Environmental comparison of bicycling vs driving
There's a transportation blog on the Minneapolis Star Tribune newspaper website put on by Roadguy (Jim Foti) of the Strib (as we fondly call the paper). Iposed the question to him about the true costs of cycling probably a year ago or so, to see what he could come up with or what his readers could come up with. He was quite intrigued with the question and did some research but only came up with a couple of websites that gave an estimate of the energy cost of the foodwe eat, as in energy expended (fuel) per Calories we eat.<br><br>The response was underwhelming. The usual participants answered in their predictable ways and the thread went no where. One response was, "Of *course*cycling uses much less energy than driving--just look at the size and speed difference!!!" Duh. But that wasn't my question. Anyway, I eventuallycouldn't take it any more and jumped in. Here's my response, which seemed to kill off the topic completely. I haven't revisited it but ininterest of just "getting the discussion going," here it is:<br><br>Well, since I started this I imagine I should post a comment or two, if anyone is still following this thread. Somewhere along the way my questions seem tohave been misinterpreted as "does biking to work consume more energy than driving?" Just from a common sense aspect, I don't think anyone wouldargue that it does.<br><br>But there is an environmental cost to biking to work, and I am curious what it is. The general concensus for such a question seems to be that it's toocomplex an issue and therefore there is no answer. Well, there has to be. And it can be solved by first defining what you want to solve, developing a model,and refining the model to the point the problem is solved.<br><br>My base question is "what is the net savings of me biking to work?" For starters, I want a simple model or equation from which I can get a ballparkfigure: energy consumed by driving minus energy consumed by biking give a net energy savings of ?.<br><br>The commute: 47 miles by car and 50 by bike.<br>The energy: 1.3 gallons, and 2000 Calories.<br>Converting the 2000 Calories to equivalent gallons of gas is dicey. Based on info from various websites, I'll choose 30,000 Calories per gallon of gas,and 10 Calories of gas to produce 1 Calorie of food. The 2000 Calories I consume is equivalent to (10*2000/30,000 =) .7 gallons. Net savings? 1.3 gal - .7gal = .6 gal.<br><br>From there, how do I want to develop and enhance and refine and improve this model? It was mentioned that the energy cost of transporting that 1.3 gallons mayneed to be included. If so, the energy cost of transporting the .7 gallons needed to produce and transport food needs to be included also. That 1.3 gallonsis transported from the Rosemount [a Twin Cities suburb] refinery. That .7 is also transported from the Rosemount refinery out to North Dakota to run theheavy equipment to grow and harvest some of that food. A figure on one of the websites says that on average, the food we consume travels 1500 miles. I'mcontent to leave the transportation costs out of the equation, assuming they generally cancel each other out.<br><br>Whether the 2000 Calories comes from love handles or last night's spaghetti, it still has the same energy cost--paid earlier or paid last night. I'mgoing to drop that concern from my model. [Someone insisted the Calories for biking are free as we're all obese anyway. <img src="http://static.yuku.com//domainskins/bypass/img/smileys/laugh.gif" alt="image">]<br><br>Car and bike costs: I have a car and bike anyway, so do those costs actually need to be figured in? Yes, as they aren't "free" from a point ofwear and tear on the environment. But I don't know how to accurately assess the cost of those miles on the car. My first approach is to assume that theentire cost of the car, $17,000, be translated into cost of energy--mining, transportation, factory costs, labor costs (the living people are using resourcestoo!). Add in anticipated maintenance over the life of the car ($8000?), and I come up with 200,000 miles (it's a Toyota :-) and $25,000 for initial costplus maintenance. Let's say that $25,000 represents 12,500 gallons based on when the car was made (i.e. $2 per gallon when I bought it). That gives a carcost of one gallon per sixteen miles driven. My revised model now stands at (1.3 gal actual gas + 47 miles / 16 mpg car cost) - .7 gal = 3.5 gallons savings. <br><br>Bike costs? Another hard one. A thousand? Two or three thousand? My bike cost $650 in '92 and I've spent more than that on maintenance over theyears. $2000 so far for 60,000 miles on it? That needs to be added into the equation too.<br><br>Next revision: Is bike commuting replacing Calories I'd have burned while exercising? Well...I'm pretty lazy, and if I don't commute, theexercise, well, just doesn't happen...<br><br>Is my model flawed? Sure. I'm making assumptions for which I'd really like more solid data. But it gives me a raw savings number for myself. "Do I want to add in the extra carbon dioxide I produce while biking?" Naw, it's part of the food cycle and I'll be eating it again, ascompared to the carbon dioxide given off by burning gas that will never make it back to petroleum products in a timely fashion.<br><br>I like Roadguy's thought about a good group of science students tackling this [or some RLOL'ers???<img src="http://static.yuku.com//domainskins/bypass/img/smileys/roll.gif" alt="image">]. By breaking down the problem, they can research these costs--growing andproducing food, producing packaging for food products, true energy costs of producing a vehicle, energy costs of disposing worn out packaging and oil and biketires, extra showers and washing clothing, more or less wear and tear on roads, etc.--and come up with a more accurate model. What's it good for? For me,it would satisfy a curiosity. Everything has an energy cost, and I like some more solid numbers other than the vaguery of "I know x is cheaper thany." Do I really know that? Sometimes common sense isn't!<br><br>[Have at it.... Jeff]<br>
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