This analysis makes the same mistake that innumerable other analysts have made before: that going a mile is something worth doing. If you stipulate that everything is a mile apart, then you're guaranteed to get this outcome.
The point of walking is that if you throw out the cars then everything is much closer together, and then you don't have to walk a mile. If I start from the Ferry Building in San Francisco and walk a mile up Sacramento street, I'll pass thousands of establishments of all kinds. If I start at the Ponte Vecchio in Florence and walk a mile I will pass literally every single thing there is in the old city. In a walkable city you'd never need to walk a mile, so finding out what is the most energy efficient mode of going a mile is relatively pointless. What you actually need to know is the most energy efficient form of building, not the of transport.
On the other hand people walk, jog and run and bike and stationarily bike many miles for nothing but to keep in shape. So people waste a lot of energy after overconsuming energy.
I'm not trolling. This kind of analysis is frequently trotted out to argue against transit, cycling infrastructure, and even sidewalks. Take for example this (totally moronic) post at the Freakonomics blog:
It's an anti-transit argument based entirely on energy per passenger-mile traveled, which is only relevant if you think a passenger-mile is a good thing which should be maximized.
How many Ethiopian restaurants, improv theaters, and dueling piano bars did you pass? A lot of niche interests can't sustain themselves at all with only a small fraction of a small population.
Well you got me on the piano bars but as far as Ethiopian food goes there are dozens in my relatively walkable city and I just spot-checked the first car-choked blasted expanse that came to mind (Phoenix) and there are only five in a much larger metro area.
If I was an Ethiopian restaurant owner would I prefer a restaurant in a dense neighborhood with five families living in apartments right on top of me, or would I prefer to be in a strip mall at the corner of an American suburb with nobody in walking distance and only a few hundred families within a mile? I know which one I'd want.
Odd, are you in a destination for Ethiopian immigrants? I would have expected something more like the single restaurant serving the entire Napa valley. Most people don't even know Ethiopia has a cuisine, much less seek it out.
All of those things are most likely to be found in dense cities like New York and Chicago, not the far less walkable exurban sprawls (although those places do need parking because people come from afar)
This should not really be very surprising as walking is not very efficient. You should be comparing driving to cycling, as both are wheeled forms of transportation. Cycling is up to 5x more efficient than walking (https://www.exploratorium.edu/cycling/humanpower1.html)
So, if you compare driving to cycling, cycling wins hands down. And, this is with the artificially low cost of fossil fuels. If fossil fuels properly factored in all the environmental damage, cycling's efficiency advantage would be even higher.
Did you read the article? They compare bicycling too.
Also, a lot of fossil fuels are used grow and transport food the food you eat. It's not immediately obvious to me that the fossil fuel impact of growing the food, transporting it, and packaging it is less than the fuel to move a car in the first place.
If you're going that far perhaps factor in the costs of drilling and shipping fossil fuels on the other side ... admittedly it probably is a factor or so less than the proportion associated with foodstuffs - but - the foodstuffs side has plenty of room for optimisation whereas the fossil fuels side is on a degenerative trend
"Up to" doesn't mean much. Biking is explicitly considered in the original piece:
> Surprisingly, from a pure energy perspective (using the methodology mentioned above), biking, walking, and running are the three most expensive types of transportation listed
"Up to" is reasonable because it varies so much. Energy efficiency of cycling depends strongly on aerodynamics. A fully faired recumbent like you see in the human powered vehicle record attempts will do much better than a normal upright bicycle, probably better than 5x walking. Skin-tight clothing vs. normal clothing makes a big difference. Even shaving legs makes a very small but measurable difference. And because drag increases with the square of the air speed, aerodynamics is more important when you're riding fast. This contributes to the wasted energy on hills too, because you descend much faster than you ascend.
For these reasons it doesn't make much sense to talk about exact figures for energy efficiency of cycling without specifying what type of bicycle, what clothing, what weather conditions, what terrain, what braking technique, how much the rider weighs, their riding position, how fast they're riding, etc. The tires and the drivechain make a noticeable difference too.
