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Calories burned in 10 minutes of activity |
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Cycling, 9.5mph |
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Walking, 3.5mph |
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So cycling is 117% more efficient than walking. That's because cyclists travel nearly three times faster than walkers, but use only about 25% more calories to do so.
Running the numbers for men's calories yields a similar result.
Some have complained that 3.5mph is a rather brisk pace for walking, while 9.5mph is slow for cycling. It doesn't really matter, because while a faster pace burns more calories, you finish your trip faster and so spend less time burning calories. Runners have known for years that you burn about 125 calories per mile no matter how slow or fast you go.
This completely misses the point. The point is simply to show how incredibly energy intensive meat-based diets are, by using an interesting comparison. That's it. And that's true whether we consider transportation infrastructure or not.Even if we did consider infrastructure, someone deciding whether to walk or drive to their destination does not suddenly have to contemplate buying a vehicle and constructing a roadway to drive it on. The car has already been purchased, the roadway has already been built. Those energy costs were sunk long ago. Nobody buys a car to make a single trip.
Think of it this way: You have a choice to bike or walk somewhere, or take your car. That's a choice that many people make every day. I'm simply comparing the fuel costs for each choice at that point in time.
Again, the point is simply that meat production wastes horrific amounts of energy, no matter how you slice it or spin it.
In any event, Chris Goodall, who later wrote a similar article to this one, writes: "These numbers [e.g., the energy required to produce a car] are not enough to remotely affect the conclusion that car travel is less carbon intensive than walking, if the walker replaces lost energy with animal products."
He says that making a car produces 3 tons of carbon. Over a 200,000-mile life, that's a 0.033 lbs. of carbon per mile. It's not significant.
Goodall also sums up my frustration with the reception to our articles very well: "I was extremely naive not to realise that the analysis would be perceived as an encouragement to drivers. I didn't intend it to be read that way. My purpose was to draw attention to the carbon intensity of modern food production, particularly of meat."
And you think the amount energy to produce the gasoline is somehow different if it's put into a car than if it's put into a tractor? Wow.Even if this were relevant -- which it is not -- Chris Goodall (see above) says that you'd add another 15% to the carbon total to account for the production of the gas. In our example, you'd be adding it to both sides (i.e., into both the car and the tractor), so that couldn't be less relevant.
I'm just flabbergasted at how far people will go to miss the point. Yes, the comparison assumes that all else is equal because that's the whole point of the comparison! Once you change the variables then you're comparing something completely different. If we want to compare the energy used by for traveling a given distance by different methods then that is what we're comparing. We're not trying to measure every trip that every person takes, that's completely irrelevant. We're simply making a single, interesting, trip vs. trip comparison. That's it.
What about it? Eighty percent of beef raised in the U.S. is grain-fed, not grass-fed. If you're eating beef, you're almost certainly eating grain-fed beef. Even if you're not it makes little difference, because the fact that all the 20% grass-fed beef is spoken for is what forces industry to go grain-fed for the other 80%. Fewer grass-fed cattle can be supported on that same pasture as grain-fed, which is why most beef is grain-fed. If we shift to grass-fed then beef gets more expensive and there's less of it produced. There is simply not enough land to support America's beef addiction by grazing cattle, even at higher prices.As for raising cattle on land unsuitable for growing crops, again, there isn't nearly enough land available. If you suggested otherwise, you simply have no idea how staggering America's beef consumption really is.
In any event, the world's leading researcher on energy in agriculture, Dr. David Pimental, says that even grass-fed beef uses about half the energy as grain fed, meaning it's still more energy-intensive than growing crops for food. (American Journal of Clinical Nutrition) And Spiegel reports that 1 lb. of grass-fed beef is equivalent to driving 32 miles.
In short, if we changed the beef industry from grain-fed to grass-fed, there would be a lot less beef, and it would be a lot more expensive. For those reasons it's not going to happen, and even if it did, it would still use much more energy than growing crops.
You can relax, you're still saving a ton of energy. I'm not going to do a detailed analysis, but here's a back-of-the-envelope version:Your 24.4-mile round trip would use about a gallon of gas in an automobile, which would cost about $3.00. Since the costs of water and energy for laundry are much lower than that, they can't possibly use more energy than driving.
