Conversion of Wastes into Bioelectricity

Trent BenefieldRyan Risinger

http://www.ecofriend.com/eco-tech-energy-producing-microbes-generate-electricity-from-mud.html

http://shanghaiist.com/2012/06/13/progressive-residential-electricity-tariffs.php

1

Summary

Why is this important?

MET's (Microbial Electrochemical technologies)

Prior Work

Electricity Generation

Chemical Production in MEC's (Microbial Electrolysis Cells)

Compare with conventional technologies

Improvements

Conclusions

References

2

Why is this important?

Treating wastewater takes 15 GW power in U.S.

Domestic, industrial, and animal wastewater has considerable potential energy (~1.5x10^11 kWh)

• ~17 GW power equivalent

Additional 600 GW power annually from agriculture biomass

http://www.ecofriend.com/generating-electricity-from-waste-water.htm l 3

MET's

• Microbial Electrochemical Technologies

Use microorganisms to generate electricity and produce chemicals

Process able to use wide variety of wastes

• Acetates, protein, lignocellulose, etc.

http://www.sfi.mtu.edu/FutureFuelfromForest/LignocellulosicBiomass.htm http://www.terradaily.com/reports/

New_Processing_Steps_Promise_More_Economical_Ethanol_Production.html

4

Prior Work

• Basic technology has been around since the early 19th century.

• In 1931 a series of microbial fuel cells was created that produced 31 volts, but the current was only 2 milliamps.

• Recently in Australia, Foster's Brewing Co. has produced a large scale bioreactor (660 gallons) that uses the brewing process wastewater as a fuel source. It produces clean water and 2 kilowatts of electrical power.

5

Electricity Generation

• Exoelectrogenico example: Geobacter, Shewanella

• Use of "electron shuttles"o Flavin, and phenazine

Electron transport chain

• Anode: Bacteria release electrons/protons

• Cathode: Oxygen is oxidizer

http://chemed.chem.wisc.edu/chempaths/GenChem-Textbook/Electrochemical-Cells-695.html6

Wide variety of wastes in process

• Need variety of microbes

• More power=more specialized wasteso Acetates, Lactate

• More complex wastes=more interactions needed to break down moleculeso Syntrophic interactions, similar to anaerobic digestion

http://www.methanedivers.com/http://wishart.biology.ualberta.ca/BacMap/cgi/getSpeciesCard.cgi?accession=NC_003552&ref=index_12.html

7

8

Chemical Production in MEC's

Microbial Electrolysis Cells

Applying power can produce variety of chemicals

• biofuels, by producing hydrogeno Produced at the cathodeo More thermodynamically efficient than water splitting

-.13 V minimum addition, -1.2 V for water splitting

Voltage required for Hydrogen production: -.41 V

Voltage at anode: -.28 V

-.41 V minus -.28 V = -.13 V

B. E. Logan et al., Microbial electrolysis cells for high yield hydrogen gas production from organic matter. Environ. Sci. Technol.42, 8630 (2008).

9

http://en.wikipedia.org/wiki/File:Microbial_electrolysis_cell.png

10

Organic chemicals produced at cathode

• Apply voltage

• Methane is most common in MEC'so produced by H2 evolved at cathode

• NaOHo Cation exchange membrane separatoro Produced due to pH gradients between chamberso Anode: proton build upo Cathode: proton deficiency

• Hydrogen Peroxideo H2O normally produced at cathode

O2 + 2H2O + 2e- -> H2O2 + 2OH-

11

12

Compare with conventional technologiesCurrent wastewater processing technologies

• Developing since over a century

• Requires -0.3 kWh/m^3 electricity

• Carnot Cycle limitations

Membrane bioreactors

• Requires 1-2 kWh/m^3 electricity

• Economical with very large digesters only

• Needs concentrated waste streams

• Warmer temperatures

• Low energy recovery

• Decreasing need for sludge handlingS. Hays, F. Zhang, B. E. Logan, Performance of two different types of anodes in membrane electrode assembly microbial fuel cells for power generation from domestic wastewater. J. Power Sources196, 8293 (2011).

