Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

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.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Get just this article for as long as you need it


Prices may be subject to local taxes which are calculated during checkout

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.


  1. Solar Energy Perspectives (International Energy Agency, 2011).

  2. BP Statistical Review of World Energy (British Petroleum, 2015).

  3. Green, M. A. Commercial progress and challenges for photovoltaics. Nat. Energy 1, 15015 (2016).

    Article  Google Scholar 

  4. Crabtee, G. W. & Lewis, N. S. Solar energy conversion. Phys. Today 60, 37–42 (2007).

    Article  Google Scholar 

  5. Lewis, N. S. & Nocera, D. G. Powering the planet: chemical challenges in solar energy utilization. Proc. Natl. Acad. Sci. USA 103, 15729–15735 (2006).

    Article  Google Scholar 

  6. Tao, C. S., Jiang, J. & Tao, M. Natural resource limitations to terawatt-scale solar cells. Sol. Energy Mater. Sol. Cells 95, 3176–3180 (2011).

    Article  Google Scholar 

  7. Peter, L. M. Towards sustainable photovoltaics: the search for new materials. Philos. Trans. A Math. Phys. Eng. Sci. 369, 1840–1856 (2011).

    Article  Google Scholar 

  8. Mazzio, K. A. & Luscombe, C. K. The future of organic photovoltaics. Chem. Soc. Rev. 44, 78–90 (2014).

    Article  Google Scholar 

  9. McCormick, A. J. et al. Biophotovoltaics: oxygenic photosynthetic organisms in the world of bioelectrochemical systems. Energy Environ. Sci. 8, 1092–1109 (2015).

    Article  Google Scholar 

  10. Hasan, K. et al. Photo-electrochemical communication between cyanobacteria (Leptolyngbia sp.) and osmium redox polymer modified electrodes. Phys. Chem. Chem. Phys. 16, 24676–24680 (2014).

    Article  Google Scholar 

  11. Hasan, K. et al. Photoelectrochemical wiring of Paulschulzia pseudovolvox (algae) to osmium polymer modified electrodes for harnessing solar energy. Adv. Energy Mater. 5 (2015).

  12. McCormick, A. J. et al. Photosynthetic biofilms in pure culture harness solar energy in a mediatorless bio-photovoltaic cell (BPV) system. Energy Environ. Sci. 4, 4699–4709 (2011).

    Article  Google Scholar 

  13. Hambourger, M. et al. Biology and technology for photochemical fuel production. Chem. Soc. Rev. 38, 25–35 (2009).

    Article  Google Scholar 

  14. Tanaka, K., Tamamushi, R. & Ogawa, T. Bioelectrochemical fuel-cells operated by the cyanobacterium, Anabaena variabilis. J. Chem. Technol. Biotechnol. 35, 191–197 (1985).

    Article  Google Scholar 

  15. Zou, Y., Pisciotta, J., Billmyre, R. B. & Baskakov, I. V. Photosynthetic microbial fuel cells with positive light response. Biotechnol. Bioeng. 104, 939–946 (2009).

    Article  Google Scholar 

  16. Bradley, R. W., Bombelli, P., Rowden, S. J. & Howe, C. J. Biological photovoltaics: intra- and extra-cellular electron transport by cyanobacteria. Biochem. Soc. Trans. 40, 1302–1307 (2012).

    Article  Google Scholar 

  17. Bombelli, P. et al. Quantitative analysis of the factors limiting solar power transduction by Synechocystis sp. PCC 6803 in biological photovoltaic devices. Energy Environ. Sci. 4, 4690–4698 (2011).

    Article  Google Scholar 

  18. Squires, T. M. & Quake, S. R. Microfluidics: fluid physics at the nanoliter scale. Rev. Mod. Phys. 77, 977 (2005).

    Article  Google Scholar 

  19. Ferrigno, R., Stroock, A. D., Clark, T. D., Mayer, M. & Whitesides, G. M. Membraneless vanadium redox fuel cell using laminar flow. J. Am. Chem. Soc. 124, 12930–12931 (2002).

    Article  Google Scholar 

  20. Wang, H.-Y., Bernarda, A., Huang, C.-Y., Lee, D.-J. & Chang, J.-S. Micro-sized microbial fuel cell: a mini-review. Bioresour. Technol. 102, 235–243 (2011).

    Article  Google Scholar 

  21. Yang, J., Ghobadian, S., Goodrich, P. J., Montazami, R. & Hashemi, N. Miniaturized biological and electrochemical fuel cells: challenges and applications. Phys. Chem. Chem. Phys. 15, 14147–14161 (2013).

    Article  Google Scholar 

  22. Kjeang, E. et al. High-performance microfluidic vanadium redox fuel cell. Electrochim. Acta 52, 4942–4946 (2007).

    Article  Google Scholar 

  23. Ren, H., Torres, C. I., Parameswaran, P., Rittmann, B. E. & Chae, J. Improved current and power density with a micro-scale microbial fuel cell due to a small characteristic length. Biosens. Bioelectron. 61, 587–592 (2014).

    Article  Google Scholar 

  24. Lea-Smith, D. J., Vasudevan, R. & Howe, C. J. Generation of marked and markerless mutants in model cyanobacterial species. J. Vis. Exp., e54001 (2016).

  25. Zhang, P. et al. Operon flv4-flv2 provides cyanobacterial photosystem II with flexibility of electron transfer. Plant. Cell. 24, 1952–1971 (2012).

    Article  Google Scholar 

  26. Brody, J. P. & Yager, P. Diffusion-based extraction in a microfabricated device. Sens. Actuators A Phys. 58, 13–18 (1997).

