanted to get around, I rode my bike. I didn’t have a soccer mom to cart me everywhere I wanted to go. Today, unless a soccer mom takes a kid somewhere, they stay home & play on the computer or video games.
Kids riding bikes to school again solves several problems:
1. Obesity rates in kids would be reduced;
2. School buses leave as big a carbon footprint (although they would still have to be used for group trips, like ballgames, band events, etc.);
3. Kids could get exposed to cycling and the benefits thereof, and hopefully keep doing it through college and on into adulthood; and,
4. It would improve people’s health by reducing diabetes, heart attack & stroke rates, thus helping out Obama’s healthcare plan, by reducing costs.
But . . . oops! My bad! I guess my “solution” doesn’t take into account all the kiddie farts passed into the atmosphere, thus causing methane & CO2 levels to go up. But wait . . . if the school cafeterias would stop serving bacon, eggs, cheese, pizza, hot dogs and all that other bad stuff, and serve more fruit and veggies, perhaps the methane emissions wouldn’t be as bad. But then, there’s the expelled CO2 from the little darlings having to pant while they pedal. Oh well, I guess I’ll just forget this idea, and go get in my gas-guzzling SUV and drive around until I come up with an idea that will work.
Daniel, there’s a much more direct way to compute this.
* vO2(max) for a sedentary person around 40. Now, by definition a person who rides 20 miles each way to commute isn’t a sedentary person and so will be expected to have a higher vO2(max). On the other hand, you don’t ride at max output all the time, so let’s be conservative and say 20.
* that’s 20 ml/kg/min. Let’s assume a 100 kg rider for simplicity, so that’s 2000 ml/min, or 2 liter/min. 2 liter/22.4liter/mole give us about 1/11 mole, or 0.09 mole. (Mathematica says 0.08929 but these figures ain’t that good.) The molar mass of CO2 is 44 g, so we get 0.09×44g = 3.9g/min.
At 20 mph, it takes 3 minutes to go a mile, so we get 12 g/mi. This agrees with the numbers several others have quoted to within the limits of precision.
Observe that we have by these figures about 2 l/min of O2. The normal atmosphere is about 20 percent oxygen, so that would be around 10 l/min total volume, what’s called the respiratory minute volume. This is during significant, but not maximal, exercise.
For check, using the figure of 3ml/kg/min and a mass of 100 kg again, we get total volume of O2 of 300 mlm so minute volume is about 1.5 l/min.
As you will observe from the link, average respiratory minute volume is in the neighborhood of 6 l/min. This appears to be very consistent with the estimates above.
59 mythbuster says:
“Alice, 1 m^3=1000 L, so that means .0003 m^3/min are exhaled at rest. This equals .0006 kg.”
Yes, I corrected my mistake in 53. I was hugely embarrassed by the way!
Ronnie, when are you going to correct yours?
Ronnie, you say “This is all quick and dirty, and if my figures are wrong, please provide me with more accurate data or correct my math.”
It seems that your calculations are based on the figure of 0.009 kg/min of CO2 being expired at rest. As I have shown in 53, this figure is about 15 times too high, making your result 15 times too high! Actual CO2 expired at rest is about 0.0006 kg/min according to this article http://answers.google.com/answers/threadview?id=86080 (notice the extra zero?). When are you going to issue an update to your article, or cite your 0.009kg/min figure?
Charlie in 54 has calculated using an alternative method, and he got 12g/mile, compared with your 15,000 miles for 4,860 kg of CO2, which works out at 324g/mile. Charlie has your result 27 times too high! Daniel has also shown that 0.009kg/min can’t be correct.
Cross-posted to Ronnie at rokem@netzero.net as I think articles with huge inaccuracies should be corrected.
It seems the author has become aware of some of the shortcomings of his calculations. Nevertheless, he stands quasi-defiant in support of his main thesis. This does a serious disservice to the conservative community which might otherwise cite his incorrect results in support of some policy decision or another. How embarrassing is that?
Instead of performing a realistic recalculation, the author observes that there are different outcomes between several of those who performed calculations challenging the author’s own. Now it seems its just a free-floating debate since the results – all of which are different than the author’s – seem to have taken on a varied nature. However, humility and accuracy would call upon the author to perform an accurate calculation or withdraw the first as unsupportive of his main conclusions with an appropriate warning for those who would read and cite his work in the future.
