Eat your leftovers

How America’s wasted food could power Switzerland for a year

Nov. 20, 2010

AUSTIN, Texas — Of all the polices and campaigns to save energy in the U.S., from switching to compact fluorescent light bulbs to pumping billions of dollars into corn ethanol production, one of the simplest and most underused ways to curb energy use might be in the advice our grandmothers have been giving us all along: Eat your leftovers.

Michael Webber
Dr. Michael Webber

Each day, American households on average throw away at least one and a half pounds of food that, depending on which numbers you look at, represent between a quarter and a half of all the food produced in the U.S. Worse yet, the amount of squandered food is said to increase during the holiday season, a reflection of the same overindulgence that spurs overeating this time of year and pushes losing weight or getting fit to the top of the New Year’s resolution list.

But with every half-full, expired milk carton or rotten apple that is wasted, so is the energy it took to produce them.

Food waste has been studied for the past two decades, but for the first time a new study by Cockrell School of Engineering Professor Michael Webber quantifies the amount of energy in the U.S. lost in food waste. The study was published in the American Chemical Society’s Environmental Science and Technology journal earlier this year and shines a light on a policy option that’s long been overlooked but is gaining attention as food shortages around the world have drawn awareness to the relationship between food and energy.

The study, co-authored by former research associate and University of Texas at Austin chemical engineering and Plan II alum Amanda Cuéllar, calculated that the U.S. could save roughly 2 percent of its total energy consumption in one year if it stopped wasting food.

The number might sound small, but it’s the energy equivalent to saving 350 million barrels of oil.

“That’s about twice as much energy as Switzerland consumes in a year for all purposes, so we could power them up and then some,” said Webber, an assistant professor in mechanical engineering and the associate director of the Center for International Energy and Environmental Policy at The University of Texas at Austin. “The amount of energy embedded in the food we throw away is more than all the energy we get from the corn ethanol we produce in a year, so this is a big number and it’s a big, underutilized policy option for us to consider.”

Food waste and energy in America by food group, percent of food energy wasted and total energy lost

Webber is not alone in his thinking. The study has caught the attention of the National Institutes of Health, U.S. Department of Agriculture and the U.S. Environmental Protection Agency, among others, who are teaming up with him with hopes of conducting an updated study on the ties between food and energy and how much of both are lost during production, distribution and preparation. Webber and the agencies are trying to secure funding for the research, with the intent of starting a broader program of study in 2011.

“As a nation, we’re struggling with energy issues and reducing food waste is not the only answer to problem, but it might be one of the easiest to implement,” Webber said.

How America throws away a quarter of its food

Webber first became conscious of food waste while working as a waiter for six years during high school and college, where he got his undergraduate degrees in Plan II and aerospace engineering at The University of Texas at Austin.

Years later, just after earning his Ph.D. in mechanical engineering at Stanford University in 2001, his interest was piqued again when he invented a laser-based sensor used to measure the ammonia emissions from cow manure, a precursor to the formation of air pollution.

The purpose of Webber and Cuéllar’s study was to synthesize separate bodies of research on energy in the food system and food waste to determine how much energy is embedded in food waste. One research question that motivates the study is whether improving the food system’s efficiency could have substantial energy savings and help reduce greenhouse gas emissions.

They calculated the energy required to produce food from agriculture, through transportation, processing, retailing, preparation and consumption, and found energy is wasted on all levels of the food chain.

Of wasted food, fruits and vegetables require the least energy to produce, but are among the most commonly squandered foods, while meat requires nearly 30 times more energy and is the least wasted food. Nearly a third of all fats, oils, grains and dairy products in the U.S. are thrown away, according to the study.

Poster that reads 'Food is a weapon. Don't waste it! Buy wisely. Cook carefully. Eat it all.'

During the two World Wars, being penny-wise with food was considered a patriotic duty and was emphasized through propaganda posters such as “Food is a weapon — don’t waste it,” pictured above. After the wars, such sentiments diminished as incomes in the U.S. grew and an increased supply of food caused prices to drop.

Webber said the findings most likely underestimate the problem because it uses statistics on food waste from 1995, the most recent data available from the U.S. Department of Agriculture. The federal data estimate that 27 percent of food in the U.S. is wasted, but some research suggests the number is closer to 50 percent.

When it comes to the amount of energy required to produce food, the study estimated it takes at least 8 percent of the nation’s total energy though others project the number is now 16 percent, Webber said. The federal data, he said, does not account for waste at fisheries, on the farm and during processing – three things that are needed for a more accurate understanding of our food waste.

“The waste for food isn’t happening at one particular place. It’s happening all up and down the food supply chain, from the farm, the trucks carrying the food away from the farm, at the processing plants, restaurants and of course at home,” Webber said. “I think we all have some old jar of pickles in the back of our fridge that we should throw away.”

Changing attitudes about food

Webber’s study focused on food waste in the U.S., so it is unclear how Americans compare to other countries when it comes to wasting food, but traditionally larger portion sizes are served in the U.S., suggesting that more of it also ends up in trashcans.

Food was not always so devalued in America. During the two World Wars, being penny-wise with food was considered a patriotic duty, one that could help the war effort, and was emphasized through propaganda posters like “Food is a weapon — don’t waste it” and “Food will win the war.”

The sentiment was not just a patriotic guilt trip. It was a necessity. The Great Depression fell between the wars, and in spring 1942 the Food Rationing Program was implemented as most Americans struggled simply to get by.

In his new book, “American Wasteland,” food waste expert Jonathan Bloom writes that parents of Baby Boomers faced a decision on how to treat their children that pitted their experiences with hunger in the 1930s and 1940s against the postwar euphoria and abundance sweeping the nation. They could either preach to their children to clean their plates or let them eat whatever they wanted. The latter idea won, Bloom writes.

Pesticides and chemical fertilizers soon became commonplace, allowing U.S. farmers to produce and sell more food, and the increased supply meant food prices dropped while incomes in the U.S. grew.

“There’s a behavioral issue here and it’s related to how much we spend on food,” Webber said. “Food’s relatively cheap in America, so we don’t value it as much and we don’t mind if we throw it away.”

Webber said further research on energy and food waste is needed to better understand the problem, but taking several steps at the policy-level could go a long way, like encouraging smaller portion sizes, creating public awareness campaigns on food waste and energy, and investing in temperature-sensitive expiration labels that indicate whether food has been exposed to the wrong temperature for too long.

“We use a crude system right now and there’s a lot of food that’s good well past the expiration date, and there’s also some that goes bad before it’s supposed to because it was exposed to the wrong temperature at some point,” Webber said.

At the consumer level, we can reduce our contribution to food and energy waste by taking simple, basic steps at home, in the grocery store and at restaurants.

For starters, Webber suggests planning a food menu before each trip to the grocery store so it’s easier to keep track of when vegetables, fruits and other perishables need to be eaten throughout the week.

Careful attention should also be given to how food is stored and wrapped in the refrigerator so it doesn’t spoil as quickly, and consumers should remember to buy only what they will eat.

When in doubt, follow grandma’s advice: Eat your leftovers.

For more information, contact: Melissa Mixon;
Banner photo and photo of
Dr. Michael Webber: Christina Murrey

Infographic design: Robin Peeples