MICROBIAL FUEL CELLS-PPT

1. MICROBIAL FUEL CELLS Presented by SHABEEBA.V 4PA11BT023

2. CONTENTS Introduction What are fuel cells? What are microbial fuel cells principle Construction of MFC Components of MFC Working of MFC Thermodynamics of MFC MFC Design Types of MFC Applications of MFC Advantages of MFC Limitations of MFC Conclusion References

3. INTRODUCTION Use of the fossil fuels can trigger global energy crisis and increased global warming hence there is considerable interest in research fraternity on green production In an era of climate change, alternate energy sources are desired to replace oil and carbon resources. Subsequently, climate change effects in some areas and the increasing production of biofuels are also putting pressure on available water resources. Microbial Fuel Cells have the potential to simultaneously treat wastewater for reuse and to generate electricity; thereby producing two increasingly scarce resources Microbial fuel cell technology represents a new form of renewable energy by generating electricity from what would otherwise be considered waste, such as industrial wastes or waste water etc

4. Continuation…. M.C Potter was the first to perform work on the subject in 1911 in E.coli,A professor of botany at the University of Durham In 1931, however, Barnet Cohen drew more attention to the area when he created a number of microbial half fuel cells that, when connected in series, were capable of producing over 35 volts, though only with a current of 2 milliamps In 1911 B.H. Kim devoloped mediatorless MFC was a milestone in MFC, Enhanced the commercial viablity,by eleiminating costly mediator chemicals. Microbial fuel cells have come a long way since the early 20 th century.

5. What are fuel cells? Device that converts chemical energy from fuel into electricity through chemical reaction with oxygen or another oxidizing agent.

6. What are Microbial fuel cells? Chemical energy to electrical energy Catalytic reaction of microorganisms Bio-electrochemical system Mimics bacterial interaction primary flow diagram

7. Based on redox reactions Harness the natural metabolism of microbes to produce electricity Bacteria converts substrate into electrons Electrons run through the circuit to generate power Principle

8. CONSTRUCTION OF MFC:

9. Components of MFC Anode Cathode Exchange membrane Substrate Electrical circuit Microbes

10. Anode; Conductive,bio compatible & chemicaly stable with substrate Stainless steel mesh,graphite plates or rods Bacteria live in the anode compartment and convert substrate to CO2,H2O and energy Bacteria are kept in an oxygen less environment Anode compartment

11. Cathode; Electrons and protons recombine at the cathode O2 reduced to water Pt catalyst is used Cathode compartment

12. Exchange membrane; NAFION or ULTREX Protons flows through the EM Proton and electrons recombine on the other side. Can b a proton or cation exchange membrane Exchange membrane

13. Electrical circuit After leaving anode, electrons travel through the circuit These electrons power the load Electrical circuit

14. Substrates; Substrates provide energy for the bacterial cell Influences the economic viability and overall performance such as power density and coloumbic efficiency of MFC Concentration,composition and type Organic substrates-carbohydrates, protein,volatile acids,cellulose and waste water Acetate is commonly used as substrate

15. Substrates used in MFC Substrate type Concentrations Current density (m A/cm 2) Acetate 1g/L 0.8 Lactate 18mM 0.005 Glucose 6.7Mm 0.7 Sucrose 2674mg/L 0.19 Glucaronic acid 6.7mM 0.18 Phenol 400mg/L 0.1 Sodium fumerate 25mM 2.05 Starch 10g/L 1.3 Cellulosic particles 4g/L 0.02 Xylose 6.7mM 0.74 Domestic wastewater 600mg/L 0.06 Brewery wastewater 2240mg/L 0.2

16. Microbes used in MFC Axenic bacterial culture Metal reducing bacteria Shewanella putrefaciens Geobacter sulfurreducens Rhodoferax ferrireducens Clostridium beijerinckii Mixed bacterial fuel culture Desulfuromonas , Alcaligenes faecalis, Enterococcus faecium, Pseudomonas aeruginosa , Proteobacteria ,

17. Continuation….. Clostridium butricum Bacteroides and Aeromonas species nitrogen fixing bacteria (e.g . Azoarcus and Azospirillum)

18. Working of MFC

19. Continuation……. Anode and cathode separated by cathode specific membrane Microbes at anode oxidize organic fuel generates electrons and protons Protons move to the cathode compartment through the membrane Electrons transferred to the cathode compartment through external circuit to generate current Electrons and protons are consumed in cathode chamber, combining with O2 to form water A nodic reaction: CH 3 COO - + H 2 O → 2CO 2 + 2H + +8e - acetate Cathodic reaction: O 2 + 4e - + 4 H + → 2 H 2 O

