• ...A one-pound box of prewashed lettuce contains 80 calories of food energy. According to Cornell ecologist David Pimentel, growing, chilling, washing, packaging, and transporting that box of organic salad to a plate on the East Coast takes more than 4,600 calories of fossil fuel energy, or 57 calories of fossil fuel for every calorie of food.

    Michael Pollan (2006). “The Omnivore's Dilemma: A Natural History of Four Meals”, p.180, Penguin