    Article  Google Scholar 

  27. Kamholz, A. E., Weigl, B. H., Finlayson, B. A. & Yager, P. Quantitative analysis of molecular interaction in a microfluidic channel: the T-sensor. Anal. Chem. 71, 5340–5347 (1999).

    Article  Google Scholar 

  28. Lea-Smith, D. J. et al. Thylakoid terminal oxidases are essential for the cyanobacterium Synechocystis sp. PCC 6803 to survive rapidly changing light intensities. Plant. Physiol. 162, 484–495 (2013).

    Article  Google Scholar 

  29. Zhao, F., Slade, R. C. & Varcoe, J. R. Techniques for the study and development of microbial fuel cells: an electrochemical perspective. Chem. Soc. Rev. 38, 1926–1939 (2009).

    Article  Google Scholar 

  30. Logan, B. E. et al. Microbial fuel cells: methodology and technology. Environ. Sci. Technol. 40, 5181–5192 (2006).

    Article  Google Scholar 

  31. Qian, F., Baum, M., Gu, Q. & Morse, D. E. A 1.5 μl microbial fuel cell for on-chip bioelectricity generation. Lab. Chip 9, 3076–3081 (2009).

    Article  Google Scholar 

  32. Bombelli, P., Müller, T., Herling, T. W., Howe, C. J. & Knowles, T. P. A high power-density, mediator-free, microfluidic biophotovoltaic device for cyanobacterial cells. Adv. Energy Mater. 5, e1401299 (2015).

    Article  Google Scholar 

  33. Kjeang, E., Djilali, N. & Sinton, D. Microfluidic fuel cells: a review. J. Power Sources 186, 353–369 (2009).

    Article  Google Scholar 

  34. Shaegh, S. A. M., Nguyen, N.-T. & Chan, S. H. A review on membraneless laminar flow-based fuel cells. Int. J. Hydrog. Energy 36, 5675–5694 (2011).

    Article  Google Scholar 

  35. Li, Z., Zhang, Y., LeDuc, P. R. & Gregory, K. B. Microbial electricity generation via microfluidic flow control. Biotechnol. Bioeng. 108, 2061–2069 (2011).

    Article  Google Scholar 

  36. Müller, T. et al. Particle-based simulations of steady-state mass transport at high Péclet numbers. arXiv preprint arXiv:1510.05126 (2015).

  37. Lea-Smith, D. J., Bombelli, P., Vasudevan, R. & Howe, C. J. Photosynthetic, respiratory and extracellular electron transport pathways in cyanobacteria. Biochim. Biophys. Acta (BBA) Bioenerg. 1857, 247–255 (2016).

    Article  Google Scholar 

  38. HaoYu, E., Cheng, S., Scott, K. & Logan, B. Microbial fuel cell performance with non-Pt cathode catalysts. J. Power Sources 171, 275–281 (2007).

    Article  Google Scholar 

  39. Kakarla, R. & Min, B. Photoautotrophic microalgae scenedesmus obliquus attached on a cathode as oxygen producers for microbial fuel cell (mfc) operation. Int. J. Hydrog. Energy 39, 10275–10283 (2014).

    Article  Google Scholar 

  40. Schneider, K., Thorne, R. J. & Cameron, P. J. An investigation of anode and cathode materials in photomicrobial fuel cells. Philos. Trans. Math. Phys. Eng. Sci. 374, 20150080 (2016).

    Article  Google Scholar 

  41. Qian, F. & Morse, D. E. Miniaturizing microbial fuel cells. Trends Biotechnol. 29, 62–69 (2011).

    Article  Google Scholar 

  42. Williams, J. G. Construction of specific mutations in photosystem II photosynthetic reaction center by genetic engineering methods in Synechocystis 6803. Methods Enzymol. 167, 766–778 (1988).

    Article  Google Scholar 

  43. Castenholz, R. W. Culturing methods for cyanobacteria. Methods Enzymol. 167, 68–93 (1988).

    Article  Google Scholar 

  44. Lea-Smith, D. J., Vasudevan, R. & Howe, C. J. Generation of marked and markerless mutants in model cyanobacterial species. J. Vis. Exp. 1–11 (2016).

  45. Duffy, D. C., McDonald, J. C., Schueller, O. J. & Whitesides, G. M. Rapid prototyping of microfluidic systems in poly(dimethylsiloxane). Anal. Chem. 70, 4974–4984 (1998).

    Article  Google Scholar 

  46. So, J.-H. & Dickey, M. D. Inherently aligned microfluidic electrodes composed of liquid metal. Lab. Chip 11, 905–911 (2011).

    Article  Google Scholar 

  47. Herling, T. et al. Integration and characterization of solid wall electrodes in microfluidic devices fabricated in a single photolithography step. Appl. Phys. Lett. 102, 184102 (2013).

    Article  Google Scholar 

  48. MacKay, D. J. C. Solar energy in the context of energy use, energy transportation and energy storage. Philos. Trans. Math. Phys. Eng. Sci. 371, 20110431 (2013).

    Article  Google Scholar 

  49. Dabiri, J. O. et al. A new approach to wind energy: opportunities and challenges. AIP Conf. Proc. 1652, 51–57 (2015).

    Article  Google Scholar 

  50. De Castro, C., Mediavilla, M., Miguel, L. J. & Frechoso, F. Global solar electric potential: a review of their technical and sustainable limits. Renew. Sust. Energ. Rev. 28, 824–835 (2013).

    Article  Google Scholar 

Download references


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

Authors and Affiliations



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.

Corresponding authors

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

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

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

Supplementary Table

Supplementary Table 1.

Rights and permissions

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Saar, K.L., Bombelli, P., Lea-Smith, D.J. et al. Enhancing power density of biophotovoltaics by decoupling storage and power delivery. Nat Energy 3, 75–81 (2018).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing