It is well known that all energy on any planet [whether coal, oil, nuclear, etc.] is dependent on stellar activity for its existence. In most cases it is from the rays of the stellar body shining down on the plant life. The chlorophyll [from indigenous class M worlds] within the plants uses the energy to transform water and carbon dioxide into oxygen and carbohydrates, [which are uses for food].

But that is only part of the process, for if it only required the absorption of solar energy by the plants chlorophyll molecules, artificial systems would be common.

But experiments conducted for the Office of Scientific Research to determine how plants account and correct for the loss of solar energy as heat, have left much to be considered.

Ongoing research into this area may one day produce a wide range of energy alternatives.