Food for thought: How energy is squandered in food industry

For a nation fixated on the responsible use of resources, we're surprisingly wasteful with energy when it comes to putting food on the table.

From the diesel fuel tractors that harvest our crops, to the refrigerated trucks that transport products cross-country, to the labor-saving technology found in the home such as toasters and self-cleaning ovens, the U.S. food system is about as energy inefficient as it gets. And it's only getting worse.

A fall 2010 report by the Department of Agriculture's Economic Research Service, ERS, called "Fuel for Food: Energy Use in the U.S. Food System," found that while energy consumption per capita fell by 1 percent between 2002 and 2007, food-related energy use grew nearly 8 percent, as the food industry relied on more energy-intensive technologies to produce more food for more people.

Between 1997 and 2002, in fact, over 80 percent of the increase in annual U.S. energy consumption was food related.

And estimates for 2007 suggest the U.S. food system accounted for nearly 16 percent of the nation's total energy budget, up from 14.4 percent in 2002, according to the report, which measured both the direct energy used to power machines and appliances (like trucks and microwave ovens) as well as the "embodied" energy used to manufacture, store and distribute food products.

"This is what they call a fossil fuel party," says Kamyar Enshayan, director of the Center for Energy & Environmental Education at the University of Northern Iowa. "We've created a food system that relies heavily on fossil energy, and it's become so globalized that there are literally grapes from South Africa in the grocery store in Cedar Falls, Iowa. It's a long-distance shipping economy, which makes all of us vulnerable to disruptions in the supply chain and other unforeseen emergencies."

That's particularly troublesome, he notes, when so much of the U.S.  particularly the Midwest  has such potential for primary production.

"We have the best soils and a great climate and yet, most of what we eat is imported," says Enshayan. "You have to step back and say, 'Wait, why is a region like Iowa not feeding itself?"

The environmental consequence of relying so heavily on a national and international network of suppliers is even greater, he notes.

"It dulls our imagination and prevents us from paying attention to what sustains us," says Enshayan. "The loss of water and soil quality is right in front of us, but since our food doesn't come from it, why worry?"

And then, of course, there's the impact on our climate.

"The production and distribution of food has long been known to be a major source of green house gas and other environmental emissions, and, for many reasons, it is seen by many environmental advocates as one of the major ways concerned consumers can reduce their carbon footprints," writes Christopher Weber, an environmental engineering professor at Carnegie Mellon University, in a 2008 paper called "Food-Miles and the Relative Climate Impacts of Food Choices in the Unites States" that he co-authored with H. Scott Mathews.

According to the report, the average household's climate impact related to food is estimated to be 8.1 t CO2/yr, or tonnes of CO2 equivalent a year, a common measure for determining how much global warming a type of greenhouse gas may cause.

To put that figure into perspective, driving a car that gets 25 miles per gallon roughly 12,000 miles produces 4.4 t CO2/yr.

Why So High

One of the reasons energy use in the food system is growing so rapidly is that there are more of us to feed.

The U.S. population grew by more than 9.7 percent to 308.7 million in 2010, according to the Census Bureau.

A second culprit is higher food expenditure for the amount of food marketed to U.S. consumers, which boosted food system energy use in America by 25 percent, the USDA report notes.

By far, though, the use of energy-intensive technologies as a substitute for manual labor is the biggest contributor.

An example: High tech, energy-intensive hen houses  and the growing use of liquid, frozen and dried egg products (instead of whole eggs)  increased energy use per egg by 40 percent between 1997 to 2002, the USDA report found.

The same is true in kitchens across the country.

In fact, with our penchant for labor saving technologies, (not to mention the second refrigerator in the basement) households are the biggest energy users in the food chain  29 percent of total food system energy use, according to the USDA.

ERS estimates that food related home energy use increased by 3.9 percent per meal between 1997 and 2002.

"Consumers are relying on blenders and food processors instead of knives and chipping blocks, and self cleaning ovens have replaced EASY-OFF and elbow grease," the report states. "Modern appliances, while sometimes more energy efficient, still require energy to manufacture and operate."

Buying Local?

There's little debate, then, that energy use in the global food system is unsustainable.

But there's less agreement over how best to extract efficiencies.

Environmentalists insist the answer is to "buy local," since fewer transport miles translate into fuel savings and fewer emissions.

But that's not a complete solution.

In a 2001 study published by the Leopold Center for Sustainable Agriculture at Iowa State University, the "conventional" food transportation system, which uses national suppliers to stock grocery stores with fruits and vegetables is, indeed, the most energy intensive.

But the local system touted by conservationists, in which farmers market directly to consumers through community supported agriculture enterprises like farmers markets, was also found to be less efficient than using a regional network of suppliers.

"From a purely transportation perspective, the regional system was by far the most efficient," says Pirog, associate director of the Leopold Center, who maintains the findings are equally valid today. "We found that the regional food system was anywhere from 8 to 17 times more fuel efficient than the national system, but also 4 times more efficient than the local system."

The energy impact of food production, of course, also depends on geography.

While some studies have shown that vegetables grown locally require two to three times less energy than their imported counterparts, a 2008 study at Cornell University surprisingly found that it required four to six times more energy to produce perishable crops year-round in greenhouses in upstate New York than to truck them in from California.

That's partly because of the increased fossil fuels required to heat the greenhouses, but also because the larger mega-farms in the West benefit from economies of scale, or the cost and energy advantages of producing large volumes.

"Accounting for energy use in agriculture is very complex," says Miguel Gomez, an assistant professor at Cornell's Dyson School of Applied Economics. "We've done studies that look at these huge farms with irrigation and transportation, and compared them with more localized food supply chains, and in terms of energy use it is not clear which one is more efficient."

While new heat retention technologies that use solar power and compost to warm greenhouses may eventually give local farms the energy upper hand, a more immediate solution (from an environmental perspective) to reduce energy consumption may be to change the way we eat.

In his food-miles paper, Weber notes that red meat is about 150 percent more intensive on green house gas emissions than chicken or fish.

"Thus, we suggest that dietary shift can be a more effective means of lowering an average household's food-related climate footprint than 'buying local,'" he writes. "Shifting less than one day per week's worth of calories from red meat and dairy products to chicken, fish eggs or a vegetable-based diet achieves more GHG reduction than buying all locally-sourced food."

Adds Pirog: "We are still using way too much energy and fossil fuels to produce and provide our food, but there is much room for improvement. There are all sorts of natural systems being studied [for farm production] and some of the larger food companies are starting to see the value of more regional multi-state procurement systems rather than just relying on getting everything from China."

Copyright 2011 CNBC.com.