Trends in Biotechnology
ReviewMicrobial solar cells: applying photosynthetic and electrochemically active organisms
Introduction
Society is facing local and global challenges to secure the needs of people and planet 1, 2. One of those needs is energy, which should be available in the form of electricity or fuels, ideally produced from a renewable source via an efficient and clean conversion process. Microbial solar cell (MSC) is the collective name for new biotechnological systems that integrate photosynthetic and electrochemically active organisms to generate in situ green electricity or chemical compounds, such as hydrogen, methane, ethanol and hydrogen peroxide 3, 4, 5. The MSC builds on the discovery of electrochemically active bacteria and the subsequent development of microbial fuel cells (MFCs) 6, 7, 8, which typically clean wastewater and generate electricity from biodegradable organic compounds present. Within the MFC, electrochemically active bacteria at the anode oxidize organic compounds and deliver electrons to the anode. These electrons flow through a power harvester to the cathode, where electrons are delivered to reduce oxygen [9]. In an MSC, photosynthetic organisms use sunlight to produce organic matter that is further converted into electricity using the MFC 10, 11. The most-investigated MSC is the plant MFC, which has a living plant that delivers organic matter via its roots to electrochemically active bacteria in the MFC 10, 12, 13, 14, 15, 16, 17.
Our aim is to review the principles and performance of MSCs, and to describe the challenges and the outlook for future applications of these technologies. Various MSCs have been described recently and these can be categorized according to the way solar energy is captured and the mode of organic matter transfer from the photosynthetic portion to the fuel cell. Both the reported and potential performance of different MSCs are analyzed to identify bottlenecks and possible solutions. Currently, it is not possible to predict the cost-effectiveness of the technology; however, on the basis of known advantages of MSC technology, potential applications and tradeoffs with other renewable energy generation technologies are discussed.
Section snippets
Principles and performance of MSCs
The basic principles of MSCs, as illustrated in Figure 1, are: (i) photosynthesis; (ii) transport of organic matter to the anode compartment; (iii) anodic oxidation of organic matter by electrochemically active bacteria; and (iv) cathodic reduction of oxygen. We have categorized the MSCs below according to the way in which solar energy is captured and the mode of organic matter transfer: a higher plant with rhizodeposition; a phototrophic biofilm with diffusion; or a photobioreactor or coastal
Challenges in improving energy recovery
Reviews in the previous section of the most recent expectations for theoretical power generation and the performance achieved reveal that PMFCs and phototrophic biofilms have the highest power generation (50 and 7 mW/m2, respectively) 14, 35 and highest estimated net power potential (67 and 61 mW/m2, respectively). Thus, PMFCs and phototrophic biofilms are the most promising MSC systems. Overall, MSCs are robust, with operating times in the range 5–175 days (Table 1) 12, 34. By contrast, other
Prospects and future applications
We have shown that MSC technology is advancing, with the most promising MSCs using higher plants or phototrophic biofilms. The basic principles of MSCs have been demonstrated; now it is time to improve the systems for real-life applications. Compared to conventional solar cells, MSCs have some attractive properties that warrant further development and will influence future applications of this technology [78]:
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MSCs can produce not only electricity, but also a wide range of fuels and chemicals;
Acknowledgements
This research received funding from the European Community Seventh Framework Programme FP7/2007-2013 under grant agreement no. 226532. In addition, work was funded by SenterNovem, the Dutch governmental agency for sustainability and innovation from the Ministry of Economic Affairs (grant no. EOSLT06020) and NUON. We thank Nora Sutton, Marc Spiller, Jan Arends and the anonymous reviewers for their valuable comments on the manuscript.
References (89)
Principle and perspectives of hydrogen production through biocatalyzed electrolysis
Int. J. Hydrogen Energy
(2006)Towards practical implementation of bioelectrochemical wastewater treatment
Trends Biotechnol.
(2008)Bioanode performance in bioelectrochemical systems: recent improvements and prospects
Trends Biotechnol.
(2009)- et al.
Microbial fuel cells: novel biotechnology for energy generation
Trends Biotechnol.
(2005) Concurrent bio-electricity and biomass production in three plant–microbial fuel cells using Spartina anglica, Arundinella anomala and Arundo donax
Bioresour. Technol.
