Membrane and Fluid Contactors for Safe and Efficient Methane Delivery in Methanotrophic Bioreactors

Clark

2020

ChemSusChem

Mediated microbial electrosynthesis (MES) represents a promising strategy for the capture and conversion of CO2 into carbon‐based products. We describe the development and application of a comprehensive multiphysics model to analyze a formate‐mediated MES reactor. The model shows that this system can achieve a biomass productivity of ∼1.7 g L−1 h−1 but is limited by a competitive trade‐off between O2 gas/liquid mass transfer and CO2 transport to the cathode. Synthetic metabolic strategies are evaluated for formatotrophic growth, which can enable an energy efficiency of ∼21 %, a 30 % improvement over the Calvin cycle. However, carbon utilization efficiency is only ∼10 % in the best cases due to a futile CO2 cycle, so gas recycling will be necessary for greater efficiency. Finally, separating electrochemical and microbial processes into separate reactors enables a higher biomass productivity of ∼2.4 g L−1 h−1. The mediated MES model and analysis presented here can guide process design for conversion of CO2 into renewable chemical feedstocks.

Section: Methodsmentioning

confidence: 99%

A Comprehensive Modeling Analysis of Formate‐Mediated Microbial Electrosynthesis**

Clark

2020

ChemSusChem

“…where is the diffusivity of species following Meraz et al to account for differences in the mass transfer coefficient ( L ). 33 We calculate the equilibrium solubility of CO2, O2, and H2 according to the empirical relationship for the Bunsen solubility coefficient ( ),…”

Section: Gas-liquid Mass Transfermentioning

confidence: 99%

A comparative life cycle analysis of electromicrobial production systems

Adams

2021

Preprint

Electromicrobial production (EMP) processes represent an attractive strategy for the capture and conversion of CO2 into carbon-based products. We describe the development and application of comprehensive reactor, process, and life cycle impact models to analyze three major EMP systems relying on formate, H2, and acetate as intermediate molecules. Our results demonstrate that EMP systems can achieve a smaller carbon footprint than traditional bioprocessing strategies provided the electric grid is composed of >~90% renewable energy sources. For each of the three products we consider (biomass, enzymes, and lactic acid), the H2-mediated Knallgas bacteria system achieves the lowest overall global warming potential, indicating that this EMP strategy may be best-suited for industrial efforts based on current technology. We also identify environmental hotspots and process limitations that are key sites for future engineering and research efforts for each EMP system. Our analysis demonstrates the utility of an integrated bioelectrochemical model/life cycle assessment framework in both analyzing and aiding the ecodesign of electromicrobial processes and should help guide the design of working, scalable, and sustainable systems.

“…In our model, we assume a value of 300 hr -1 , which corresponds to a power demand of 4000 W m -3 with a superficial gas velocity of ~0.11 m s -1 . We note that the actual value in a given reactor is highly dependent on the gas feeding mechanism, [40] the reactor geometry and gas contacting strategies, [41] and components integrated into bioreactors, [27] so any model of experimental results must rely on carefully measured values before valid comparisons can be made.…”

Section: Gas/liquid Mass Transfer Coefficientsmentioning

confidence: 99%

Bioelectrochemical engineering analysis of formate-mediated microbial electrosynthesis

Clark

2020

Preprint

Mediated microbial electrosynthesis (MES) represents a promising strategy for the capture and conversion of CO2 into carbon-based products. We describe the development and application of a comprehensive multiphysics model to analyze a formate-mediated MES reactor. The model shows that this system can achieve a biomass productivity of ∼1.7 g L-1 hr-1 but is limited by a competitive trade-off between O2 gas/liquid mass transfer and CO2 transport to the cathode. Synthetic metabolic strategies are evaluated for formatotrophic growth, which can enable an energy efficiency of ∼21%, a 30% improvement over the Calvin cycle. However, carbon utilization efficiency is only ∼10% in the best cases due to a futile CO2 cycle, so gas recycle will be necessary for greater efficiency. Finally, separating electrochemical and microbial processes into separate reactors enables a higher biomass productivity of ∼2.4 g L-1 hr-1. The mediated MES model and analysis presented here can guide process design for conversion of CO2 into renewable chemical feedstocks.