Electromethanogenesis for biogas upgrading People at SDU: Amelia-Elena Rotaru Mon Yee Oo & Bo Thamdrup
Who is an electromethanogen? How are they retrieving electrons? How to use EET to upgrade biogas?
Electron uptake by methanogens Strategies of electron transfer: D. vulgaris H 2 or formate S. fumarooxidans Direct electron transfer G. metallireducens M. hungateii M. hungateii M. harundinacea M. concilii M. barkeri Rotaru 2014a, Rotaru 2014b, Rotaru 2015
Methanosaeta Geobacter
DIET in consortia Ethanol Electrogen G. metallireducens Acetate DIET 4e - + 4H + Ace e - 14 C-bicarbonate CH 4 + CO 2 Electrotroph Mseta. harundinacea CO 2 0.5 14 CH 4 2 0.6 mmol 1.5 1 0.5 Methane Ethanol Acetate Specific activity 14 CH4 / 14 CO 2 (CPM µmol -1 ) 0.5 0.4 0.3 0.2 0.1 0 0 20 40 60 80 100 days Rotaru 2014a 0 1 21 28 days
Rotaru 2014a 6
Methane (%) Rotaru 2014a 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Pili k.o. Geobacter Methanosaeta 0 20 40 60 80 100 120 140 160 180 200 Time (days)
Cytochrome-c containing Archaea Kletzin 2015
What other methanogens are implicated in EET?
Methanogens associated with EET DIET M. harundinacea DIET M. concilii DIET Methanosaeta spp. WE Methanospirillum hungateii DIET Methanoplanus petrolearius DIET DIET Methanobacterium sp. IM1 ZVI Methanobacterium palustre WE Methanobrevibacter spp. WE M. maripaludis KA1 ZVI and Mic1c10 ZVI Methanococcus voltae DIET Original tree by Ohtomo 2013
Environ. Sci. Technol. 2009, 43, 3953 3958 Environ. Sci. Technol. 2009, 43, 3953 3958 a theoretical potential as high as 1.1 V under neutral ph l Conversion of conditions (1). The Conversion MEC is a type of modified MFC Direct Biological ofthat has been used to efficiently store electrical energy as a biofuel nt into Methane by (hydrogen gas) (2). Hydrogen gas evolution from the cathode, Current into(3-5). Methane by is not spontaneous The voltage produced genesis Electricalhowever, by electrogenic bacteria on the anode using a substrate such Electromethanogenesis as acetate (EAn = -0.2 V) is insufficient to evolve hydrogen gas at the cathode (Ecell ) -0.414 V, ph)7). By adding a small voltage, hydrogen gas can be produced using MECs at very high energy efficiencies evaluated in terms of just energy energy C electrical HENG, Dalone E F(200-400%) E N G XorIboth N Gelectrical, and substrate heat of combustion energy (82%) (3). One D O U G L A S Fdisadvantage. C A L L of, electrically A N D Bassisted R U C method E E. ofl hydrogen OGAN* 008. Revised manuscript received production (electrohydrogenesis) is that a precious metal Engineering Environmental Institute and Department of Civil and March 6, 2009. catalyst such as platinum is usually used on the cathode. Environmental Engineering, 212 Sackett The process, Hydrogen compression is also Building, an energy-intensive Pennsylvania State University Park, Pennsylvania 16802 anduniversity, hydrogen storage can be problematic (6). Renewable biomethane is typically produced by methaare needed to produce renewable nogens from a few substrates such as acetate, formate, and stored and used Received for transportation, biohydrogen gas in anaerobic (7). Based on December 12, 2008. Reviseddigesters manuscript received ction. Here we demonstrate that thermodynamic calculations, methane could also be promarch 5, 2009.duced Accepted March through 6, 2009. electrochemically carbon dioxide reduction duced using a biocathode containing at a voltage of 0.169 V under standard conditions, or -0.244 mical systems (abiotic anode) or V under more biologically relevant conditions at a ph)7, by (MECs; biotic anode) by a process the reaction sis. At a set potential of less DEFENG XING, AND BRUCE E. LOGAN* nstitute and Department of Civil and 212 Sackett Building, The SHAOAN, University Park, Pennsylvania 16802 ode biofilm examined by (A) SEM of cells on the carbon cloth and bacterium-specific probe MB1174-Alexa Fluor 488 (green). carbon dioxide was reduced to + + 8e- f CH4 + 2H2O (1) 2 + 8H er electrochemicalnew reactor containing sustainable methodscoare needed to produce renewable ode, and no precious metal energy carriers This thatsuggests can be for transportation, thatstored methaneand couldused be produced without an rrent capture efficiency was 96%. organic fuel, at about the same potential needed for hydrogen ents made using linear sweep or chemical production. Here we demonstrate that heating, production with an organic fuel (such as acetate). Methane e biocathode substantially increased capture production by eq 1 has the addedaadvantage of CO2containing methane can directly be produced using biocathode to a plain carbon cathode where into a fuel (but not sequestration). A purely electrochemical ogen gas could be produced. Both inroute methanogens electrochemical systems (abiotic anode) of methane production in practice is energy intensiveor and very small hydrogen