At the U.S. average cost of a $0.002/gallon, a 20-gallon shower costs $0.04.
A load of laundry uses about 35 gallons ($0.07) and 2 kWh of electricity ($0.20). At a guess, you could wash about eight trips' of cycling clothes in a load, so that $0.27 per load would be about $0.03 per trip.
So your water and energy costs per trip are about $0.07. That tells me that the extra energy required by your biking is insignificant compared to the amount of energy you're saving by not driving. If there were lots more energy required to provide the water for your shower and laundry, then the price of water would be a lot more. But it's not, so you're in the clear: The additional energy required to shower and do your laundry is tiny compared to the energy you're saving.
Carbon Footprint Calculator. My custom calculator is one of the few that shows you how going vegetarian or vegan compares to driving.
Eating Fossil Fuels, by Dale Allen Pfeiffer
Cattle more damaging to the planet than cars. (UK's Independent). Excerpt:
A United Nations report has identified the world's rapidly growing herds of cattle as the greatest threat to the climate, forests and wildlife. And they are blamed for a host of other environmental crimes, from acid rain to the introduction of alien species, from producing deserts to creating dead zones in the oceans, from poisoning rivers and drinking water to destroying coral reefs.The 400-page report by the Food and Agricultural Organisation, entitled Livestock's Long Shadow, also surveys the damage done by sheep, chickens, pigs and goats. But in almost every case, the world's 1.5 billion cattle are most to blame. Livestock are responsible for 18 per cent of the greenhouse gases that cause global warming, more than cars, planes and all other forms of transport put together.
Burning fuel to produce fertiliser to grow feed, to produce meat and to transport it - and clearing vegetation for grazing - produces 9 per cent of all emissions of carbon dioxide, the most common greenhouse gas. And their wind and manure emit more than one third of emissions of another, methane, which warms the world 20 times faster than carbon dioxide.
Livestock also produces more than 100 other polluting gases, including more than two-thirds of the world's emissions of ammonia, one of the main causes of acid rain.
Ranching, the report adds, is "the major driver of deforestation" worldwide, and overgrazing is turning a fifth of all pastures and ranges into desert. Cows also soak up vast amounts of water: it takes a staggering 990 litres of water to produce one litre of milk.
In order to make the bicycle much more energy-efficient than the auto, we need to significantly lower the energy that it takes to create and transport food. That's much easier said than done. See Food, Energy, and Society.
One way to help do this is to eat less (or no) meat that is obtained by feeding animal (become a vegetarian).
(1) 68 times more energy required to produce beef than potatoes.
Beef: In April 2004 Dr. David Pimentel of Cornell University shared with me an advance copy of his paper Livestock Production and Energy Use, which says that it takes 40 kilocalories (kcal) of fossil energy to produce 1 kcal of beef protein. This number updates the 35:1 ratio published in his earlier book Food, Energy and Society (1996, with Marcia Pimentel). These numbers include only production, not processing, packaging, transport, refrigeration, and the methane produced by animals and their waste. The numbers for potatoes below likewise are only for production, so we're comparing apples to apples. Of course, beef likely uses even more energy vs. potatoes than we calculate here, considering the extra energy required for refrigeration and safety protocols. Finally, note that these figures consider all forms of fossil energy, not just gasoline. This includes fossil-fuel-based fertilizers. With that long introduction, here is the calculation for the energy required for beef production:
- 40 kcal fossil energy per 1 kcal beef protein
- 40 kcal fossil energy per 1 gram beef (1 gram of 85% lean beef has 0.25 grams of protein according to the USDA database, which is 1 kcal of protein)
- 18,160 kcal fossil energy per 1 lb. beef (40kcal x 454 grams)
- 0.585 gallons of gasoline equivalent per 1 lb. beef (18,160 kcal ÷ 31,000 kcal/gallon; see below for the 31,000 conversion factor)
- 0.516 gallons of gasoline per 1000 calories of beef (1 lb. of beef is 1135 food kilocalories, according to the USDA Food & Nutrient database)
A Japanese study concurs with the above, clocking in at 43 kcal of fossil energy per 1 gram of beef. As with Pimental, they do not include processing, packaging, refrigeration, transport, or the methane produced by animals and their waste.