Several others have pointed out the incorrect nature of certain of the author’s assumptions and therefore his resulting erroneous conclusions. As usual, there a several ways to show the author’s assumptions are incorrect.
With that in mind, I prefer my use of the Ideal Gas law and the author’s mass per unit time coupled with the established fact that exhausted human breathe is approximately 4.5% CO2 because each is simple, easily verified, well established and requires no speculation or complexity. Alice at 68 has pointed out other equally useful critiques leading to the same conclusion: the author is quite wrong.
As one trained as a chemical engineer in college before I became a lawyer, I like the simple, accurate and verifiable over the complex, exotic or speculative when it comes to chemistry and physics calculations. Simple is good.
As yet, we still don’t know what services the author provided to Dupont. What were they?
It seems the author has become aware of some of the shortcomings of his calculations. Nevertheless, he stands quasi-defiant in support of his main thesis. This does a serious disservice to the conservative community which might otherwise cite his incorrect results in support of some policy decision or another. How embarrassing is that?
Not embarrassing at all. The original post stated that there might be shortcomings. It’s only embarrassing if you’re a Moby and not actually a conservative.
The author, me, made it clear that my calculations were off the cuff and that my initial value for CO2 at rest may have been inaccurate and I invited commenters to offer corrections. I’m not sure how I could have been any more open to correction. All criticisms have stood and no “corrections” have been deleted.
I guess it’s not enough to ask people the check my work. Apparently some expect me to make a public mea culpa as well.
Fine. I have no problem saying that I made a mistake. Nobody’s perfect.
Though when two different corrections vary by a factor of almost two, it’s hard to call either one of them reliable.
Please tell me just how wrong was I? Off by 1500%? 2700%?
I stand by my statement humans exhale a non-trivial amount of CO2, particularly when working hard physically.
Do you disagree with that statement? It doesn’t matter if my figures were off by a factor of 15 or even 30. The results are still non-trivial.
As for my having been employed at DuPont, what difference does it make what I did there, and how is that any of your business?
How about giving us a list of your legal clients and what their cases were?
Unlike you, I never tried to use the argument from authority by inferring that I was a chemical engineer (parsing your comment, I see that you say you were “trained as”, not “graduated as”). I didn’t use my employment record as credentials to discuss the subject so whom I worked for is irrelevant. For the purposes of this article, it would have made no difference if I said I worked for Ford, AT&T or Greenpeace for the matter.
If you perceived an implication that I was claiming to be a chemist or engineer because I mentioned formerly working for a company primarily known to the public as a producer of chemicals, that was not my intention at all. As a writer I thought “DuPont” was stylistically superior to “day job working for someone else before I started working for myself and I no longer had to commute”.
As it happens, though, I probably do have more credentials as an environmental professional than you do. Among other things I did in the 20+ years I worked there, including technical lab work, IT support & LAN management, I managed all of the lab’s waste streams, including both solid and liquid wastes, hazardous and non-hazardous. You may be a lawyer, but I’m probably better acquainted with SARA, RCRA and CFR 49, than you are. Know how to fill out a UHWM? Do you even know what a UHWM is? FWIW, I also “trained as” an engineer in a graduate engineering program for waste management. Got a 4 point too.
As for my calculations, though I may have relied on inaccurate data, I made no math errors, so that slam is unfounded. My supervisors may have had their complaints, but nobody at DuPont ever questioned the accuracy of my work.
Note to readers: I have emailed members of the faculty at Wayne State University’s medical school to get accurate figures on CO2@rest and CO2max.
CO2 respired by living beings has a different chemical signature than that of cars or factories.
Did you take into account that people breathe while they drive, or are we assuming that we hold our breath for our entire commute to work every day?
The other day I was passed by a Prius while bicycling. I thought: “I am greener than thou”. Then I saw this article, and had to check it out for myself.
Ronnie Schreiber has two errors–a major and a minor one.
1. The figure for an adult male to “exhale 0.00899 kg/min (or about 9 gm/Kg)of CO2 at rest” with the standard adult male being figured at 70 Kg, seems to me to be exaggerated by a factor of 2100(!). I figure on about 0.3 gm/minute/adult of exhaled CO2 at rest. My calculations are as follows: Pure CO2 is about 2Kg/cubic meter (Wikipedia) or 2gm/liter. Assuming exhaled air has 5% CO2 (all approximations for simplicity of calculation) then 2gms will be exhaled in 40 liters or 1gm/20 liters. Normal resting minute volume is 5-8 l/min. Let’s assume 6 l/min. Thus 6:20= 0.3 gm exhaled CO2 /min at rest.
