The aerobic system of energy production uses glycogen, but primarily glucose as its energy source.
Glucose is taken in by the cell and broken into pyruvate in the process of glycolysis, the first step in aerobic cell respiration. It takes place in the cell cytoplasm.
Pyruvate is then used in the Krebs cycle in the cell mitochondria in the second step of respiration which produces high energy electron carriers. These high energy electron carries such as NADP are then employed in the electron transport chain, the last step of the respiration process, where a large number of ATP molecules is produced.
By the time the process of aerobic respiration ends, 36 to 38 molecules of ATP are produced from one single molecule of glucose.