Your food expenditures vary with the amount of work you do, no different than your car's fuel expenditures. They are most certainly not a sunk cost for this purpose.
Actually not so much surprisingly - the key exceptions being if you are working in very cold climates where the body has to generate more heat to keep you alive or you're training competitively for very physically sports.
It turns out that about 70-80℅ of what most people consume goes into simply keeping them alive (research basal metabolic rate & daily calorific requirement) and the impact of "work you do" is only a small variation - with the above exceptions.
Also interestingly (unable to search the paper reference on phone) there is research that shows that dramatically different lifestyles like Namib desert nomadic hunter-gatherer vs. typical urban don't actually differ on metabolic rates (accounting for non-fat weight)
What is the claim you're making? Assume 80% of Example Man's diet is his rest energy requirement. The other 20% goes toward discretionary things like moving. This means that if Example Man doubles his discretionary activity, his food consumption will increase by 20% rather than 100%.
It does not mean that if walking three miles takes one apple worth of energy, Example Man actually only needs to consume 0.2 apples in order to walk an extra three miles. He needs to eat the full one apple. This article doesn't consider food as a percentage of your diet at all; it considers food as the cost of moving. Your point isn't relevant.
You should have posted that at the top level, so this could be the top comment. While the statistics are nice to look at, I have read the article you mentioned, too (was on HN a while ago) and instantly thought that metabolism unfortunately renders the whole calculation useless and wrong.
> While the statistics are nice to look at, I have read the article you mentioned, too (was on HN a while ago) and instantly thought that metabolism unfortunately renders the whole calculation useless and wrong.
Why did you think this? Can you articulate a change that metabolism would make to the calculation?
It adapts, like my parent comment has said. Most of our energy is spend on keeping the system running, not running with our feet. If we start to run, we burn more energy, because our metabolism has not adapted yet, once it adapts (see his example with Africa), there is very little change. Obviously this is simplified.
But the argument could be made that the average American runs a calorie surplus so some percentage of the food/fuel cost could be deducted, for Americans, at least, no?
I guess the issue is surplus relative to what - recommended daily calorie intake vs. the calories required to maintain excess weight. My point was the former, yours seems to be the latter.
Well, I started off by saying "no, food expenditures are not a sunk cost, they are directly related to the amount of work you do". The idea here is that doing x extra work leads to eating x' extra food, where x' is some constant multiple of x (and "food" is measured in energy).
Your response, as far as I can see, says that because Americans already run a caloric surplus, x extra work should only lead to x' - k extra food intake, where the missing k energy is made up by the existing caloric surplus. I responded then and respond again now that this perspective makes no sense; the extra work is an ongoing expenditure and must be exactly balanced by an ongoing intake. For the supposed caloric surplus to be offset against the extra work of extra walking, the person would need to be experiencing constant weight gain beforehand. Nobody[1] is.
You may think that Americans weigh too much, but that's irrelevant; a change in weight is a nearly-pure one-time effect with no influence on dietary requirements. They are eating exactly the amount they already use for the activities they already do.
Am I missing something about your point?
[1] Actually, people with Prader-Willi syndrome will eat if it is possible to eat, no matter how full they are. They will experience constant weight gain if not subject to external control. But they have a serious genetic defect.
Not really, I don't like cycling in the city (not secure enough about not being plastered by a truck, especially considering how little fuck UK drivers seem to give) so I walk to work for almost 2 years now.
I started because I wanted to lose like 8-10lbs during a time when I couldn't exercise regularly at the gym which were lost within about 6 weeks.
I walk fast at about 6KM(my gait isn't very long because I wear either jeans or dress pants and I am of average height, but still I'm doing 130-135 steps per minute) an hour according to Google Fit/Apple Health, and I walk between 11-15KM a day (~2-2.5 hours I take a longer route through Hyde Park if the weather is nice and I'm not in a rush getting to or from work).
This daily walk alone increased my daily rough caloric requirement to about 2800-3000 calories, that's 600-800 (k)calories over my daily default if i don't do any physical activity other than getting up and commuting to work on the tube.
