The process by which low energy carbon compounds are transformed into high energy compounds such as glucose is called photosynthesis.
The process of photosynthesis begins when radiant light energy from the sun is absorbed by a green pigment in plants called Chlorophyll. Carbon from carbon dioxide is then captured by the plant, and higher energy carbon molecules, such as glucose, are built. Chemical potential energy is stored in glucose's carbohydrate bonds, and these bonds can be broken to fuel the production of ATP.