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Department of Biology. Microbial energy conversion and practical application to an algal fuel cell. Peter Weigele MIT Biology and Edgerton Center Biological Energy Interest Group (BEInG) Presentation for 10.391 Sustainable Energy February 15, 2007. There's no place. ...like home!. - PowerPoint PPT Presentation
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Microbial energy conversion andpractical application to
an algal fuel cell.
Peter WeigeleMIT Biology and Edgerton CenterBiological Energy Interest Group (BEInG)
Presentation for 10.391 Sustainable Energy February 15, 2007
Department ofBiology
http://visibleearth.nasa.gov/
The Keeling curve
Today’s message:
Life has an incredible diversity of mechanisms for theinterconversion of different forms of energy, includingsunlight, inorganic and organic chemical energy.
Biological productivity and energy conversion underlies fossilfuels, ethanol, biodiesel, and cellulose-based technologies.
The range of respiratory and photosynthetic mechanisms should be examined as a “toolkit” for further development of biological energy conversion technologies.
(need more pedagogical exploration of photosynthesis and cellulose at MIT!)
A Culinary and Cultural Staple in Crisis:Mexico Grapples With Soaring Prices for Corn -- and Tortillas
By Manuel Roig-FranziaWashington Post Foreign ServiceSaturday, January 27, 2007; A01
“Mexico is in the grip of the worst tortilla crisis in its modern history. Dramatically rising international corn prices, spurred by demand for the grain-based fuel ethanol, have led to expensive tortillas.”
Food and fuel subject to the same market forces?
9 x 109 by 2050
Photosynthesis
Organisms make their own food by fixing (reducing) inorganic carbon to make energy rich carbohydrates
Reducing power derived from the light driven oxidation of water (an amazing process).
Carbohydrates subsequently respired for a net gain of NADH and ATP, intracellular energy carriers.
Example: 18 ATP needed to synthesize one glucose, 30 ATP generated by complete oxidation of glucose back to CO2. Energy difference is input of solar energy.
Respiration
All organisms derive their biosynthetic abilities from the stepwise oxidation of energy rich compounds (respiration).
Oxidation generates reduced intracellular electron carriers.
Oxidation of electron carriers is used to establish and maintain chemical gradients across cellular membranes (emf to pmf).
Proton motive force consumed to synthesize ATP, an energy carrier.
ATP synthase
Electrons go where they are most wanted...
Oxygen is a potent electron acceptor.
Freely diffuses across biological membranes.
Electrons can accomplish work as they traverserespiratory systems en route to oxygen.
Aerobic respiration
Aerobic respiration: O2 as terminal electron acceptor
“Bacteria are beautiful” by Diane Newman
Oxygen limited in many environments, e.g. sediments
Bacteria can use minerals as terminal electron acceptors,e.g. Ferric oxides (Iron III)
Electrons are exported out of the cell by soluble, electroncarriers OR by using cell surface protein complexes.
Other example of anaerobic respiration is fermenation(6 ATP/glucose versus 30ATP/glucose).
Anaerobic respiration
Anaerobic respiration with Iron(III) as extracellular terminal e- acceptor
“Bacteria are beautiful” by Diane Newman
solubleelectroncarriers
see also www.geobacter.org
http://www.pnas.org/cgi/doi/10.1073/pnas.0604517103
Protein nanowires also found in gram negative aerobes, cyanobacteria, and methanogens
Schematic of a microbial fuel cell
...anode is a continually replenished electron acceptor!
Sediment battery: a type of microbial fuel cell
Bacterial biomass from electricity
Running a microbial fuel cell in reverse can driveotherwise thermodynamically unfavorable chemistry.
Summary, part I: The microbial fuel cell could be a core technology for energy conversion
microbial metabolismex vivo protein complexes
anode/cathode compositionelectron carriers
fuel cell construction
cellulose-derived carbohydratesenergy rich wastewater
organic sedimentssunlight
electricity
electricityhydrogenalcoholsmethanetreated water
MFC
Part II: Photosynthesis
cyt bfcomplexcyt bf
complex
FNRFNRFdFd
photo-system I(P700)
photo-system I(P700)
LightHarvestingComplex(LHCII)
LightHarvestingComplex(LHCII)
LightHarvesting
Complex(LHCI)
LightHarvesting
Complex(LHCI)
thylakoid lumen
stroma
2 H2O 4 H+ + O2
OECOEC
H+
H+
H+
H+
ADP + Pi ATPNADP+NADPH
photo-system II(P680)
photo-system II(P680)
PCPC
light light
1 23
4
5F1F0
ATP-synthase
Q
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
1
2
3
4
5
Part III:A simple, low-cost algal fuel cell
for research and education
Principle of H2 generation by microalgae
Deprive algae of external oxygen
Diminish their capacity to generate oxygen from water splitting by limiting availability of sulfur
Algae use protons as terminal electron acceptor
Reduced protons make H2, a reaction catalyzed by an oxygen sensitive enzyme called hydrogenase
Pathway explored by Maria Ghirardi, Michael Siebert, Tasios Melis and colleagues
Chlamydomonas rheinhardtii making colonies on solid medium
Photobioreactors: modular, scalable
Algal growth using an airlift bioreactor
Gas Dispersion Tube Only
Airlift with Gas Dispersion Tube
PVC insert to create air-lift for improved mixing
PVC tubing + caps + fittings + tubing + pump = gas recirculator
The finished recirculating pump
Gas managment and fuel cell
Luer fittings and stopcocks fromCole-Parmer
petstore
40 bucks from fuelcellstore.com
Bioreactor setup
Fuel cell under load
Photobioreactor
Fuel Cell
Online Data Monitoring
H2
e-
Data collection using an A/D converter
Dataq model 154, ~$100, microvolt resolution
algal growth on solid substrate
grow algae with bubbling air and S+ medium
inoculate large bioreactor containing S- medium
seal, start pump, and collect data
measure cell mass, and chlorophyll concentration
Experimental overview
Chlamydomonasrheinhardtii
Unknown: “WP2” Unknown: “WP1”
Do other kinds of green, microalgae make H2?
Testing different algal strains (note clumping Chlamy)
Algal strain choice impacts H2 production: As Indicated by Varying Voltage Output
data from 10.28 Team C, 2006
data from 10.28 Team C, 2006
10.28 Team C
Asish Misra
Sohrab Virk
Joia Ramachandani
Sophmore biology students from Nashoba Regional HS
Kay Leigh Kay
Andrew Hoy Mackey Craven
Sam Jewell
Nina Kshetry
Many, many thanks!
Tom KnightJon KingChris Kaiser
Samantha SuttonJason Kelly
openwetware.org
Edgerton CenterSteven BanzaertSandi Lipnonski
New blood!John M. CravenAndrew Hoy
J.F. Hamel and 10.28
Team CJoia RamachandaniAsish MisraSohrab Virk
David Form, NRHSAshley, Meaghan, Kay Leigh, Jackie, and Kay
6 CO2 + 6 H2O --> C6H12O6
Marine Synechococcus
Marine Synechococcus: a gram negative bacteriumperforming oxygenic photosynthesis.
Hill-billy photobioreactor
200 nm
Syn9host: Synechococcus WH8109contractile tail177,300 bp225 orfs