There's more energy in wasted food than there is in the Gulf of Mexico


Recently, while doing some research on the carbon footprint of food, I ran across some studies that reported Americans ate, on average, 3774 calories of food each day.

Something about that smelled funny to me.

Sure, Americans eat a lot. But 3774 calories a day? I have family members who subsist almost solely off fried meat and various sorts of potatoes and I'm not convinced that even they hit that number on a regular basis. When I took my questions to the researchers, I found out that my hunch was correct. Americans aren't, technically, eating an average of 3774 calories per day. This figure is calculated by looking at food produced, divided by the number of Americans. It assumes we're eating all that, but, in reality, according to environmental scientist Gidon Eshel we really only eat about 2800 calories per day. That whopping 3774 includes both what we eat—and what we waste.

And what we waste—not just at home, but from the farm field, to the grocery store, to our Tupperware containers full of moldy leftovers—is a big deal.

We use a lot of energy producing, transporting, processing, storing and cooking food we don't eat. About 2150 trillion kilojoules worth a year, according to a recent study. That's more kilojoules than the United States could produce in biofuels. And it's more than we already produce in all the oil and gas extracted annually from the Gulf of Mexico.

Reducing that waste requires both changes in the way we eat at home, and systematic changes that address waste at every part of the food cycle. Right now, I've talked to a lot of researchers who can identify the problem, but don't have a lot of suggestions for concrete solutions. I'm sure they're out there, though, and I'll report back as I track them down.

Image: Some rights reserved by Flickr user Nutloaf


  1. This sounds like more of an opportunity than a problem. Just find ways to turn the wasted food into biofuel. Renewable energy, without competing with hungry children for feedstock.

    1. Where are all these so called hungry kids in the US? Seems 99% of the people I see around are obese, including the kids.

  2. A major source of the waste is due to the large scale transportation, storage and sale of foods as we do in the U.S. system. Supermarkets, however convenient, are more like department stores than a farmer’s stand along the road.

    I have been amazed at how efficient, healthy and low cost foods could be distributed through programs like Bountiful Baskets and S.H.A.R.E. Programs like these distribute produce and other foods at low cost in regular orders, with little delay. The food is healthy, delicious, and cheap.

    What we need now to eliminate food waste is like the innovations that Dell brought to PC manufacturing years ago. Eliminate the warehouses. Speed up delivery. Reduce costs.

    We’d live in a better world if we could distribute food more efficiently.

    If you’re interested in cheap food, be sure to check out these non-profit programs:

    I’m sure there are similar programs in other areas. If you know of any, please post below. Lots of hungry people out there.

  3. That doesn’t even count the calories fed to animals that doesn’t end up in you, something like ten times as much. So, really, at least 20,000 calories each are wasted.

    Incidentally, this is why the somewhat lower yield per acre of organic farms doesn’t matter a bit. Eat just a few percent less meat, and the change in yield ends up making no difference.

  4. Breakfast:
    Denny’s Grand Slam 1028
    Venti Carmel Macchiato 312

    In-N-Out Cheeseburger 480
    In-N-Out French Fries (125g) 400
    In-N-Out 15oz Chocolate Shake 690

    KFC Chicken Pot Pie 690
    KFC Potato Wedges 260
    Large Pepsi 400

    Before bed:
    x6 12 oz. Pabst Blue Ribbon 900

    = 5160

    USA! USA! USA!

  5. Okay, fine, but isn’t the devil in the details? Don’t get me wrong, I’m a Michael Pollan-loving, flag-waving locavore, but something on the face of this smells wrong to me. From growing my own food in my garden, I am astonished by the waste that I create; from the food that goes bad on the vine due to bugs or rot or that which I accidentally allow to over ripen. And I also don’t think that I should be required, as Anon #7 suggests, to eat the moldy food and potato skins that I would normally compost. Additionally, we all have food that goes bad on us in the fridge. Sometimes it’s because we’re lazy and irresponsible, sometimes it’s because you got a bum bag of lemons that were fated from the start.

