Our water. This is no surprise, it takes an insane amount of clean water to make things we use in our lives from computer chips, to cars, to, well, more water. I assumed water would be needed in the creation of Ethanol, the much touted 'green' alternative energy source here in the Midwest, a salvation looked to by farmers who are being pressed by international competition and agri-corps. But I never knew how much water it takes to make 1 gallon of Ethanol and was shocked to learn it takes 3.7 gallons! Ethanol has been a controversial alternative fuel for decades, mostly because it takes more energy per unit to produce with current methods than can be derived out of it as a fuel source.