Abstract
A sustainable future depends on increased participation of renewable energy, high efficiency energy utilization and resource conservation. Microbial fuel cells (MFCs) are novel biotechnological instruments that can generate renewable energy from sustainable materials through microbial metabolism, thereby providing a new possibility for bioenergy production from organic sources. In this study, a co-generation system of bioethanol and electricity using a yeast microbial fuel cell (MFC) was investigated. The co-generation system was found to have a high power output (5.2 ± 0.5 W/m3 ) and high ethanol yield (92.5 ± 2%) when traces of methylene blue (MB) (6.25 mg/L) were added. Substrate concentration, temperature, initial anodic pH, MB addition were crucial impactors on power performance and ethanol production. Yeast domestication is an efficient way to foster power performance and ethanol production by screening the yeast which can generate electricity and ethanol simultaneously as well promoting yeast tolerance to MB. The electron extraction from ethanol fermentation is mainly from the glycolysis process in the cytosol and some from the respiration chain. However, the extraction of electrons has limited influence on changing the yeast central metabolic pathway under very low MB addition and low glucose feeds. When the glucose feed concentration was lower than 250 g/L, electron extraction during the fermentation process has no significant effect on ethanol production. However, under 300 g/L glucose loading, electron extraction contributes to a stable intracellular redox potential resulting in a 1.5% increase in ethanol production and a 5 and 10% decrease in glycerol and trehalose production, respectively.