Living Car Free - Burning Fuel Motor VS. Human

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But Roody, there are three factors, local, organic and cost. So I'm a selfish biker but not unaware. I've learned about the ethical dimensions on LCF and how the same considerations can seep over into other areas of your life. So, what I read your rule of thumb to be is local AND organic or avoid the product. So I sinned by buying organic but not local, seduced by the jezebel cost. Well, last weekend I convinced a suburban family to dig up some grass and plant food. They didn't think much of the idea until they saw that Michelle Obama was doing it so that made it OK. Weird how people think.
We can just do the best we can do. The food system is set up to favor big business agriculture, so it isn't easy to get outside that cage! Off the top of my head i can thing of a few guidelines:
Organic--Generally, organic food is better for the environment because no pesticides are used, and less fossil fuel is used in it's production (this is because fertilizers are mostly made out of natural gas, of all things). After that, all bets are off for organic food being better for the environment. Obviously, organic strawberries grown in Morocco and airfreighted to Portland have a HUGE carbon footprint. OTOH, organic bananas grown in Costa Rica and shipped by boat to Boston have almost NO carbon footpring, because boats are extremely efficient. The same banana shipped to Boston, then trucked to Denver, will have a pretty big footprint. Starting just this week, stores in the US are required to label produce and meats with the country of origin.
Local--Environmentally, this is usually the best bet. Less carbon is emitted to ship food a shorter distance, obviously. However, if local food isn't organic, they may use pesticides and the fertilizers made from natural gas. But a lot of food marketed as locally grown is also organic, or nearly organic. One advantage is that you can usually ask the local grower about their growing practices and fuel usage. Many of them use pesticides rarely or never, or they use artificial fertilizers sparingly on only some of their crops.
Cost--Shop around. You will pay more for local and organic foods in many cases, but the quality might be better too. The cheapest place for local produce is the farmer's market or, cheaper yet, a CSA. You have to buy seasonally to get the best deals.
Remember, it isn't all or nothing. Buy as much local food as you can, but don't feel bad if you have to buy imported food also. Like I said, the system is deliberately set up to make it difficult and expensive to buy food that's produced by small local growers. Write your congressman if you think, like I do, that this is a bad deal for American consumers.
lyeinyoureye
03-24-09, 12:40 AM
There actually is one other factor you need to include: the amount of calories a person burns driving the 100 miles. It's NOT zero. Here's one calculator (no idea if it's accurate): http://www.shapeup.org/interactive/rmr1.php Most people will burn somewhere around 70-100 calories per hour just resting (and driving a car is not resting). According to this website ( http://www.healthstatus.com/cgi-bin/calc/calculator.cgi ), driving would burn about 2 1/3 x the number of calories as being at rest. So, given an average car speed of 40 mph (for a commute), I think it'd be around 5-8 calories per mile?That's a good point, people do burn more calories awake than asleep, even if they're just sitting on their rear. If you're going to that you should also do the same for a cyclist, since the energy consumption figures for cycling are already on top the amount of calories our body naturally burns when sitting idle, and they travel at half that sped or less they'll require twice as many calories per mile in terms of their energy consumption per mile. Granted, this isn't exactly a favorable comparison, since it results in a ~6-8 calorie per mile increase while the driver would see about half that, and along those lines it's also a good example of why we should restrict the energy accounted to only that needed to move the rider/bike. For instance at 15mph a cyclist on an upright bicycle with skinny tires needs ~115W, or ~115Wh to go 15 miles, which is ~7.4Wh/mile at the wheels, or ~24cal/mile since we are only ~30% efficient at turning food into mechanical energy, anyway, all the good stuff is here (http://www.me.psu.edu/lamancusa/ProdDiss/Bicycle/bikecalc1.htm). So, like I was saying, tacking on ~6cal/mile for a cyclist and ~3cal/mile for the driver isn't exactly a favorable situation for the cyclist, but at the same time it also isn't a whole lot different either.