production due to high electrode potentials and the lack of suitable microbial electrolysis cells (MECs; biotic anode) by a process erefore support a mechanism of catalysts able to efficiently reduce this overpotential (8). The required voltage couldat theoretically be eliminated called electromethanogenesis. a set potential ofwhen lessusing from current and not from hydrogen an organic substrate due to a positive electrochemical cell ominated by a single Archaeon, than -0.7 V (vspotential Ag/AgCl), carbon dioxide reduced to ) 0.071 V with acetate), for methane production (Ecellwas re. When a current was generated compared to a negative potential for hydrogen production. methane lm on the anode growing on using a two-chamber electrochemical reactor containing a theoretical potential as high as 1.1 V under neutr conditions (1). The MEC is a type of modified MFC th been used to efficiently store electrical energy as a b (hydrogen gas) (2). Hydrogen gas evolution from the ca however, is not spontaneous (3-5). The voltage pro by electrogenic bacteria on the anode using a substrat (B) fluorescence microscopy of extracted cells as acetate (EAn = -0.2 V) is insufficient to evolve hyd gas at the cathode (Ecell ) -0.414 V, ph)7). By ad small voltage, hydrogen gas can be produced using M very high energy efficiencies evaluated in terms o electrical energy alone (200-400%) or both electrical e and substrate heat of combustion energy (82%) (3 disadvantage of electrically assisted method of hyd production (electrohydrogenesis) is that a precious catalyst such as platinum is usually used on the ca Hydrogen compression is also an energy-intensive pr and hydrogen storage can be problematic (6). Renewable biomethane is typically produced by m nogens from a few substrates such as acetate, format biohydrogen gas in anaerobic digesters (7). Base thermodynamic calculations, methane could also b duced electrochemically through carbon dioxide red at a voltage of 0.169 V under standard conditions, or V under more biologically relevant conditions at a ph the reaction CO2 + 8H+ + 8e- f CH4 + 2H2O
(12) United States Patent Cheng et al. (10) Patent N0.: (45) Date of Patent: US 8,440,438 B2 May 14, 2013 (54) ELECTROMETHANOGENIC REACTOR AND PROCESSES FOR METHANE PRODUCTION (75) Inventors: Shaoan Cheng, State College, PA (US); Bruce Logan, State College, PA (U S) rrna sequence analyses. International Journal of Systematic Bacte riology. 1993. 43(2): 278-286.* Wolin, EA et al. Formation of methane by bacterial extracts. Journal of Biological Chemistry. 1963. 238(8): 2882-2886.* Bond, et al., Electrode-Reducing Microorganisms That Harvest Energy from Marine Sediments, Science, 295: 483-485, 2002. Bond, et Electricity Production by Geobacter sulfurreducens
Direct via outermembrane redox proteins Indirect using electrochemically produced H 2 /formate Indirect using H 2 produced enzymagcally at the cathode H + CO 2 e - H + H + gradient e - H + e - H 2 H 2 -ase CO 2 H 2 CH 4 CH 4 CH 4
Direct via outermembrane redox proteins Indirect using electrochemically produced H 2 /formate Indirect using acetate produced by acetogens H + CO 2 H + gradient e - CO 2 e - H + H + e - H 2 Acetogen ACE CO 2 CH 4 CH 4 CH 4
a Methanosarcina µmol methane 1000 900 800 700 600 500 400 300 200 100 which cannot use H 2 or formate Disconnected cathode Poised cathode PotenGal vs. ref. electrode (V) CO 2 CO 2 0-0.1-0.2-0.3-0.4-0.5-0.6-0.7-0.8 Poised potenjal vs. Ag/AgCl (Volt) 0 0 10 20 30 40 50 60 70 80 Days -0.9 by Mon Yee Oo
New potenjostats
Geobacter sulfurreducens on a cathode polarized at -600mV by AMEL2550 25-4.00E-03 1.15 2.31 3.47 days 20 mm 15 10 mm Current (A) -6.00E-03-8.00E-03 5 0 Cells on non-poised cathode 0 1 2 3 4 5 Jme (days) -1.00E-02 by Mon Yee Oo
Cyclic voltametry 3 redox couples 2.50E-02 1.50E-02-0.305 V vs. Ag/AgCl -0.105V vs. SHE current (A) 5.00E-03-5.00E-03 Marsili 2010-0.225 V vs. Ag/AgCl -0.025 V vs. SHE -1.50E-02-2.50E-02-0.435 V vs. Ag/AgCl -0.235 V vs. SHE Media Electrode + Media -1-0.8-0.6-0.4-0.2 0 0.2 0.4 PotenJal versus Ag/AgCl (Volts) by Mon Yee Oo
Time line A. ordered potengostats June 2015 Sept 2015 Mon started Oct-Nov 2015 Mon tests Methanosarcina and sludge in MES using a powersource Jan 2015 Mon tests AMEL potengostats with Geobacter NEXT Special glassware ordered Nov 2015 A. started Jan 2016 ordered a 8- channel mulgstat End of dec 2015 PotenGostats arrived Feb 2016 The 8-channel mulgstat arrived Feb 2016 Mon tests the PalmSense mulgstat with Geobacter Feb 2016 A. tests Clostridium in MES using the AMEL potengostats
What next?
Who? How? H 2 sensor test Digester community on cathodes OpGmize consorga on cathodes NEXT Methanosarcina Methanosaeta on cathodes ComparaGve Methanosarcina Methanosaeta Transcript-/prote-ome Gene-deleGon studies Methanosarcina PEOPLE: Mon, Karen, Amelia, Bo, Lars, Lars-Peter, Niels-Peter, Cornelia