If i don't increase my caloric intake i would lose between 0.5 and 1 KG a week so in this case and in every other case the "food expenditure" isn't a sunk cost, now you might say that my caloric intake doesn't have much impact on the grand scheme and you would be correct, if I need to eat another slice of pizza or another muffin it doesn't affect anything in the long run, if anything it probably means we might "waste" a bit less food.
But given the current cost of each food calorie that you intake if everyone all of a sudden goes up to 3000 Kcal daily requirement it will have an effect on the environment and the economy.
What you should take from it is not that walking is bad for the environment but is that the global food production is highly inefficient ATM, food is cheap especially in the US but it comes at a pretty big price also.
Yes, it is taking the total calories used (actually its not that clear). It should be comparing the extra calories burned by cycling minus the calories burned sitting. Driving the car, you will still be burning most of those calories as well as burning the gasoline.
Not necessarily. If returns from your retirement savings exceed your outgoings then you're maintaining net positive income till the day you die. Granted as things stand, this case would not represent the majority of people.
Not all fuel consumption is the same. Gasoline is way under-priced in the US when traffic, pollution and road construction costs are factored in. On the other hand, high quality, sustainably farmed produce is overpriced, most significantly from sustained subsidies for corn and the associated increase in the cost of arable land.
There is also the cost of getting the food to you. Often the most efficiently produced food will be produced some distance from you and a surprisingly large fraction of the cost will be shipping.
Is this an autonomous car, deadheading? If not, you should consider the resting calorie consumption of the passenger. On a highway, that is indeed negligible; but a crosstown trip in Washington, DC, used to take me about six minutes per mile.
The article on travel efficiency shows that a walking person requires about 210 calories per hour at 4 km, about 2.5 miles/hour, call it 85 calories/mile. For an American consuming 2500 calories/day, a given hour requires about 104 calories: divide that by 2.5, reckon 41 calories in the time it takes to walk a mile. Now the cost of walking over resting is about 42 calories, and we have walking down about where he has biking.
Please correct me, for it's likely that I have missed something here.
Good catch! Not to mention that the calorie consumption of someone driving a car is likely significantly more than someone idly daydreaming, both from the physical activity of steering, braking, shifting etc and possibly also from the focus required.
people who drive probably aren't going to eat less because they're walking less. also, walking (to me) isn't just about saving money, it's about good habits and contributing less to traffic and pollution
edit: people travel farther distances in cars than on foot, usually. nobody would replace a 20 mile commute by car with 20 miles of walking.
Not so interesting because they compare food (with highly variable cost and reason for consumption) to fuel. Going by the cheapest calories available, the way you would to fill your car with the most economical gasoline, walking is cheaper. (source is the article)
The math on walking, at least, seems little off: 210 calories per hour divided by 2.5 miles per hour is 84 calories per mile, which is about 23.5¢ per mile.
Also the cost of driving should really use the average fleet fuel economy of a country together with the fuel price in that country. That works out to a hair under 10¢ per mile for 2014 fuel economy and today's gas prices.
The takeaways remain the same, though: Human-powered transportation isn't especially efficient (unless you're burning calories you would have eaten anyway), and driving is subsidized up the wazoo in the US.
That's what I hoped this article was about when I saw the headline. I was disappointed it was only about the $ cost of food and not the externalities.
Thanks for sharing. It's interesting to see though that a biking paleo dieter is still 2x as efficient from a passenger-mile standpoint as a roughly average 25 mpg vehicle, and the average US diet is still better than a double occupancy Prius.
This is a really important point. For many people, bike commuting is partly a way to avoid having to schedule an extra hour a day dedicated solely for exercise, so the calories are indeed "free"
Of course, this assumes that you're perfectly fit already and that every calorie burned translates into additional consumption.
For the vast majority of Americans, that assumption is incorrect. From personal experience, it's actually the opposite: I eat less on the days where I go for a long walk.
Another data point: a light electric vehicle (ebike, boosted board, etc.) is about 1-2¢ per mile (~100-200 Watt-hours per mile at 10¢ per kilowatt-hour).