- 32.3 kg of CO2e per kg of beef
- 5959 kg of CO2e per animal
- 184.5 kg per animal (5959 ÷ 32.3)
- 32.8 GJ energy consumption per animal
- 0.00018 GJ per gram (32.8 ÷ 184.5 ÷ 1000)
- 43 kcal of fossil energy per gram (0.00018 x 239,005.736138 conversion factor)
Ogino, A., H. Orito, K. Shimada, and H. Hirooka. (2007). Evaluating environmental impacts of the Japanese beef cow-calf system by the life cycle assessment method. Animal Science Journal 78: 424&endash;432.In Beyond Beef, Jeremy Rifkin, 1992, p. 225 says it takes a gallon of gasoline to produce a pound of beef. Rifkin cites as his source Alan B. Durning, "Cost of Beef for Health and Habitat," Los Angeles Times, 21 September 1986, p. 3. I assume this old data is in error.
Note that there is some disagreement over the number of kilocalories in a gallon of gasoline. There are a few reasons for that. First of all, the kilocalorie is a measure of energy, but gasoline is not energy itself, it is a fuel that can be used to produce energy. Also, gasoline is not a static substance -- the quality of gasoline varies from one batch to the next depending on the source material, processing methods, etc. Here are the competing sources I found:
- 34,800 - Woodrow Wilson Biology Institute
- 32,143 - Prof. Joe Straley and S. A. Shafer, University of Kentucky
- 31,499 - Ken DeLong
- 31,000 - HowStuffWorks.com
- ~30,000 - Dr. David Pimentel, Cornell University
- 28,807 - (derived, see below)
I derived the 28,807 figure thusly: According to the EPA there are about 113,500 BTUs in a gallon of gasoline. (Vigan Prassar says it's 125,000, but the EPA's data appears more credible since it contains more detail.) One kcal is equivalent to 3.97 BTUs (Google calculator), so the 113,500 BTUs in a gallon of gasoline is equivalent to 28,807 kcal.
In Dr. Pimentel's earlier work he assigns a whopping 38,000 kcal per gallon, but he confirmed for me in a telephone conversation on April 8, 2004 that ~30,000 is a better figure.
Potatoes: On pp. 134-135 of Food, Energy and Society we see that the production of 34,384 kg of potatoes in New York required 152 litres of diesel, 272 litres of gasoline, and 47 kWh of electricity. This gives us:
- 152 litres of diesel = 40.15 gallons of diesel
- 272 litres of gas = 71.85 gallons of gas
- 47 kWh = 160,411 BTUs (1 kWh = 3413 btus) (And note that most electricity in the U.S. is produced with fossil fuels.)
- 160,411 BTUs = 1.41 gallons of gasoline (113,500 BTUs per gallon, as per EPA)
- Total energy to produce 34,384 kg of potatoes = 40.15 + 71.85 + 1.41 = 113.4 gallons
- 34,384 kg potatoes = 75,804 lbs. potatoes
- 113.4 gallons / 75,804 lbs. = 0.0015 gallons of fossil energy per lb. of potatoes
- 1 lb. of potatoes = 395 calories, as per the USDA Food & Nutrient Database
- 1000 calories ÷ 395 cals/lb = 2.53 lbs. of potatoes
- 0.0015 gallons of fossil energy per lb. of potatoes x 2.53 lbs. of potatoes = 0.003795 gallons per 1000 calories of potatoes
- When I spoke with Dr. Pimentel by telephone on April 8, 2004 to confirm my calculation above he said that I should double my result to include fossil-based fertilizers, so let's call it 0.00759 gallons.
Beef vs. Potatoes: We thus have 0.516 gallons per 1000 calories of beef vs. 0.00759 gallons per 1000 calories of potatoes. That means that beef requires 0.516 / 0.00759 = 68 times as much fossil energy to produce as potatoes.
(2) Meat-eaters are "driving" an extra 14 miles a day, vs. not eating meat.
(3) Energy for walking compared to energy for driving.
