Exergy progresses towards turning Agri-food waste into electrical energy through the latest MFC activity


In this present project, we look at how to turn agri-food waste into electricity by the use of Microbial Fuel Cells (MFCs). MFCs have attracted a lot of attention in the past decade as innovative renewable and carbon-neutral bio-electrochemical devices, capable of generating energy from wastewater (WW) effluents through the action of electroactive microorganisms. In this particular type of fuel cell, microorganisms at the anode break the organic matter down into carbon dioxide, protons and electrons. The electrons flow from the anode to the cathode generating an electrical current, while the protons flow across a proton exchange membrane to combine at the cathode with the electrons and an electron acceptor, usually oxygen, to form water. The generated power output from each MFC can be used for small devices and different applications are being proposed currently by Scientifics in this area.
The source of feedstock is 50-60% kerbside collection and it ends up in a batch anaerobic digester producing biogas and digestate. The digestate is then collected from and employed as feedstock for the electricity production in the MFCs.
On March 28th, Rocio Roldan (project manager from Exergy Ltd) and Miltiadis Samanis (external visitor) carried out the first meeting on the microbial fuel cell design and development at Bath Universitiy. This is being undertaken by Exergy’s research engineer Sara Monasterio under the supervision and support of Mirella Di Lorenzo (Bath Uni).
The meeting started at the University of Bath, beginning with a presentation of the results obtained so far, along with near future considerations based on the current outcomes. Regarding the potential design for the novel MFCs, a preliminary set up was explained which is going to be designed and printed in the following months in order to carry out experiments at laboratory scale with industrial scale forward-looking perspectives. After that, a tour across the labs was carried out in order to provide a better understanding of the experimental activity. Some processes were also explained in detail, such as the preparation and impregnation of the catalysts (to be further developed). Finally, an additional brainstorming was carried out between Exergy’s chemical engineers and Mirella Di Lorenzo (lecturer at Bath Uni and expert in the field) taking advantage of the external visit of Miltiadis from Cyprus with the aim to define further steps related to the reactor design.
“I am really impressed with the different applications and the cross-sectorial potential of the chemical engineering (and biotechnology) in different fields along with the science basis. Microbial fuel cells might be used either for the treatment of wastes (solid or from sewage activities from different industrial sectors) or for the generation of electricity (at small scale nowadays), even for both applications at the same time. I am positive that biotechnology will be the path to cover daily solutions which are not covered in a sustainable way nowadays, even at really competitive and cheap prices. Funding for research and development of these kind of solutions is essential to reach a marketable technology that can be applied at industrial level in the next decades” – Says Rocio Roldan, chemical engineer and project manager at Exergy Ltd.
“MFCs have been proposed as an attractive means to treat WWS while generating electricity. One of the biggest limitations of this technology that still prevents practical applications is, however, associated with the difficulty in the scaling-up. The miniaturisation of the fuel cell design and the arrangement of multiple miniature units in stack is currently considered one of the most viable approach to overcome this limitation. In addition, a wide variety of organic matter, originating from any sort of WW, has been tested as fuel in MFCs, and performance varied according to the biodegradability and bioavailability of the organic substrate” – Says Sara Monasterio, research engineer at Exergy Ltd.

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