    I’m not saying that your conclusions are wrong but I do strongly suggest that first, some food waste is just a part of (first world?) life and that, second, don’t use lies, damned lies, and statistics to bolster what is an important environmental, cultural, and policy issue in this country.

  6. I read with great interest, many years ago, about an electron-beam food irradiator, capable of sterilizing a sealed container of food for almost indefinite shelf-life.
    This technology was described as being about the same size and complexity as a typical microwave oven.
    So, some twelve or thirteen years later, I ask, “Where’s my home food irradiator?”
    With an electron beam (ie, no heavy particles, no persistent radiation danger, no isotopes to fall into the wrong hands) this technology would go a long way to solving the problem of food waste.

    1. Of all the “things we were supposed to get in the future,” I think that’s the one I’d like the most.

  7. Let’s end the massive agricultural subsidies for things like corn and soy, and maybe the market could work its magic.

  8. 2015 trillion kilojoules! Wow! Not one soul in a ten has the foggiest idea how much a kilojoule is! But that’s an amazing number! Because it is very large!

    The abstract of Cuellar & Webber’s paper puts the amount of energy lost to food waste at 2% of the annual energy consumption of the United States. Not as impressive a number as 2015 trillion, I fear, but one that makes it far easier to understand why from an energy perspective, this issue usually garners little more than a “Meh.”

    Still, 27% of food wasted. Wow. And that number came from… drill drill drill… Kantor & Lipton 1997. Who got a bunch of their numbers from the USDA… which is still using “some” numbers from the 1970s. (I’m pulling this from just below table 2, here, gang: “The 1997/95 USDA report also makes use of food waste factors from previous reports, some from the 1970s.”) We don’t do things these days the way we did them in the 1970s.

    Then Cuellar & Webber say, “Due to unaccounted food losses and the potential for increased waste due to economic conditions we expect the results in the present analysis to represent a lower bound.” This comes out of nowhere– particularly the “economic conditions” bit. Maybe it’s sense; maybe it’s madness. We can’t tell from this paper, because it just throws it out there and hurries on to explaining a simple arithmetical operation using Big Sigma notation.

    If there is a specific practice that wastes food, let it be called out and identified; then we can try to figure out what it would cost (in dollars and energy) to stop it. Without that, the numbers– whether 2015 trillion kilojoules, 2%, 27%, or “a skosh under a metric snootload”– are a mere buzz of technobabble.

  9. STOP!

    Food Calories are not ‘calories’. They are kilo-calories. It is very important to get the conversion factor right or you could be off by a factor of 1000 before you even get out of bed.

    (I’m not making any kind of statement about whether the article is accurate or not, but this misconception seems to be popping up more and more these days).

    In summary, if you eat a bag of chips labelled 144 calories, that’s really 144kcal, which is also 602kj.

    Wolfram alpha can make sense of all this for you:

    1. I was going to comment on that.
      It’s an important error because some people know that the average adult intake should be around 2000 K calories, but then they get all confused because marketers deliberately drop the K on every product.

  10. Reducing the amount of food in the math in USA is a drop in the bucket in the world view.

    It’s a feel-good measure. Not bad for awareness, diet and health; but a drip to the global problems of food distributions, energy, and global solutions for the major problems of food and energy world wide.

  11. I was a grocer and food buyer for a lot of years- here is the scoop.

    Fresh produce spoils in the store at 6-8% of total purchases. Groceries 3-5% . Prepared Foods and Meat 6-12% depending on management.

    The customers end up tossing fully half of what they buy at home.

    My guess as to why: No one has time to manage the food at home, and the food is too cheap to make careful management profitable (both at home and at retail)

    American supermarket do about 500B a year in business – all other food stores and restaurants are another 500B.

    Why is it so cheap? Think hard, you know the answer.

