The apple might be an emblem of simplicity, but accounting for all the energy needed to produce one is another matter. You have to factor in pesticide production, fertilizer manufacturing, irrigation, harvesting, sorting, and transportation. Electricity and diesel fuel are needed to drive all these steps, and coal mining and oil extraction come with their own energy costs. And that’s just the apple. These numbers, compiled by a team at the KTH Royal Institute of Technology, in Stockholm, show that energy inputs can vary wildly from one foodstuff to another.
As they were gathered in Sweden, the numbers don’t necessarily apply to the food in your local supermarket. But they do help illuminate how much energy consumption is dependent on diet. “Food choices matter,” says Gidon Eshel, an environmental scientist at Bard College, in New York state. In the United States, for example, food accounts for between one-fifth and one-quarter of a person’s energy footprint, Eshel says. He’s calculated that, for the average American, simply replacing meat-based calories with eggs and dairy products would result in an energy savings akin to switching from a Camry to a Prius. —Brandon Keim