Micro Paper Fuel Cell Runs Continuously

Iowa State University researchers have demonstrated a proof-of-concept three-dimensional paper-based microbial fuel cell (MFC) that could take advantage of capillary action to guide the liquids through the MFC system and eliminate the need of external power.

The research team’s study paper has been published in the current issue of the journal TECHNOLOGY.

The paper-based MFC ran for five days and showed the production of current as a result of biofilm formation on the anode. The system produces 1.3 μW of power and 52.25 μA of current yielding a power density of approximately 25 W/m3 for this experiment.

These results show that the paper-based microbial fuel cells can create power in an environmentally friendly mode without the use of any outside power.

Nastaran Hashemi, PhD, Assistant Professor of Mechanical Engineering and the senior author of the paper said, “All power created in this device is useable because no electricity is needed to run the fluids through the device. This is crucial in the advancement of these devices and the expansion of their applications.”

The biofilm formation on the carbon cloth during the test provides further evidence that the current measured was the result of the bio-chemical reaction taking place. This is important because the biofilm plays a vital role in current production of a microbial fuel cell. Increased biofilm size and thickness ultimately leads to increased current production. Individual bacterial cells metabolize electron-rich substances in a complex process involving many enzyme-catalyzed reactions. The electrons are then free to travel to the anode through one of many modes of electron transport.

Electron transport is very complicated, and evidence suggests that it is unique to each type of bacteria. For the bacteria Shewanella Oneidensis MR-1, the most predominantly known ways of shuttling electrons from the individual bacteria cells to the anode are through direct contact, excreted soluble redox molecules, and biological nanowires.

Of these electron paths, it is widely believed that excreted soluble redox molecules serving as extracellular electron shuttles makes up for as much as 70% of electron transfer mechanisms from individual bacterial cells to the electrode. Moreover, it is shown that direct contact between individual S. Oneidensis MR-1 and the electrode has little impact on the current generation, supporting a mediated electron transfer mechanism.

Biofilm helps with the adsorption of the redox molecules to the electrode, which makes it important to have in high power density microbial fuel cells. There are not many studies on power production from paper-based microbial fuel cells running for few days.

Without enough time for biofilm to form, the reported current and power data would predominantly be associated with extracellular electron transfer, which suggests it does not fully represent electrical producing capabilities of the microbial fuel cells.

This device for the first time demonstrates the longer duration of use and ability to operate individually, a development that could help increase the number of situations where microbial fuel cells can be applied.

The Iowa State University team is currently exploring options to better control the voltage output and create constant current. Controlled environment tests will aid in the regulation of the systems output and yield more stable results. For optimal usability and decrease in cost, the team would also like to explore a device that would not need to use Nafion and Potassium Ferricyanide in its application.

Additional research team and co-authors of the paper are Niloofar Hashemi, Joshua Lackore, Farrokh Sharifi, Payton Goodrich, and Megan Winchell.

Its a bit of a stretch to imagine how this technology is going to take a future role. So far there isn’t a lot of power involved, but that will change as devices change. The intrigue comes from the biology making current. Its working and the potential is simply unknowable for now. Its a fascinating field. This could be the steadiest most reliable little generator known in a few years.

Source: http://newenergyandfuel.com/http:/newenergyandfuel/com/2016/07/12/micro-paper-fuel-cell-runs-continuously/