    Happy trails

    1. My guess as to why: No one has time to manage the food at home, and the food is too cheap to make careful management profitable (both at home and at retail)

      I think that, and the fact that just about anything can be bought in bulk with best-before dates well into the future have a lot to do with it. The first time my American fiance went grocery shopping in Finland, he was shocked by the small unit size of packaged food, and by how quickly it expired. He was used to shopping at wholesale clubs and buying about a month’s worth of food at a time.

      I think having a car to transport large quantities of groceries also has something to do with it. I didn’t have a car until my fiance brought his, so I typically bought small quantities of food at least once a week. I shopped more often for fresh fruits and vegetables because in the past, I was so broke I literally could not afford to throw food away.

  12. Having my largest garden ever this year (1000 square foot), I have a new perspective on food waste. When my tomatoes finally succumbed to early blight and I pulled them, the amount of ripe tomatoes rotting on the ground was astounding. They fell under the thick parts of the plant that I never saw. You may call it waste, but if you saw how many pounds of tomatoes I harvested beforehand, you’d call it nothing at all. I didn’t even bother scooping the “waste” into the compost; I simply dug it into the beds where it could compost itself into valuable nutrients to be consumed by next year’s tomatoes, or whatever else I grow in that bed. Sunlight goes into the tomato plants, tomato plants grow fruit, fruit composts in the ground, cue music for “the circle of life” by Elton John. The only “waste” in that equation is my labor, and I guarantee you I’m calorie-positive on my garden, at which point who cares if I dig the excess into the ground instead of my waistline?

    Granted, the type of waste this study is talking about is probably more than what I’m talking about, but the distinction between agricultural “overage” and actual “waste” is important.

  13. Did you take out the food that US exports, both unprocessed and processed, as well as ‘food’ that are not consumed by human (ex. soy beans, corn for gasohol, etc.)? The numerator will get smaller. The conclusion might not be be affected by this adjustment, though. I’m sure foods are wasted on a grand scale.

  14. I’m not sure which is worse. That about a quarter of the food calories we produce is wasted (never mind the leverage that represents in actual energy waste), or that even adjusted for actual consumption the average American eats 2800 calories (okay, fine…kilocalories :) ) a day!

    We (Americans) don’t have the corner on wastage, but we sure excel at it.

    On the bright side, when the shit hits the fan (no, I mean worse than it already has), we’ll be able to compensate in a huge way just by being more efficient about how we use up the world.

  15. Having just spent a month here in the US with my nieces (from the UK) Even they are horrified at the portion sizes and packaging sizes of everything in the US. It is no surprise that so much is wasted when you are given more than you can eat and you can only buy packages containing more than you want! Address these two first and the wastage problem will reduce itself proportionately.

  16. Found this – how to calculate calories:

    We normally refer to kilocalories as Calories, so when you see 800 calories on a food label it actually means 800 kilocalories, and the same applies when you calculate an activity that burns 800 calories. When referring to food consumption and energy expenditure we refer to them in multiples of 1,000. Thus 1,000 calories = 1 kilocalorie or kcal.

    A calorie is the amount of energy (or heat) needed to increase the temperature of one gram of water by 1C. So 1000 calories = 1 kilocalorie, is the energy it takes to raise the temperature of 1kg of water by 1 degree Celsius.

  17. More or Less on BBC Radio 4 did an excellent piece on measuring food wastage a while back. Depending on your location you may or may not be able to find it here

    They were skeptical of reports that threw numbers like a third around. These tended to count all organic food as waste, including things like carrot ends, potato peel, chicken bones, tea bags and so on. It assumed something more along the lines of 8%.

    Municipal composting power plants is the obvious answer although I don’t know if they actually turn out to be particularly energy effecient.

  18. I didn’t find the number 2150 trillion kilojoules in the article referenced so I assume it was converted from BTUs.

    I would just want to say that it is a rather peculiar way to use SI-units; 2,15 exajoules or 2150 petajoules would be much easier for a brain accostumed to SI-units.

    That small point said, it was rather thought-provoking article, thanks for that.

