Kollam, Kerala (ISJ Exclusive) ? Amrita School of Biotechnology has developed a technology to tap power� from waste water. Called Microbial Fuel Cells (MFCs), the technology developed by Amrita School converts chemical energy of feedstock into electricity by exploiting the metabolism of the microorganisms. Though the technology is still in its early stage, it offers great potential as an alternative to fossil fuel based energy generation.
Microbial Fuel Cells or MFCs is a biochemical reactor that relies on microbes for the source of electron unlike the chemical fuel cells. The microorganisms that participates in the electrotransfer to the electrode is technically called the exoelectrigens (exo means outside, electrigen means generators of electrons). Like in a typical chemical battery, MFC is also constituted of a positively charged electrode called Anode and a negatively charged Cathode. The anodic and cathodic chambers are physically separated by a Proton Exchange Membrane (PEM). The exoelectrigens interact with anode and transfer the electrons, which then flows through the circuit.
Eventually the electron is donated to the cathode. Excess electrons gained in the cathode needs to be scavenged to ensure a continuous generation of electricity in the MFC. Oxygen or other chemicals can function as a cathodic reagent (or catholyte) that can finally accept electrons from the cathode. Important is the flow of electrons in the system, so is the equilibration of protons (and other positively charged ions) in the two chambers. The effective transport of protons is facilitated by the PEM. Additionally, the PEM prevent oxygen from seeping (which is ideal for exoelectrogenesis) from the cathodic chamber to that of anodic chamber.
?MCFs can produce electricity from organic waste water. The waste water acts as a substrate for the microorganisms. Microbial digestion of the organic waste will generate electrons which the MFC can harvest. The exoelectrigens can be, in this case, the normal microorganisms present in the waste water. Additionally, the usage of waste water and its subsequent digestion also results in its treatment rendering it fit for discharge. In a nutshell, the MFC function as an energy generator and a bioremediation unit,? said Ajith Madhavan, Senior Lecturer at Amrita School of Biotechnology. ?It is a developing technology for sustainable energy production and waste treatment.?
[caption id="attachment_1821" align="aligncenter" width="861"] Prototypes of MFC/PMFC of differential volume fabricated in glass/acrylic/paper.
(A) MFC/PMFC fabricated in acrylic with the- anodic chamber capacity 600mL. (B) MFC (heterotrophic) fabricated in acrylic with the-anodic chamber capacity at 600mL. (C) PMFC (modular panel with 4 cells) fabricated in acrylic with the-anodic chamber capacity at 600mL. (D) MFC (heterotrophic) - AA battery scale- fabricated in glass with the-anodic chamber capacity at 2mL. (E) PMFC/MFC-made in whatman no.1 filter paper with the-anodic chamber capacity at 0.25�L.[/caption]
?MFCs can be employed as a grid connected and/or as off-grid decentralized energy source. If appropriate technology enables MFC to be scaled up (for eg.m2 magnitudes) to a larger extent, the power so generated can be directly exported to the utility grid. Apart from that, it can potentially be used as standalone units to power rural lighting systems, mobile phones, navigation buoys, lap tops etc. The grid interactive MFC/PMFC units can be operated from waste treatment plants which act as a renewable source of organic substrates. Sediments of water bodies, industrial wastes (molasses and whey from food industries, etc) can also be potential substrates that help in operating the MFC in a continuous manner,? Madhavan told Indian Science Journal.
The global energy demand will soar to 45% by the year 2030 with an average annual increase of 1.6% (as projected from 2006 onwards). India along with China will account for nearly half of this demand. In such a scenario, complete dependence and inefficient use of conventional energy sources which is reflected in the energy intensity (energy consumption compared to gross domestic product indices) of our country that remains higher than USA and the entire sub-continent of Asia, will be disadvantageous.
Image courtesy: Amrita School of Biotechnology