Diffusion-driven proton exchange membrane fuel cell for converting fermenting biomass to electricity

Malati, Peter; Mehrotra, Poonam; Minoofar, P.; Mackie, David M.; Sumner, James J.; Ganguli, Rahul

doi:10.1016/j.biortech.2015.07.001

Cited by 3 publications

(13 citation statements)

References 12 publications

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“…To demonstrate these capabilities, the vapor-fed FC was run as a bio-hybrid FC with an ongoing yeast fermentation as the ethanol source. The fermentation was run with a rich medium (YPD) that is known to rapidly poison FCs [38]. Even with an RO separation membrane to help purify the ethanol from the fermentation, liquid-fed bio-hybrid FCs have a >90% reduction in power density over a period of 1 week when running on rich media [48].…”

Section: Resultsmentioning

confidence: 99%

“…A microbial culture produces a biofuel, and the culture liquid (fermentate) is used directly in a FC to produce electrical power with minimal processing [38, 39]. Of course, this introduces complications, because the biotic and abiotic processes interact harmfully with each other.…”

Section: Introductionmentioning

confidence: 99%

“…Prior work has demonstrated that spent yeast fermentations can be used in a direct ethanol FC without purification if the growth medium minimizes such components [39]. Further work has shown that the use of rich media (allowing for faster ethanol production) with a bio-hybrid direct ethanol FC is possible, provided that a reverse osmosis (RO) membrane is used to passively separate the anode from the fermentation [38]. However, over long time periods (1 week), catalyst poisoning decreases FC performance, presumably from amino acids that manage to get past the RO membrane [43].…”

Section: Introductionmentioning

confidence: 99%

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Vapor-fed bio-hybrid fuel cell

Benyamin

Jahnke

Mackie

2017

Biotechnol Biofuels

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BackgroundConcentration and purification of ethanol and other biofuels from fermentations are energy-intensive processes, with amplified costs at smaller scales. To circumvent the need for these processes, and to potentially reduce transportation costs as well, we have previously investigated bio-hybrid fuel cells (FCs), in which a fermentation and FC are closely coupled. However, long-term operation requires strictly preventing the fermentation and FC from harming each other. We introduce here the concept of the vapor-fed bio-hybrid FC as a means of continuously extracting power from ongoing fermentations at ambient conditions. By bubbling a carrier gas (N2) through a yeast fermentation and then through a direct ethanol FC, we protect the FC anode from the catalyst poisons in the fermentation (which are non-volatile), and also protect the yeast from harmful FC products (notably acetic acid) and from build-up of ethanol.ResultsSince vapor-fed direct ethanol FCs at ambient conditions have never been systematically characterized (in contrast to vapor-fed direct methanol FCs), we first assess the effects on output power and conversion efficiency of ethanol concentration, vapor flow rate, and FC voltage. The results fit a continuous stirred-tank reactor model. Over a wide range of ethanol partial pressures (2–8 mmHg), power densities are comparable to those for liquid-fed direct ethanol FCs at the same temperature, with power densities >2 mW/cm2 obtained. We then demonstrate the continuous operation of a vapor-fed bio-hybrid FC with fermentation for 5 months, with no indication of performance degradation due to poisoning (of either the FC or the fermentation). It is further shown that the system is stable, recovering quickly from disturbances or from interruptions in maintenance.ConclusionsThe vapor-fed bio-hybrid FC enables extraction of power from dilute bio-ethanol streams without costly concentration and purification steps. The concept should be scalable to both large and small operations and should be generalizable to other biofuels and waste-to-energy systems.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-017-0755-7) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Vapor-fed bio-hybrid fuel cell

Benyamin

Jahnke

Mackie

2017

Biotechnol Biofuels

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“…The setup of the bio-hybrid FC was a variant of what has been previously reported in the literature [ 16 , 26 ]. Specifically, a Dow Filmtec SW30HR RO membrane (Sterlitech Corporation: Kent, WA, USA) was fixed between two chambers (glass half-U tubes) with a fermentation in one chamber and a 5% glucose draw solution in the other.…”

