In recent years, many research groups have proposed green energy technologies that are aimed at producing significant electrical current without polluting the environment. One such technologies utilizes the natural solar energy conversion system of nontoxic cyanobacteria (such as Spirulina) to produce photocurrent in bio photo electrochemical cells. Under illumination, cyanobacteria perform external electron transport which can be exploited to reduce the anode in the electrochemical cell. However, the mechanism of electron transport between the photosynthetic membrane and the anode is still unknown. It has been postulated that electrons may be mediated by small molecule metabolites, naturally found within the cells. In this study, the electron mediator NADH was identified as such potential mediator in several organisms using excitation emission matrixes. Addition of the identified molecules to the bio photo electrochemical cell significantly increases its photocurrent production.