jdmitch
03-24-09, 06:36 AM
That's a good point, people do burn more calories awake than asleep, even if they're just sitting on their rear. If you're going to that you should also do the same for a cyclist, since the energy consumption figures for cycling are already on top the amount of calories our body naturally burns when sitting idle, and they travel at half that sped or less they'll require twice as many calories per mile in terms of their energy consumption per mile. Granted, this isn't exactly a favorable comparison, since it results in a ~6-8 calorie per mile increase while the driver would see about half that, and along those lines it's also a good example of why we should restrict the energy accounted to only that needed to move the rider/bike. For instance at 15mph a cyclist on an upright bicycle with skinny tires needs ~115W, or ~115Wh to go 15 miles, which is ~7.4Wh/mile at the wheels, or ~24cal/mile since we are only ~30% efficient at turning food into mechanical energy, anyway, all the good stuff is here (http://www.me.psu.edu/lamancusa/ProdDiss/Bicycle/bikecalc1.htm). So, like I was saying, tacking on ~6cal/mile for a cyclist and ~3cal/mile for the driver isn't exactly a favorable situation for the cyclist, but at the same time it also isn't a whole lot different either.
Except, it's already been done for the cyclist in the figures posted.
dynodonn
03-24-09, 09:19 AM
Personally, my main reason for bicycling isn't being concerned about calorie intake and expenditures(except when traveling through various neighborhoods after work around dinner time with all the cooking aromas in the air :D), but more about cycling enjoyment and over all annual financial expenditures of cycling versus motor vehicle ownership. Even with my increased calorie intake, my overall cycling/food expenditures are still lower than my motor vehicle/food expenditures.
lyeinyoureye
03-24-09, 01:21 PM
Except, it's already been done for the cyclist in the figures posted.No it hasn't. The figures for the cyclist are just what's require to move the bike given the efficiency at which humans convert food to mechanical work, it doesn't include their idle BMR which is pretty much constant through the day when awake and drops when asleep at night, but is more or less always on.
jdmitch
03-24-09, 01:43 PM
No it hasn't. The figures for the cyclist are just what's require to move the bike given the efficiency at which humans convert food to mechanical work, it doesn't include their idle BMR which is pretty much constant through the day when awake and drops when asleep at night, but is more or less always on.
Maybe we're looking at two different studies, but from what I've gathered the 40 cal / mile estimate is inclusive of BMR (or I should say is conservative enough to be considered to include BMR).
Maybe we're looking at two different studies, but from what I've gathered the 40 cal / mile estimate is inclusive of BMR (or I should say is conservative enough to be considered to include BMR).
I don't know what studies you're referring to. The 40 calorie per mile figure is a rule of thumb used by exercise kinesiologists who are interested in caloric expenditures above basal metabolism rate (BMR).
Total calories expended by an organism = BMR calories + calories expended in exertion
However, you just ignore or disregard the BMR calories because they're always the same.
Personally I think we're overextending the figures a bit. They are all guesstimates, and you can't tack on too many decimal places, so to speak.
lyeinyoureye
03-24-09, 07:14 PM
Maybe we're looking at two different studies, but from what I've gathered the 40 cal / mile estimate is inclusive of BMR (or I should say is conservative enough to be considered to include BMR).It's exclusive AFAIK. For instance, this bicycle power calculator (http://www.me.psu.edu/lamancusa/ProdDiss/Bicycle/bikecalc1.htm) I linked earlier only includes the energy needed to move the bike/cyclist, not the share of BMR over the time spent riding. That said, I did a bit more research, and 28% efficiency when converting food to energy is almost certainly on the high side. For instance this biomechanics (http://books.google.com/books?id=wQS8H7dppHkC&pg=PA48&lpg=PA48&dq=%22efficiency+of+human+muscle%22&source=bl&ots=SvtZzyJ2o2&sig=wAS3G0DEEa7NFbIKkSXxFLpszDk&hl=en&ei=u4PJSef2NZGUsAOEoc3tBw&sa=X&oi=book_result&resnum=7&ct=result) text places it at ~20% in terms of metabolic efficiency. This paper (http://jeb.biologists.org/cgi/content/full/210/13/2390) places the peak efficiency at ~25%, but doesn't mention what average efficiency would be. It also illustrates why cyclist should spin instead of stomp, which is pretty cool IMO. :commute:
jdmitch
03-25-09, 07:32 AM
It also illustrates why cyclist should spin instead of stomp, which is pretty cool IMO. :commute:
Yeah, I started picking up on that withing just a few clicks.
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