Long-Term Electromethane Production in Continuous Flow Alkaline Microbial Electrolysis
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2018-09-14
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Abstract
Microbial Power to Gas (P2G) is a promising technology for storing renewable energy in the form of natural gas (methane). Energy storage is necessary because renewable energy is often produced at times when it is not demanded. Methane can be used as a transportation fuel in combustion engines due to its low energy density. Microorganisms can produce methane in a single compartment microbial electrolytic cell at room temperature and neutral pH. However, this technology faces several challenges, including anode corrosion, membrane failure, and the fact that the final product is a mixture of methane, hydrogen and CO2. Here, the performance of a continuous-flow MEC (without a membrane separator) was studied for microbial P2G, while monitoring hydrogen and methane gas production at the cathode, as well as microbial community changes over time, all in a pH 10 medium. A steel cathode was found to be preferred over various carbons, as the carbons changed their morphology and surface chemistry with time. Platinized titanium mesh was developed for oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) carried out on stainless steel cathode in order to produce hydrogen necessary for biologically produce methane. The results showed that this alkaline environment is a superior alternative to neutral one for methane production. High rate of hydrogen production was observed in bicarbonate buffer with 97% columbic efficiency. Methane generation reached up to 17 µL/L reactor/day in 1.0 M bicarbonate buffer solution (BBS). Methanobacters a hydrogenotrophic methanogen along with Delta proteobacteria, and Archobacter, an aerobic sulfide, formate and acetate oxidizer, were significantly enriched in MEC. These results showed in this study indicates that inoculation and enrichment procedures are necessary to the initial success of larger-scale systems.
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Salehi, V. (2018). Long-Term Electromethane Production in Continuous Flow Alkaline Microbial Electrolysis (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/32964