Exolectrogenic activity of a green microalgae, Chlorella vulg.

Bio-photovoltaic cells (BPVs) are a new photo-bio-electrochemical technology for harnessing solar energy using the photosynthetic activity of autotrophic organisms. This is a new technology for the production of sustainable and "clean" energy. Currently power outputs from BPVs are generally low and suffer from scarce efficiencies. However, a better understanding of the electrochemical interactions between the autotrophic microorganisms and conductive materials will be likely to lead to increased power yields. In the current study, the green microalgae Chlorella vulgaris was investigated for exoelectrogenic activity. To assess the exoelectrogenic activity of C. vulgaris a particular bio-photovoltaic cell was designed and built. The most important element is represented by the electrode configuration, based on inexpensive materials, with the anode immersed in the cultural broth and the cathode exposed to the atmosphere. This configuration represents a very interesting simplification for the cell design, furthermore allowing a simple illumination of the algal culture via a light source positioned above the cell, perpendicular to the electrode surface. This new kind of bioelectrochemical system does not need organic substrate and mediators, and the net production of CO2 is zero. This device was then characterized by measuring the electrical performance of the BPV. A power density of 14 μW/m2 was recorded, revealing interesting potentialities for green unicellular algae fuelled BPVs.