Biomass Production from Electricity Using Ammonia as an Electron Carrier in a Reverse Microbial Fuel Cell

Khunjar, Wendell; Şahin, Asli; West, Alan C.; Chandran, Kartik; Banta, Scott

doi:10.1371/journal.pone.0044846

Cited by 47 publications

(35 citation statements)

References 44 publications

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“…The ability to perform OER at low overpotential in neutral pH ranges (pH 6-8) has been achieved with the development of a cobalt phosphate (CoP i ) catalyst (31). This OER catalyst features many of the properties of the oxygen-evolving catalyst of photosystem II (PSII) including its structure (32)(33)(34) and its ability to self-assemble (35,36), repair itself (37), and manage the proton-coupled electron transfer chemistry of water splitting akin to the Kok cycle of PSII (38). Of pertinence to this study, the catalyst can perform OER in natural waters of a wide variety of solution environments including buffers capable of supporting biological growth (39).…”

Section: Significancementioning

confidence: 99%

Efficient solar-to-fuels production from a hybrid microbial–water-splitting catalyst system

Torella

Gagliardi

Chen

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

381

265

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Photovoltaic cells have considerable potential to satisfy future renewable-energy needs, but efficient and scalable methods of storing the intermittent electricity they produce are required for the large-scale implementation of solar energy. Current solar-to-fuels storage cycles based on water splitting produce hydrogen and oxygen, which are attractive fuels in principle but confront practical limitations from the current energy infrastructure that is based on liquid fuels. In this work, we report the development of a scalable, integrated bioelectrochemical system in which the bacterium Ralstonia eutropha is used to efficiently convert CO2, along with H2 and O2 produced from water splitting, into biomass and fusel alcohols. Water-splitting catalysis was performed using catalysts that are made of earth-abundant metals and enable low overpotential water splitting. In this integrated setup, equivalent solar-to-biomass yields of up to 3.2% of the thermodynamic maximum exceed that of most terrestrial plants. Moreover, engineering of R. eutropha enabled production of the fusel alcohol isopropanol at up to 216 mg/L, the highest bioelectrochemical fuel yield yet reported by >300%. This work demonstrates that catalysts of biotic and abiotic origin can be interfaced to achieve challenging chemical energy-to-fuels transformations.

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Section: Significancementioning

confidence: 99%

Efficient solar-to-fuels production from a hybrid microbial–water-splitting catalyst system

Torella

Gagliardi

Chen

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

381

265

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“…We have verified that the cathode performance does not deteriorate when exposed to media effluent from the bioreactor, 16 an important milestone for establishing an integrated system. To observe changes in cathode performance with time, long-term studies for the nickel and glassy carbon cathodes were conducted.…”

Section: Constant Current Electrolysis-constant Current Experimentsmentioning

confidence: 64%

“…Journal of The Electrochemical Society, 160 (1) G19-G26 (2013) Equation (15) can be rewritten in terms of circuit elements as shown below: [16] where R e = 1 4κro is electrolyte resistance, [17] and the charge-transfer resistance R t = RT αFiss . Zsim software was used to fit this model to impedance data.…”

Section: Resultsmentioning

confidence: 99%

“…16 Power for the electrochemical system is expected to be the dominating operating cost of the overall process, and therefore optimization and design of the electrochemical reactor is essential. For the reactor that is coupled with N. europaea bioreactor, this involves study of nitrite reduction to ammonia at buffered neutral electrolytes as shown in reaction 1.…”

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confidence: 99%

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Electrochemical Reduction of Nitrite to Ammonia for Use in a Bioreactor