How about the cost of manufacturing a car, which has a cost in fuel? Also, most of the cost of food is labor for its preparation. You're paying for a lot more than just calories. Food is not made to be energy dense like gasoline, it's made to be tasty and nutritious.
The article touches on this, but doesn't directly address it: whether they're using gross calories or net calories. Gross is the total calories you burn during that mile. Net is how many additional calories you are burning as a result of walking versus being sedentary.
Glancing at the wikipedia article which the author uses doesn't clarify this, nor does Wikipedia's citation. I didn't check the citation's citation.
Clearly we want net calories. Average humans burn ~100 kcal per hour doing their normal activities during the day, so that could potential change the figure from 210 kcal per hour walking, to 110.
This analysis should take the additional calories it takes to walk vs sit to represent a fair cost of walking. Or add the cost of calories for sitting should be included in the driving option as these are part of the process.
This is a good thought exercise, but kind of comes across like a random equation looking for an explanation rather than interesting observation in search of an explanation.
I can't imagine the person driving doesn't spend as much or more than the person walking on food.
If we are saying that this small amount of money VS drinking oil is where the line is crossed, then are we not all comfortably well past this zone anyways?
So another way of saying this is listening to music is most efficient if you listen to a pre recorded song or you whisper only.
This is a good point, petrol is clearly way too cheap.
(We have of course long improved on bicycles. An ultra aero lowracer recumbent can get 30mph on 120W, covering the 100k for a mere 1kWh at average 25% efficiency)
Interesting. I think the article would benefit from a graph of the raw data, i.e., calories per mile, in addition to dollars per mile. I actually wouldn't mind paying more for food, in return for the pleasure of walking or biking. At the same time, walking and biking are not an option for a lot of trips, depending on distance and cargo. Since my daily bike commute is 8 miles round trip, it's a pretty inexpensive pleasure.
and added the highest-calorie individual meat (steak), rice (white rice), beans (black beans), salsa (chili-corn), sour cream, cheese, and guacamole, and still got only 1365 kcal.
While adding every single topping does reach 2425 kcal, one would have to order 4 kinds of meat, tofu, 2 kinds of rice, 2 kinds of beans, fajitas, 4 kinds of salsa, sour cream, cheese, guacamole, and lettuce. I would think that should count as "trying"! :-)
There's a huge opportunity cost of not being able to travel as fast and far as a car lets you. You can't* get an Uber or bum a ride from a friend to your mother's house in the middle of nowhere on Christmas morning. There's few parts of the country where walking/biking year round is feasible.
I'm really surprised at the comparison of motorbikes to cars. I don't own a motorbike, but my impression was that compared to cars the fuel costs are trivial. This data suggests a cost reduction of only ~25%. Was it dumb of me to expect a cost reduction of >75%?
Cars are a lot more efficient than they were a few years ago, and motorcycles have gone the other way. You can still get a motorcycle that gets 60 MPG or better, but the mainstream has decided to use their thermodynamic budgets to build engines with very high specific power and hold the line around 40 MPG or even less.
Nobody should buy a motorcycle imagining that they have lower operating costs. Aside from fuel, motorcycles have high budgets for tires, engine maintenance (due to the aforementioned appetite for high specific power, and relative lack of scale in their manufacturing), insurance, likelihood of theft or other total casualty, need to continuously refresh your riding apparel on approximately 5 year basis, expensive consumable items like drive chains and sprockets, and so on and so forth. Also there is generally a lack of miles over which to amortize the time-denominated costs like insurance.
The point of walking is that if you throw out the cars then everything is much closer together, and then you don't have to walk a mile. If I start from the Ferry Building in San Francisco and walk a mile up Sacramento street, I'll pass thousands of establishments of all kinds. If I start at the Ponte Vecchio in Florence and walk a mile I will pass literally every single thing there is in the old city. In a walkable city you'd never need to walk a mile, so finding out what is the most energy efficient mode of going a mile is relatively pointless. What you actually need to know is the most energy efficient form of building, not the of transport.