Microbial electrosynthesis (MES) from CO2 is resilient to fluctuations in renewable energy supply

• Published in: Energy conversion and management Vol. 177; pp. 272 - 279
• Main Authors: del Pilar Anzola Rojas, Mélida, Mateos, Raúl, Sotres, Ana, Zaiat, Marcelo, Gonzalez, Ernesto Rafael, Escapa, Adrián, De Wever, Heleen, Pant, Deepak
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-12-2018; Elsevier Science Ltd
• Subjects: Acetate production; Acetic acid; Acid production; Alternative energy; Biofilms; Biological activity; Carbon dioxide; Carbon sequestration; Cathodic biofilm; Cathodic protection; CO2 valorization; Communities; Electric power; Electricity; Fluctuations; Microbial activity; Microbial community; Microbial electrosynthesis; Microorganisms; Next-generation sequencing; Outages; Power supplies; Renewable energy; Solar energy; Wind power; Microbial electrosynthesis; Cathodic biofilm; Renewable energy; Acetate production; CO2 valorization; Microbial community
• ISSN: 0196-8904; 1879-2227
• DOI: 10.1016/j.enconman.2018.09.064

•Power supply interruption affects the performance of the system for a reduced period of time.•MES showed to be recovered after power supply interruption.•Longer off periods did not result in longer recovery times.•MES system proved to be ready for real-field application powered with renewable energy.•The cathodic biofilm was dominated by bioelectrochemically active acetogenic bacteria.
Microbial electrosynthesis (MES) allow CO2 capture and utilization for the electricity-driven bioproduction of organics such as acetic acid. Such systems can be coupled to any renewable electricity supply, especially those derived from solar and wind energy. However, fluctuations or even absence of electricity may cause damages or changes in the microbial community, and/or affect the performance and robustness of MES. Therefore, the transformation of gaseous CO2 into organic products in a MES was assessed continuously during 120 days of operation. Time-increasing power outages, from 4 h to 64 h, were applied in order to evaluate the effects of electric energy (current) absence on microbial community, organics formation, production rates and product accumulation. Acetic acid was the main product observed before and after the power outages. A maximum titer and production rate of 6965 mg L−1 and 516.2 mg L−1 d−1 (35.8 g m−2 d−1) of acetic acid were observed, respectively. During the absence of power supply, it was observed that acetic acid is oxidized back to CO2 which suggests microbial activity and/or pathway reversal. However, the electro-autotrophic activity recovered after the power gaps, and acetic acid production was restored after reconnecting the energy supply, reaching a current density of −25 A m−2. The microbial community of the biofilm responsible for this behavior was characterized by means of high-throughput sequencing, revealing that Clostridium, Desulfovibrio and Sporomusa accounted for 93% of the total community attached onto the cathodic biofilm. Such resilience of electrotrophic microorganisms reinforces the opportunity to couple bioelectrochemical systems to renewable energy, overcoming the eventual electrical power fluctuations.