Energy is required to make food. Whether we feed cows to produce milk or apples from the trees, energy is required in different forms from the beginning to end. 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. Here is a list of some items of foods in Sweden.
Even specially bred hens for this purpose convert food to eggs with only 15-20% efficiency. To produce 1 kilogram of eggs the energy required is 18 Mega Joules.
Shelled Shrimp, wild
High energy cost comes from fuel required to run a shrimp boat. Energy required for 1 Kg of Shrimp when it reaches your home is 220 Mega Joules
Fuel required in importing adds to the energy cost. But lower perishing rate means that they can be transported by cheaper means like ship. Energy required for 1 Kg of apples when it reaches your home is 8.6 Mega Joules
Requirement of food for dairy cows is far less than cows reared for meat. Milk energy requirement makes it most efficient. Energy required for 1 Kg of milk when it reaches your home is 5 Mega Joules
Note: These calculations refer to the energy requirements for these products in Sweden in September 2013