  19. well, in our city we container food from supermarkets. due their policies of throwing it away when it expires or when wrappings are ripped of for some reason.( transportation …)
    Once a week we are making a big tour with our bus/van and drive up supermarkets to collect the “waste”. Some supermarkets for some reason dont want us to do so. They drain the food with some shitty milk, washing powder or pickle muck. they are comming up with new stuff all the time. We take it to our place (“Container Bar”) were people can donate(some cents or 1$) and take what they want and as much they want. We also cook with it every sunday in bigger numbers and people from the whole city come up to eat. summer months are a bit hard. the food is rotting away instantly. rest of the year is fine.
    sometimes employees insult us for no reason.
    sometimes police is checking our id when they see us. but usually nothing happens… its the same as always. people and community’s just need to organize. its simple :)

  20. Kevin Costner has allegedly developed a device that skims methane off the ceiling of Taco Bell.

  21. Serving sizes in the US have always been intimidating, especially when you’re raised to not waste food. On our last trip to California my partner and I tried sharing most of our meals. Never left a restaurant hungry.

    Maybe one solution would be to treat food waste like returnable cans, any food that can be converted to biofuels would result in a credit.

    1. >> On our last trip to California my partner and I tried sharing most of our meals.

      Then you are guilty of food piracy.

  22. In the United States, we’re pretty efficient at producing, transporting, and buying food. That efficiency converts neatly to waste when it hits the average US household. I think the problem and solution must be at the household level.

    We should be canning more food, dehydrating more food, freezing more food. If we do those things, we won’t need to buy as much. These are things we used to know how to do, but food is now so cheap that there’s no need to save it. We can just buy more later.

    If we were poorer, that might not be our attitude. Therefore I suspect that this problem will solve itself.

  23. Here’s a question: is the waste a bad thing?

    Wasting electricity is bad, because it (usually) means more coal being mined and burned and more toxic crap thrown into the atmosphere.

    But food is solar-powered. There is waste in farm production and transportation, but that’s not what this statistic is. It’s about the energy contained in the food, and that comes from the sun. A huge amount of sun shines on the Amazon Rainforest, and humans only eat a tiny percentage of it. Is that all a waste?

    1. Yes, it’s a waste if it gets thrown in a landfill where it can’t break down or ever make its way back into the ecosystem as compost. In the Amazon, the decay back into the system is immediate and uninterrupted. Here we throw food waste down the sink disposal where it has to be cleaned out of the public drinking water system…or throw it away with all the rest of the waste that doesn’t decompose.

      I have a crackpot sci-fi theory that deep inside the base of all the world’s great mountains lies some previous civilizations landfills.

      1. Actually, our municipal water system takes the solids out of the waste stream and composts it then sells it as a soil amendment. It’s a damn good one, too – smells bad for a couple weeks then provides really amazing nutrients for the plants. You can still tell where I used some in my yard three years ago because the grass is thicker and greener.

        @SamSam: Sadly, our city closed their trash burning power plant. They had a constant problem with dioxin pollution and the residents around it faced serious health risks due to that. They finally gave up, closed it, and sold it off for pennies on the dollar. It’s since been torn down. They couldn’t make a go of it financially, who knows if better management or newer equipment would be able to do so.

  24. In other news, just think of all that solar power that is wasted by landing on grassland, which some poor bugger has to mow.

    Seriously, while the wasted energy in transport and fertiliser may be important, the calorific value of the wasted food is not, since it is mostly just sunlight.

    And good luck transforming your mouldy peaches into biofuels. It’s a bit more difficult than that. Least of all the problem that collecting my tiny amount of fruit/vegetable waste would use more fuel than it could generate, even if you had some magic omnifruit harvester (I think that only exists in Penny Arcade comics and it’s a little unsafe).

    1. Seriously, while the wasted energy in transport and fertiliser may be important, the calorific value of the wasted food is not, since it is mostly just sunlight.

