Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Microbial Fuel Cells: Optimization Of The Anode Compartment For Improved Electron Transfer


A microbial fuel cell mimics a biological system, in which bacteria do not directly transfer the energy-rich electrons gained out of the feeding to their characteristic electron acceptor. Instead, the electrons are diverted towards an electrode (anode) and subsequently conducted over a resistance or power user, and a cathode (see figure). At the cathode, these electrons are used to reduce oxygen with the formation of water. This way, bacterial energy is directly converted to electrical energy.

Microbial fuel cells have so far known limited success because of the low output observed. The maximum attainable potential over a biofuel cell, based on the potential difference between the redox couple, is 1.15V. However, the real fuel cell potential is mostly lower due to the potential losses observed at both the anode and the cathode, and the internal resistance of the fuel cell. Lowering these losses at the anode can be obtained chemically through enlargement of the specific electrode surface or the use of redox mediators, and biologically by the selection of adapted bacteria.

The internal resistance is mainly caused by the resistance of the electrolytes and of the proton exchange membrane (PEM), and can be lowered by increasing the reactor turbulence and the electrolyte/PEM conductivity.

The Laboratory for Microbial Ecology and Technology (LabMET) and the Laboratory for Non-Ferrous Metallurgy cooperate to obtain chemical and biological anode optimization.

The biological optimisation has been performed through selection of suitable microbial consortia. Electrochemical active bacteria were selected from a bacterial culture originating from anaerobic sludge by repetitive bacterial transfer into new fuel cells. The culture was able to transfer electrons efficiently to the graphite electrodes, and could supply a considerably higher output than previously reported, up to 4,31W/m2 of electrode surface (664 mV, 30.9 mA). A series of tests was performed to elucidate the behaviour of the biofuel cell in relation to several glucose loading rates, clarifying operational parameters. Molecular analysis was performed to determine the nature of the bacteria present in the biofuel cell. The identified bacteria were mainly facultative anaerobic, capable of hydrogen production. Cyclic voltammetry showed an evolution towards an electrochemically more active mixed bacterial culture during the experimental period.

Chemical optimization is the next step in the research. The effect of chemical redox mediators, inserted into the electrode matrix, onto the electron transfer can be of significant importance to further boost up the biofuel cell output. Preliminary tests have indicated the viability of this approach.

The results obtained at LabMET open perspectives towards future applications. The first application will very likely involve the use of microbial fuel cells to generate electricity out of plant juices, obtained on site. This way, a forest can become a bio-power plant. Long term research will focus on low power mobile applications. Hence, the question at the restaurant might one day be: "Waiter, one sugar cube for my coffee, and one for my mobile phone..."

Korneel RABAEY | alfa

More articles from Power and Electrical Engineering:

nachricht Neutrons pave the way to accelerated production of lithium-ion cells
20.03.2018 | Technische Universität München

nachricht Monocrystalline silicon thin film for cost-cutting solar cells with 10-times faster growth rate fabricated
16.03.2018 | Tokyo Institute of Technology

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Space observation with radar to secure Germany's space infrastructure

Satellites in near-Earth orbit are at risk due to the steady increase in space debris. But their mission in the areas of telecommunications, navigation or weather forecasts is essential for society. Fraunhofer FHR therefore develops radar-based systems which allow the detection, tracking and cataloging of even the smallest particles of debris. Satellite operators who have access to our data are in a better position to plan evasive maneuvers and prevent destructive collisions. From April, 25-29 2018, Fraunhofer FHR and its partners will exhibit the complementary radar systems TIRA and GESTRA as well as the latest radar techniques for space observation across three stands at the ILA Berlin.

The "traffic situation" in space is very tense: the Earth is currently being orbited not only by countless satellites but also by a large volume of space...

Im Focus: Researchers Discover New Anti-Cancer Protein

An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.

The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

New solar solutions for sustainable buildings and cities

23.03.2018 | Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

Latest News

For graphite pellets, just add elbow grease

23.03.2018 | Materials Sciences

Unique communication strategy discovered in stem cell pathway controlling plant growth

23.03.2018 | Agricultural and Forestry Science

Sharpening the X-ray view of the nanocosm

23.03.2018 | Physics and Astronomy

Science & Research
Overview of more VideoLinks >>>