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 Bicycling Wastes Gas? 

Editor's note: This article is widely misquoted and widely misunderstood. Most of the criticism I see of it in blogs around the Internet shows that the readers missed the point completely. I suspect that people come here, read the headline, get angry, and then don't bother to digest the article. The point is not that "Taking the car is good for the environment" (which was the title of one blog post). The point is that just like some kinds of transportation use a lot more energy than others, some kinds of food use a lot more energy than others too, and what you eat is as much a part of your energy footprint as how you get around. Please read the article carefully. Thank you.

Most people think that bicycling doesn't use gas, but actually it does. It takes lots of fossil fuel to produce the food for the cyclist's calories -- and cycling requires more food fuel than driving.

Of course, we can't just stop eating, but we can definitely choose what we eat, and here's the kicker: meat requires much more fossil fuel to produce than vegetables and grains. How much more? About 145 times more for beef than for potatoes.1 The reason for this is simple: Cattle consume 14 times more grain than they produce as meat. They're food factories in reverse. So it takes a lot more water, land, and of course, energy to produce that meat. In short, the more meat you eat, the more gas you waste.

David Pimentel of Cornell University calculates that it takes nearly twice as much fossil energy to produce a typical American diet than a pure vegetarian diet. This works out to about an extra 150 gallons of fossil fuels per year for a meat-eater. This means that meat-eaters are "driving" an extra eleven miles every day whether they really drive or not, when we look at how much extra fuel it takes to feed them.2

In fact, meat production is so wasteful that walking actually uses more fossil energy than driving, if the calories burned from walking come from a typical American diet, as reported in Diet for a New America:

"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."3

The same is not true of bicycling vs. driving, because bicycling is more than twice as efficient as walking (calories consumed per distance traveled) -- bicycling uses less fossil energy than driving even if the cyclist were eating nothing but beef.4 But to focus on this misses the point. It's no bombshell that cycling uses less fossil energy than driving. What's important is that meat-eaters use twice as much fossil energy as pure vegetarians -- whether they're bicycling or not.

What does this mean in practical terms?

It means that the amount of gas you use isn't just related to how you get from place to place, it's also related to what you eat. Meatless diets require half as much fuel to produce than the standard American diet. Pimentel calculated that if the entire world ate the way the U.S. does, the planet's entire petroleum reserves would be exhausted in 13 years. The typical American could save almost as much gas by going vegetarian as by not driving.5

Food for thought.

-- Michael Bluejay

Criticism from readers

 

You say it takes more energy to walk somewhere than to drive your car, but this is a fairly meaningless statement since it took a whole lot of energy to create that car and the road it is driving on. -- Edward Pilbrow, Electrical and Computer Engineering, University Of Canterbury, New Zealand

Congratulations on missing 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.

Your analysis does not include the energy that was expended to discover, extract, ship, refine, and then ship and distribute the gasoline.

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.

Your analysis is wrong because it assumes that everything else is equal, but in fact, people who drive tend to go farther distances than those who don't.

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 trip vs. trip comparison. That's it.

What about grass-fed beef?

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 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.

I'm concerned that by biking 24.4 miles roundtrip to and from work I'm not saving as much energy as I thought, since I take an extra shower when I arrive home, and I wash clothes more frequently.

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.

 

Appendix:

How Much More Efficient is Cycling than Walking?

Calories burned in 10 minutes of activity
123-lb. Woman
170-lb. Man

Cycling, 9.5mph
56
74

Walking, 3.5mph
45
59

(1) Cyclists cover 2.7 times as much distance in the same period of time as walkers. (9.5 mph / 3.5 mph)6

(2) 45 walking calories x 2.7 = 121.5 walking calories to cover same distance.6

(3) 121.5 calories vs. 56 calories: (121.5-56)/56 = 117%

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. In that case, cycling is even more efficient than walking.

Related Articles

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.

Footnotes

(1) 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, etc. 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
  • 40,000 kcal energy per 1000 kcal beef protein
  • 40,000 kcal energy per 250 g beef protein
  • 40,000 kcal energy per 1350 g beef (85% lean ground beef, raw, USDA database)
  • 13,481 kcal energy per 455 g beef
  • 13,481 kcal energy per 1 lb. beef
  • 0.435 gallons of gasoline equivalent per 1 lb. beef (assumed 31,000 kcal per gallon; see below)

    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 - David Hershey, faculty, Washington University Medical School, and 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.

    Though in Dr. Pimentel's earlier work he assigns a whopping 38,000 kcal per gallon, he confirmed for me in a telephone conversation on April 8, 2004 that ~30,000 is a better figure.

Potatoes: On p. 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)
  • 160,411 BTUs = 1.41 gallons of gasoline (113,500 BTUs per gallon, as per EPA)
  • Total energy = 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

    Regarding the electrical energy used, most electricity in the U.S. is produced with fossil fuels.

    When I spoke with Dr. Pimentel by telephone on April 8 to confirm my calculation above he said that I should double my result to include fossil-based fertilizers, so let's call it 0.0030 gallons.

Comparison: We thus have 0.435 gallons per lb. of beef vs. 0.003 gallons per lb. of potatoes. That means that beef requires 0.435 / 0.003 = 145 times as much fossil energy to produce as potatoes.

(2) Page 147 of Food, Energy and Society shows that it takes 35,000 kcal of fossil energy to produce 3500 kcal for a typical daily American diet, while it would take only 18,000 kcal to produce a pure vegetarian diet. 3500 kcal is rather high for a daily diet, so we'll assume 2500 kcal instead. With that figure it takes 12,857 extra kcal a day for the non-vegetarian diet, or 4,692,805 extra kcal per year. At 30,000 kcal per gallon of fuel that's an extra 156 gallons per year. At 25 mpg, that fuel could power a car for 3900 miles. Divided by 365 days in the year, that works out to 10.7 miles per day.

(3) 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

(4) 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 itself. 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. However, meat-eaters use about twice as much fossil energy as pure vegetarians, whether they're bicycling or not.

(5) Beyond Beef, Jeremy Rifkin, 1992, p. 225

(6) Calories burned by various forms of exercise

According to the University of Michigan, it takes seven calories of fossil fuel on average to produce one calorie of food.

Here's how agricultural energy consumption is broken down in the U.S.:

  • 31% for the manufacture of inorganic fertilizer
  • 19% for the operation of field machinery
  • 16% for transportation
  • 13% for irrigation
  • 08% for raising livestock (not including livestock feed)
  • 05% for crop drying
  • 05% for pesticide production
  • 08% miscellaneous

    From Comparison of energy inputs for inorganic fertilizer and manure based corn production, McLaughlin, N.B., et al. Canadian Agricultural Engineering, Vol. 42, No. 1, 2000.

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