I spend a fair amount of time thinking about how to reduce my family's dependence on energy, particularly energy derived from fossil fuels. I commute to work by bicycle or bus, install compact fluorescents when light bulbs burn out, replace major appliances with the most efficient ones I can afford, and cast jealous glances at my friends who drive hybrids or alternative-fueled vehicles. But until recently, I didn't think of myself as an energy glutton simply because of the food I eat.
Then I read an astonishing statistic: It takes about 10 fossil fuel calories to produce and transport each food calorie in the average American diet. So if your daily food intake is 2,000 calories, then it took 20,000 calories to grow that food and get it to you. That 20,000 calories of energy is embedded in the food. In more familiar units, this means that growing, processing, and delivering the food consumed by a family of four requires the equivalent each year of almost 34,000 kilowatt-hours (kWh) of energy, or more than 930 gallons of gasoline (for comparison, the average U.S. household annually consumes about 10,800 kWh of electricity, and about 1,070 gallons of gasoline).
In other words, we use more than three times as much energy to obtain our food as to fuel our homes (nearly as much as we use to fuel our cars). The power of this equation is especially revealing when applied to school lunch. According to 2005 USDA National School Lunch Program participation figures, 29.6 million American school children were served nearly five billion meals at school last year. Typically these meals are highly processed, filled with conditioners, preservatives, dyes, salts, artificial flavors, and sweeteners. Usually they're individually portioned and packaged, and travel thousands of miles to the school cafeteria.
School meals are commonly delivered frozen, wrapped and sealed in energy-consumptive packaging, and in need of some interval in a warming oven to thaw before being served to students. Studies of packaging and plate waste in school cafeterias indicate that, every day, as much as half, by weight, of these hasty, unappetizing, low-nutrient, highly processed and packaged meals is tossed by students — unopened, unappreciated, untasted, unrecycled, and uncomposted. The energy needed to collect and transport the waste generated by school lunch must also be added to the net energy embedded in the meal.
Overall, about 15 percent of U.S. energy goes to supplying Americans with food, split roughly equally between crop and livestock production and food processing and packaging. David Pimentel, a professor of ecology and agricultural science at Cornell University, has estimated that if all humanity ate the way Americans eat, we would exhaust all known fossil fuel reserves in just seven years.