Monday, March 20, 2006

What's the mileage on that bicycle?

"Huh! what's that again?"
"You heard that right. Do you know the mileage on that bicycle?"

The logic goes thus. Everything we eat is produced somewhere, processed somewhere and transported to our supermarket and from there to our homes. It takes energy to do that. A major contribution of the energy needed to produce, process and transport our food comes from fossil fuels (the stuff USA is officially addicted to, since January'06). When you eat that sandwich, you are effectively gulping down gasoline. Every time you ride that bicycle, you are burning some of the same energy which came from the fossil-fuels. Naturally this bears the question, "How many miles can you go on that bicycle for every gallon of gasoline you consume (indirectly... through the food you eat)?". Got it? Good!

Lets go over the answer step by step:
1> How much energy does a gallon of gasoline have?
This is called the calorific value of the fuel. This EPA webpage says that the energy content of gasoline is an average 113,000 BTU/gallon. That translates to 28,476 kcal/gallon. (1 BTU = 0.252 kcal)

2>How many gallons of gasoline do you (indirectly) consume?
This depends on the type of your diet. The table below shows the amount of fossil fuel input for different types of diet. These numbers are from the book, "Food energy and society", by David and Marcia Pimentel [1]. Note that all these numbers are for a 3600 kcal daily diet (remember 1 food Cal. = 1 kcal). It is interesting to note here that average American eats ~1500 Cal. more than the daily requirement of 2100 Cal. I have converted the fossil fuel input number into gallons of fuel using the calorific value given above.

3> How many food Calories do we burn while bicycling?
My search yielded a number of different values. I found this table on and a few other websites [this pdf, page 21]. It says that 0.049 Calories are burnt per pound, per minute while cycling at the speed of 15 mph. Another table is given in the Dietary guidelines for America, and can be found on many websites [CDC webpage, also this pdf - page 4]. This says that a person weighing 154 lb, will burn 290 Cal. when bicycling at a speed less than 10 mph, for one hour. Translates to 0.031 Cal. per lb per minute. A person weighing 154 lb, bicycling at 10 mph will have to go 125.7 mile to burn 36oo Cal. daily intake.

DietFossil fuel input(kcal)[1]Fossil fuel input(gallon)Miles to burn 3600 Cal.Mileage (MPG)
Vegetarian (0%)18,2750.64 125.7196
Lacto-Ovo (14%)25,2300.89125.7142
Average US (28%)34,5601.21125.7104

There goes the answer to the question. Bicycling is fun, it is a good exercise and nothing beats the mileage on that bicycle.

[1] Pimentel D, Pimentel M. "
Food, energy and society". Colorado University Press, 1996.

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Related posts:
Vegetarianism, Greens Eat Greens

Thursday, March 16, 2006

Elephant Diaries

There is good news about our baby elephant, Lualeni. She is now the mini-matriarch of the herd of baby elephants in the Nairobi nursery, run by David Sheldrick wildlife trust.

The second part of the news is that the BBC documentary, "Elephant Diaries" [view trailer] aired on Animal Planet on March 5th (Oscar awards night). It is too bad that I didn't publicize it on the blog well in advance and snatch some of the Oscar viewers. We don't have cable, so a friend graciously recorded the documentary for us. It was really great to see the story of this amazing elephant family. We also got a chance to see our baby elephant, Lualeni, on TV. YAY!

When the documentary was filmed Lualeni had just joined the crowd and was not mixing with the others just yet. Elephants are very social animals and have very strong ties to members of their herd. Lualeni's mother was killed by poachers probably in front of her eyes. She was rejected by other elephant herds and was finally rescued by David Sheldrick wildlife trust. When she joined the nursery she was a unhappy little elephant. She kept to herself during grazing and feeding and refused to interact with the other babies. After four months in the nursery though she overcame her grief and now is a very happy, playful elephant. She is now the elderly elephant in the Nairobi nursery and is kind of the mini-matriarch of the herd, looking after other baby new-comers. Here is a audio clip, with Daphne Sheldrick, who established the nursery and the trust, talking about Lualeni.

CBS 60 minutes traveled to Kenya in mid-January to do feature work on the David Sheldrick wildlife trust. Hopefully that feature too will air soon.

I am very much fond of elephants. They are amazing creatures who have a life-span similar to humans. They are social creatures much like us. They are very powerful and yet they can be very gentle creatures. They are endangered because of the constant encroachment by humans on their habitat and due to poaching for ivory. The job that people like Daphne Sheldrick and the amazing team of keepers are doing in raising orphaned baby elephants is very admirable and worth of support. The keepers try to provide the elephant babies the love and care they would have received from their herd. The babies develop a strong bond with the keepers. The trust tries to raise the elephant with the aim of returning them to the wild one day. Towards this end, it keeps them as close to the wild and as much in touch with the jungle as it can. Male elephants graduate earlier than female elephants and are quicker to move into the wild joining the wild herds. The BBC documentary features, Emily, one of the earliest female babies from the nursery, who has recently graduated and moved on into the wild.

Apart from the nursery, the trust also conducts anti-poaching and de-snaring activities and runs a nursery for baby rhino orphans and conducts a lot of conservation related and community outreach activities. Please visit the trusts website and support these wonderful creatures.

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Wednesday, March 08, 2006

Greens Eat Greens

This is a continuation of my previous post about Vegetarianism. In that post, I pointed out that one of the reasons for joining the "veggie" band was - "because it is good for the environment". In other words, "eating greens is important if you truly wish to become Green". In this post, I try to explore this issue of vegetarianism and environment.