Şahin

Lin

Khunjar

et al. 2012

J. Electrochem. Soc.

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One novel means of biofuel production requires the reduction of nitrite ions to produce ammonia (which serves as an electron source for genetically-modified, carbon dioxide-fixing bacteria). The feasibility of this process depends on the performance of both the electrochemical reactor and a coupled bioreactor. We report on characterization of the electrochemical process involving nitrite reduction to ammonia in buffered electrolytes in the pH range between 6.0 and 8.0. A limiting current plateau was observed and determined to be due to flux of phosphate buffer (the primary source of protons) to the electrode surface. Importantly to the development of a sustainable process, current efficiencies of nitrite reduction to ammonia of 100% on both nickel and glassy carbon electrodes are possible. A divided flow-by porous electrode cell was designed as a proof of principle by coupling it to the bioreactor. It was observed that the overpotential of glassy carbon cathode decreased by ∼500 mV over 10 days which would correspond to 24% decrease in power requirements for the electrochemical reactor.As global energy consumption increases, efficient biofuel production from renewable energy resources may be increasingly important. Current methods frequently rely on natural photosynthesis, but these photosynthetic approaches suffer from low energy conversion efficiencies. The maximum theoretical biomass production efficiency from photosynthesis is 11.9%, and in real systems is closer to one percent. 1 Additionally, the conversion of biomass to biofuels that are compatible with the transportation-fuels infrastructure presents a challenge. New approaches with improved energy to biomass/biofuel conversion efficiency are presently being considered. Figure 1 illustrates one approach in which electrical energy is used indirectly to reduce carbon dioxide into a target fuel or chemical. Such a system, which is essentially a microbial fuel cell running in reverse, has the potential to direct renewable energy into high energy organic compounds. One manifestation of this approach was demonstrated by Li et al. using the lithoautotrophic organism Ralstonia eutrophia. 2 A bioreactor containing this organism is coupled to an electrochemical reactor that can reduce CO 2 to CHOO − . The organism takes in CHOO − from the electrochemical reactor and it is genetically engineered to produce isobutanol and 3-methyl-1-butanol. In our approach, we avoid the necessity of electrochemical reduction of CO 2 and instead rely on the biological reduction of CO 2 using a chemolithoautotrophic organism.Using electrical energy to drive bacteria to produce chemicals has been explored in microbial electrolysis cells in which cells have direct contact with an electrode. 3-5 The system proposed here features an electrochemical reactor (for energy capture) and a bioreactor (for bioproduction) that are spatially and temporally decoupled. This decoupling allows for independent optimization of both processes.

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“…Another example used the concept of a reverse microbial fuel cell to transform electricity to energy forms that can be used by microbes. Electricity was first used to reduce nitrite to ammonia, the latter of which can be used as an energy source for cell growth and CO2 fixation in the chemoautotroph Nitrosomonas europaea (Khunjar et al, 2012). …”

Section: New Energy Supply For Co2-fixation In Autotrophic Microbesmentioning

confidence: 99%

Synthetic biology for CO2 fixation

Gong

Zhang

2016

Sci. China Life Sci.

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Recycling of carbon dioxide (CO2) into fuels and chemicals is a potential approach to reduce CO2 emission and fossil-fuel consumption. Autotrophic microbes can utilize energy from light, hydrogen, or sulfur to assimilate atmospheric CO2 into organic compounds at ambient temperature and pressure. This provides a feasible way for biological production of fuels and chemicals from CO2 under normal conditions. Recently great progress has been made in this research area, and dozens of CO2-derived fuels and chemicals have been reported to be synthesized by autotrophic microbes. This is accompanied by investigations into natural CO2-fixation pathways and the rapid development of new technologies in synthetic biology. This review first summarizes the six natural CO2-fixation pathways reported to date, followed by an overview of recent progress in the design and engineering of CO2-fixation pathways as well as energy supply patterns using the concept and tools of synthetic biology. Finally, we will discuss future prospects in biological fixation of CO2.carbon dioxide fixation, synthetic biology, CO2-fixation pathway, energy supply Citation:

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Biomass Production from Electricity Using Ammonia as an Electron Carrier in a Reverse Microbial Fuel Cell

Cited by 47 publications

References 44 publications

Efficient solar-to-fuels production from a hybrid microbial–water-splitting catalyst system

Efficient solar-to-fuels production from a hybrid microbial–water-splitting catalyst system

Electrochemical Reduction of Nitrite to Ammonia for Use in a Bioreactor

Synthetic biology for CO2 fixation

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