Howard Odum

A whole generation of citizens thought that the carrying capacity of the earth was proportional to the amount of land under cultivation and that higher efficiencies in using the energy of the sun had arrived. This is a sad hoax, for industrial man no longe eats potatoes made from solar energy, now he eats potatoes partly made of oil.

                                                                                                      Howard Odum

I got two ideas from Howard Odum, an ecologist and member of the World War II generation who died in 2002.

If an energy source -- be it fossil fuel, nuclear, or solar -- produces a calorie of energy, that calorie isn't its yield, because of all the energy costs of obtaining, transporting, storing and using it. The yield is what it makes, minus what it takes to get it.

Embodied energy is the energy available to us, or that we can use to obtain other energy in some resource: oil, the sun, wind, gravity, manure, water, and so on.