In this overview an attempt was made in order to delineate the biogeochemical cycling of carbon, nitrogen and phosphorous in the Earth’s system and also to relate their occurrence with the Earth’s system Thermodynamics. These global cycles result in the maintenance of a unique thermodynamic state of the Earth’s system which is far from thermodynamic equilibrium. The transfer of matter and energy between the Earth’s systems reservoirs is studied in relation to processes using solar radiation to conserve energy e.g. photosynthesis. The generated chemical energy is used to sustain life, but also to provide additional free energy to geochemical reactions, thereby altering their rates.