(2010)The microbe electric: conversion of organic matter to electricity
Curr. Opin. Biotechnol.
(2008)- et al.
Assessment of energy performance in the life-cycle of biogas production
Biomass Bioenergy
(2006) Nanostructured polypyrrole-coated anode for sun-powered microbial fuel cells
Bioelectrochemistry
(2010)Improved performance of porous bio-anodes in microbial electrolysis cells by enhancing mass and charge transport
Int. J. Hydrogen Energy
(2009)Harnessing energy from marine productivity using bioelectrochemical systems
Curr. Opin. Biotechnol.
(2010)
VERTEX: carbon cycling in the northeast Pacific
Deep Sea Res. A Oceanogr. Res. Pap.
Electrocatalytic and corrosion behaviour of tungsten carbide in near-neutral pH electrolytes
Appl. Catal. B Environ.
Rhizosphere carbon flow in trees, in comparison with annual plants: the importance of root exudation and its impact on microbial activity and nutrient availability
Appl. Soil Ecol.
Effects of thermo-chemical pre-treatment on anaerobic biodegradability and hydrolysis of lignocellulosic biomass
Bioresour. Technol.
Loading rate and external resistance control the electricity generation of microbial fuel cells with different three-dimensional anodes
Bioresour. Technol.
Is resistance futile? Changing external resistance does not improve microbial fuel cell performance
Bioelectrochemistry
A review of the substrates used in microbial fuel cells (MFCs) for sustainable energy production
Bioresour. Technol.
Ion transport resistance in microbial electrolysis cells with anion and cation exchange membranes
Int. J. Hydrogen Energy
Microbial electrolysis cell with a microbial biocathode
Bioelectrochemistry
Electron transfer pathways in microbial oxygen biocathodes
Electrochim. Acta
Catalysis of oxygen reduction in PEM fuel cell by seawater biofilm
Electrochem. Commun.
Microbial fuel cells operated with iron-chelated air cathodes
Electrochim. Acta
Light energy to bioelectricity: photosynthetic microbial fuel cells
Curr. Opin. Biotechnol.
Solar photovoltaics R&D at the tipping point: a 2005 technology overview
J. Electron Spectrosc. Relat. Phenom.
The first demonstration of a microbial fuel cell as a viable power supply: powering a meteorological buoy
J. Power Sources
Butler–Volmer–Monod model for describing bio-anode polarization curves
Bioresour. Technol.
Analysis of the green roof thermal properties and investigation of its energy performance
Energy Build.
Investigation of thermal benefits of rooftop garden in the tropical environment
Build. Environ.
The early adoption of green power by Dutch households. An empirical exploration of factors influencing the early adoption of green electricity for domestic purposes
Energy Policy
Comparative analysis of different supporting measures for the production of electrical energy by solar PV and wind systems: four representative European cases
Sol. Energy
Global patterns in human consumption of net primary production
Nature
New applications and performance of bioelectrochemical systems
Appl. Microbiol. Biotechnol.
Bioelectrochemical ethanol production through mediated acetate reduction by mixed cultures
Environ. Sci. Technol.
Direct electrode reaction of Fe(III)-reducing bacterium, Shewanella putrefaciens
J. Microbiol. Biotechnol.
Green electricity production with living plants and bacteria in a fuel cell
Int. J. Energy Res.
Solar energy powered microbial fuel cell with a reversible bioelectrode
Environ. Sci. Technol.
Microbial fuel cells generating electricity from rhizodeposits of rice plants
Environ. Sci. Technol.
Plant/microbe cooperation for electricity generation in a rice paddy field
Appl. Microbiol. Biotechnol.
Long-term performance of a plant microbial fuel cell with Spartina anglica
Appl. Microbiol. Biotechnol.
Factors affecting electric output from rice-paddy microbial fuel cells
Biosci. Biotechnol. Biochem.
Microbial community analysis of anodes from sediment microbial fuel cells powered by rhizodeposits of living rice plants
Appl. Environ. Microbiol.
Microbial fuel cells – challenges and applications
Environ. Sci. Technol.
Photosynthetic microbial fuel cells with positive light response
Biotechnol. Bioeng.
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