2. He uses VOmax for his bicycling exertion figure. This, in athletes, can be up to 15X resting VO. Since we are talking here of the bicycle for transportation, I would say that 3X resting VO (or resting minute volume) would be a more realistic figure.
Thus, I get about 1 gm/ minute exhaled CO2 during moderate bicycling. A moderate bicycling speed is 15 mph. Thus, 60gm CO2 is exhaled in 15 miles. Using the 15000 mile EPA standard, the bicyclist will exhale 60,000gm (60 Kg CO2), while the Prius will produce around 4000 Kg. Therefore, about 70X more CO2 is emitted by the Prius than by the bicyclist.
Ronnie, ronnie, ronnie,
“I stand by my statement humans exhale a non-trivial amount of CO2, particularly when working hard physically. Do you disagree with that statement? It doesn’t matter if my figures were off by a factor of 15 or even 30. The results are still non-trivial.”
Yes it does matter if your results are off by that much. why? because the conclusion of your article was that cyclists produce more CO2 than several makes of car. But if your calculations are off by as much as other commenters have shown, then your entire article is off-base. Sure, cyclists produce “non-trivial” amounts of CO2, but it’s way less than automobiles do. I mean, did anyone ever think there WASN’T an environmental impact of riding a bike to work? no, we just thought — and we were right — that it was less of an impact than hauling our asses and a ton or so of steel to work via internal combustion engine.
Own up to your mistakes by retracting (i.e. severely editing or removing entirely) the main point of your argument, but don’t just pull a lame sleight of hand and say all you were aiming for was to show non-triviality. clearly, you wanted to show that cycling was less polluting than riding in a car. you couldn’t show it, so remove your post.
and people say environmentalists unthinkingly accept scientifically flawed arguments about global warming…
Oops! third-to-last sentence of my comment should have read:
“clearly, you wanted to show that cycling was MORE polluting than riding in a car. you couldn’t show it, so remove your post.”
while i’m at it, might as well mention that i shouldn’t have said “polluting” there either. way too vague of a term. let’s just change that to:
“clearly, you wanted to show that cycling produced more CO2 than riding in a car. you couldn’t show it, so remove your post.”
cheers
A bit late, but I just read the article.
While commuting by car may be less efficient CO2-wise, it still provides other tangible benefits over biking. Most importantly, it allows the commuter to be more productive, due to much less of his time being used up in transit to and from the job.
It’s akin to libs constantly squawking about the US using 20 percent of the world’s energy, but only being 6% of the world’s population. What they refuse to admit is that the US also produces something like 24% of the world’s economic output. Which makes the US a very efficient user of that energy.
I’ll bet the annual ROI of my carbon budget is several times that of Al Gore’s.
The best bet for the planet is when all of us can work from home. There is no need for commute and no need for CO2 emissions.
When air travel became costly, telepresence gained a lot of market. Businesses cut down travel. Similarly 60% of america can easily do their jobs from home. No Commute, No carbon footprint. and… buy a treadmill.
5.4 tonnes of CO2/year if you cycle!
Take a step back, don’t even consider you calcualtions for a while.
How much food do you eat a day? Even gorging myself, I’d struggle to eat 4kg of food.
4kg/day x 365 days = 1.46 tonnes. Where does the extra 4 tonnes come from, mass has to be conserved!!
If you believe this silly article, try this experiment.
Put 1 gallon of fuel in the empty tank of your car. Drive on level ground, until you run out of gas.
Now push it home. I don’t know about you, but I can easily cycle over forty miles [with hills and a headwind], but I bet I wouldn’t want to push a very small car more than maybe 20 yards.
To suggest that moving a metal box that weighs ~2 tons uses less energy than moving a bicycle that weighs 25 pounds is either living in cloud-cuckoo land or being rather dishonest.
Cycling is around three times as efficient in terms of energy use as walking. At an output of 30 watts a 70 kg 155 lb human can walk at 5 kh / 3 mph or cycle at 15 kh / 9 mph. Even the weediest car engine is ~ 15 horspower, many are vastly more powerful – the most p[owerful I know of is 1000 hp.
Sounds like something’s wrong, doesn’t it? Yes it’s the figures used in the header article are wrong!
So, according to the claim, if a car uses less energy than cycling, and walking uses three times as much energy as cycling, then driving is even more efficient than walking.
Total and utter hogwash.
Wow. A 1300kg Prius generates less CO2 than a human with a 10kg bicycle, while the bicycle travels at about half the average speed. That is very amazing. That means that the invention of the internal combustion engine is about 13 times more efficient that a plain old human body pedalling. This joke is not funny.
The only good thing about this debacle is reading intelligent comments from B Buckner who points out that the human CO2 comes from plants. I eat the same whether I cycle or not, so I don’t see how I can manufacture more CO2.
By the way gnubi: when you calculate times of a bike vs a car, consider that the average American spends about 20% of their wage on transport. That means all day on Friday, you are only turning up, so that you can pay the bills, to enable you to drive to work. Now that is a waste of time. Sell your car, and retire early. Or sit there like an idiot in a traffic jam for about 1 year of your life. It’s up to you.
Has anyone taken into consideration the health benefits of people riding a bike? A person may live five, maybe even 10 years longer if they ride a bike, which will increase the amount of carbon needed to support the basic features of life.
Look at it this way: A pretty high intensity workout would be 900 calories per hour. We will use a carbohydrate, glucose: C6H12O6. C6H12O6 + 6O2 = 6CO2 + 6H2O. Carbohydrates have 4 kilocalories per gram. The molecular weight of glucose is ~180.1 grams per mol. so for the above reaction, you take 180 grams of glucose, ~192 g of O2, and you get 6*(44 g) (264g) CO2, and 180*4 kilocalories (720.4 kilocalories energy.) So at the rate of 900 calories per hour, you can operate for 720.4/900 hours (.800), or 48 minutes. Personally, I bike at about 19 miles per hour with about that consumption, plus my basal metabolic rate. But basal metabolic rate CAN BE IGNORED because the driver in the car is going to have it too. So at a velocity of 19 miles per hour, for .800 hours, you can travel 15.2 miles off of one mole of glucose, or 180.1 g, or 720.4 kilocalories.
Gasoline has an energy content of 34.8 MJ/L. This is 8311.837 kcal/liter, or 8311.837/.2642 for 31460.3974 calories per gallon. Someone here was wondering about comparing a bike to a prius. According to their website, http://www.toyota.com/prius-hybrid/, it gets 51 miles per gallon. So to go 15.2 miles, it would requite 31460.3974*(15/51) kcal. This is 9253.0580 kcal. A using a bicycle requires 720.4/9253.0581, or 0.0778, or 7.778 % of the energy.
Now, because gasoline does NOT have a chemical formula, because it is a mixture of hydrocarbons, let’s use Octane, which is C8H18. assuming a rough caloric content of 9 calories per gram. Octane has a molecular weight of 114.23 g/mol. To burn one mol of octane, you would generate ~9*114.23 (1028.07)cal of energy. Octane burns like this: C8H18 + 12.5 O2 –> 8CO2 + 9H2O + 1028.07 calories of energy. Remember, I came up with the figure of 9253.0580 kcal to travel 15.2 miles. 9253.0580/1028.07 (9.000) mols of octane. One mol of octange generates 8 mols of CO2. Go back up near the top, and you’ll see that the molar mass of CO2 is 44.010 grams per mol. There will be 9 mols of octane, and each mol of octane releasing 8 mols of CO2, or 72 mols of CO2. 72*44.010 = 3168.72 g of CO2 produced to travel 15.2 miles in a toyota prius, versus 264g per 15.2 miles. So bicycles + humans produce 264/3168.8 g , or 8.33% of the carbon footprint that cars do to travel the same distance. For a less fuel efficient car, about 4.25% of the carbon to go the same distance.
Note this is not 100% accurate, but it is a pretty decent rough estimate. Even the math could have been better- I noticed myself that I used 44 g/mol for CO2 mass in the bicycle part, and in the car part, 44.010 g/mol. Let me know if there is anything else you think I should add and/or change!
Make love with your bicycle, not war with gasoline!
OH NO. I did make a mistake in that. you have to add the product of the basal metabolic rate & ratio of car speed/bike speed!
I mean add it to the caloric figure for bicycling that 15.2 miles!!! someone do this please ><
You are making a specious argument for three reasons:
1. We import 2/3 of our oil, a significant amount of which comes from countries whose interests lie at odds with ours (Venezuela, Saudi Arabia). Saudi Arabia is also known to fund terrorists, who take pleasure with killing our troops overseas. By not driving our car, we reduce our imports from those countries. [Along with inflating tires and other measures that save oil).
2. By not driving, we prevent NOx emissions from polluting our atmosphere (Those of you who live in LA or Beijing should know what I’m talking about). Nitrogen Oxides contribute to acid rain and photochemical smog (composed of NOx, tropospheric ozone, VOCs, et al.). Everyone knows smog causes respiratory illness. Driving less is essential to reducing health costs associated with NOx emissions.
3. Riding bicycles to work and back is a fun form of exercise. Something like 3/4 of adults are overweight in the United States (http://www.forbes.com/2007/02/07/worlds-fattest-countries-forbeslife-cx_ls_0208worldfat_2.html). That is shameful. There are astronomical health costs associated with being overweight. Besides, people need to exercise anyway, and to combine exercise with commuting kills two birds with one stone.
Am I wrong on any of these points?
Anonymous (83): It depends. People don’t need to exercise- it just shortens their lifespan. The difference in lifespan can account for a lot more oil/coal consumption, which, of course, produces more CO2.
And I think that the author of the article doesn’t quite portray things right. Sure, under good conditions, someone can ride 20 miles per hour… You know, downhill, or pretty fit on a road bike. But a greater majority of people enjoy mountain bikes for the more comfortable & safer ride- and a 20 mph average speed is a crazy figure on a mountain bike.
Cute but ignorant.
Which part was cute, and which part was ignorant? It is true- living longer uses a lot more energy. I was opposing the author’s point of view first, but I had to put my argument in there. It was mostly sarcasm, because who wants to die earlier than they have to? BUT it IS a fact that if you use cycling as a form of exercise, rather than get none at all, you WILL use more fossil fuels than if you drive in a car and have a McHeart Attack at the age of 40, 50- whatever- 10-15 years younger.
I want to live long, and I really don’t care about my energy consumption as long as it lets me live longer
Maybe the part that was ignorant was if you were an efficiency whore like I am, you MIGHT not use the energy you save by riding a bike (over using an automobile) in those 10-15 years that you may add onto your life. (I hate exercise, unless it’s biking ;D)
Ronnie Schreiber,
The simple experiment that of course shows your article is all complete rubbish is this:
On level ground with one gallon of fuel in your car drive until you run out of fuel. By your calculation, you should be easily able to tow it back with a bicycle, or push it back on foot.
I know you would not be able to. In-fact it’s most unlikely that you would be able to push a car with occupants for even one mile, let alone thirty or so.
You made the claim that bicycle CO2 emissions are greater than a car’s when shared. CO2 emission is directly related to power use. Your calculations are very seriously flawed.
It is for you to show why your claims are correct, by confirming them with other readily accessible data. Or carry-out the above experiment with independent and demonstrably objective witnesses.
Of course automobiles, cars, call them what you will, are vastly less efficient than bicycles.
The nemesis of these false claims is this analysis:
‘The Energetic Performance of Vehicles’ J.L. Radtke
The Open Energy and Fuels Journal, 2008, 1, 11-18
Of all personal transport vehicles, bicycles reign supreme, even over shared cars.
Nice thought exercise. However, it doesn’t really stack up when other factors are included.
I’m going to assume that the human generated c02 argument is being tackled by others. From the sounds of it, that was massively overstated.
Things that aren’t considered:
1. The US fleet is, on average, about 9 years old, not 1. That means 1/2 are older than 9 years with correspondingly worse c02.
2. Basing the c02 emissions on a 2009 car advertised as new does not take into account the loss of efficiencies over time, and an increase in c02 as the car gets older.
3. The further back in time you go, the less efficient and larger the capacity vehicle, increasing c02 again.
4. Fossil fuels are previously sequestered sources of C02. The c02 cycle may not be in balance, but it certainly won’t be in balance by adding yet more c02 without significant counterbalances.
5. The assumption is the fuel in the tank of a car has had no impact getting there. Fuel must be transported many times, using fossil fuels before it ever arrives at the gas station.
6. The embedded energy is producing a car is not included. This is a massive component.
7. The embedded energy in maintaining the infrastructure is massive.
With bad math & excluding reality, you can justify anything.