In today's globalized world, the food we consume is not necessarily produced in our backyard or even in our country. That bottle of water you may have on your table or that sandwich you just ate for lunch or dinner contained ingredients which probably came from all over the world. Energy is expended at each and every stage in the food production~packaging~delivery chain. Let us have a comparative look at the important steps in this chain for vegetables and for meat (e.g. beef).

  • Growing and harvesting (Fertilizers, Pesticides, Seeds, Farm implements etc.)
  • Packaging (material, process)
  • Transportation and storage (refrigeration, fuel for transport etc.)
  • Processing (most grains are processed into some other product before consumption)
  • Growing and harvesting feed stock for animals (Fertilizers, Pesticides, Seeds, Farm implements etc.)
  • Transportation of feedstock
  • Energy input to the animal farm facility (includes stuff like growth hormones or other drugs given to the animals)
  • Transportation of animals to meat processing facility
  • Meat production
  • Packaging
  • Transportation to final consumer.

It is clear that meat production involves more number of steps than vegetable production. The energy input in most of the cases is in the form of fossil fuels. Most of the fertilizers, chemical pesticides used have significant fossil fuel input in it. Transportation and farm machinery etc. requires fuel. The packaging (e.g. plastic boxes, wrapping etc.) requires fossil fuel inputs. Every morsel of food we consume provides us with energy, which is commonly measured in Calories. 1 food Calorie = 1000 thermodynamic calories or 1 kcal (I can't believe I was unaware of this fact so far!). The energy contained in fossil fuels is also given in terms of "calories/kg" or the calorific value of the fuel. So a simple measure of the energy efficiency of our diet is:
The ratio of calories of energy that we get from the diet to the calories of (largely fossil fuel) energy that go into producing that diet and bringing it to our homes.
% efficiency = 100 x (kcal energy output from food) /(kcal energy input into food)
Now, I am not the first one to come up with this concept. Energy sources are valuable and there have been a lot of studies done to understand how much energy we consume and the way we consume it. David and Marcia Pimentel from Cornell University have done extensive research in this area. Their book, Food Energy and Society [1] contains a lot of data regarding the energy input for various kinds of food production systems. They have calculated the amount of fossil fuel energy (measured in kcal) input in the food production system per kcal of food protein produced, for different food groups (meats, legumes, vegetables etc.). Note that the energy output is only for the protein content of the food a not total energy content. Most meats have large protein content while most grains and vegetables don't. I am tabulating some of the data which is relevant to our purpose here {from [1], chapters 8, 9, 10 and 11}:

Food Products% energy efficiency
Animal Products
Range Beef10%
Range Lamb6.3%

The numbers speak for themselves. It is clear that producing meat and animal products is a highly inefficient operation (in terms of energy efficiency as defined above). It is not simply about fossil fuel consumption. Producing meat/animal products consumes a large amount of land and water as well. But that is a totally different topic of discussion. For some interesting information on that I refer you this study [2]. David and Marcia Pimentel also compare various types of diets in their book. Data collected by them shows {from [1], page 147} that a non-vegetarian diet requires twice as much fossil fuel energy input as compared to a vegetarian diet. Lacto-ovo diet falls somewhere in between these two.

Another interesting study I found online while searching for references is a yet to be published paper [3] by Gidon Eshel and Pamela Martin of The University of Chicago. They have used the energy input data given in [1] to compare the total green house gas (GHG) burden of many different diets (red-meat based, average American diet, lacto-ovo, vegan) with varying percentage of animal products. Without going into details, here are some interesting results one can find in this study {from[3], Figure 3}:
  • The difference between GHG burden of average US diet (27% Animal products) and a totally vegan diet is ~1.5 ton per person per year. Compare this to the difference in GHG burden of Toyoto Camry and Toyota Prius which is ~1.05 ton per person per year.
  • Switching from a red meat based diet (27% animal products) to a lacto-ovo diet (27% animal products) is equivalent to switching from a Toyota Camry to a Prius in terms of the GHG burden.
Anyway, there are many interesting articles, studies, books out there which more or less agree that a plant based diet is more efficient and sustainable than a meat based diet. If you are seriously thinking about switching from that SUV to an energy efficient car, why not think about switching to a plant based diet? At the very least, you can think about cutting down the proportion of meat you consume. If you are a true Green, think about eating green too.

Given below are the references mentioned above and links to other articles I came across while researching for this post. One of the links given have many good tips if you want to switch to a veggie diet. In my next post I want to answer the question - "how many miles per gallon does my bicycle give?". I think I have enough data gathered to do the calculation, so stay tuned.

Update (03/20/2006): What's the mileage on that bicycle?

[1] Pimentel D., and M. Pimentel (Editors), 1996. Food, Energy and Society, University Press of Colorado, 363p. ISBN: 0870813862 [link]

[2] Pimentel D., and M. Pimentel, 2003: Sustainability of meat-based and plant-based diets and the environment. American Journal of Clinical Nutrition, 78(3), 660S-663S. [subscription reqd.]

[3] Eshel, G. and P. A. Martin, 2006: Diet, Energy and Global Warming. In press, Earth Interactions. [pdf link thanks to Judith's blog]

[::] Eating Fossil Fuels by Dale Allen Pfeiffer [pdf link]

[::] Why Our Food is so Dependent on Oil by Norman Church

[::] The Ethics of Eating Meat by Charles Eisenstein. (Makes a case for farm raised animals and ethical meat eating)

[::] Fossil Fuels and Energy Use @ The Sustainable Table (Has many useful tips to have a more sustainable kitchen for both vegetarians and meat eaters).

[::] Veg How To? @ VegForLife (tips for converting to the veggie creed)

Meat Production's Environmental Toll by Stephen Leckie @ Toronto Vegetarian Association

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