Diet for a New America reported this in 1987:"It is actually quite astounding how much energy is wasted by the standard American diet-style. Even driving many gas-guzzling luxury cars can conserve energy over walking -- that is, when the calories you burn walking come from the standard American diet! (62) This is because the energy needed to produce the food you would burn in walking a given distance is greater than the energy needed to fuel your car to travel the same distance, assuming that the car gets 24 miles per gallon or better." From Diet for a New America by John Robbins (1987, p. 375), further attributed as chapter footnote (62) to Hur, Robin and Fields, David, "How Meat Robs America of its Energy," Vegetarian Times, April 1985.
But when I run the numbers myself I find that the car is still more wasteful. The sources for these figures are from my carbon calculator sources page.
- The Car
- Average fuel economy for U.S. passenger vehicles (20.36)
- Fuel required to drive 20.36 miles (1 gallon)
Walking
- Time to walk 20.36 miles @ 3.2 mph (6.4 hours)
- Calories required (1434) (224 caloriies per hour for 150-lb. person; this is 74.7 calories/mile)
- Calories required after adjustment (2165) The U.S. produces 3774 calories of food per person per day, as per note #2. I don't know the actual number of calories consumed, but let's call it 2500. So we need to multiply our calories by 3774÷2500=1.51, because 1434x1.51 calories are produced for every 1434 calories eaten.
- Energy to produce food, typical American diet (21,650 kcal) (2165 x 35,000/3500 as per note #2 above)
- Energy to produce food, typical American diet (0.72 gallons) (21,650 kcal / 30,000 kcal/gallon)
So it's a myth that walking uses more energy than driving. But to focus on this misses the bigger picture. What's important to know is that the more meat you eat, the more gas you waste. Meat-eaters use about twice as much fossil energy as pure vegetarians, no matter how they get around.
If the walker got her/his fuel entirely from beef, then walking does require more energy than driving. A problem with showing this is that the energy figures I found for beef production include production only -- they exclude processing, packaging, transport, refrigeration, and the methane produced by animals and their waste. Adding these things would certainly make the beef-eating walker more wasteful than the driver, since even without including these extra items the contest is already very close. In fact, using a different set of assumptions than I do, the Pacific Institute (PDF) calculates that a beef-eating walker produces more CO2 than a car does for the same trip. Anyway, here are my calculations, but it's underestimated since it excludes processing, packaging, transport, refrigeration, and animal-produced methane.
Walking, if fuel for walking is beef (underestimated; see above note)
- Fossil energy required to produce 1 kcal beef protein (40 kcal) (As per note #1)
- Fossil energy per 1 gram of beef (40 kcal) (1 gram of 85% lean beef has 0.25 grams of protein according to the USDA database, which is 1 kcal of protein)
- Fossil energy per 2.5 kcalories of beef (40 kcal) (100 grams of beef is 250 calories, according to USDA)
- Fossil energy per kcalorie of beef (16) (40 ÷ 2.5)
- Fossil energy per 1434 kcalories of beef for walker (22,944) (1434 x 16)
- Fossil energy in gallons (0.76) (22,944 ÷ 30,000 kcal/gallon
(3) Energy for bicycling compared to energy for driving.
The original version of this web page stated that bicycling actually uses more fossil energy than driving, if the source of the cyclist's calories are from beef. (Yes, we know that nobody eats only beef, it was just an example to show the staggering amounts of energy required to produce beef.) I based those calculations on figures in Pimentel's Food, Energy and Society (1996), which Dr. Pimentel has since confirmed for me are overstated. (Thanks to reader Jeremy Hubble for giving me the clue I needed to set me on the path to discovering the error in the data.) The original figure I used was 13,000 kcal of energy for 140 g of beef (93 kcal per kcal of beef protein). The new figure is 40 kcal of energy for 1 kcal of beef protein. Beef production still wastes staggering amounts of fossil fuel compared to grain and vegetable production, it's simply not so wasteful that biking uses more gas than driving. Remember, though, meat-eaters use about twice as much fossil energy as pure vegetarians, whether they're bicycling or not.
(5) Save more gas saved by going vegan than by giving up driving two days a week.
This is from my carbon footprint calculator, which lets you see how eating vs. driving stacks up.An earlier version of this page quoted Beyond Beef (p. 225) by Jeremy Rifkin, which said that going vegetarian saved almost as much gas as not driving at all. Now that I run the numbers myself, I believe Rifkin's estimate was an exaggeration.
(6) Calories burned by various forms of exercise
Other notes
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