PhD Studentship at the University of the West of England (UWE), (Bristol Robotics Laboratory and Faculty of Health and Life Sciences)

Brief introduction to the project

Bioelectrochemical systems are receiving increased attention from the international community as viable alternative energy sources with numerous concomitant benefits, such as waste (food) and wastewater treatment, pure water generation (from the cathode) and the potential to sense the environment in terms of BOD and levels of water contaminants. As knowledge about this technology evolves, systems limitations become more evident. A key limitation is the maximum bio-electrochemical potential difference (open circuit voltage) that can be produced. This is governed by the bacterial internal metabolic (most negative) redox couple (NADH/NAD+) and the standard redox potential associated with the catholyte employed, which has been calculated to be 1.14V (for an oxygen-diffusion based cathode). This value, albeit the theoretical maximum, is insufficient to energise real world applications. Therefore there is a genuine need to use multiple MFCs connected as stacks (or networks). There are two main reasons for miniaturising the size of individual MFCs:

1. a network of multiple units will naturally carry a large footprint, unless individual MFC units are miniaturised;
2. small-scale MFCs have previously been shown to be more efficient – in terms of power density – when compared to relatively large size systems (Ieropoulos et al. 2008).

Further details: Project Aims

1. Improve the performance of a single unit MFC from the current design to a smaller unit size. Fabricate 24 to 48 such units.
2. Design a modular system for convenient clustering of small scale MFC units into stacks with options for rapidly changing connections between units, in terms of both fluidic and electrical configurations (i.e. automation).
3. Compare the performance of individual units and stacks using cyclic voltammetry, chronoamperometry and most importantly electrochemical impedance spectroscopy, along with polarisation and maximum power transfer endurance experiments.
4. Practical application: combination of the data and knowledge from 1, 2 and 3 above so that MFC stacks can be developed and built for powering real world applications.

Relevant publications

Ieropoulos, I., Greenman, J., Melhuish, C. and Hart, J. 2005. Energy accumulation and improved performance in microbial fuel cells Power Sources, 145:253-256.

Ieropoulos, I., Greenman, J., Melhuish, C. and Hart, J. 2005. Comparison of three different types of microbial fuel cell. Enzyme and Microbial Technology, 37:238-245.

Melhuish, C., Ieropoulos, I., Greenman, J. and Horsfield, I. 2006. Energetically autonomous robots: Food for thought Autonomous Robots, 21:187-198.

Ieropoulos, I., Greenman, J. and Melhuish, C. 2008. Microbial Fuel Cells based on carbon veil electrodes: Stack configuration and scalability. Int. J. Energy Res, 32:1228-1240.