Direct utilization of fermentation products in an alcohol fuel cell

Due to energy demands and environmental concerns there has been a great interest in searching out renewable energy sources as an alternative to fossil hydrocarbons. These must also be environmentally sustainable and convenient to implement. Glucose has been proposed as a renewable energy source for several reasons including its energy density, safety, sustainability, and the ability to be scavenged from native ecosystems or from waste streams. Here we describe the use of a bio-hybrid fuel cell to oxidize the glucose to ethanol and limit parasitic power losses by using the fermented alcohol with minimal preparation in a direct alcohol fuel cell. Moving from using dilute alcohol in deionized water to the complex matrices of fermented media raises many questions about the performance and lifetime of the fuel cell and its components. These questions include but are not limited to the effects of starting materials and byproducts of the fermentations and the performance of the catalytic oxidation of ethanol at metal catalysts in batch mode. This study examines the effects of multiple components such as ionic strength, cation size, buffering strength, alcohol concentration, fermentation/fuel cell byproducts, and interfering organics on fuel cell operation. ► Used fermented sugar in a passive DAFC; only solids >0.2 μm removed from fermentate. ► DAFC performance on fermentate can be comparable to that of aqueous ethanol. ► Ionic strength and ethanol concentration of the fermentate had the largest effects.