Though it has been studied for a long time, many issues still limit the performance of microbial fuel cells, including low power output and efficiency. How do you think is the potential and the future of MCF? What ideas do you have to screen a good microbial source, to extend substrate choice and to improve electrode design by new material?
Several reviews adress this case. I would suggest the paper by Clauwaert et al. as a basis (see link).
http://link.springer.com/article/10.1007%2Fs00253-008-1522-2#
This is a very general question which would require a whole review. As already pointed out by Sylvia Gildemyn recent (!) review papers may be a good point to start with. Do you have scopus, scifinder or web of science available for a detailed research?
You can also search for individual aspects:
Anode materials:
- 3D materials
- Surface modification
Cathode material:
- Chemical cathode? Microbial cathode? Noble-metal free ORR catalysts?
- Open ari cathode or dissolved oxygen?
- Hydrogen evolution instead of oxygen reduction?
Biocatalyst:
- Every bacterial consortium should be adapted to the target substrate. Thus, if wastewater was the substrate, then the bacteria should stem from wastewater (or from sludge), ….
- Sophisticated adaptation procedures are available (cultivation of secondary biofilms..)
Reactor design
- Needs to be optimized towards low internal (ohmic) resistance…
Separator:
- Design with or without a membrane?
You see, there are indeed very many aspects to consider. There are quite a number of research and also review papers and also two books dealing with these individual aspects ..
Best regards,
Uwe Schröder
I actually dissagree that genetically modified microbes will be a good solution for microbial fuel cells. MFC are open systems, which would release the modified bacteria to the environment. We certainly don't want that. We are actually just beginning to understand that nature already provides many interesting tools and pathways to achieve the performance that we need. We just need to learn how to exploit these features.. Remember, over the past fifteen years we have witnessed an increase of anode performance of at least factor 1000.. Without genetics..
For biotechnological processes like microbial electrosynthesis genetic modifications will be an option. These closed systems do not release bacteria to the environment, and the genetic combination of electrochemical and synthesis could yield strains with desired properties...
I think that Uwe has offered some crucial points already. I donot work on MFCs and am not an expert in the field, but I have studied bioelechemistry and biomolecular electron transfer for many years. From a general point of view, to imrpove the overall efficiency and power of MFCs, you need to do at least three aspects: 1) genetic selection and engineering of bacteria, 2) improving assembly of the key components and 3) optimization of bioelectrochemical electron transfer (ET) pathways. In addition, MFCs could be combined with other energy devices such as supercapacitors to construct more efficient hybrid devices. You might like to take a look at two recent articles regarding understanding ET of electractive biofilms and biofuel-supercapacitor hybrid devices (attached).
In microbial fuel cells (MFCs) electrical current is generated from oxidation-reduction reactions that occur within living microorganisms with the oxidation of an organic compound at the anode generating electrons that produce an electric current (De Schamphelaire and Verstraete, 2009, Powell et al., 2011). The maximum power generation of microbial fuel cells oxidising biomass is currently only up to 1 W m-2 (Thorne et al., 2011, Howe, 2012) and could only produce the power equivalent to 3.8 toe ha-1 (Howe, 2012) below that from convetional biomass sources.
A recent development in microbial fuel cells is a photo-microbial fuel cell or bio-photovoltaic fuel cell where photosynthetic algae growing at the anode generate the electrons, thereby removing the need for an organic substrate (Thorne et al., 2011, Howe, 2012). However Bio-photovoltaic fuel cells currently have very low efficiency and energy production is between 1 and 1.5 orders of magnitude lower than microbial fuel cells oxidising biomass (Howe, 2012).
De Schamphelaire L and Verstraete W (2009) Revival of the Biological Sunlight-to-Biogas Energy Conversion System. Biotechnology and Bioengineering 103, 296-304.
Howe C (2012) Direct Electricity Generation from Microalgae using biophotovoltaics. In Algal biotechnology; biofuels and beyond. (ed.), Vol. pp. UCL, London.
Powell EE, Evitts RW, Hill GA, and Bolster JC (2011) A Microbial Fuel Cell with a Photosynthetic Microalgae Cathodic Half Cell Coupled to a Yeast Anodic Half Cell. Energy Sources Part a-Recovery Utilization and Environmental Effects 33, 440-8.
Thorne R, Hu HN, Schneider K, Bombelli P, Fisher A, Peter LM et al. (2011) Porous ceramic anode materials for photo-microbial fuel cells. Journal of Materials Chemistry 21, 18055-60.
Although MFC technology is developed well on power density, it is still hard to apply widely. In future, I believe one of important work is to find out where MFC is suitable to work in situ in waste water treatment or in environment.
Several factors exits, which effects the efficiency and stability of MFCs, including types of cathode and anode materials, compositions of anolyte and catholyte, ion exchange membrane, electron transfer and type of bacteria
1) reducing distance between electrode
2) reducing electrolyte resistance by increasing ion concentrations in electrolytes
3) by increasing electrode surface area
4) by reducing resistance of proton exchange medium
I uploaded a pdf file which might be very useful to your studies. please, look at it.
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