      Ah well, there you’re wrong. In the U.S. anyway, industrially-produced food is largely made of petrochemicals. The sunlight is just a convenient way to coax the plant into converting petrochemicals, in the form of synthetic fertilizer, pesticide, and diesel fuel to run equipment, into food. After the plant has done its work, further inputs of petroleum are used to convert the raw plant material into a processed food product.

      Even in the case of fruits and vegetables, which are sold raw and in their original form, massive inputs of petroleum are present, in the form of diesel fuel to transport the food from its source–sometimes in foreign countries, but often thousands of miles away in the U.S.–to its destination.

      And then, in the most extreme example, you have greenhouse-grown, hydroponic products, like some lettuces, in which case even light is provided artificially. Sunlight was so yesterday!

  25. What helps is to buy local (use less energy to transport), buy seasonal (less energy use ti grow/feed), and buy on the market (buy what you need, and use less packaging materials).
    Oh yeah; leave your car at home and use a bike.

  26. While we may waste a lot of food due to rot, it’s probably an even worse problem in the third world.

    Planet Money/This American Life’s series on Haiti and the problem with mangoes illustrates the issue. Because the mango growers don’t have a way to wash the mangoes, or even plastic crates to store them in, they loose a huge percentage of the crop.

  27. And good luck transforming your mouldy peaches into biofuels. It’s a bit more difficult than that.

    I think that a whole bunch of people, including all the people telling others not to confuse Calories with calories, are confused about the premise of this article.

    Although the article’s title is “There’s more energy in wasted food than …”, and the photo shows moldy fruit, and the article starts with a discussion on the amount of Calories in wasted food, it seems to just be about the wasted energy in actually producing, transporting and storing the food. Energy measured in things like gallons of petrol. It’s not talking about the energy locked into the wasted food. But this was a little confusing because the article seemed to be about to go in a different direction.

    If we stayed in that direction, however, it actually isn’t so hard to turn moldy peaches into energy. Mass incineration is a very viable way of getting more energy out of the trash we throw away each day. If done well, it can be very clean burning, and, besides getting practically “free” energy (energy that would otherwise have been thrown away), it cuts down on solid waste. It really seems unfortunate that every city doesn’t invest in large trash incinerator plants.

  28. Ok, so I took the numbers the author posted and did my own calculations and well, the author doesn’t know their algebra. It only comes out to be only 1 trillion joules. I believe the author did their algebra wrong because they were not thinking in food calories and in chemistry based calories. Stupid mistake that a lot of my students make but it would explain why they are off by a thousand.

  29. 1.21 GIGAWATTS?!

    St. Paul, Minnesota runs a combined heat and power plant running on wood residue biomass. Why couldn’t we do the same thing throughout the entire USA? Walk out behind the restaurant or grocery and dump your wasted chow into the energy recycling bin. Put the unemployed to work sorting biomass.

    Free cooling and heating, completely renewable, and we could even stop paying farmers not to grow corn.

  30. *ONLY* 2800 A day??!!! No wonder we’re fat. I barely eat half that, so who’s eating my share? Dare I watch “the Biggest Loser” and find out?

  31. I’m glad the first comment was about composting: that’s what I do! The other side of that coin is, use that compost to grow your own food!

    Also, as somebody who worked in the restaurant industry for 7 years, I am frankly surprised the number is not higher. Every day we would haul out trash bags so full of wasted food . . . everything from scraps left from prep, to “dead” food (customers sent it back, or it never went out because it was screwed up, etc) and just food that had past expiry, I mean multiple trash bags so heavy only the strongest employees could lift them. Every day in every restaurant, and none of this stuff is composted or recycled.

