Animal fats and plant oils are sometimes used as sources of fuel for automobile engines. How is energy harvested from these molecules? They contain long chains of hydrogen and carbon that, when broken, release the energy stored in the bonds linking the atoms together. They contain hydrogen and carbon tails linked by disulfide bridges that, when broken, release chemical energy. They contain multiple phosphate groups that each release energy when "liberated" from the molecule chemically. They contain long hydrophobic regions that, when mixed with water, generate explosive resistances. They contain long carbon tails, and each atom has unpaired electrons that are released on exposure to extreme heat and pressure.