BugNRG
The 'Bacterial Battery'

Abstract: BugNRG will fly two simple Bacterial Fuel Cells (BFCs) in orbit, and is designed to study the effects of microgravity on the output and efficiency of these BFCs. Some BFCs operate well on earth, but usually show to have a low efficiency. Previous studies have shown that bacteria become more active in microgravity and produce and reproduce faster than when they are subjected to normal terrestrial gravity. If microgravity enhances the bacterial activity, an increase in efficiency (and hence output) of a BFC will result from this effect.

Address corresponding authors:
Sebastiaan John de Vet, first year Bachelor student Aerospace Engineering at the Technical University of Delft, Fact. Aerospace Engineering, Tel: +31(0)6-12369325 or +31(0)346-563708 Email: sebastiaan.devet@wanadoo.nl
Renske Rutgers, first year Bachelor student Economics, University Utrecht, School of Economics (USE) Tel: +31(0)6-10409619 or +31(0)38-4600873, Email: R.Rutgers@students.uu.nl


Introduction: BugNRG is an experiment designed to study the effects of microgravity on the output and efficiency of Bacterial Fuel Cells (BFCs). A BFC is similar to an ordinary fuel cell, but only with a biological component in the anode chamber. This biological component converts biological fuel (e.g. glucose or fructose) into the components needed for the fuel cell process. BugNRG will fly two identical BFCs, and will measure and register the output characteristics (voltage and amperage) during the entire flight time in orbit.

Experiment rationale: Why? Despite the high efficiencies of BFCs reached by some research groups to date, the majority of these and other systems show to have a very low efficiency and output. Recent and past studies have shown the effects of microgravity on bacteria. This involvement of microgravity in various cellular and sub-cellular processes often results in more productive bacteria (e.g. bacteria that produce antibiotics) and also leads to higher reproductive activities. It is the bacterial component of the BFC that makes the system susceptible to influences of microgravity. If microgravity enhances the bacterial activity, an increase in efficiency (and hence output) of a BFC will result from this effect. Understanding how microgravity (and therefore gravity) influences BFCs provides a valuable insight for further development of BFCs in general. Long-term microgravity is needed to study the output of a BFCs caused by the entire transformation process of the fuel into electricity. The environment of the International Space Station provides the suitable circumstances for this study.

Experiment conduct (when launched, how executed, what facilities used etc.) : To study these bacterial fuel cells, it is required to record the following characteristic parameters of a fuel cell; 1. the change in voltage by time, and do so with an accuracy that approaches 10% of the produced voltage 2. the change in amperage by time, and do so with an accuracy that approaches 10% of the produced amperage After the space-based experiment is flown, an identical reference (earth-based) experiment will be carried out, to compare the differences (if present) between gravity and microgravity. This earth-based experiment can only be carried out afterwards so that the operational-parameters of that experiment can be kept the same. The output and efficiency during the operational use of BFCs depends on several components. The actual transformation of the fuel into electricity is a slow process. This process depends on the molarities of the available fuel for the bacterial component of the fuel cell. Secondly the duration of the transformation process depends on the species of bacteria used in the system. Thirdly, the size of the population determines the rate in which the food is transformed. Finally, the duration of the transformation process depends on the normal 'life'-parameters of bacteria e.g. temperature. Bacteria species that can be () are E-coli bacteria, Rhodoferax ferrireducens and Geobacter. Because these bacteria species do not necessarily need light to live, it is desirable to place the bacteria in an obscured container. In such a configuration, the luminescence level can be kept the same in both the in-orbit experiment, as the reference experiment. Secondly, the choice for mediator and oxidiser will be determined when the species of bacteria is selected. Possible mediator and oxidiser that can be used are respectively Methylene Blue and Potassium hexacyanoferrate. The electronics box of the experiment is the only part required to be returned to earth for data reduction purposes. The experiment itself is an autonomous experiment and only requires activation before storing it onboard of the Soyuz.

Hypothesis / expected results: It is the bacterial component of the BFC that makes the system susceptible to influences of microgravity. If microgravity enhances the bacterial activity, an increase in efficiency (and hence output) of a BFC will result from this effect.

Benefits for your field of research: Given the most recent progressions in the efficiency of BFCs, the utilization of these BFCs in real systems may become reality within the next few years. Several application have already drawn attention such as; the use of glucose in blood for the powering of pace-makers; energy supplies for various small electronic systems that can be applied in naval technology onboard submarines (US Navy has shown specific interest in the results of other research groups), and perhaps the usage of BFCs in microgravity environments such as onboard the International Space Station. Understanding how microgravity (and therefore gravity) influences BFCs provides a valuable insight for further development of BFCs in general.

References: Bennetto, H.P., Electricity generation by microorganisms, National Centre for Biotechnology Education, University of Reading.

Visit the bugNRG web site for additional information.


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