P. L. McCarty, J. Bae, J. Kim, Domestic wastewater treatment as a net energy producer—can this be achieved? Environ. Sci. Technol.45, 7100 (2011). 21749111 13

Waste Type Heat of Combustion kcal/kg

Charcoal 7213

Animal Fats 9450

Wood Chips 4785

Coffee Waste 4371

Acetic Acid 3446

Sunflower Stalk 4300

Tobacco Waste 2910

http://lehrafuel.com/briquetts-calorific-value.html

Examples of Types of Possible Feed

http://www.balboa-pacific.com/WasteToEnergy/BTU_Values.pdf

14

Improvements

Increase power output in microbes

• Addition of Enterococcus faecium increase power output by 30-70%o Little power produced on its own

More research required

Pretreat incoming biomass Increases digestibility

• Lime (calcium hydroxide) pretreatment

• Breaks down lignin in lignocellulose

http://en.wikipedia.org/wiki/File:Cellulose-2D-skeletal.pnghttp://www.sfi.mtu.edu/FutureFuelfromForest/LignocellulosicBiomass.htm 15

Conclusion

• Technology is has lots of potential for energy generation.

• Current research still can't achieve large electricity generation.

• Many different feeds with varying potential energies

• Improvements are still possible (varying microbial cultures, pretreatmment)

• One of the greatest advantages is to recycle wastewater with drastically less electricity input.

16

References1. P. L. McCarty, J. Bae, J. Kim, Domestic wastewater treatment as a net energy producer—can this

be achieved? Environ. Sci. Technol.45, 7100 (2011). 21749111

2. B. E. Logan, Extracting hydrogen and electricity from renewable resources. Environ. Sci. Technol. 38, 160A (2004).

3. R. D. Perlack et al., “Biomass as feedstock for a bioenergy and bioproducts industry: The technical feasibility of a billion-ton annual supply,” vol. ORNL/TM-2005/66, report no. DOE/GO-102995-2135 (Oak Ridge National Laboratory, Oak Ridge, TN, 2005).

4. B. E. Logan, Exoelectrogenic bacteria that power microbial fuel cells. Nat. Rev. Microbiol. 7, 375 (2009).

5. E. Marsili et al., Shewanella secretes flavins that mediate extracellular electron transfer. Proc. Natl. Acad. Sci. U.S.A.105, 3968 (2008).

6. H. von Canstein, J. Ogawa, S. Shimizu, J. R. Lloyd, Secretion of flavins by Shewanella species and their role in extracellular electron transfer. Appl. Environ. Microbiol. 74, 615 (2008). 10.1128/AEM.01387

7. T. H. Pham et al., Metabolites produced by Pseudomonas sp. enable a Gram-positive bacterium to achieve extracellular electron transfer. Appl. Microbiol. Biotechnol. 77, 1119 (2008). 10.1007/s00253-007-1248

17

8. Logan, Bruce E. and Korneel Rabaey. "Conversion of Wastes into Bioelectricity and Chemicals by Using Microbial Electrochemical Technologies." Science 337 (2012): 686-689. Print.

9. "Microbial Fuel Cell" Wikipedia. n.p., n.d. Web. September 10, 2012.

10. P. D. Kiely, J. M. Regan, B. E. Logan, The electric picnic: Synergistic requirements for exoelectrogenic microbial communities. Curr. Opin. Biotechnol. 22, 378 (2011).

11. D. F. Call, B. E. Logan, Lactate oxidation coupled to iron or electrode reduction by Geobacter sulfurreducens PCA. Appl. Environ. Microbiol. 77, 8791 (2011). 10.1128/AEM.06434

12. A. M. Speers, G. Reguera, Electron donors supporting growth and electroactivity of Geobacter sulfurreducens anode biofilms. Appl. Environ. Microbiol. 78, 437 (2012). 10.1128/AEM.06782

13. B. E. Logan et al., Microbial electrolysis cells for high yield hydrogen gas production from organic matter. Environ. Sci. Technol.42, 8630 (2008).

14. P. Clauwaert et al., Combining biocatalyzed electrolysis with anaerobic digestion. Water Sci. Technol.57, 575 (2008).

15. P. Parameswaran, H. Zhang, C. I. Torres, B. E. Rittmann, R. Krajmalnik-Brown, Microbial community structure in a biofilm anode fed with a fermentable substrate: the significance of hydrogen scavengers. Biotechnol. Bioeng.105, 69 (2010).

16. R. A. Rozendal, H. V. V. Hamelers, C. J. N. Buisman, Effects of membrane cation transport on pH and microbial fuel cell performance. Environ. Sci. Technol.40, 5206 (2006). 18

17. K. Rabaey, S. Bützer, S. Brown, J. Keller, R. A. Rozendal, High current generation coupled to caustic production using a lamellar bioelectrochemical system. Environ. Sci. Technol.44, 4315 (2010).

18. S. T. Read, P. Dutta, P. L. Bond, J. Keller, K. Rabaey, Initial development and structure of biofilms on microbial fuel cell anodes. BMC Microbiol.10, 98 (2010). 10.1186/1471-2180-10

19

http://www.171arw.ang.af.mil/questions/

20