Wasted Food Energy

Wasted Food Energy

Reducing food waste could translate into big energy savings.


Wasted food, wasted energy. I'm Bob Hirshon and this is Science Update.

Wasting food is wasting a huge amount of energy. This according to mechanical engineer Michael Webber at the
University of Texas at Austin. He says about 10 percent of energy use in the U.S. goes into growing, processing, packaging, and shipping food. And a good chunk of that energy goes into food that gets thrown out somewhere along the way: about 2,000 trillion BTUs every year.

This is hundreds of millions of barrels of oil; this is more energy than the country of Switzerland uses in an entire year for all purposes; this is more energy than we save by switching to compact fluorescent light bulbs; or more energy than we produce from all the corn ethanol we make in a year as a nation.

Webber notes that even a modest reduction in food waste could make a big contribution to America's energy conservation efforts. I'm Bob Hirshon, for AAAS, the science society.

Making Sense of the Research

There's a lot of talk today about saving energy: for example, by replacing standard light bulbs with compact fluorescents, carpooling rather than driving alone, washing clothes in cold water instead of hot, and so on. All of these are good things to do. However, this study points out that a substantial amount of energy could be saved just by wasting less food.

Wasted food doesn't just include not finishing your meal, or letting broccoli rot in the fridge, although that's certainly part of it. Food waste happens at every point along the way from farm to table. Some crops that are grown aren't harvested; some that are harvested are thrown away before they leave the farm; some food gets thrown away during packaging, processing, and shipping; unsold food gets thrown away by grocery stores and restaurants. That's just a partial listing. And while some of the food that gets thrown away is of poor quality, much of it is perfectly good, or at least was good at one time. 

All told, the study's authors say that 27 percent of edible food produced in the United States ends up wasted. And a lot of energy goes into producing that food.  As you heard, it adds up to about 2,000 trillion BTUs per year. (A BTU, or British Thermal Unit, is about the amount of energy needed to heat one pound of water one degree Fahrenheit.) That's enough to air condition at least 200 billion good-sized living rooms; you heard other comparisons in the radio story as well. 

Making the calculation wasn't simple; the researchers had to break down foods by type, and estimate the energy use per pound of each type of food, as well as what percentage of each type of food is typically wasted. Fresh fruits and vegetables, dairy products, fats and oils, and caloric sweeteners (sugar, corn sweeteners, etc.) were the most wasted—about a third of the edible product from each of these categories gets thrown away. The authors believe their energy estimates are conservative, because the latest available figures were several years old, and their study didn't even account for some types of energy expenditure, like the energy needed to dispose of wasted food.

Reducing food waste won't be easy; it's obviously not as simple as asking kids to clean their plates. The authors suggest studying exactly when and why food gets disposed of, whether that waste could be decreased, and whether the waste-reduction strategy would in fact lower energy use. It's a big undertaking, but could be worth it.

Now try and answer these questions:

  1. How does wasting food waste energy?
  2. When and where might food be wasted during its production and consumption?
  3. Did this study make you think more about the steps involved in getting food to consumers?
  4. What's challenging about reducing food waste?

Going Further

For Educators

An earlier Science NetLinks Science Update lesson, Wasted Food, describes a study that measured how much food a typical household throws away.

Astronauts on long-term space missions will need a lot of food, and can't afford to waste anything. The Science NetLinks Science Update lesson Space Food looks at some strategies that might provide efficient nourishment on future missions.

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