A biological method for yielding oxygen comprising two steps, first the step of generating oxygen and second the step of extracting oxygen for subsequent usage. In the first step, oxygen is produced by a photosyntheicc reaction wherein the photosynthetcc reaction is carried out by a chlorophyll containing entity, which is any cellular, for example algae, or extracellular complex containing chlorophyl, for example isolated chloroplast, in a liquid medium so that atleast a part of the oxygen so produced is in dissolved state in the liquid medium. The second is a step of extracting oxygen from the liquid medium for subsequent usage wherein atleast a part of the oxygen so extracted is obtained by imparting a physical change to the liquid medium. In the second step, the oxygen that is dissolved in the liquid medium is extracted from the liquid medium for subsequent usage. Subsequent usage includes storage of the oxygen for future use as well as direct use without intermediate storage.