  32. My guess as to why: No one has time to manage the food at home, and the food is too cheap to make careful management profitable (both at home and at retail)

    I think it has more to do with forgotten knowledge. I think that people think they are properly storing their food in the fridge when they may not, and the quickness at which the food rots is just considered normal. For example, most people buy a head of lettuce at the supermarket. Stick it in a plastic bag at the supermarket and take it home. Once home they toss the plastic bag in the vegetable bin and voila the lettuce is stored. Little do they know that the lettuce that is in contact with the plastic bag is going to rot quickly. If only they had taken the lettuce out of the bag and wrapped it in a paper towel before returning it to the plastic bag, it would last much much longer. Now if they had forsaken the bag altogether, the lettuce would wilt quickly in the super dry refrigerator environment. Even in the vegetable drawer which doesn’t really work all that well.

  33. I could never stand working in a restaurant because just going to them I’m amazed by how much food people throw away. I’ll see fully half of a person’s meal just left behind, they don’t even take it to go. Not only is it a waste of food but I have to wonder if these people care about how much money they wasted. You bought a $16 entree and ate $8 worth? Stay home next time.

  34. I’m freegan. 95% of my food comes from supermarket dumpsters. trader joes is my fave. i don’t know why the stores aren’t sending the edible but unmarketable stuff to food banks. our town does have ‘second helpings’, which collects uneaten food from restaurants, and trains volunteers into chefs.
    I notice my roommates will fix eggs or open a can, instead of looking in the fridge to see what fresh food needs to be eaten today.
    Part of the problem is immigration policies. We don’t have Indian kids begging on the sidewalks, so we are insulated from seeing the harm done by american wastefulness. Part of the problem is the schools, which are doing their best to disrupt traditional american food practices and recruit customers for fast food joints.

  35. In case it hasn’t been pointed out already: Food energy is not industrial energy because no one has ever figured out how. How much energy is wasted producing and transporting food? That has absolutely nothing to do with how much chemical food energy is dumped in a landfill.

  36. As an unemployed (without benefits for the past 2 months) single mom I have to watch each penny I spend and waste no food. You’ll become very creative and efficient in using your resources. We are lucky to have been invited by a friend to live on her farm. So we have a veggie garden and chickens. Nothing goes to waste here! Scraps go either to compost or the chickens. We are also lucky to have access to local, fresh food via and since the farmers only bring what the customers have ordered on-line there is no waste at the farmers end either! It has some positive sides to be on a tight budget: you waste less, eat healthier, and lose some weight as well!

  37. I wonder if a methane digester would work? I don’t know the mechanics behind them, but if they could perform efficiently small scale, I could see them being an option like a home wind turbine or solar panels. Maybe they’d feed a battery bank?

    Here’s a good article about the use of them with dairy farms here in Michigan and at Michigan State.

  38. In Back To The Future 2 (one of the greatest films of all time) “Doc” Emmett Brown has a Mr. Fusion hooked up to the time machine. He inserts garbage- tin cans, wrappers, AND banana peels/other food refuse. This has been in the back of my mind since I first saw the film- there is energy stored in our waste, and when it decomposes (I’m talking about just foodstuffs here) that energy is released. There has to be a way to harness this energy like the Mr. Fusion.

  39. The supermarket’s wholesome-looking produce department represents a huge amount of waste. Produce is damaged in transport and in being displayed, much of it must be kept chilled, and much more of it spoils before it’s eaten, either before or after it’s purchased. Freeze-dried fruits and vegetables in gallon cans are a great alternative for me: the freeze-drying process seems to use much less energy than the constant chilling of fresh produce does, and the transportation of freeze-dried food uses less energy because the food weighs so little. No home refrigeration is required, the food lasts for decades unopened and for at least a year after opening, it’s easy to use just the amount needed, the nutritional value is high, only warm water is needed to prepare the food (saving more energy), and there is no waste at all. I only learned this because a disability made it impossible to buy fresh produce, so I began ordering cans of single ingredients from camping-supply stores. I wish more people knew that they could easily boost their produce intake this way; lettuce and cucumbers are the only produce that I haven’t found available freeze dried (and eggs, milk, meats, and cheeses are also sold that way). Freeze drying isn’t just for survivalists and backpackers; it makes sense.

  40. I’ve been thinking about for a while. I drive by hundreds of orange trees that never get harvested every year!

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