20. Thermodynamics of MFC U sing Gibbs free energy ∆G r = G r + RT ( lnπ) Cell electromotive force W = E emf Q = ∆G r , Q = nF E emf = ∆ G r∕ nF Overall reaction in terms of the potential as E emf = E emf –RT∕nF ln(π ) positive for a favourabl reaction directly produces a value of emf for the reaction

21. MFC Design D ifferent configurations are possible Widely used is a two chamber MFC built in traditional ‘H’ shape Two chamber connected by a tube containing a seperator usually CEM or plain salt bridge

22. Types of MFCs Mediator MFC Mediator free MFC Microbial electrolysis fuel cell

23. Continuation…… S oil based MFC Phototrophic biofilm MFC Nanoporous MFC Sediment MFC Membrane less MFC

24. Applications of MFC W aste water treatment Power generation Secondary fuel production Bio-Sensors Desalination Educational tool

25. Advantages of MFC Generation of energy out of biowaste / organic matter Direct conversion of substrate energy to electricity Omission of gas treatment Aeration B ioremediation of toxic compounds

26. Limitations of MFC Low power density High initial cost Activation losses Ohmic losses Bacterial metabolic losses

27. Conclusion MFCs have been explored as a new source of electricity generation during operational waste water treatment . Phototropic MFCs and solar powered MFC also represent an exceptional attempt in the progress of MFCs technology for electricity production . It can be used for production of secondary fuel as well as in bioremediation of toxic compounds . However, this technology is only in research stage and more research is required before domestic MFCs can be made available for commercialization Provided the biological understanding increases, the electrochemical technology advances and the overall electrode prices decrease, this technology might qualify as a new core technology for conversion of carbohydrates to electricity in years to come.

28. Reference 1. Microbial fuel cells.Retreived March 25,2015 from http://www.microbial fuel cell.org/www/ 2.Electricity generation from microbial fuel cells.Retreivd March 25,2015.http://illumin.use.edu/printer/134/microbial-fuel-cells-generating-power-from-waste/ 3.Allen, B. (1993). Microbial fuel cells. electricity production from carbohydrates . 27-40. 4.Ashley, f. (2010, may- june ). Microbial electrosynthesis ,feeding microbes electricity to convert carbondioxide and water. 5.Badwal.SPS. (2014). Emerging electrochemical energy conversion and storage technologies. frontiers in chemistry, 79 . 6.Bennetto. (1990). electricity generation by micro organisms. microbial ecology,1(4) , 163-168. 7.Biffinger, j. C. (2007). diversifyin biological fuel cell design by use of nanoporous filters. enviornmental scince and technology , 1444-49. 8.Chen, T., Barton, & Binyamin. (2001, september). a miniature bio fuel cell . 123(35) . 9.Cohen, B. (1931). The Bacterial culture as an Electrical half-cell. journal of bacteriology, 21 , 18-19 10.DelDuca, M. a. (1963). Dovelopments in industrial microbiology. journal of industrial microbiology 4 , 81-84. 11.Elizabeth, E. (2012). generating eectricity by nature way. Biotechnol 8,556-600 12.Gong, & Radachowasky. ( n.d). benthic microbial fuel cell as direct power source for an acoustic modem and seawater oxygen/temperature sensor system. environmental science and technolgy (11 ), 5047-53. 13.Helder, m. (2011). microbial solar cells:applying photosynthetic and electrochemically active organisms. trends in biotechnology , 41-49. 14.kim, p. (1999). direct electrode reaction of fe(III ) reducing bacterium.shewanell putrifaciens. Nature 9 , 127-131. 15.Lithgow, R. (1986). Interception of electron transport cain in bacteria with hydrophilic redox mediators. 178-179. 16.Matasunga, S. &. (1976). continuous hydrogen production by immobilized whole cells of Clostridium butrycum . 24:2 , 338-343. 17.Min, B. L. (2005). Electricity genertion using membrane and salt bridge microbial fuel cell ,water reasearch . 39(9) , 1675-86. 18.Mohan, V., & raghavulu, v. (2008). influence of anodic biofilim growth on bio electricity production in single chamber meditaor less microbial fuel cells. biosensors and bioelectronics, 24(1) , 41-47. 19.Mohan, v., krishnan, M., & srikanth. (2008). harnessing of microbial fuel cell employin aerated cathode through anerobic treatment of chemical wastewater using selectively enriched hydrogen producing mixed consortia. 87(12) , 2667-2676. 20.Potter, M. (1911). electrical effects accompanying the decomposition of organic compounds. 84 , 260-276. 21.Strik, D. (2008). Green electricity production with living plants and bacteria in a fuel cell. international journal of energy research, 32(9) , 870-876.

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