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Enhancing power density of biophotovoltaics by decoupling storage and power delivery


Biophotovoltaic devices (BPVs), which use photosynthetic organisms as active materials to harvest light, have a range of attractive features relative to synthetic and non-biological photovoltaics, including their environmentally friendly nature and ability to self-repair. However, efficiencies of BPVs are currently lower than those of synthetic analogues. Here, we demonstrate BPVs delivering anodic power densities of over 0.5 W m−2, a value five times that for previously described BPVs. We achieved this through the use of cyanobacterial mutants with increased electron export characteristics together with a microscale flow-based design that allowed independent optimization of the charging and power delivery processes, as well as membrane-free operation by exploiting laminar flow to separate the catholyte and anolyte streams. These results suggest that miniaturization of active elements and flow control for decoupled operation and independent optimization of the core processes involved in BPV design are effective strategies for enhancing power output and thus the potential of BPVs as viable systems for sustainable energy generation.

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The research leading to these results has received funding from the Engineering and Physical Sciences Research Council (K.L.S., T.P.J.K.), the Leverhulme Trust (P.B., C.J.H., T.P.J.K.; RPG-2015-393), the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013) through the ERC grant PhysProt (agreement no. 337969), the Biotechnology and Biological Sciences Research Council (T.P.C.; BB/J014540/1), the Environmental Services Association Education Trust (D.J.L.-S.) and the EnAlgae consortium (P.B., C.J.H.). We thank L. Lea for help in constructing Fig. 1.

Author information

K.L.S., P.B., T.M., E.M.A., C.J.H. and T.P.J.K. designed the study K.L.S., P.B., D.J.L.S. and T.P.C. performed the experiments.

Competing interests

The authors declare no competing financial interests.

Correspondence to Christopher J. Howe or Tuomas P. J. Knowles.

Supplementary information

  1. Supplementary Information

    Supplementary Figures 1–5, Supplementary Table 2, Supplementary References.

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    Supplementary Table 1.

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Further reading

Fig. 1: The charging and delivery processes in a flow-BPV.
Fig. 2: Construction and performance of the μ-BPV.
Fig. 3: The effect of flow rate on the device performance.
Fig. 4: Dependence of the μ-BPV performance on cell concentration and genotype, device configuration, and comparison with literature data.