Slide 1: Electricity Production by Microbial fuel cell Samuel Raj. B
Madurai Kamaraj University
PhD Principle investigator
Dr.SRD Jebakumar INTRODUCTION : INTRODUCTION Energy generation and waste disposal are two key challenges in the quest for sustainable societies.
Microbial fuel cells provide an elegant solution by linking both tasks
Microbial fuel cell (MFC) technology represents a new form of renewable energy by generating electricity from what would others considered as waste. INTRODUCTION Slide 3: GENERAL PRINCIPLES OF MICROBIAL FUEL CELLS A microbial fuel cell (MFC) converts chemical energy, available in a bio-convertible substrate, directly into electricity.
To achieve this, microorganism are used as a catalyst to convert substrate into electrons.
A MFC consists of an anode, a cathode, a proton or cation exchange membrane and an electrical circuit.
A MFC is usually made up of two chambers one anaerobic and one aerobic. Slide 4: Pseudomonas
These bacteria will directly transfer an electron to any type of conductive material (Cathode) ELECTRICIGENS Slide 5: Exoelectrogens
Transfer electrons exocellularly in three ways
Membrane bound electron carriers
Nanowires (Conductive appendages)
Anode is used instead of the normal terminal electron acceptors
Common species Geobacter and Shewanella MFC Microbiology Slide 6: PURE MIXED
CULTURE CULUTRE VS Produce lower level of electricity
Grow slower Produce higher level of electricity
Grow much quicker
Work as community Slide 7: How Does it Work? How do electrons reach the electrode? : How do electrons reach the electrode? Early evidence was that bacteria produced their own mediators
Pseudomonas spp. Produce mediators such as pyocyanin (Rabaey et al. 2004)
Recent data suggests that Shewanella spp. use other methods… Carrier (oxidized) Carrier (reduced) Bacterium Fe (III) Mediators produced by Pseudomonas spp. have distinct colors. (Photo provided by Korneel Rabaey, Ghent University, Belgium; 2005). New finding: bacteria use “nano-wires” : New finding: bacteria use “nano-wires” Other bacteria can transfer electrons directly to the electrode
Shewanella spp. Bacterium Electrode Yuri Goby (2005). “Composition, reactivity and regulation of extracellular metal-reducing structures produced by dissimilatory metal-reducing bacteria.” Pres. DOE NABIR meeting, April 20, 8:10 am, Warrenton, VA. e- e- e- Electricity Production in an Cathode Microbial Fuel Cell : Electricity Production in an Cathode Microbial Fuel Cell Proton Exchange membrane load Anode Cathode bacteria Oxidation products (CO2) Fuel (wastes) e- e- O2 H2O H+ Source: Liu et al., Environ. Sci. Technol., (2004) Slide 11: - Increase power with air-cathode (oxygen does not need to be dissolved in water
Remove proton exchange membrane (PEM) load Anode Cathode bacteria Oxidation products (CO2) Fuel (wastes) e- Oxidant (O2) Reduced oxidant (H2O) H+ e- MFC- Air cathode systems Slide 12: Mechanism of Electricity production Bacteria (Anode)
Electron transport chain
protons & electrons
Electron transport through cell membrane using OmcB, OmcS, OmcF Slide 13: Protein electron carriers cytochrome C- type
Electrical circuit with a load or resistor to the Cathode
The potential difference (Volt) between the anode and the cathode, together with the flow of electrons (Ampere) results in the generation of electrical power (Watt). Slide 18: Future out look
MFC designs need improvements before a marketable product will be possible.
Issues of the scale-up of the process remain critical issues. While full-scale, highly effective MFCs are not yet within our grasp, the technology holds considerable promise, and major hurdles will undoubtedly be overcome by engineers and scientists.
The growing pressure on our environment, and the call for renewable energy sources will further stimulate development of this technology, leading soon to its successful implementation. Slide 19: THANK YOU