Clean Your Plate, Save Energy

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ENERGY WASTE About 2% of U.S. energy consumption gets tossed into the kitchen trash can.

When you look to conserve energy around your house, you might insulate drafty windows or replace incandescent light bulbs. But a new study suggests that you should focus on your kitchen's trash can. Researchers now estimate that the U.S. throws away about 2000 trillion Btu of energy each year as food waste—a figure equivalent to Sweden's annual energy consumption (Environ. Sci. Technol., DOI: 10.1021/es100310d).

This year, the U.S. Department of Agriculture estimated that food production accounted for 15.7% of the nation's total energy demand. But the last time the USDA calculated how much food people throw away was 15 years ago. In that 1995 study, the department reported that 27% of food produced in the U.S. went to waste. 

Michael Webber and Amanda Cuéllar of the Center for International Energy and Environmental Policy at the University of Texas, Austin, wanted to calculate the energy we lose today by throwing away food.

Using government agricultural data and previous studies, the researchers estimated the amount of energy used at each stage of our food’s life, from farming to industrial food processing to cooking. They crunched the numbers for each part of the food pyramid separately, including grains, dairy products, meats, and fats and oils. To estimate how much food we waste now, they extrapolated from the 1995 USDA data and assumed that the rates increased linearly.

When they tallied up all the lost energy for each food group, dairy was the biggest energy sink; and the sum of all wasted foods accounted for about 2% of the nation's annual energy consumption. Although that seems small, Webber calls it a big deal: In 2007, oil companies extracted about the same amount of energy from offshore crude oil production.

But with relatively low food prices in the U.S., few good solutions exist to prevent people from throwing away energy. So Webber suggests that the USDA start a new baseline study of how much food we waste to help better illustrate the energy consequences.

David Pimentel, who studies energy use and sustainable agriculture at Cornell University, concurs. He thinks that Webber and Cuéllar's energy estimate is a little high, but he's glad they "took a whack at it."  

Chemical & Engineering News

ISSN 0009-2347

Copyright © 2011 American Chemical Society