Section: Methodsmentioning

confidence: 99%

“…On the processing side, a wide range of standard separation techniques (e.g., distillation, sorbents, pervaporation) have been used to concentrate the fuels and remove unwanted byproducts [ 2 , 12 , 13 ]. There has also been considerable interest in using fuel cells (FCs) with biofuels, especially ethanol [ 14 ] due to the ability of FCs to run on dilute biofuel streams, and depending on the source, with minimal parasitic power losses due to purification [ 15 , 16 ]. FCs also have much higher electrical power densities than MFCs (typically 3 orders of magnitude), which greatly reduces the required size for a given fuel stream.…”

Section: Introductionmentioning

confidence: 99%

Aspergillus oryzae–Saccharomyces cerevisiae Consortium Allows Bio-Hybrid Fuel Cell to Run on Complex Carbohydrates

et al. 2016

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Consortia of Aspergillus oryzae and Saccharomyces cerevisiae are examined for their abilities to turn complex carbohydrates into ethanol. To understand the interactions between microorganisms in consortia, Fourier-transform infrared spectroscopy is used to follow the concentrations of various metabolites such as sugars (e.g., glucose, maltose), longer chain carbohydrates, and ethanol to optimize consortia conditions for the production of ethanol. It is shown that with proper design A. oryzae can digest food waste simulants into soluble sugars that S. cerevisiae can ferment into ethanol. Depending on the substrate and conditions used, concentrations of 13% ethanol were achieved in 10 days. It is further shown that a direct alcohol fuel cell (FC) can be coupled with these A. oryzae-enabled S. cerevisiae fermentations using a reverse osmosis membrane. This “bio-hybrid FC” continually extracted ethanol from an ongoing consortium, enhancing ethanol production and allowing the bio-hybrid FC to run for at least one week. Obtained bio-hybrid FC currents were comparable to those from pure ethanol—water mixtures, using the same FC. The A. oryzae–S. cerevisiae consortium, coupled to a bio-hybrid FC, converted food waste simulants into electricity without any pre- or post-processing.

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Using Reverse Osmosis Membranes to Couple Direct Ethanol Fuel Cells with Ongoing Fermentations

Jahnke

Benyamin

Sumner

et al. 2016

Ind. Eng. Chem. Res.

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Separations in biological systems remain a challenging problem and can be particularly so in the case of biofuels, where purification can use a significant fraction of the energy content of the fuel. For small-molecule biofuels like ethanol, reverse osmosis (RO) membranes show promise as passive purifiers, in that they allow uncharged small molecules to pass through while blocking most other components of the growth medium. Here, we examine the use of RO membranes in developing biohybrid fuel cells, closely examining the case where a direct ethanol fuel cell (DEFC) is coupled with an ongoing yeast fermentation across an RO membrane. We show that, contrary to initial good performance, the acetic acid produced by the DEFC readily diffuses back across the RO membrane and kills the fermentation after a few days. We introduce an amelioration chamber where the acetic acid is converted to acetate ions. The RO membrane rejects the acetate ions due to their charge, preventing acetic acid buildup in the fermentation. We also show that some small, charged components of the fermentation such as amino acids are imperfectly rejected by RO membranes. Because of the high sensitivity of DEFCs to low concentrations (10s of μM) of amino acids, even a very slow diffusion of amino acids across the RO membranes can limit biohybrid fuel cell lifetimes.

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Diffusion-driven proton exchange membrane fuel cell for converting fermenting biomass to electricity

Cited by 3 publications

References 12 publications

Vapor-fed bio-hybrid fuel cell

Vapor-fed bio-hybrid fuel cell

Aspergillus oryzae–Saccharomyces cerevisiae Consortium Allows Bio-Hybrid Fuel Cell to Run on Complex Carbohydrates

Using Reverse Osmosis Membranes to Couple Direct Ethanol Fuel Cells with Ongoing Fermentations

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