Improving conversion efficiency of solar energy to electricity in cyanobacterial PEMFC by high levels of photo-H2 production

Abstract In this study, we described an efficient electrical power generating system containing cyanobacterial photo-H 2 production and custom-built proton exchange membrane fuel cell (PEMFC). The filamentous N 2 -fixing cyanobacterium Anabaena cylindrica was used as the photo-H 2 producer. A photosynthesis inhibitor-diuron (DCMU) was used for the enhancement of photo-H 2 production in the culture under argon gas. For the first time, a total of 1.0 μM DCMU was found to be the most effective treatment, as this produced 3.6 fold higher levels of H 2 in microalgae. By measuring polarization curve, the gas mixture collected from the culture was proven to be an effective fuel for electrical generation through a custom-built PEMFC. When the PEMFC was directly combined with the culture tube, the cells generated as much as 843 mV during a 5-day incubation due to the efficient conversion of solar energy to H 2 by A. cylindrica . Light energy conversion efficiency (LCE) for both solar energy to H 2 and solar energy to electricity were also determined. The LCE for the cyanobacterial conversion of solar energy to H 2 reached a peak at four days with a maximal value of 2.05% and an average value of 1.70% ± 0.17. The corresponding LCE for the conversion of solar energy to electricity in this system was 1.13% at peak and 0.94% ± 0.09 on average.